Crack path in foam cored DCB sandwich fracture specimens

A simple laminated beam analysis is presented for analysis of the propagation path of a core crack in symmetric and unsymmetric double cantilever beam (DCB) sandwich fracture specimens with a polymer foam core. The analysis determines the sign of shear stress ahead of the crack tip from the discontinuity of bending strain in the legs of the DCB specimen, and hence, the kinking direction. The beam analysis, furthermore, assesses the stability of the crack path and provides the steady-state location of the crack after kinking (if it kinks). The analysis was in overall agreement with predictions of kink angle obtained from detailed finite element modeling and experimental crack paths in DCB specimens with a H100 foam core.