The stress field in a [0°/90°] laminated composite plate containing a finite line crack

This paper deals with the construction of an asymptotic solution for the stress field in a laminated composite plate, with [0/90] stacking sequence. The plate contains through the thickness a line crack of length 2c and its perimeter boundaries are sufficiently far away from the crack so that no edge effects are present. The stress field is derived explicitly, and includes a correction factor to account for the laminate effects in the third dimension. The stress a., is a maximum at an angle of theta approximate to 83degrees (see Figure 3). The stress field may now be used to bridge the gap between macro and micro mechanics and to derive a series of fracture criteria, at the micro and macro level, which ultimately will provide us with a better understanding of the formation of the damaged zone ahead of the crack tip. For example, the stress field is used to derive one such approximate fracture criterion for mode I loading and for a self similar type of fracture, similar to that of Griffith. This criterion shows how the periodic length of the material lay-up microstructure effects the fracturing characteristics of the material system. Comparison with some experimental observations for two different material systems shows a fairly good agreement which substantiates the predicted influence.