Bounded Elastic Moduli Multiplier Technique for Limit Loads: Part 1—Theory

Abstract

Statically admissible stress distributions are necessary to evaluate lower bound limit loads. Over the last three decades, several methods have been postulated to obtain these distributions using iterative elastic finite element analyses. Some of the pioneering techniques are the reduced modulus, r-node, elastic compensation, and linear matching methods, to mention a few. A new method, called the bounded elastic moduli multiplier technique (BEMMT), is proposed and the theoretical underpinnings thereof are explained in this paper. BEMMT demonstrates greater robustness, more generality, and better stress distributions, consistently leading to lower-bound limit loads that are closer to elastoplastic finite element analysis estimates. It also leads us to question the validity of the prevailing power law-based stationary stress distributions. Part 2 of this paper offers several case studies to validate this claim.