Finite element study of lean duplex stainless steel semi-elliptical hollow section members with circular perforation subjected to torsion

In this paper, a finite element analysis based systematic parametric study has been conducted on perforated Lean Duplex Stainless Steel semi-elliptical hollow section members subjected to torsion. Upon validation of finite element modelling procedure with experimental results, a parametric study was conducted on members with single circular perforation, on either flat or curve element of semi-elliptical hollow section. The diameter of the perforation was varied from 10% to 90% of the flat element length. Five different failure modes were identified for perforated members and reported in this study. The finite element results generated from the parametric study were further used to propose design equations. Initially, design equations for unperforated members were proposed in three different formats - (a) Direct Strength Method, (b) European code and (c) Deformation Based Method (in line with Continuous Strength Method). A reduction factor, expressing as a function of both cross-section slenderness and perforation diameter, was incorporated to extend these proposed design equations to perforated members. Efficacy of all proposed design rules were assessed by conducting reliability analysis.