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  • 301.
    Mendoza, Ana Isabel
    et al.
    KTH-Royal Institute of Technology, Fibre and Polymer Technology, Stockholm, Sweden.
    Moriana, Rosana
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. KTH-Royal Institute of Technology, Fibre and Polymer Technology, Stockholm / SLU-Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Hillborg, Henrik
    ABB-Corporate Research, Power Technology, Västerås, Sweden.
    Strömberg, Emma
    KTH-Royal Institute of Technology, Fibre and Polymer Technology, Stockholm, Sweden.
    Super-hydrophobic zinc oxide/silicone rubber nanocomposite surfaces2019In: Surfaces and Interfaces, ISSN 2468-0230, Vol. 14, p. 146-157Article in journal (Refereed)
    Abstract [en]

    This study presents comparative assessments on hydrophilic and hydrophobic ZnO nanoparticles and their deposition methods on the surface hydrophobicity of silicone rubber (PDMS) and glass substrates. The influence on the surface hydrophobicity and wettability of all the variables regarding the deposition methodologies and the interaction of the nanoparticles with the substrates were within the scope of this study. The different surfaces created by spraying, dipping and drop-pipetting deposition methods were assessed by static contact angle measurements and contact angle hysteresis from advancing and receding angles, as well as by the calculation of the sliding angle and the surface energy parameters. An accurate methodology to determine the contact angle hysteresis was proposed to obtain repetitive and comparative results on all surfaces. All the measurements have been correlated with the morphology and topography of the different surfaces analysed by FE-SE microscopy. The spray-deposition of hydrophobic ZnO nanoparticles on PDMS resulted in super-hydrophobic surfaces, exhibiting hierarchical structures with micro-and nanometer features which, together with the low surface energy, promotes the Cassie-Baxter wetting behavior. This study provides the fundamental approach to select critically the most promising combination in terms of materials and deposition techniques to create silicone-based super-hydrophobic surfaces with potential to be applied in high voltage outdoor insulation applications.

  • 302.
    Mohammed, Abdullah
    et al.
    Department of Production Engineering, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden.
    Schmidt, Bernard
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Wang, Lihui
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Department of Production Engineering Royal Institute of Technology 100 44 Stockholm, Sweden.
    Gao, Liang
    Huazhong University of Science and Technology, Hubei, China.
    Minimizing Energy Consumption for Robot Arm Movement2014In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 25, p. 400-405Article in journal (Refereed)
    Abstract [en]

    Robots are widely used in industry due to their efficiency and high performance. Many of them are operating in the manufacturing stage of the production line where the highest percentage of energy is consumed. Therefore, their energy consumption became a major focus for many robots manufacturers and academic research groups. Nevertheless, the optimisation of that consumption is still a challenging task which requires a deep understanding of the robot’s kinematic and dynamic behaviours. This paper proposes an approach to develop an optimisation module using Matlab® to minimise the energy consumptions of the robot’s movement. With the help of Denavit-Hartenberg notation, the approach starts first by solving the inverse kinematics of the robot to find a set of feasible joint configurations required to perform the task, solving the inverse kinematics is usually a challenging step which requires in-depth analyses of the robot. The module then solves the inverse dynamics of the robot to analyse the forces and torques applied on each joint and link in the robot. Furthermore, a calculation for the energy consumption is performed for each configuration. The final step of the process represents the optimisation of the calculated configurations by choosing the one with the lowest power consumption and sends the results to the robot controller. Three case studies are used to evaluate the performance of the module. The experimental results demonstrate the developed module as a successful tool for energy efficient robot path planning. Further analyses for the results have been done by comparing them with the ones from commercial simulation software. The case studies show that the optimisation of the location for the target path could reduce the energy consumption effectively.

  • 303.
    Monge, Malco
    et al.
    University of Skövde, School of Technology and Society.
    Eriksson, Alexander
    University of Skövde, School of Technology and Society.
    Transporter från lastbil till järnväg: en fallstudie på Kährs2007Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Gustav Kährs AB is a company that is considering a change of transportation from trucks to railroad. Kährs headquarter is situated in Nybro. The company makes wooden floors and stores them in their central warehouse in Kalmar. Today all transports from the warehouse are carried out by trucks; the goods are then transported to the harbor in Helsingborg and then shipped to Bremen. Kährs is considering switching to railroad transportation between Kalmar and Helsingborg.

    The problem has been formulated as follows:

    “Is it worth to switch transportation method from tuck to railroad considering the following aspects: the environment, lead times, costs and investments?”

    To gain a deeper insight of the consequences that a switch would have on lead times, costs, investments and the environment we have chosen to conduct a case study. The purpose of this case study is not to reach a definitive answer to the problem but rather to give an open discussion on the subject. This fits our formulated problem fine, because the question if it is worth or not is a subjective matter.

    This thesis has been built around a model that consists of all the different aspects that have been mentioned within the formulated problem. From this model we have derived a calculation model to calculate if it is worth to make a switch from tucks to railroad from a cost perspective. From the calculation model we have further derived different scenarios were today’s situation is compared to alternative means of transportation involving railroad. The different scenarios include different harbors and investments like cranes, forklifts and extension of railroad.

    The calculation model focuses on the costs being generated by each scenario. The result of the analysis is that today’s truck solution had the most advantages compared to the other scenarios. But what final solution is chosen depends on what characteristics Kährs values. If the environment is an important factor, if Kährs feels that it is important to position itself as an environmental friendly company then the railroad would be an interesting alternative. The question is if Kährs is prepared to deal with the increased costs that this alternative generates. Perhaps the company doesn’t feel that the savings on the environmental side are reason enough to stand the extra costs.

    The answer to our formulated problem is that we don’t consider it worth shifting from tuck to railroad. But in the end it is all about what characteristics Kährs consider to be important.

  • 304. Munoz Alonso, Carlos
    et al.
    Unda Garcia, Alejandro
    Design and analysis of a large transportable vacuum insulated cryogenic vessel2010Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This project has been undertaken by Alejandro Unda García and Carlos Muñoz Alonso for Veprox AB (www.veprox.se), a Swedish engineering company, in collaboration with the School of Technology and Society at the University of Skövde (www.his.se). This thesis represents the final project for the Bachelor Degree Exam in Mechanical Engineering during the academic year 2009-2010.

    To achieve this project, we were helped and supported by Peter Höglund, Veprox AB Office Manager; Tomas Walander, Supervisor and M. Sc. student and Karl Mauritsson, Examiner and Lecturer, both belonging to the Department of Mechanical Engineering at the School of Technology and Society of the University of Skövde.

    This project is aimed to study, design and analyze a large transportable vacuum insulated cryogenic vessel that will be attached to a truck in order to keep, maintain and transport by road liquid methane at a temperature of -162 °C.

    Considerations such as different pressure loads, dimensions, materials as well as their mechanical properties, constraints, masses, insulation systems and weather-environmental conditions (Northern Europe) are made in the mechanical analysis. Furthermore, calculations and dimensions satisfy the requirements given by the Swedish Standards Institute (S.I.S) following the standards SS-EN 13530-1: Cryogenic vessels - Large transportable vacuum insulated vessel; Part 1: Fundamental requirements and SS-EN 13530-2: Cryogenic vessels - Large transportable vacuum insulated vessel; Part 2: Design, fabrication, inspection and testing.

    The CAD software Pro/Engineer Wildfire 4.0 is used to visualize the models for the chosen designs. In addition, the finite element module Pro/Mechanica is used to obtain results of mechanical analyses in order to determine if the stresses are within margins.

  • 305.
    Muñoz García, Marina
    et al.
    University of Skövde, School of Engineering Science.
    Hurtado Sierra, Juan Carlos
    University of Skövde, School of Engineering Science.
    Structural analysis of the 17th century warship Vasa: Influence of the dowels on the stiffness of the hull2014Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    After 333 years under depths of the Baltic Sea, the warship Vasa was salvaged and nowadayslies in a dry dock inside the Vasa Museum in Stockholm. Its current support system, which consists on eighteen cradle-stanchions pairs of steel, is not able to handle the present loads in a satisfactory manner. Experimental tests showed that the Vasa's hull is gradually deforming mainly due to creep behavior.

    Thus, in order to preserve the Vasa for future generations, a new support system has to be implemented in a foreseeable future. There are several factors to take into consideration for its construction, which are: the degradation of the oak, its current mechanical properties and its inhomogeneity in addition to the climatic conditions of the Museum and the impossibility of taking unlimited specimens for its analysis. Hence, it is crucial to investigate the areas where the stresses and deformations are critical in the ship and how affected is the stiffness of the hull, its most important component.

    In this dissertation work two Finite Element Analyses are accomplished. The first study consists on the creation of a superelement of a section of Vasa's hull with the intention of investigating the influence of the dowels on the stiffness of the hull. In the second analysis a simplied model of the entire warship Vasa is created in order to analyze it and locate possible critical areas on the hull due to its own weight and the stresses originated by the support system. The software selected for these simulations are Abaqus and CreoSimulate 2.0.

    From the first study it is concluded that that the dowels do not have a signicant influence in the stiffness coeffcients of the hull. The second analysis determines that the maximum stresses are located on the bottom part of the hull. This dissertation work concludes with a suggested future work.

