Application of Whitney and Nuismer stress fracture criterion to composites loaded in shear

Acknowledgement of the current lack of research conducted upon assessing the damage tolerance of a composite loaded in inplane shear and predictions on residual strengths for this loading condition has provoked attempts to rectify this apparent void in composite research. A literature survey in this field has identified three key issues for this apparent deficit: lack of a suitable test method; difficulty in achieving pure shear, and non-existence of a suitable failure criterion. Through a combination of mechanical testing and stress analysis, using finite element analysis, an existing shear test method has been modified for the specific use of evaluating the damage tolerance of composites loaded in inplane shear. To predict the residual strcngth of a composite loaded in inplane shear, an existing stress failure criterion, originally developed for uniaxially loaded composites with notches or cracks was adapted for this loading condition. Both the adapted test method and the modified stress failure criterion proved to be suitable for this task.