Methodological aspects of creep prediction for heat-resistant steels and alloys. Part 2. Prediction over wide ranges of temperatures and loading times

Abstract

Evaluation of creep and long-term strength of metallic materials over wide temperature and stress ranges by calculation with equations on the basis of a limited body of initial data is proposed. The efficiency of evaluation can be greatly increased by systems analysis of known experimental data.

Cyclic thermal creep model for the bodies of revolution

“…Since such structural elements operate under the joint action of force and thermal fields, evaluation of their deformation behavior is one of the important problems for ensuring necessary service life. As is known, the level and frequency of load and temperature variations can greatly influence creep and time to fracture [1][2][3][4][5][6][7].Increasing requirements to materials consumption, life, and reliability gave rise to significant results obtained in creep and creep rupture strength calculations for materials and structures [1,[5][6][7]. Polymer structural elements are usually subjected to analysis for studying the interaction between cyclic force and thermal fields [8].…”

“…Since such structural elements operate under the joint action of force and thermal fields, evaluation of their deformation behavior is one of the important problems for ensuring necessary service life. As is known, the level and frequency of load and temperature variations can greatly influence creep and time to fracture [1][2][3][4][5][6][7].…”

“…where z stands for any unknown of system (2), and x, t, and x are formally independent variables. Since z i is the periodic function of x, its average-per-period values are equal to zero…”

“…Substitute expansions (12) and (13) into system of equations (2) and solve the relations using period averaging (9). Then for the equilibrium equations and for the stress-strain relations we accordingly have …”