On the influence of eccentricity on Thick Adherend Shear Tests

Abstract Two main mechanical tests are commonly used to measure the critical shear stress of an adhesive, the Single Lap Shear (SLS) test and the Thick Adherend Shear Test (TAST). In these tests, the assessment is performed with mode mixity. In this work, a two-dimensional Finite Element Model of an asymmetric TAST is set-up and a few mechanical tests are performed on titanium/epoxy specimens. The model takes into account a shift of the adhesive joint on the loading axis. The impact of a shifted loading is estimated on two specimen geometries though a sensitivity analysis. Then, a method is suggested to assess the state of stress that caused the specimen failure. The results show that the failure location and the mode mixity can be tuned by the shift. Furthermore, it is shown that a standard TAST geometry is remarkably sensitive to a shifted loading. As a consequence, this parameter should be set with a submillimeter accuracy or a modified version of classical shear tests should be used. The reported results are consistent with one another and the method used provides a clear link between the critical stresses of the model and the mechanical response of the specimen until failure.