Strain rate-dependent deformation and failure process of adhesive joints

Rate-dependent deformation and failure process of adhesive joints are investigated in this study. For this purpose, acrylic foam pressure sensitive adhesive (PSA) was employed with aluminum adherents. Tensile and shear loading of the adhesive joint was applied at displacement rates ranging from 5 to 500 mm/min. Results show that the failure process under tensile loadings start with initiation of cavities, hardening through fibrillation process and final fracture of the fibrils. For shear loading the failure process is a combination of fibrillation processes, shear flow, and by interfacial sliding. Both modulus and strain energy density at fracture reach maximum value at a displacement rate of 100 mm/min under tension, while continuously increase with displacement rate under shear loading. Adhesive failure dominates at low loading rate (below 10 mm/min.), while mixed-mode and cohesive failure are common at faster loading rates above 250 mm/min. Finite element employing Yeoh constitutive model adequately predicts viscous shear deformation of the PSA joints.