Hygrothermal effect on the strain energy release rates and mode mixity of asymmetric delaminations in generally layered beams

Abstract

An analytical framework is presented to calculate the mode I and II components of the strain energy release rate (SERR) of a delamination between two generally layered sub-laminates, considering the residual hygrothermal stresses effect. First, the sub-laminates are modeled as Timoshenko beams, the crack tip is assumed rotationally flexible and the mode partitioning is based on the global method. Next, SERR and mode mixity are obtained for an arbitrarily loaded delaminated beam and reduced for some typical delamination fracture tests. An asymmetrically delaminated fiber metal laminate (FML) is analyzed under double cantilever beam (DCB) and end-notched flexure (ENF) configurations. For the ENF configuration, the inherent contact problem was analytically approached. We demonstrate that the thermal effect on the SERR and mode mixity of the FML, rather ignored so far in the literature, can be non-negligible. Finally, the analytical results are validated against numerical predictions using the finite element method.