Life prediction for composite laminates subjected to spectrum fatigue loading

Jeffery R. Schaff, Barry D. Davidson

Research output: Contribution to conferencePaperpeer-review

8 Scopus citations

Abstract

A model is presented for predicting the residual strength and life of composite laminates subjected to randomly ordered spectrum fatigue loadings. It is assumed that the laminates undergo proportional loading, that the residual strength is a monotonically decreasing function of the number of fatigue cycles, and that the probability of failure after an arbitrary number of cycles can be represented by a two parameter Weibull distribution. The model also incorporates a `cycle mix factor' which accounts for the drastic reduction of fatigue life that may be caused by a large number of changes in the stress amplitude of the loading. For uniaxially loaded laminates, the experimental data that is necessary to characterize the model consists of static tension and compression strengths, S-N curves based on constant amplitude fatigue life distributions for three stress ratios, and a limited amount of two-stress-level fatigue test results. The model is verified by comparing predicted fatigue life distributions to experimentally observed fatigue life data for angle-ply and quasi-isotropic graphite/epoxy laminates subjected to different tension and compression dominated FALSTAFF (Fighter Aircraft Loading STAndard For Fatigue) load spectrums. Very good correlation between experimentally observed and theoretically predicted fatigue life distributions is obtained for all laminates and loading spectrums studied.

Original languageEnglish (US)
Pages89-109
Number of pages21
StatePublished - Dec 1 1994
Externally publishedYes
EventProceedings of the 1994 International Mechanical Engineering Congress and Exposition - Chicago, IL, USA
Duration: Nov 6 1994Nov 11 1994

Other

OtherProceedings of the 1994 International Mechanical Engineering Congress and Exposition
CityChicago, IL, USA
Period11/6/9411/11/94

ASJC Scopus subject areas

  • Engineering(all)

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