Creep Analysis of Metallic Structures in the Presence of Thermal Gradients Using Newer Constitutive Relations

Several newer constitutive relations have recently been proposed for describing the mechanical behavior of metals and alloys under elevated temperature creep conditions. A salient feature of the mathematical structure of many of these relations is that they typically express the nonelastic strain rates as functions of the current values of stress, temperature, and some other suitably defined state variables. A computational scheme is presented in this paper for the inelastic analysis of metallic structures subjected to both mechanical and thermal loadings and obeying constitutive relations of the type described before. Several numerical examples for the creep of thick-walled spheres, cylinders, and rotating disks in the presence of thermal gradients are presented. The particular constitutive relations used in these calculations are due to Hart. The proposed computational scheme is found to be very efficient from the view point of both computational time and effort. The effects of previous cold work on the stress redistribution and creep of these structural elements are discussed.