Mixed-mode thermoelastic fracture analysis of orthtropic composites

This study demonstrates ability to determine the in-plane stress intensity factors, K_I and K_II, simultaneously under mixed-mode conditions in orthotropic composites by the combined use of least-squares, stress representations which are valid away from the crack and distant measured temperatures. Recognizing the stresses near a crack-tip are dominated by the stress intensity factors, it has not been uncommon to neglect the higher-order stress terms when evaluating these factors. However, and among other considerations, it is typically difficult to obtain accurate temperature information very near the crack-tip. It can therefore be advantageous to employ measured data which originate away from the crack and to retain six to eight terms in the stress functions when evaluating the stress intensity factors. On the other hand, errors in K_I and/or K_II can be appreciable if only the r^-1/2 terms are employed with distant input information.