Calculating plastic collapse loads using a novel work criterion

Abstract

Initially design by analyses in pressure vessel design codes was based on the elastic stress categorization approach. This way of design has been found to be somewhat subjective and so depends on the skill and experience of the analyst. Ways of classifying elastic stresses like the 'stress linearisation' method were developed. In principle pressure vessel design codes recognized that a better way of design was to adopt an inelastic approach. The inelastic approach was not practical before the early 1990's due to computer limitations. In the late l 970's and early l 980's computers still lacked the processing power they have today. To make up for this, researchers developed pseudo-inelastic or reduced modulus methods of design. At first these reduced modulus methods were used for the categorization of elastic stresses. As computer power increased, some inelastic methods of design, targeted to prevent specific modes of failure, were developed. When running an elastic-plastic analysis including strain hardening and large deformation or alternatively using experimental analysis, the designer is faced with the problem of how to define the plastic load.