Elastic–Plastic Fracture Mechanics Guidance and Analysis Validation

Abstract

Damage tolerance is an important consideration in space structures applications. However, many space and launch vehicle components experience large cyclic stresses and cannot be evaluated using linear elastic fracture mechanics (LEFM). In these instances, elastic–plastic fracture mechanics (EPFM) can be used in the damage tolerance verification process. This paper provides practical guidance on the use of LEFM and EPFM as they relate to space structures. The limitations of LEFM-based approaches to damage tolerance verification are explored, demonstrating that inappropriate application of LEFM can be unconservative. Criteria are provided to help the engineer determine if EPFM analysis is required for a given scenario. Finally, a practical method of EPFM-based damage tolerance analysis is introduced and validated against test data from several test campaigns with excellent correlation to experimental data.