| Abstract: | The most widely used adhesive test specimen is the lap shear test. Variations of this test have been standardized by the American Society for Testing Materials (ASTM) and other societies or agencies. The results of these tests are generally given in terms of the failure load divided by the area of overlap, but a finite element analysis indicates that the maximum shear stress and the induced normal stress can be much larger than the average. An argument can be made that the induced secondary Mode I stresses, near the bond termini, are more closely related to failure than are the average shear stress or even the maximum shear stress. Experimental and finite element results are presented in this paper to show that this is indeed the case. In addition, ways to reduce these induced stresses in lap shear tests are discussed and evaluated. |
