Stress analysis near the tip of a curvilinear interfacial crack between a rigid spherical inclusion and a polymer matrix

Abstract

Craze and shear band formation at poorly adhering glass spheres in matrices of glassy polymers are known to be preceded by the formation of a curvilinear interfacial crack between sphere and matrix. In this study the axisymmetric finite element method has been used to analyse the stress situation near the tip of a curvilinear interfacial crack formed between a rigid spherical inclusion and a polymer matrix upon an applied uniaxial tension. Important factors that determine the stress state near the crack tip were found to be the crack length, the orientation of the crack tip with regard to the tension direction and the extent of interfacial slip between the inclusion and matrix. The results of the analyses were compared with the physical reality of craze and shear band formation at poorly adhering glass spheres. Reasonable agreement was found with respect to both the maximum interfacial crack length that can be reached until a craze or shear band forms at the crack tip and the planar orientation of craze growth perpendicular to the direction of the major principal stress.