  • 306.
    Mårdberg, Peter
    et al.
    Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden.
    Carlson, Johan S.
    Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden.
    Bohlin, Robert
    Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden.
    Delfs, Niclas
    Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden.
    Gustafsson, Stefan
    Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden / Industrial Development, Scania CV, Sweden.
    Using a formal high-level language and an automated manikin to automatically generate assembly instructions2014In: International Journal of Human Factors Modelling and Simulation, ISSN 1742-5549, Vol. 4, no 3/4, p. 233-249Article in journal (Refereed)
    Abstract [en]

    This paper presents an approach to automatically generate predetermined motion time system (PMTS) based assembly instruction lists from simulations within digital human modelling (DHM) software. A formal high-level instruction language is used to instruct an automated manikin to perform assembly operations. The manikin, the language and the assembled objects are composed into a discrete model. In a post-computational step, the model is used to construct PMTS instruction lists by mapping the manikin motions, assembled objects and the language instructions onto a set of PMTS keywords. The described approach is implemented in the DHM software IMMA and tested on industrial cases of manual assembly in the automotive industry.

  • 307.
    Mårdberg, Peter
    et al.
    Frauhofer-Chalmers Research Centre for Industrial Mathematics.
    Carlson, Johan S.
    Frauhofer-Chalmers Research Centre for Industrial Mathematics.
    Bohlin, Robert
    Frauhofer-Chalmers Research Centre for Industrial Mathematics.
    Hanson, Lars
    Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden / Industrial Development, Scania CV, Södertälje, Sweden.
    Högberg, Dan
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Using Ergonomic Criteria to Adaptively Define Test Manikins for Design Problems2012In: Advances in Applied Human Modeling and Simulation / [ed] Vincent G. Duffy, Boca Raton: CRC Press, 2012, p. 265-274Chapter in book (Refereed)
    Abstract [en]

    Digital manikins give a powerful aid in evaluating assembly station ergonomics. A proper verification of an assembly station can avoid costly changes that might occur later on due to injuries and discomfort among the workers.

    However, how to select relevant test manikins for an evaluation is a non-trivial task, since the work of identifying which anthropometric variables that are critical is a tedious and time consuming process.

    Usually only a few variables are selected as a base for building the test manikins. Even if there exist Digital Human Modeling (DHM) software which allow the user to evaluate batches of manikins, the designer still have to select the anthropometric variables of those batches. When several dimensions are considered, the designer have to either use a set of predefined manikins, or determine which anthropometric variables to test and generate manikins based on the confidence intervals of these variables.

    When considering more complex assembly tasks, is it then true that these predetermined test manikins cover all the cases, or does there exist manikins that suffer from bad ergonomics even though all the test manikins turned out well?

    In this paper, we propose a new algorithm for automatically building a set of test manikins. The set is iteratively constructed from the ergonomics results obtained by simulating the assembly operation. Different manikins perform the assembly operation and the ergonomics is evaluated. The anthropometric variables which affect the ergonomics are identified and used to iteratively build up the next manikin. In this way the test manikins are always selected throughout the whole set instead of only considering the boundary manikins, or assuming that the same set of predetermined manikins represents the entire set in every assembly operation.

    The algorithm has been compared with a boundary method, and the results shows that the algorithm can find manikins with worse ergonomics than those tested by the boundary method.

  • 308.
    Nackfors, Glenn
    University of Skövde, School of Engineering Science.
    Factory optimization using DES2016Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Discrete Event Simulation (DES) has been a powerful tool for modeling and optimization of production lines for many years. Developing detailed models may be very time consuming and might also be computationally costly to execute, especially if optimization techniques are to be applied. Aggregation techniques, simplifying a detailed system into fewer objects, can be an effective method to reduce the required computational resources as well as a way to shorten the development time. An aggregated model can be used to identify the main constraints in a system, dimensioning inter-line buffers, and focus development activities on the critical issues from a system performance perspective.

    An aggregated model of a real-world plant wide production system has already been developed in the discrete event simulation software FACTS Analyzer. Due to the limitations of FACTS Analyzer this model was instead rebuilt using the discrete event simulation software Plant Simulation which, while less user friendly, has much more configuration options. This model is then validated against the FACTS Analyzer model to ensure accurate results that can be implemented on a real life system.

    In addition some typical optimization experiments are carried out on the Plant Simulation model and the results analyzed. The first of these optimizations alters the buffer sizes to find the minimum amount of buffer capacity needed to get the minimum lead time while maintaining the highest possible throughput. The second optimization uses the same parameters but also adds alteration of the batch size. Both of these optimizations shows that it is possible to get better results with lower settings on both the buffer capacity and batch size then the default value.

    At the end of the report the project is evaluated and conclusions are drawn on what can be improved in the model, such as adding more streamlined updating of variant sequence.  Additionally future experiments that can be interesting to look at is specified based upon the results from the project.  

  • 309.
    Nackfors, Glenn
    et al.
    University of Skövde, School of Engineering Science.
    Hodo, Damir
    University of Skövde, School of Engineering Science.
    Utveckling av ett standardiserat operatörsobjekt i plant simulation2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work in automation technology at 30 credits is conducted at Volvo Cars Cooperation (VCC) in collaboration with the University of Skövde.

    With the current staffing method VCC are experiencing difficulties achieving an optimal utilization of operators as there has been difficult to ascertain how much work an operator can handle. Operators are an often overlooked part of simulation studies because they are complex to model. The completed thesis consists of developing a standardized operator object in the simulation software Plant Simulation, developed by Siemens. Using this object, it will be easier to staff optimally with respect to the number of work areas, operator skills and how many operators that are required for the given work areas.

    The existing VCC Plant Simulation library already has an object for operators. This operator object was used as the basis for the development of the new operator object. When developing the new object, data collection was made in form of both qualitative and quantitative data to find out what functionality the new object needed. The existing object was evaluated against the functionality requirements to determine what were needed to be added, removed or modified. Five main areas were considered important to develop: (1) operators that can work across two or more work areas, (2) walking time for operators, (3) learning effect, (4) the learning curve for operators and (5) operators who work on different shifts. The learning curve was only partly developed, but the other four areas were fully implemented.

    In order to test and analyze the object, three experiments were carried out using different case studies, where one of these cases studies was a real production line. The experimental design was jointly created with the VCC reference group and the University of Skövde. The main objectives of the experiments were to reduce the number of operators and increase throughput per hour. The result of the optimisation of the real production line showed that a significantly smaller staffing could be achieved without a major effect on the throughput.

    The results of the project were that a standardized operator object was developed according to the specifications and objectives set for the project. This object provides the ability to quickly and easily implement operators in a simulation model. To verify the applicability of the operator object, it was successfully imported and used for simulation-based optimisation in three different simulation models. The operator object also contains functionalities that provide more realistic operators, such as the walk time to the operations, operators that can work across several work areas and competence for operators as well as learning.

    The results of this project involve a simpler implementation of more realistic operators and thus lead to more realistic simulation models. 

  • 310.
    Ng, Amos H. C.
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Bernedixen, Jacob
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Volvo Car Corporation, Sweden.
    Pehrsson, Leif
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Volvo Car Corporation, Sweden.
    What Does Multi-Objective Optimization Have to Do with Bottleneck Improvement of Production Systems?2014In: Proceedings of The 6th International Swedish Production Symposium 2014 / [ed] Johan Stahre, Björn Johansson & Mats Björkman, 2014Conference paper (Refereed)
    Abstract [en]

    Bottleneck is a common term used to describe the process/operation/person that constrains the performance of the whole system. Since Goldratt introduced his theory of constraint, not many will argue about the importance of identifying and then improving the bottleneck, in order to improve the performance of the entire system. Nevertheless, there exist various definitions of bottleneck, which make bottleneck identification and improvement not a straightforward task in practice. The theory introduced by Production Systems Engineering (PSE) that the bottleneck of a production line is where the infinitesimal improvement can lead to the largest improvement of the average throughput, has provided an inspirational and rigorous way to understand the nature of bottleneck. This is because it conceptually puts bottleneck identification and improvement into a single task. Nevertheless, it is said that a procedure to evaluate how the efficiency increase of each machine would affect the total performance of a line is hardly possible in most practical situations. But is this true?In this paper, we argue how multi-objective optimization fits nicely into the theory introduced by PSE and hence how it can be developed into a practical bottleneck improvement methodology. Numerical results from a real-world application study on a highly complex machining line are provided to justify the practical applicability of this new methodology.

  • 311.
    Ng, Amos H. C.
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Shaaban, Sabry
    Department of Strategy, ESC La Rochelle, La Rochelle, France.
    Bernedixen, Jacob
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Studying unbalanced workload and buffer allocation of production systems using multi-objective optimisation2017In: International Journal of Production Research, ISSN 0020-7543, E-ISSN 1366-588X, Vol. 55, no 24, p. 7435-7451Article in journal (Refereed)
    Abstract [en]

    Numerous studies have investigated the effects of unbalanced service times and inter-station buffer sizes on the efficiency of discrete part, unpaced production lines. There are two main disadvantages of many of these studies: (1) only some predetermined degree of imbalance and patterns of imbalance have been evaluated against the perfectly balanced configuration, making it hard to form a general conclusion on these factors; (2) only a single objective has been set as the target, which neglects the fact that different patterns of imbalance may outperform with respect to different performance measures. Therefore, the aim of this study is to introduce a new approach to investigate the performance of unpaced production lines by using multiple-objective optimisation. It has been found by equipping multi-objective optimisation with an efficient, equality constraints handling technique, both the optimal pattern and degree of imbalance, as well as the optimal relationship among these factors and the performance measures of a production system can be sought and analysed with some single optimisation runs. The results have illustrated that some very interesting relationships among the key performance measures studied, including system throughput, work-in-process and average buffer level, could only be observed within a truly multi-objective optimisation context. While these results may not be generalised to apply to any production lines, the genericity of the proposed simulation-based approach is believed to be applicable to study any real-world, complex production lines.

