SEDL / STP / STP1296-EB / STP16241S

A Practical Methodology for Elastic-Plastic Fatigue Crack Growth

McClung, RC
Manager and Institute scientist, Southwest Research Institute, San Antonio, TX

Chell, GG
Manager and Institute scientist, Southwest Research Institute, San Antonio, TX

Russell, DA
Principal engineer and member, Technical Staff, Boeing North American (formerly Rockwell International), Canoga Park, CA

Orient, GE
Principal engineer and member, Technical Staff, Boeing North American (formerly Rockwell International), Canoga Park, CA

Pages: 21    Published: Jan 1997

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Abstract

A practical methodology is being developed to characterize elastic-plastic fatigue crack growth (EPFCG) behavior. The methodology will be implemented in engineering software for crack growth analysis and life prediction of advanced reusable aerospace propulsion systems. The correlating parameter upon which the methodology is based is the range of the J-integral, ΔJ. Existing J solutions are summarized, and robust methods for developing new J solutions under various loading configurations are introduced and validated. Some practical crack growth algorithms required to translate a J calculation into a quantitative prediction of EPFCG life are highlighted. Crack closure plays a significant role in the engineering characterization of EPFCG rates, and simple algorithms to estimate closure stresses are described. Other algorithms address the tearing-fatigue interaction near final instability and the estimation of required material properties. Early results from experimental verification tests are reported.