ECN publication
Empirical trends and prediction models for fatigue crack growth under variable amplitude loading
Published by: Publication date:
ECN NUC 1996
ECN report number: Document type:
ECN-R--96-007 Other
Number of pages: Full text:
157 Download PDF  

The goal of this report is to review fatigue crack growth behaviour of metallic materials, specifically of steels, under variable amplitude loading. Chapter 1 focuses on load-time data processing to convert a load-time history measured in service into a test load sequence that accurately simulates the service loading on a given component. Decisions and choices which can critically affect fatigue test results involved in subsequent steps in developing a meaningful test load sequence are considered in details. In Chapter 2, first a summary is given of the trends in fatigue crack growth including the threshold behaviour and small crack effects observed in variable amplitude fatigue tests under both simple and complex load histories. Next, an evaluation follows on mechanisms proposed for causing the load interaction phenomenon and on their capability of qualitative explaining experimental results. In Chapter 3, deterministic models of several categories developed for predicting crack growth under variable amplitude loading are reviewed and evaluated based on reported comparisons between predicted and observed results. Consistently with the interest of the present study, a special emphasis is laid on modelling crack growth in steels. Appendix A offers a basic information on the crack closure mechanisms. In Appendix B, crack tip plastic zones in fatigue are defined and the schemes for estimating their sizes are presented. Appendix C gives an outline of the incremental treatment of fatigue crack growth. 74 figs., 3 appendices, 290 refs.

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