Study on Fracture of Orthotropic Material for Cracks under Pure Shear Stress

Abstract

Of growing importance under sever circumstances is the study on stress analysis and fracture mechanics for composite material structures. Particularly, the primary concern in design of structures and machines should be the initiation of cracks due to excessive deformation, exfoliation in material or other material defects. In evaluating safety, it is indispensable from the structural design point of view that the k value should be made known by an analysis conducted in advance. In this study, the stress intensity factor (Mode II) under a pure shear stress was obtained using the photoelastic method and caustic method, applying an isotropic material and an orthotropic material (copper fiber epoxy composite (C.F.E.C.) developed by the authors), each containing a crack, to the fracture mechanics. Results were compared with theoretical values. As a result, this method was found useful and the effect of the direction of the primary axis of this material on the stress intensity factor was clarified.