SEDL / STP / STP1332-EB / STP14968S

An Analytical Model for Studying Roughness-Induced Crack Closure

Chen, N
graduate research assistantSenior research engineer, University of Illinois at Urbana ChampaignCaterpillar Inc., Technical Center, Peoria, IL

Lawrence, FV
Professor, University of Illinois at Urbana-Champaign, Urbana, IL

Pages: 17    Published: Jan 1999

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Abstract

A 2-D analytical model of the combined effects of plasticity-induced crack closure (PICC) and roughness-induced crack closure (RICC) has been developed. A zigzag crack growth path was employed to simulate surface roughness. The two opposing fatigue crack surfaces were translated by the mixed-mode displacement occurring near the deflected crack tip. This translation caused a mechanical interference of the opposing crack surfaces as the crack closed, that is, caused RICC. The gradual transition from RICC- to PICC-dominated crack closure was handled naturally by this model. The influence of the geometrical features of the surface roughness, R-ratio, and the cyclic load range on RICC were examined using the PICC-RICC model. The effect of microstructure on the RICC was examined. Despite the simple, 2-D nature of the model, it predicted the trends of experimental data on near-threshold crack growth behavior reported in the literature.