  • 312. Ng, Amos H. C.
    et al.
    Urenda Moris, Matias
    Svensson, Jacob
    Multi-Objective Simulation Optimization for Production Systems Design using FACTS Analyser2008In: Proceedings of the 2nd Swedish Production Symposium, 2008, p. 101-109Conference paper (Refereed)
    Abstract [en]

    This paper proposes a new general method for supporting production systems design within the context of Multi-objective Simulation Optimisation. Under this framework, different Production Control Mechanisms can be compared based on their optimal settings, which will be illustrated with a pedagogical simple flow line as well as an engines assembly line in automotive industry. Results from these case studies have provided significant insight into the importance of applying MOSO for Multi-Criteria Decision Making in general production systems design. At the same time, it also outlines the concept of applying significant dominance to handle uncertainty from stochastic simulation output, which has been implemented into a Web-based DES system called FACTS Analyser, specifically designed for conceptual factory design, analysis and optimisation.

  • 313.
    Ng, Amos H.C.
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. School of Engineering, Jönköping University, Sweden .
    Bandaru, Sunith
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Frantzén, Marcus
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Volvo Car Corporation, Sweden .
    Innovative Design and Analysis of Production Systems by Multi-objective Optimization and Data Mining2016In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 50, p. 665-671Article in journal (Refereed)
    Abstract [en]

    This paper presents an innovative approach for the design and analysis of production systems using multi-objective optimization and data mining. The innovation lies on how these two methods using different computational intelligence algorithms can be synergistically integrated and used interactively by production systems designers to support their design decisions. Unlike ordinary optimization approaches for production systems design which several design objectives are linearly combined into a single mathematical function, multi-objective optimization that can generate multiple design alternatives and sort their performances into an efficient frontier can enable the designer to have a more complete picture about how the design decision variables, like number of machines and buffers, can affect the overall performances of the system. Such kind of knowledge that can be gained by plotting the efficient frontier cannot be sought by single-objective based optimizations. Additionally, because of the multiple optimal design alternatives generated, they constitute a dataset that can be fed into some data mining algorithms for extracting the knowledge about the relationships among the design variables and the objectives. This paper addresses the specific challenges posed by the design of discrete production systems for this integrated optimization and data mining approach and then outline a new interactive data mining algorithm developed to meet these challenges, illustrated with a real-world production line design example.

  • 314.
    Ng, Amos H.C.
    et al.
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Engineering Science.
    Skoogh, Anders
    Chalmers University of Technology, Gothenburg, Sweden.
    Lämkull, Dan
    Volvo Car Corporation, Gothenburg, Sweden.
    Optimal Maintenance Resources Allocation Using Automated Simulation-based Optimisation and Data Management2015In: Simulation in Production and Logistics 2015 / [ed] Markus Rabe, Uwe Clausen, Stuttgart: Fraunhofer IRB Verlag, 2015, p. 437-446Conference paper (Refereed)
    Abstract [en]

    This paper introduces a Streamlined Modelling and Decision Support (StreaMod) approach in which input data management, simulation model generation/update and simulation-based optimisation are synergistically integrated into a largely automated process. The aim of this automated process is to support decision making related to the optimal maintenance resources allocation that could improve the performance of production/logistics systems. The basic novelty of the StreaMod optimisation methodology lies on the formulation of an optimal maintenance allocation problem of a production/logistic system into a bi-objective optimisation problem, so that optimal resources/changes to improve the throughput of the system can be sought in a single optimisation run. The successful application of this methodology in a real-world automotive factory will also be addressed in this paper.

  • 315.
    Nilsson, Amanda
    et al.
    University of Skövde, School of Engineering Science.
    Lindqvist, Hanna
    University of Skövde, School of Engineering Science.
    Framtidens produktionspersonal i den Smarta fabriken2016Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The project has explored the topic Smart factory with main focus on the future production staff. The project aims to investigate how the production staff is affected by Volvo Cars Skövde Engine Plant (SkEP) becoming a Smart factory, in the era of Industry 4.0. The definition of the Smart factory is a demand of Mobile- and wireless technologies, Human-oriented, pursue a Flexible production with Sustainable manufacturing, as well as utilization of CPS (Cyber-Physical Systems), IoT (Internet-of-Things) and Cloud storage. The current situation and the future five to twenty years were examined in order to define the future production staff. This by conducting an observational study and several interviews. The studies’ results were that SkEP cannot be regarded as smart since several demands are inadequate by definition. Five years are considered too short of a time for the plant to fulfill the demands. However, according to the interviews and literature, SkEP are expected to become smart in twenty years after time refinement of existing technologies and implementation of new ones. The authors estimate Leadership, Information, IT and Production lay-out to be the areas that require the most effort. The future production staff are expected to be flexible with workplace, working hours and able to manage multiple variants. They should be included in self-supporting teams where every individual possesses an expertise, are motivated and participating. Production staff should perform complex, varied jobs with more responsibility by endorsement of decision support systems. The staffs’ competence should consist of technical education, high basic and lay-out knowledge and the ability to contribute to the collection of information and analyses. Interaction with technology is expected to expand and the personnel must therefore have a well-established comprehension of technology. The concept Smart factory is extensive and relatively new, which means that it is constantly evolving. Thus it is important for SkEP to be updated and adjust to the impact from the outside world.

  • 316.
    Nord, Jens
    et al.
    University of Skövde, School of Technology and Society.
    Johansson, Peter
    University of Skövde, School of Technology and Society.
    Vägen till Lean Production: Historien bakom Lean och dess nutida användning2007Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There are many important challenges for industry of today, and efficient manufacturing is one of them. To manage some of these challenges many businesses put a lot of faith in the management philosophy called Lean Production. The first objective of this report is to find out how three different Swedish companies have worked with the complex toolbox of Lean production and how they have implemented these tools. The second objective of this report is to analyze possible similarities between the implementations of Lean and the fourteen management principles of efficient manufacturing according to Toyota.

    In 1911 Fredrick Winslow Taylor published an article, “Principles of Scientific Management”, on how to make industry more efficient. Henry Ford, the father of modern cars, accepted Taylor’s ideas and applied them in his new car factory in Detroit in 1912. Taylor’s fundamental ideas together with Ford’s enterprising attitude and the modern assembly line led to large sales success of the T-Ford. Some decades later the Japanese car manufacturer Toyota interested themselves in the American management of making cars due to financial difficulties. In 1950 Toyota started the process of developing their own production management system, Toyota Production System. The Japanese production system was successful and lifted Toyota out of the financial crisis. The 1973 oil crisis limited the sales of big American cars in favour of smaller and cheaper Japanese ones. The American car makers paid attention and financed a research project at Massachusetts Institute of Technology in order to develop an even better production system, Lean Production.

    The three case studies, two factories of AstraZeneca in Södertälje and a Volvo Powertrain factory in Skövde have developed different strategies in implementing Lean Production. The empirical studies are based on personal interviews with people understanding the development work in each organisation. The first AstraZeneca factory shows a noncommittal approach where the employees take a great part in the decision-making process. The second AstraZeneca factory shows a more strict approach where the result-orientated tools are in the centre of interest. The Volvo Powertrain factory has gained experience from this kind of development work through the past twenty years. They have had both the time and knowledge to implement a wide range of tools and methods.

    To make the Lean projects permanent and a way of life rather than just a set of tools it is important for organisations to implement both the human relation approach and the structural tool-oriented approach. The human relation approach focuses on the employees, their self-esteem and their right to be a part of the decision-making. The core of the structural approach is the result oriented tools and methods. The case studies clearly show that the fourteen principles of Toyota Production System represent a holistic view on logistics development. If some of the principles are not represented in a project there is a big risk that the project will fail. Resilience is the key word to increase the chance of being Lean.

  • 317.
    Nordén Hermansson, Erik
    et al.
    University of Skövde, School of Engineering Science.
    Davidsson, Filip
    University of Skövde, School of Engineering Science.
    Utveckling av fallplåt: för en maskingradsax2014Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    To cut sheet metal into proper dimensions, for example shears can be used. They are available in many different variations where one is the guillotine shear. Rapido, manufactured by CIDAN Machinery, is a guillotine shear mainly targeted for small businesses which doesn´t cut regularly and with large size variations. This requires all manual material management which is stressful for the operator. The customers prefer the sheet metal to be available to be collected directly after the cut and at the same side of the machine as the input table. That’s why the sheet metal slides down on a plate called the sheet metal collector, located underneath the input table, in the current design. Because the input table has an ergonomic level of 85 cm, the sheet metal is collected from a much lower and uncomfortable level of 9 cm above the ground. The company wishes to approve the situation for the operator by offering an alternative sheet metal collector that makes the sheet metal available at higher level. The new solution shouldn´t raise the manufacturing cost more than 8%, to be profitable.

    A literature study is made to investigate solutions to similar problems and safety requirements. Concepts are generated and evaluated in an objective manner, for example by brainstorming and a concept selection matrix. One of the concepts is chosen for further development and design where standard components are top priority e.g. because of the reduction in environmental impact. Although standard components can´t solve for all functions and thus are unique parts designed. Some calculations are done analytically and by using the finite element method to verify the strength of the unique parts.

    In the resulting solution the operator can collect the sheet metal 37 cm above ground level and from a better position closer to the human body. The solution requires 15 new parts, of which 8 are standard components, and small modifications of 10 parts already in use. The increase of manufacturing cost is approximately 6 %. Pneumatics is used to lift the sheet metal which the operator only needs to activate, but the control function is not developed within the project.

