Elastic interaction of interfacial spherical-cap cracks in hollow particle filled composites

This work analyzes the elastic interaction between two spherical-cap cracks present along the outer surface of a hollow particle embedded in a dissimilar medium under remote uniaxial tensile loading. A semi-analytical approach based on an enriched Galerkin method is adopted to determine stress and deformation fields as functions of particle wall thickness and cracks’ configuration. The present analysis is limited to multiple interfacial spherical-cap cracks; that is, crack propagation is restrained to the particle-matrix interface and possibility of crack kinking in the matrix is not considered. Interfacial crack growth characteristics, conditions for stable crack propagation, equal crack growth, and shielding are established through energy release rate analysis. The study is relevant to the analysis of tensile and flexural failure of syntactic foams used in marine and aerospace applications. Results specialized to glass-vinyl ester syntactic foams demonstrate that particle wall thickness can be used to control crack stability and growth characteristics as well as tailoring the magnitude of the shielding phenomenon. Predictions are compared to finite element findings for validation and to results for penny-shaped cracks to elucidate the role of crack curvature.