Study on the mechanical behavior of adhesive interface by digital image correlation

The shear modulus of the adhesive layer and the failure mode of adhesive structure on single lap joint specimens under tensile tests are investigated in this paper. The aluminum-aluminum adherends are bonded by two different adhesives: polydimethylsiloxane (PDMS) and epoxy. The full deformation fields are measured using the digital image correlation (DIC) method with the images on the middle part of the adhesive layer recorded by a high resolution microscope. Then, the shear modulus values of the two adhesives are calculated with a simple pure shear strain model. A numerical model is proposed to simulate the single lap joint structure under tensile load in comparison with the experimental results. The results show that this method can successfully estimate the shear modulus of the adhesive layer. The failure behavior of epoxy adhesive/adherend interface is also analyzed and discussed.