ISSN: 1945-7553
CODEN: JTEVAB
Page Count: 13

A Damage Function and Associated Failure Equations for Predicting Hold Time and Frequency Effects in Elevated Temperature, Low Cycle Fatigue

Ostergren, WJ
Manager, Mechanics of Materials, Gas Turbine Products Division, General Electric Co., Schenectady, N. Y.

Abstract

A new approach is developed for predicting strain-controlled, low cycle fatigue life at elevated temperature using a proposed energy measure of fatigue damage. This measure of damage, defined as the net tensile hysteretic energy of the fatigue cycle, can be approximated by the damage function σ_TΔε_p, where σ_T is the maximum stress in the cycle and Δε_p is the inelastic strain range. The damage function is applied to predicting effects of hold time and frequency, when time-dependent damage occurs, through failure relations incorporating a variation of Coffin's frequency modified approach. Failure equations are developed for two postulated categories of time-dependent damage.

Keywords:
fatigue (materials), strains, damage, elevated temperature, hold time, frequency

Paper ID: JTE10520J
DOI: 10.1520/JTE10520J
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