Stress Intensity Factor Extractions in NX™ Nastran Using h-Elements

Abstract

An investigation into using standard h-elements for Stress Intensity Factor (SIF) extraction using the Contour Integral Method (CIM) was explored for using several round robin geometries and their publicly available results. The results were plotted against other commercially available software results. Results for corner cracks at a hole with a/t = 0.2-0.3 were generally within 1%, with greater deviation at the free surfaces. Results for through cracks in very thick specimens (width = thickness) and a/t = 0.1 under-predicted by 3%-4%.

The work showed that the CIM may be used with standard h-elements. A code could be automated to perform all appropriate translations, extractions, and integrations. The most accurate meshing techniques were discovered for NX™ NASTRAN. Convergence and reasonable agreement with benchmark cases were performed. Shortcomings were identified for very thick specimens. Several areas of code enhancement were identified, and a few were employed.