    Even though the resulting solution doesn´t reach an ideal collecting height, of 80-110 cm, the company´s requirements is yet fulfilled. An additional function for ejecting the sheet metal is found to improve the ergonomics and is therefore included in the objectives for the project. Such function is included in the concept phase, but it isn´t further developed because of time constraints.

    Further investigations of CE-requirements need to be made before releasing the improved machine on the market since all necessary documents wasn´t available. More suggests of improvements is presented to the company, for example should silencing materials be used on the collector to reduce unpleasant noise.

  • 318.
    Noremalm, Tobias
    et al.
    University of Skövde, School of Technology and Society.
    Bodén, Joakim
    University of Skövde, School of Technology and Society.
    Utveckling av skivspelare som påverkas minimalt av inre och yttre störningar2012Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The examination project was carried out in collaboration with Transient Design which is a company in the HiFi industry. The thesis project describes the development of a turntable. The project had the objective to propose a design concept as well as to propose relevant technical solutions.The work began with a pilot study which aimed to be a foundation upon which the rest of the project was built. The two big sections of this stage were the market research which aimed to create a better picture of the intended target group and also literature studies. The literature studies covered subjects such as vibration theory and technical measuring equipments. When a good foundation for the project had been established the idea generation phase commenced. During this phase a large amount of different concepts for the design as well as technical solutions were created. Through several selection processes with further development in between, three concepts emerged as viable solutions. From one of these the final concept, “Walter”, was deducted. Walter was named after the founder of the Bauhaus school in Germany. This seemed appropriate since a lot of design inspiration was gathered from the Bauhaus way.The development process resulted in Walter, a very cleanly designed turntable that hides many technical developments including solutions for slide bearing construction and platter construction.

  • 319.
    Nourmohammadi, Amir
    et al.
    Faculty of Industrial & Systems Engineering, Tarbiat Modares University, Tehran, Iran.
    Eskandari, Hamidreza
    Iran Management & Technology Development Center, Tarbiat Modares University, Tehran, Iran.
    Fathi, Masood
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Design of stochastic assembly lines considering line balancing and part feeding with supermarkets2019In: Engineering optimization (Print), ISSN 0305-215X, E-ISSN 1029-0273, Vol. 51, no 1, p. 63-83Article in journal (Refereed)
    Abstract [en]

    This article aims to address the assembly line balancing problem (ALBP) and supermarket location problem (SLP) as two long-term interrelated decision problems considering the stochastic nature of the task times and demands. These problems arise in real-world assembly lines during the strategic decision-making phase of configuring new assembly lines from both line balancing and part-feeding (PF) aspects. A hierarchical mathematical programming model is developed, in which the first level resolves the stochastic ALBP by minimizing the workstation numbers and the second level deals with the stochastic SLP while optimizing the PF shipment, inventory and installation costs. The results of case data from an automotive parts manufacturer and a set of standard test problems verified that the proposed model can optimize the configuration of assembly lines considering both ALBP and SLP performance measures. This study also validates the effect of the stochastic ALBP on the resulting SLP solutions.

  • 320.
    Nourmohammadi, Amir
    et al.
    Tarbiat Modares University, Tehran, Iran.
    Eskandari, Hamidreza
    Tarbiat Modares University, Tehran, Iran.
    Fathi, Masood
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Aghdasi, Mohammad
    Tarbiat Modares University, Tehran, Iran.
    A mathematical model for supermarket location problem with stochastic station demands2018In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 72, p. 6p. 444-449Article in journal (Refereed)
    Abstract [en]

    This paper aims to investigate the effect of station demands variations on supermarket location problem (SLP). This problem arises in the real-world assembly line part feeding (PF) context where supermarkets are used as the intermediate storage areas for stations. To this purpose a stochastic SLP model is developed to optimize the total cost of PF in terms of shipment, inventory and installation costs. The computational results over a real case as well as different test instances verify that the station demands variation has an effect on the SLP solutions.

  • 321.
    Nourmohammadi, Amir
    et al.
    Tarbiat Modares University, Tehran, Iran.
    Eskandari, Hamidreza
    Tarbiat Modares University, Tehran, Iran.
    Fathi, Masood
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ranjbar Bourani, Mehdi
    University of Science & Technology of Mazandaran, Behshahr, Iran.
    An integrated model for cost-oriented assembly line balancing and parts feeding with supermarkets2018In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 72, p. 5p. 381-385Article in journal (Refereed)
    Abstract [en]

    This paper aims to deal with assembly line design from both line balancing and parts feeding (PF) aspects as two-interrelated decision problems while supermarkets are used. These problems arise in the real-world assembly lines (ALs) where decision makers are planning to simultaneously determine the optimal number of stations and the optimal number of supermarkets so that the total installation costs of ALs including line balancing and PF costs are minimized. To this purpose an integrated mathematical model is proposed and its performance is tested through solving a number of benchmark problems and a real case taken from industry.

  • 322.
    Nourmohammadi, Amir
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Fathi, Masood
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Choosing efficient meta-heuristics to solve the assembly line balancing problem: A landscape analysis approach2019In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 81, p. 1248-1253Article in journal (Refereed)
    Abstract [en]

    It is widely known that the assembly line balancing problem (ALBP) is an NP-hard optimization problem. Although different meta-heuristics have been proposed for solving this problem so far, there is no convincing support that what type of algorithms can perform more efficiently than the others. Thus, using some statistical measures, the landscape of the simple ALBP is studied for the first time in the literature. The results indicate a flat landscape for the problem where the local optima are uniformly scattered over the search space. Accordingly, the efficiency of population-based algorithms in addressing the considered problem is statistically validated.

  • 323.
    Nourmohammadi, Amir
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Fathi, Masood
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ruiz Zúñiga, Enrique
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    A Genetic Algorithm for Bi-Objective Assembly Line Balancing Problem2019In: Advances in Manufacturing Technology XXXIII: Proceedings of the 17th International Conference on Manufacturing Research, incorporating the 34th National Conference on Manufacturing Research, September 10–12, 2019, Queen’s University Belfast, UK / [ed] Yan Jin, Mark Price, Amsterdam: IOS Press, 2019, Vol. 9, p. 519-524Conference paper (Refereed)
    Abstract [en]

    Assembly line designs in manufacturing commonly face the key problem of dividing the assembly tasks among the working stations so that the efficiency of the line is optimized. This problem is known as the assembly line balancing problem which is known to be NP-hard. This study, proposes a bi-objective genetic algorithm to cope with the assembly line balancing problem where the considered objectives are the utilization of the assembly line and the workload smoothness measured as the line efficiency and the variation of workload, respectively. The performance of the proposed genetic algorithm is tested through solving a set of standard problems existing in the literature. The computational results show that the genetic algorithm is promising in providing good solutions to the assembly line balancing problem.

  • 324.
    Nourmohammadi, Amir
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Fathi, Masood
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Zandieh, Mostafa
    Department of Industrial Management, Management and Accounting Faculty, SBU, G.C., Tehran, Iran.
    Ghobakhloo, Morteza
    Department of Industrial Engineering, Minab Higher Education Center, University of Hormozgan, Bandar Abbas, Iran / Modern Technology Development and Implementation Research Center, University of Hormozgan, Bandar Abbas, Iran.
    A water-flow like algorithm for solving U-shaped assembly line balancing problems2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 129824-129833Article in journal (Refereed)
    Abstract [en]

    The problem of assigning assembly tasks to the stations arranged along a material handling device is known as assembly line balancing. This paper aims to address the U-shaped assembly line balancing problem (UALBP) which arises when a U-shaped assembly line has to be configured. It is widely known that this problem is NP-hard. Accordingly, different meta-heuristics based on a single solution (such as Simulated Annealing) or a population of solutions (such as Genetic Algorithms) have been proposed in the literature. Meanwhile, it has been argued that either of these meta-heuristics with a fixed number of solutions cannot maintain efficient search progress and thus can lead to premature convergence. Thus, this study aims at adopting a novel meta-heuristic algorithm with dynamic population sizes, namely Water Flow-like Algorithm (WFA), inspired by the behaviour of water flows in nature, to address the UALBP. The line efficiency and variation of workload are considered as the primary and the secondary objective, to be optimized, respectively. To verify the efficiency and robustness of the proposed WFA, a real case study taken from an automobile manufacturer as well as a set of standard problems are solved and the results compared with the existing approaches in the literature. The computational results demonstrate the superiority of the WFA, particularly in addressing medium to large-sized problems.

  • 325.
    Nupur, Reena
    et al.
    Department of Applied Mathematics, School of Vocational Studies and Applied Sciences, Gautam Buddha University, Noida, India.
    Gandhi, Kanika
    Bhavan’s Usha & Lakshmi Mittal Institute of Management, New Delhi, India.
    Solanki, Anjana
    Department of Applied Mathematics, School of Vocational Studies and Applied Sciences, Gautam Buddha University, Noida, India.
    Jha, P. C.
    Department of Operational Research, University of Delhi, New Delhi, India.
    Six Sigma Implementation in Cutting Process of Apparel Industry2017In: Quality, IT and Business Operations: Modeling and Optimization / [ed] P.K. Kapur, Uday Kumar, Ajit Kumar Verma, Springer, 2017, p. 279-295Chapter in book (Refereed)
    Abstract [en]

    The present competitive market is focusing on industrial efforts in producing high-quality products with the lowest possible cost. In every real-life system, there are a number of factors that cause disturbance in the process performance and their output. Process improvements through minimizing or removing such factors provide advantages such as reduced wastage or re-machining and improved market share. To help in accomplishing these objectives, various quality improvement philosophies have been put forward in recent years that can maximize the quality characteristics to ensure the enhancement of product and process. Six Sigma is an emerging data-driven approach that uses methodologies and tools that lead to improved quality levels and fact-based decision-making. This paper presents the application of the Six Sigma methodology to reduce defects in a cutting process of a garment manufacturing company in India, which is concluded through an action plan for improving product quality level. The define–measure–analyze–improve–control (DMAIC) approach has been followed here to solve the underlying problem of reducing defects and improving sigma level through continuous improvement process. The process helps in establishing specific inspection methods adapted for defect type which causes maximum rejection and to prevent their appearance in product.

