A study of blister tests for film adhesion measurement and fracture efficiency of tests for adhesive bonds
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A novel concept, the fracture efficiency, is proposed in this dissertation as a performance index of fracture specimen designs for adhesive bonds. Evaluated based on a simple quantity, the fracture efficiency parameter, the fracture efficiency represents how much crack driving force a certain specimen design can produce along the bondline for a given maximum non-singular stress in the adherends. In this dissertation, a study of membrane peeling specimens shows that various existing test geometries have little difference in the fracture efficiency. Furthermore, the study shows that it is unlikely to develop new n1embrane peeling tests with high fracture efficiency. Therefore, gross inelastic energy dissipation in the film specimen may occur when using the membrane peeling tests, and may result in large errors in the film adhesion measurement when only elastic material response is considered in the analysis. As a result, the use of a backing material for film adhesion measurement is suggested because of the significant increase in the fracture efficiency when a proper backing material is used. Besides the use as one of the guidelines for fracture specimen designs, it is also demonstrated in this dissertation that the fracture efficiency parameter can also be used to help one determine the validity of a measured bond fracture strength.
- Doctoral Dissertations