Mechanics of zero degree peel test on a tape – effects of large deformation, material nonlinearity, and finite bond length

A common adhesive tape is a composite consisting of a stiff backing and a soft adhesive layer. A simple way to test how they respond to large shear deformation is the zero degree peel test. Because the backing is very stiff compared to the adhesive, the region where the adhesive layer is subjected to large shear can be hundreds of times its thickness. We use a large deformation hyperelastic model to study the stress and displacement fields in the adhesive layer in this test. Our analytical model is then compared with finite element (FE) results. Except for a small region near the peel front or the free edge, the predicted stress and deformation agree well with the FE model. We compare our result with linear theory and find that strain hardening and large deformation of adhesive can significantly affect the distribution of shear strain and stress state in the adhesive layer. For large deformation, our analysis shows that the lateral stress (parallel to the rigid substrate) is much larger than the shear stress in the adhesive layer. We obtain an exact expression for the energy release rate. Our result shows that the energy release rate determined by the nonlinear theory differs significantly from the linear theory in the regime of short bond lengths. We study the stress state near the peel front and the free edge using a FE model. The results in this work is not specific only to adhesive tapes, but also can be used to study the effect of shear in composites with similar geometry.