  • 326.
    Nyman, Jonas
    et al.
    University of Skövde, School of Engineering Science.
    Krivokuca, Vladimir
    University of Skövde, School of Engineering Science.
    DESIGN AND CONSTRUCTION OF A STEPLESS HEIGHT ADJUSTER FOR AN ASKO DISHWASHER2019Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The standard for standing household dishwashers to date includes some means of adjusting the height of the upper basket in order to facilitate a more efficient loading of dishware. Ordinarily this is done by lifting the basket and locking it in a few positions. A more efficient and satisfactory method of handling the elevation that instils a premium sensation was to be developed. A design process was initiated and using CAD, a 3D model with associated drawings was created. A FEM analysis was conducted on the most vital components and a subsequent prototype was built. Preliminary results indicated flaws in the construction, however developing solutions appeared promising. The FEA concluded that the key components were sufficiently dimensioned for the tasks given. In the end, the project requirements were fulfilled although with set conditions modified, and without an end user trial.

  • 327.
    Ohlander, Ulrika
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre. Saab AB, Saab Aeronautics, Linköping, Sweden.
    Alfredson, Jens
    Saab AB, Saab Aeronautics, Linköping, Sweden.
    Riveiro, Maria
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Falkman, Göran
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Fighter pilots' teamwork: a descriptive study2019In: Ergonomics, ISSN 0014-0139, E-ISSN 1366-5847, Vol. 62, no 7, p. 880-890Article in journal (Refereed)
    Abstract [en]

    The execution of teamwork varies widely depending on the domain and task in question. Despite the considerable diversity of teams and their operation, researchers tend to aim for unified theories and models regardless of field. However, we argue that there is a need for translation and adaptation of the theoretical models to each specific domain. To this end, a case study was carried out on fighter pilots and it was investigated how teamwork is performed in this specialised and challenging environment, with a specific focus on the dependence on technology for these teams. The collaboration between the fighter pilots is described and analysed using a generic theoretical model for effective teamwork from the literature. The results show that domain-specific application and modification is needed in order for the model to capture fighter pilot's teamwork. The study provides deeper understanding of the working conditions for teams of pilots and gives design implications for how tactical support systems can enhance teamwork in the domain. Practitioner summary: This article presents a qualitative interview study with fighter pilots based on a generic theoretical teamwork model applied to the fighter domain. The purpose is to understand the conditions under which teams of fighter pilots work and to provide guidance for the design of future technological aids.

  • 328.
    Olmeda Noguera, Eduardo
    et al.
    University of Skövde, School of Technology and Society.
    Andrés Cervera, Santiago
    University of Skövde, School of Technology and Society.
    Bioclimatic House: Evaluation of solutions to develop a selfsustainable dwelling in Nordic countries2012Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    In  European  countries  houses  represents  36  %  of  CO 2   emissions.  To  reduce  these  emissions Bioclimatic  housing  is  proposed.  A  series  of  solutions  are  studied  in  this  project  to  acquire  a  low energy consumption building. Viability studies and guidelines of bioclimatic houses are given for the realization of this house in the Nordic countries.  A study of insulating materials and composition of the enclosures of the bioclimatic house is carried out  complying  with  the  Swedish  norm.  To  achieve  the  building  envelope  criteria  of  high  insulation and passive house construction are followed. Calculations of thermal transmittance, considering the geographical situation of the house, in a Nordic country, like Sweden are performed. One  method  to  obtain  the  energy  demand  of  buildings  is  to  use  computer  software.  A  graphic interface called DesignBuilder v 3.01. This software is utilized to study the importance of insulation and orientation in relation to the energy demand in a bioclimatic house. In  accordance  with  the  bioclimatic  construction,  renewable  energy  sources  are  chosen  to  supply electricity to the dwelling. This is to reduce the environmental impact and the ecological footprint of the household. To achieve this, three different alternatives are chosen. In addition, another goal is to study economic viability and possible agreements with an energy company in order to sell excess of energy.  A final result of the study and evaluation of the three different systems to provide energy and passive house strategies is obtained. According to the economic aspect, the Bioclimatic house should have a passive house envelope, facing south and a system combining of windmill turbine, solar photovoltaic panels and geothermal energy. The construction of bioclimatic houses helps to reduce the anthropogenic CO 2  emissions. In addition, the construction of bioclimatic houses is one way to achieve an ecologically sustainable future.

  • 329.
    Olofsson, Jakob
    et al.
    Department of Materials and Manufacturing – Casting, Jönköping University, School of Engineering, Jönköping, Sweden.
    Salomonsson, Kent
    Department of Product Development, Jönköping University, School of Engineering, Jönköping, Sweden.
    Johansson, Joel
    Department of Product Development, Jönköping University, School of Engineering, Jönköping, Sweden.
    Amouzgar, Kaveh
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    A methodology for microstructure-based structural optimization of cast and injection moulded parts using knowledge-based design automation2017In: Advances in Engineering Software, ISSN 0965-9978, E-ISSN 1873-5339, Vol. 109, p. 44-52Article in journal (Refereed)
    Abstract [en]

    The local material behaviour of cast metal and injection moulded parts is highly related to the geometrical design of the part as well as to a large number of process parameters. In order to use structural optimization methods to find the geometry that gives the best possible performance, both the geometry and the effect of the production process on the local material behaviour thus has to be considered. In this work, a multidisciplinary methodology to consider local microstructure-based material behaviour in optimizations of the design of engineering structures is presented. By adopting a knowledge based industrial product realisation perspective combined with a previously presented simulation strategy for microstructure-based material behaviour in Finite Element Analyses (FEA), the methodology integrates Computer Aided Design (CAD), casting and injection moulding simulations, FEA, design automation and a multi-objective optimization scheme into a novel structural optimization method for cast metal and injection moulded polymeric parts. The different concepts and modules in the methodology are described, their implementation into a prototype software is outlined, and the application and relevance of the methodology is discussed. 

  • 330.
    Olsson, Martin
    et al.
    University of Skövde, School of Engineering Science.
    Låstberg, Walter
    University of Skövde, School of Engineering Science.
    Development of an analytical model of the safety brake system for a chainsaw2018Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The safety braking system with the hand guard is the most important safety equipment for the user of a chainsaw. The safety system prevents serious injuries caused by a kickback. A kickback is when the running chain suddenly gets stuck e.g. by getting stuck in wood or hit a rock. Due to the potentially serious consequences of a kickback, the braking system has to fulfil strict requirements formulated by the authorities. In the present thesis, a generic analytical model of the braking system for a typical Husqvarna chainsaw is developed. The model is implemented as an Excel work sheet, which will facilitate future projects. The thesis includes sections of analytical calculations with information provided from both Catia and resources at Husqvarna. Several experiments were accomplished to strengthen and prove the analysis. The torque, index and activation force are tested. The static activation force is then completed in a simulation program to provide spread in the model. The parameters with most impact are also detected in the Excel simulation. A matrix of testing is constructed with parameters outside the tolerances for the dynamic experiment. Due to the collected data of the test, the relation between the two types of activation can be established. In comparison between samples of production with the simulation on equal numbers of 24 tests gave adifference on 4.75 % in mean value. 6 out of 32 tests could not be approved within the authorities’requirements for the acceleration with respect to the higher tolerances than production in the testing matrix. The most significant parameters for the static force were the brake spring and the angle of the knee joint. For the dynamic activation, the dimensions of the knee joint is crucial. Reasoning for errors are implemented in the discussion section e.g. the importance of data for the band. To improve the accuracy of the model a section of future work contains suggestments. One suggestion for improvement is to deliver more production values to ensure the comprehension of the experiments.

  • 331.
    Olsson, Rose-Marie
    University of Skövde, School of Engineering Science.
    Identifiering och minimering av risker i produktutvecklingsprojekt2016Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Product development is a generally risky business with great investments and numerous things that can go wrong during the projects. By defining risks and problem areas early in the projects, the occurrence of problems can be avoided. During this bachelor thesis the risk handling process of three Swedish companies were studied by interviewing project managers working there. This report also accounts for current research within risk management, as well as organizational learning and the importance of customer demands, in relation to risks in product development projects. The aim for this bachelor thesis was to give suggestions on how companies can improve their risk handling in regards to their existing product development process. This study indicates that a great understanding of customer demands, combined with a clear project structure and organizational learning, can be used to identify and minimize risks in product development projects. When the customer demands are expressed using metric variables they can also be communicated to the team so that everyone involved have the same expectations on the project, which leads to reduced uncertainties and fewer risks. The study indicates that many demands are difficult to define, but when the organization actively works to preserve and distribute definitions of customer demands that they have previously encountered, it leads to fewer misconceptions and helps reduce project delays. By using a clear structure and project process it is also possible to implement lessons learned into the organization, using existing systems and scheduled meetings as a way to preserve and distribute knowledge.

