Significance of Cyclic History Dependent Deformation Phenomena of Metals on Fatigue Life Estimation

Abstract

Simple calculations for determining estimated extremes in fatigue life of metals with or without accounting for cycle dependent hardening, softening and mean stress relaxation in fatigue analysis, are presented. These calculations aid in assessing the importance of cyclic deformation properties in cumulative damage procedures. An SAE 1045 quenched and tempered steel is considered for illustration. In general cycle dependent deformation phenomena may be important only in intermediate and long life situations. The sensitivity of predicted life to cyclic hardening or softening depends on the degree of hardening or softening a material exhibits, whereas in the case of mean stress relaxation it depends on the shape of the cyclic stress-strain curve or the strain hardening exponent. However the need for a proper accounting of cyclic history, recognized as the 'cycle counting problem' in fatigue literature, is the most important requisite of a cumulative damage analysis. Two alternative approaches of dealing with the cycle counting problem are discussed.

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Document Details

Document Type
Technical Report
Publication Date
Jun 01, 1974
Accession Number
AD0784297

Entities

People

  • H. R. Jhansale

Organizations

  • University of Illinois Urbana–Champaign

Tags

Communities of Interest

  • Air Platforms
  • Ground and Sea Platforms

DTIC Thesaurus Topics

  • Accuracy
  • Applied Mechanics
  • Counting Methods
  • Elastic Properties
  • Engineering
  • Fatigue Life
  • Hardening
  • Illinois
  • Long Life
  • Mechanical Working
  • Mechanics
  • Metals
  • Modulus Of Elasticity
  • Plastic Properties
  • Strain Hardening
  • Stress Strain Relations
  • Test And Evaluation

Readers

  • Materials Science (Mechanical Engineering).
  • Structural Health Monitoring of Composite Structures.
  • Theoretical Analysis.