Propagation of cracks from strip inclusions in composite plates under impulsive tensile load

Abstract

The problem of propagation of a crack in composite materials under the action of extensional impulsive load was considered in this paper by using a plane-stress biphase model. The specimen used was made from an orthogonal metallic strip penetrated into an elastic orthogonal soft matrix made of epoxy resin. The fracture of the matrix takes place at the bottom corners of the strip and the thus formed cracks propagate perpendicularly to the direction of the applied load. The stress condition at the crack tip during its nucleation and propagation is of Mode-I. The technique, which was used for the study of the problem, was the optical method of the transmitted caustics, combined with a 24-spark high-speed recording. The stress intensity factor K I and the propagation velocity c are determined from the analysis of the caustics along all the crack path. Interesting conclusions for the behaviour of the propagating cracks were derived.