  • 332.
    Ore, Fredrik
    et al.
    Mälardalen University, Eskilstuna / Scania CV AB, Södertälje.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Chalmers University of Technology / Scania CV AB, Södertälje.
    Delfs, Niclas
    Fraunhofer-Chalmers Centre, Göteborg.
    Wiktorsson, Magnus
    Mälardalen University, Eskilstuna.
    Human Industrial Robot Collaboration – development and application of simulation software2015In: International Journal of Human Factors Modelling and Simulation, ISSN 1742-5557, Vol. 5, no 2, p. 164-185Article, review/survey (Refereed)
    Abstract [en]

    Human industrial robot collaboration (HIRC) aims to combine the benefits of industrial robots with humans in production environments. This is a growing research field where most work focuses on the safety aspects, while little research is performed on simulation and visualisation. The aim of this paper is to present a demonstrator software for simulation, visualisation and evaluation of human industrial robot collaboration.

    Two simulation software products were combined to reach this goal. The new tool was then applied to two industrial assembly cases where productivity and biomechanical loads on humans were calculated. The resulting demonstrator software simulates and visualises human industrial robot collaboration. The quantitative output from the simulation makes it possible to compare HIRC, manual and robotic assembly stations in terms of productivity and ergonomics.

  • 333.
    Ore, Fredrik
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Eskilstuna, Sweden / Scania CV AB, Global Industrial Development, Södertälje, Sweden.
    Hansson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Scania CV AB, Global Industrial Development, Södertälje, Sweden / Chalmers University of Technology, Department of Product and Production Development, Gothenburg, Sweden.
    Wiktorsson, Magnus
    Mälardalen University, School of Innovation, Design and Engineering, Eskilstuna, Sweden.
    Method for design of human-industrial robot collaboration workstations2017In: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 11, p. 4-12Article in journal (Refereed)
    Abstract [en]

    In order to fully utilise a 3D simulation software capable of evaluating hand-guided human-industrial robot collaborative (HIRC) work tasks, there is a need of a HIRC design process for early production development stages. This paper proposes a HIRC design method that uses the possibilities of the demonstrator software in the HIRC workstation design process. The method is based on Pahl and Beitz's engineering design method; it interprets all their phases and activities into HIRC design-specific ones.

  • 334.
    Ore, Fredrik
    et al.
    School of Innovation, Design and Engineering, Mälardalen University, Eskilstuna / Scania CV AB, Global Industrial Development, Södertälje, Sweden.
    Vemula, Bhanoday
    School of Innovation, Design and Engineering, Mälardalen University, Eskilstuna.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Scania CV AB, Global Industrial Development, Södertälje / Department of Industrial and Materials Science, Chalmers University of Technology, Göteborg.
    Wiktorsson, Magnus
    School of Innovation, Design and Engineering, Mälardalen University, Eskilstuna.
    Fagerström, Björn
    School of Innovation, Design and Engineering, Mälardalen University, Eskilstuna.
    Simulation methodology for performance and safety evaluationof human–industrial robot collaboration workstation design2019In: International Journal of Intelligent Robotics and Applications, ISSN 2366-5971, Vol. 3, no 3, p. 269-282Article in journal (Refereed)
    Abstract [en]

    There is a strong interest in the scope of human–industrial robot collaboration (HIRC) in manufacturing industry for greater flexibility and productivity. However, HIRC in manufacturing is still in its infancy; industrial practitioners have many apprehensions and uncertainties concerning the system’s performance and human operators’ safety. Therefore, there is a need for investigations into design processes and methods to make sure the designed HIRC workstations successfully meet design guidelines on system performance, human safety and ergonomics for practical industrial applications. This research proposes a HIRC workstation design process. The novelty of this design process is the methodology to evaluate the HIRC workstation design alternatives by considering both performance and safety characteristics through computer-based simulations. As a proof of concept, the proposed HIRC design process is applied on an industrial manufacturing case from a heavy-vehicle manufacturing company.

  • 335.
    Ore, Fredrik
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Eskilstuna, Sweden / Scania CV AB, Global Industrial Development, Södertälje, Sweden.
    Vemula, Bhanoday Reddy
    Mälardalen University, School of Innovation, Design and Engineering, Eskilstuna, Sweden.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Scania CV AB, Global Industrial Development, Södertälje, Sweden / Chalmers University of Technology, Product and Production Development, Göteborg, Sweden.
    Wiktorsson, Magnus
    Mälardalen University, School of Innovation, Design and Engineering, Eskilstuna, Sweden.
    Human - Industrial Robot Collaboration: Application of simulation software for workstation optimisation2016In: 6th CIRP Conference on Assembly Technologies and Systems (CATS) / [ed] Rikard Söderberg, Elsevier, 2016, Vol. 44, p. 181-186Conference paper (Refereed)
    Abstract [en]

    The simulation possibilities of Human Industrial Robot Collaboration (HIRC) are limited in commercial software and published research. In order to meet this a demonstrator software has been developed. This paper presents the combination of the quantitative output from the software (measuring operation time and biomechanical load) together with existing optimisation techniques used to design the optimal HIRC workstation. An industrial case is used as an example where the optimal geometric handover position between robot and human is found. From the simulation software metamodels were created in order to represent the investigated workstation. The model was used in a multi-objective optimisation problem and resulted in a trade-off chart between operation time and biomechanical load. The result shows one example of the possibilities to combine the quantitative results from the simulation with optimisation in order to get the best solution to a HIRC design problem. (C) 2016 The Authors. Published by Elsevier B.V.

  • 336.
    Oscarsson, Jan
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Jeusfeld, Manfred A.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Jenefeldt, Anders
    Volvo Cars Corporation, Skövde, Sweden.
    Towards Virtual Confidence - Extended Product Lifecycle Management2016In: Product Lifecycle Management in the Era of Internet of Things: 12th IFIP WG 5.1 International Conference, PLM 2015, Doha, Qatar, October 19-21, 2015, Revised Selected Papers / [ed] Abdelaziz Bouras, Benoit Eynard, Sebti Foufou & Klaus-Dieter Thoben, Springer, 2016, Vol. 467, p. 708-717Chapter in book (Refereed)
    Abstract [en]

    Product lifecycle management (PLM) systems maintain amongst others the specifications and designs of product, process and resource artefacts and thus serve as the basis for realizing the concept of Virtual Manufacturing, and play a vital role in shortening the leadtimes for the engineering processes. Design of new products requires numerous experiments and test-runs of new facilities that delays the product release and causes high costs if performed in the real world. Virtualization promises to reduce these costs by simulating the reality. However, the results of the simulation must predict the real results to be useful. This is called virtual confidence. We propose a knowledge base approach to capture and maintain the virtual confidence in simulation results. To do so, the provenance of results of real, experimental and simulated processes are recorded and linked via confirmation objects.

  • 337.
    Oskarsson, Erik
    et al.
    University of Skövde, School of Engineering Science.
    Cicek, Ayhan
    University of Skövde, School of Engineering Science.
    Alternativ sammanfogning till svets på vagn2018Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Lim undersöks för att se om företaget, Cidan Machinery, kan ersätta de existerande svetsfogarna på en komponent till deras kantviksmaskiner. Detta för att undvika det merarbete vilket svetsning medför eftersom konstruktionen kan bli skev av de spänningar vilka uppstår när den svetsade konstruktionen svalnar. Med hjälp av en analys med finita elementmetoden(FEM) kan en uppfattning av var de största spänningarna i vagnen inträffar skaffas. Litteraturstudien innefattar spänningarna uppstående av svetsning, förklaring av svetsmetoden Metal Active Gas, MAG, samt alternativa metoder till svetsning. Huvudfokus läggs på limning eftersom uppdragsgivaren har önskat detta. I litteraturstudien behandlas åldring vilket är en viktig faktor vid undersökning av hållfastheten hos lim över dess livslängd. Eftersom dragprov användes för att testa olika lim tas även detta upp.De testade limmen klarade av lägre spänning än väntat vilket kan bero på ytan hos provbitarna då denna var oslipad och belagd med ett oxidskikt. Ingen direkt effekt av åldringen kan ses vilket leder till att en uppskattning av livslängd ej kan göras. Analyser av konstruktionen visar var de största spänningarna uppstår och vid jämförelse med resultatet med dragprovet kan en del svetsfogar inte ersättas med lim. Sammansättning med lim är aktuellt i detta fall men eftersom alla sammanfogningspunkter inte kan limmas för att klara av spänningarna kan företaget inte överge svetsningen helt.

  • 338.
    Palmqvist, Erik
    University of Skövde, School of Engineering Science.
    Kartläggning och förbättringar av värdeflöden genom värdeflödesanalys: En empirisk fallstudie2014Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Kongsberg Automotive (KA) in Mullsjö manufactures gear transmission systems to a common platform of passenger cars. The company does see a potential to improve the flow of products and its components by the factory. KA also manufactures many of the components in the same factory as the final assembly is done, creating good prospects for maintaining efficient value streams. Today, production is running three shifts supplemented with extra weekend shifts as needed. One objective of this study is to investigate the possibilities of a continuous three-shift and eliminate weekend shifts as these are extra costly for the company. The main objective of this study is to map the flow of two of the components in the final product using value stream mapping (VSM) method. From this position a future desired state is created in which different types of waste in the flow has been eliminated. The goal is finally to set up a concrete action plan to achieve the desired future state. The study also intends to examine whether the method of production simulation can be used as complement to value stream mapping and to quantify the identified improvements.

