University of Illinois Urbana-Champaign

Effects of mean stress and prestrain on fatigue damage summation

Topper, T.H.; Sandor, B.I.

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https://hdl.handle.net/2142/112044

Description

Title
Effects of mean stress and prestrain on fatigue damage summation
Author(s)
  • Topper, T.H.
  • Sandor, B.I.
Issue Date
1968-08
Keyword(s)
  • Stress
  • Prestrain
  • Fatigue Damage
Abstract
A cumulative damage procedure based on smooth specimen tests of 2024-T4 aluminum alloy and aircraft quality SAE 4340 steel is formulated in which the effects of prestrain and mean stress on fatigue life are investigated separately. It is assumed that life reductions due to prestrain or mean stress at a given strain level may be separately incorporated into a simple cycle ratio damage summation. Small plastic prestrains are shown to cause considerable life reductions. Larger prestrains appear to have little additional adverse effect. It was found possible to adequately correlate results with and without mean stress by a parametric representation of mean stress and strain amplitude. Analysis of arbitrary stress-strain sequences indicates that the proposed damage summation procedure gives adequate life predictions. Cycle ratio summations were close to one for both stress controlled and strain controlled tests in which sequence, number of blocks, fraction of life at mean stress, and the life fraction at which plastic straining occurred were all varied.
Publisher
Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report Name or Number
  • TAM R 318
  • 1968-0374
ISSN
0073-5264
Type of Resource
text
Language
eng
Permalink
http://hdl.handle.net/2142/112044
Sponsor(s)/Grant Number(s)
Aeronautical Structures Laboratory, Naval Air Engineering Center, Contract No. NOO-156-67-C-1875
Copyright and License Information
Copyright 1968 Board of Trustees of the University of Illinois

Owning Collections

Technical Reports - Theoretical and Applied Mechanics (TAM) PRIMARY
TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.