Integrated structural analysis and design using 3-D finite elements

Abstract

<p>When structural analysis is performed via iterative solution technique it is possible to integrate the analysis and design iterations in an integrated analysis and design procedure. The present work seeks to apply an integrated analysis and design approach due to Rizk to the problem of hole shape optimization in thick plates.</p> <p> The plates are modeled by three dimensional eight noded elements. An element by element (EBE) preconditioned conjugate gradient (PCG) method is used for the structural analysis, because this method is well suited for poorly banded three dimensional problems. The plates were optimized so as to minimize the stress concentration near the hole measured by the ratio of the Von Mises stress to the applied boundary stress. The analysis program was validated by comparision to a commercial finite-element program as well as photoelastically obtained stress concentrations. Similarly, the optinlization procedure was checked against plates optimized by a photoelastic technique. Good agreement was observed.</p> <p> The integrated analysis and design approach tested here is based on partially converged solutions of the EBE-PCG iterative process. A study of the effect of the number of iterations on analysis and derivative accuracy was performed. Based on this analysis a choice was made for the number of iterations to be used in the integrated analysis and design procedure. It was found that the cost of the design could be significantly reduced with only minimal effects on the final shape and stress concentration factor.</p>