    As a first step in the study, data had to be collected to determine the current situation. This was performed with different methods to create a broad and accurate picture of the situation. Time studies were used to either identify or verify given data. Also a review of various documents, supply lists, and tracking lists are the basis for development of the present state. The entire project has been permeated by a close contact with the staff of the company to obtain as much and credible information as possible. Participant observation has been made continuously during the study to get access to primary data. The use of value stream mapping has resulted in a current state and a desirable future state of the components flow. As part of the project, a production simulation model has been created over the current flow in order to test the hypothesis that the proposed enhancements can be strengthened and quantified by using production simulation. During the process of creating the desired future state, a workshop was held at the company where people with different functions in different departments participated. The proposed improvement that has been identified during the work has resulted in a concrete action plan to reach the future state.

    The results of the study demonstrate a great potential for improvement in the identified value streams. Theoretical calculations show that the lead time for components can be reduced by up to 2/3 and the number of products in process can be reduced by up to 50%. Also a great potential to improve the accessibility in the bottleneck has been identified. Would this availability increase about 9%, three-shift production can be applied to satisfy the current customer needs. This would result in that weekend shifts are no longer needed. The study also resulted in a conclusion that simulation is not suitable as a method for this case study. Instead, the analysis and experiments have been performed with less advanced analytical tools in agreement with the literature. Finally, the study suggests the company to invest in training when the lack of knowledge in Lean production offers a limited understanding of the work to become more efficient and flexible. 

  • 339.
    Paredes Almaraz, Israel
    University of Skövde, School of Engineering Science.
    New dynamic pallet for Volvo Trucks based in biomimicry: New support modular and adaptable to different geometries, based in the structures of the radiolarian microorganisms and honeycomb2019Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The logistics department at the Powertrain plant of Volvo Trucks seeks to improve the efficiency within their processes. A new concept solution to the supports (pallets) that hold and carry different types of engine parts during the transportation between the sequencing area and the final assembly line called “The new dynamic pallet based on biomimicry” was presented. The concept solves the issues of the constant modifications in the pallets lead by the changes in the design of the engine parts. The main objectives of the project is the creation of a dynamic pallet, dynamic in this case translates into a modular, flexible to different geometries and scalable system, also the design solution should be inspired by nature (biomimicry) to boost a new sustainable design approach related to the values of Volvo brand.

    This project required iterative research regarding the principles of biomimicry and systems found in nature. Biomimicry literally means ‘the imitation of life’ but, it is better defined as a design approach to innovation which takes inspiration from systems of nature. It is provided by Volvo as the core of the project, if the result is good then there will be a push to develop new projects following this strategy seeking sustainable solutions to solve human problems. In addition, prototyping concepts from a generation of ideas to testing results were conducted to evaluate the concepts generated. The resulting concept proposal is a whole new system but preserves the functional aspects necessary to integrate the new pallet in the current logistics performance.

  • 340.
    Parra Lete, Enara
    et al.
    University of Skövde, School of Technology and Society.
    Rodríguez García, Verónica
    University of Skövde, School of Technology and Society.
    Design of a foot for a humanoid2012Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The aim of this project is to design a new mechanism for a foot of a humanoid in order to use it as a toy with the possibility of using it also as a prosthesis or an orthopaedic robotic foot. This project has been done in collaboration with the research centre The Cognition & Interaction Lab (COIN) at the School of Humanities and Informatics of the University of Skövde. The mechanism should be able to have human-like movements. First of all, existing humanoid feet have been analysed in a market research in order to obtain an overview of existing mechanisms and how they work.

    Some interesting ideas have been developed taking into account the goals and the defined user requirements. Some concept evaluation methods have been used to choose the best idea taking into account the opinion of the research centre. This process leads to the final idea of creating a parallel actuator system using three pneumatic cylinders and it is designed in 3D using Pro/Engineer. To create the model, actuators have been chosen from the pneumatic manufacturer Parker. The 3D model was tested in Pro/E mechanism to verify that the cylinders are powerful enough to create the motion of walking.

    The conclusion is that most of the goals have been achieved. However, the cover of the foot has not been designed yet due to time constraints. For further work it would be interesting creating a plastic prototype too for testing the mechanism before creating the metallic prototype. Moreover it has to be mentioned that the opinion of the research centre has been of a substantial important for the project.

  • 341.
    Pehrsson, Leif
    University of Skövde, The Virtual Systems Research Centre. University of Skövde, School of Technology and Society.
    Manufacturing management and decision support using simulation-based multi-objective optimisation2013Doctoral thesis, monograph (Other academic)
    Abstract [en]

    A majority of the established automotive manufacturers are under severe competitive pressure and their long term economic sustainability is threatened. In particular the transformation towards more CO2-efficient energy sources is a huge financial burden for an already investment capital intensive industry. In addition existing operations urgently need rapid improvement and even more critical is the development of highly productive, efficient and sustainable manufacturing solutions for new and updated products. Simultaneously, a number of severe drawbacks with current improvement methods for industrial production systems have been identified. In summary, variation is not considered sufficient with current analysis methods, tools used are insufficient for revealing enough knowledge to support decisions, procedures for finding optimal solutions are not considered, and information about bottlenecks is often required, but no accurate methods for the identification of bottlenecks are used in practice, because they do not normally generate any improvement actions. Current methods follow a trial-and-error pattern instead of a proactive approach. Decisions are often made directly on the basis of raw static historical data without an awareness of optimal alternatives and their effects. These issues could most likely lead to inadequate production solutions, low effectiveness, and high costs, resulting in poor competitiveness. In order to address the shortcomings of existing methods, a methodology and framework for manufacturing management decision support using simulation-based multi-objective optimisation is proposed. The framework incorporates modelling and the optimisation of production systems, costs, and sustainability. Decision support is created through the extraction of knowledge from optimised data. A novel method and algorithm for the detection of constraints and bottlenecks is proposed as part of the framework. This enables optimal improvement activities with ranking in order of importance can be sought. The new method can achieve a higher improvement rate, when applied to industrial improvement situations, compared to the well-established shifting bottleneck technique. A number of “laboratory” experiments and real-world industrial applications have been conducted in order to explore, develop, and verify the proposed framework. The identified gaps can be addressed with the proposed methodology. By using simulation-based methods, stochastic behaviour and variability is taken into account and knowledge for the creation of decision support is gathered through post-optimality analysis. Several conflicting objectives can be considered simultaneously through the application of multi-objective optimisation, while objectives related to running cost, investments and other sustainability parameters can be included through the use of the new cost and sustainability models introduced. Experiments and tests have been undertaken and have shown that the proposed framework can assist the creation of manufacturing management decision support and that such a methodology can contribute significantly to regaining profitability when applied within the automotive industry. It can be concluded that a proof-of-concept has been rigorously established for the application of the proposed framework on real-world industrial decision-making, in a manufacturing management context.

  • 342.
    Pehrsson, Leif
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Research and Technology Development, Engine Manufacturing Engineering, Volvo Car Group.
    Frantzén, Marcus
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Aslam, Tehseen
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Aggregated line modeling for simulation and optimization of manufacturing systems2015In: Proceedings of the 2015 Winter Simulation Conference / [ed] L. Yilmaz, W. K. V. Chan, I. Moon, T. M. K. Roeder, C. Macal, and M. D. Rossetti, Piscataway, NJ, USA: IEEE Press, 2015, p. 3632-3643Conference paper (Refereed)
    Abstract [en]

    In conceptual analysis of higher level manufacturing systems, for instance, when the constraint on system level is sought, it may not be very practical to use detailed simulation models. Developing detailed models on supply chain level or plant wide level may be very time consuming and might also be computationally costly to execute, especially if optimization techniques are to be applied. Aggregation techniques, simplifying a detailed system into fewer objects, can be an effective method to reduce the required computational resources and to shorten the development time. An aggregated model can be used to identify the main system constraints, dimensioning inter-line buffers, and focus development activities on the critical issues from a system performance perspective. In this paper a novel line aggregation technique suitable for manufacturing systems optimization is proposed, analyzed and tested in order to establish a proof of concept while demonstrating the potential of the technique.

  • 343.
    Pehrsson, Leif
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Volvo Car Corporation, Gothenburg, Sweden.
    Lidberg, Simon
    Volvo Car Corporation, Gothenburg, Sweden.
    Frantzén, Marcus
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Aslam, Tehseen
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Aggregated Discrete Event Modelling for Simulation and Optimisation of Manufacturing Systems2014In: Industrial Simulation Conference, Skövde, June 11-13, 2014, Eurosis, 2014, 2014, p. 83-90Conference paper (Refereed)
    Abstract [en]

    In many simulation studies for factory analysis, for example, to locate the constraint of an entire factory that consists of multiple production lines, it may not be effective to put every process detail into a single model. Firstly, to develop such a factory-wide model would be very time-consuming. Secondly, it can be very computational costly to run the model, especially if simulation-based optimisation is applied to find the optimal setting from such a complex model that possesses all the details of the processes. In this regard, aggregation, with which multiple process steps are aggregated into some simpler simulation objects, is an effective method to reduce both the development and computational times. On one hand, based on the initial analysis, the simulation expert can pinpoint the sub-system that restrains the performance of the entire factory and decide if a more detailed model is needed. On the other hand, interline buffers/storages can be readily optimised by using such an aggregated model. Through an application study with data from a real-world factory, this paper introduces a novel aggregation method and illustrates the potential of the abovesaid concepts.

