On the existence of a unique stress-deformation relation for an adhesive layer loaded in shear
2005 (English)In: 11th International Conference on Fracture (ICF11), Turin, Italy 20-25 March 2005: Volume 5, Curran Associates, Inc., 2005, 3763-3768 p.Conference paper (Refereed)
An experimental method to determine the complete stress vs. deformation relation for a thin adhesive layer loaded in shear is presented. The experiments are performed by use of a classical specimen geometry, i.e. the end-notch flexure specimen, though the experiments are evaluated based on a novel inverse technique. With this technique, the instantaneous energy release rate is first evaluated by use of a theory for the specimen based on the Euler-Bernoulli beam theory. Effects of a flexible adhesive layer are considered in an approximate way. From the energy release rate, the stress-deformation relation is evaluated using an inverse method. In order for the theory to be valid, the adherends of the specimen are only allowed to deform elastically. Quasi-static experiments are performed using a servo-hydraulic testing machine. In the experiments, the displacement of the loading point is gradually increased to obtain a constant velocity of the shear deformation at the crack tip. Formation of micro-cracks and the propagation of a macro-crack are monitored during the experiments by use of a CCD-camera attached to a microscope. By varying the heights of the adherends, the size of the process zone in front of the crack tip changes from about 200 to 400 times the thickness of the adhesive layer. The results of the experiments give a fracture toughness of 2.5 kJ/m 2 , a critical shear deformation of 0.13 mm, and a maximal strength of 30 MPa independent of the specimen geometry. The experiments show consistent results. The results show that if the process zone is large as compared to the thickness of the adhesive layer, the shear stress – shear deformation relation can be considered as a constitutive property of the adhesive layer.
Place, publisher, year, edition, pages
Curran Associates, Inc., 2005. 3763-3768 p.
IdentifiersURN: urn:nbn:se:his:diva-7118ScopusID: 2-s2.0-84869784288ISBN: 978-1-61782-063-2OAI: oai:DiVA.org:his-7118DiVA: diva2:602800
11th International Conference on Fracture (ICF11), Turin (Italy) - March 20-25, 2005