Effect of residual stress on the energy release rate of wedge and DCB test specimens

Changes in the available interfacial strain energy release rate caused by residual stresses (e.g. thermal, hygroscopic and piezoelectric induced stresses) in a triple-layered specimen are analyzed using linear elastic fracture mechanics and simple beam theory. The strain energy release rate, caused by either tensile or compressive in-plane residual stresses in the adhesive, is derived. The contributions of the thermal residual and mechanical stresses to the global energy release rate are also analyzed using both a steady-state fracture analysis and a thermoelastic laminate analysis. Excellent agreement is obtained with a finite element analysis conducted for comparison and validation. The thermally induced energy release rate, GTGT, is found to be independent of crack length, but is a function of residual stress level and the geometric and material parameters of the specimen. Although the contribution due to residual stresses is expected to be small for typical double cantilever beam specimens, the residual-stress-induced energy release rate can be non-negligible for subcritical debonding in wedge test specimens exposed to aggressive environments.