  • 344.
    Pehrsson, Leif
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Bernedixen, Jacob
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Automatic identification of constraints and improvement actions in production systems using multi-objective optimization and post-optimality analysis2016In: Journal of manufacturing systems, ISSN 0278-6125, E-ISSN 1878-6642, Vol. 39, p. 24-37Article in journal (Refereed)
    Abstract [en]

    Manufacturing companies are operating in a severely competitive global market, which renders an urgent need for them to explore new methods to enhance the performance of their production systems in order to retain their competitiveness. Regarding the performance of a production system, it is not sufficient simply to detect which operations to improve, but it is imperative to pinpoint the right actions in the right order to avoid sub-optimizations and wastes in time and expense. Therefore, a more accurate and efficient method for supporting system improvement decisions is greatly needed in manufacturing systems management. Based on research in combining simulation-based multi-objective optimization and post-optimality analysis methods for production systems design and analysis, a novel method for the automatic identification of bottlenecks and improvement actions, so-called Simulation-based Constraint Identification (SCI), is proposed in this paper. The essence of the SCI method is the application of simulation-based multi-objective optimization with the conflicting objectives to maximize the throughput and minimize the number of required improvement actions simultaneously. By using post-optimality analysis to process the generated optimization dataset, the exact improvement actions needed to attain a certain level of performance of the production line are automatically put into a rank order. In other words, when compared to other existing approaches in bottleneck detection, the key novelty of combining multi-objective optimization and post-optimality analysis is to make SCI capable of accurately identifying a rank order for the required levels of improvement for a large number of system parameters which impede the performance of the entire system, in a single optimization run. At the same time, since SCI is basically built a top a simulation-based optimization approach, it is capable of handling large-scale, real-world system models with complicated process characteristics. Apart from introducing such a method, this paper provides some detailed validation results from applying SCI both in hypothetical examples that can easily be replicated as well as a complex, real-world industrial improvement project. The promising results compared to other existing bottleneck detection methods have demonstrated that SCI can provide valuable higher-level information to support confident decision-making in production systems improvement.

  • 345.
    Peralta Fernandez-Blanco, Antonio
    et al.
    University of Skövde, School of Technology and Society.
    Bellido Sanchez-Cañete,
    University of Skövde, School of Technology and Society.
    Development of a Portable Stable for Horses2009Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
  • 346.
    Perez Romero, Roberto
    et al.
    University of Skövde, School of Engineering Science.
    Lazuen Ramirez, Alvaro
    University of Skövde, School of Engineering Science.
    Analysis of rubber adhesive: FE simulation of damage propagation over rubber adhesive under fatigue in mixed-mode loading2014Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis refers to a simulation of an adhesive joint used to bond two metal sheets of a component of the side skirt bracket implemented in trucks. The adhesive joint must support fatigue and mixed-mode loading. The principal goal is the implementation of a novel material model, which governs the damage produced by a mixed-mode fatigue loading in a rubber adhesive layer.

    Two approaches to define the material model are implemented: the filament model and the principal strain model. The models are fitted against experiments, which have been performed parallel to the development of this thesis by the Mechanics of Materials (MoM) research group of the University of Skövde. The models incorporate fitting parameters with the aim of adjusting the models against experimental results. Simulations are performed using the Finite Element (FE) software, ABAQUS, and the material models are implemented using UMAT subroutines.

    The filament model is inaccurate and it is considered unable to model the mixed-mode behaviour of the adhesive joint. The principal strain model is considered a well-established method to define the damage and to predict the fatigue life of the adhesive under fatigue in mixed-mode loading.

  • 347.
    Persson, Kasper
    et al.
    University of Skövde, School of Engineering Science.
    Engström, Patrik
    University of Skövde, School of Engineering Science.
    Development of a portable computer case with focus on sustainability2017Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A stationary computer case focusing on portability and sustainability has been developed in cooperation with the computer hardware manufacturer Fractal Design. The target group was early set to computer builders on a professional as well as an amateur level and gamers that are using stationary computers. To improve the portability and sustainability of a computer case a gathering of data was done early in the project. This consisted of user testing sessions as well as surveys, literature studies of materials, life cycle and sustainability analysis.

    To get a large amount of ideas an idea generation session was done in cooperation with the users to be able to discuss solutions and to get more insight. With these ideas as a basis, more concepts were generated with help of charts and a large number of them was later prototyped to test the functions and compatibility with PC components. To select a concept, close contact with the company was kept to evaluate concepts with them as well as using concept selection charts and user tests. When a concept was chosen, it was going through engineering methods like FMEA and FEA to evaluate the construction, which kept the design process iterative. A final design was later achieved and was developed to reach up to the demands of users and the company.

  • 348.
    Pettersson, Emil
    et al.
    University of Skövde, School of Engineering Science.
    Pettersson, Emil
    University of Skövde, School of Engineering Science.
    Utmattningsberäkning av hydraulikkopplingar: Metoder och beräkningar gällande utmattningsteorier2015Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis is to investigate the fatigue life of two components in different hydraulic quick couplings. The crack which initiates the fatigue failure usually occurs in the bottom of one of the threads. Thus, the threads in the coupling are carefully investigated. A few different approaches for determining the fatigue life are studied for each component. CAD (Computer Aided Design) models for both components are created and analyzed with FEM (Finite Element Method). By analyzing these components with FEM the stresses and the strains are calculated. These values for stress and strain are used to determine the fatigue life for the different components. The first component is suffering from high cycle fatigue. Four different approaches for high cycle fatigue are investigated. These four are Wöhler-curve, Haigh-diagram, von Mises fatigue criterion and Mises-Sines fatigue criterion. It was found that all of them but the von Mises fatigue criterion give a good approximation of the fatigue life. von Mises fatigue criterion does not consider the midstress, which can be a reason for this. The three other approaches indicate that the component will be suffering from fatigue, but will be relatively close to infinite life. The Wöhler-curve indicates that the component will withstand about 470 000 loading cycles. Compared to the experimental tests where the component withstands about 700 000 loading cycles, it can be said that the approach is a good estimation of the fatigue life. Approximated material data are used. For further work it is essential to obtain experimental material data for better approximation of the fatigue life. The second component is suffering from low cycle fatigue, which means that different approaches are needed. The approaches are originally from Coffin-Manson and Morrow. A total of four low cycle fatigue criterion have been studied. The first one is made by CoffinManson and takes the plastic strain in to account, the second is made by Morrow and takes both the elastic and the plastic strain in to account.  The third is a modification of Morrow’s criterion, and will consider the midstresses as well. The fourth is a simplification of Morrow’s criterion where more common material parameters are used. These four have been compared and it can be seen that the CoffinManson criterion gives the best approximation of the reality. The Coffin-Manson criterion gives an approximation of 50 000 loading cycles to fatigue failure which, compared to that the experimental tests suffered from fatigue failure after about 40 000 loading cycles, is a good estimation of the fatigue life.

  • 349.
    Phalén, Kajsa
    et al.
    University of Skövde, School of Engineering Science.
    Lövgren Berg, Emelie
    University of Skövde, School of Engineering Science.
    Utveckling av displayställ för kreativa leksaker2016Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During spring 2016, the engineering students Kajsa Phalén and Emelie Lövgren Berg, at the University of Skövde, developed a product in cooperation with the toy company Strawbees. The company wants to sell their creative toys in stores and therefore wants to develop a sales display stand that will carry the products. A basic feasibility study has been done to define a target group of customers and other stakeholders. The feasibility study also covers marketing strategies in shops and studies were carried out to increase understanding of the target group needs. Market analysis of competitors gave inspiration from existing solutions of the problem and a collage over color codes and idioms gave the result the feeling that the company wants to convey.

    The number of products that the display stand would wear was a major focus in the beginning of the concept generation. Combinations of how the products can be placed laid the foundation for the design of the display stand. Through analysis of how competitors solved the visual design for the display stand some visual themes were created. The developed designs together with visual themes and the feeling that the company wants to convey created various concepts. The new concepts were analyzed for how they would fit into its natural environment, a toy store. Because of some shortcomings the number of concept could be limited to only two, who later became prototypes. These prototypes were tested in real size together with the products that the display stand would accommodate. A concept could then be determined and developed in detail as to the best way to reach up to the demands and wishes of the company.

  • 350.
    Popov Popov, Nikita
    University of Skövde, School of Engineering Science.
    Design and preliminary finite element analysis of structural frame of a double base for an infant child restraint system.2015Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Child restraint systems (CRS) are used for protection of the child in case of car accident. These systems have been found to have a difficult installation process that in many cases can cause greater loads on the child and as a consequence can lead to an increased risk of injury and a reduction in safety. The problems are even more significant in cases of families with two or more children and in small cars with lack of available space. Misuse and its causes are identified from literature as well as from surveys and market research. The design guidelines are gathered from existing CRS designs. Currently available automotive and CRS fastening systems are studied. A specific methodological approach is used for project development. A new concept for a child restraint system is introduced. The main aims are the design proposal of a double ISOFIX base for two children, reduction in the misuse of the CRS, improving the user experience and achieving technological, societal and environmental contributions. The second aspect is to verify the structure of the double base by means of preliminary finite-element analysis using the case of a frontal collision in accordance to current approval testing procedures. Al 2024 is chosen for design by the material selection performed in order to optimize the structure in relation to strength and weight. The finite-element preliminary static analysis is performed employing shell elements. The results are analysed with respect to the mesh convergence. In addition a linearized buckling check is carried out. Finally, the achieved results are discussed in comparison with initial assumptions and goals and future work is suggested.

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