Open Access

ARTICLE

The Bauschinger Effect's Impact on the 3-D Combined SIFs for Radially Cracked Fully or Partially Autofrettaged Thick-Walled Cylinders

by M. Perl¹, C. Levy², V. Rallabh,y²

1 University of Canterbury, Christchurch, NZ. On leave from the BenGurion University of the Negev, Beer Sheva, Israel
2 Florida International University, Miami, FL, USA

Computer Modeling in Engineering & Sciences 2006, 11(1), 37-48. https://doi.org/10.3970/cmes.2006.011.037

Abstract

The Bauschinger Effect (BE) impact on K_IN– the combined, Mode I, 3-D Stress Intensity Factor (SIF) distributions for arrays of radial, internal, surface cracks emanating from the bore of a fully or partially autofrettaged thick-walled cylinder is investigated. A in-depth comparison between the combined SIFs for a “realistic” - Bauschinger Effect Dependent Autofrettage (BEDA) and those for an “ideal” - Bauschinger Effect Independent Autofrettage (BEIA) is performed. The 3- D finite element (FE) analysis is performed employing the submodeling technique and singular elements along the crack front. Both autofrettage residual stress fields, BEDA and BEIA, are simulated using an equivalent temperature field and more than 1200 different crack configurations are analyzed. SIFs for numerous crack arrays, n, a wide range of crack depth to wall thickness ratios, a/t, various ellipticities, a/c, several values of the yieldstress to pressure ratio, ψ, and different levels of autofrettage, ε, are evaluated. Autofrettage efficiency, η, for all BEDA cases is determined, and is compared with that of BEIA. The largest combined SIF K_Nmax is found to vary with angular location along the crack front and number of cracks and therefore needs to be evaluated for each particular case. The Bauschinger Effect is found to have a dramatic detrimental impact on the fatigue life of the thick-walled cylinder. For a partially autofrettaged thickwalled cylinder, ε < 100%, it is found that the lower the level of autofrettage, the smaller the Bauschinger Effect is. Increasing ε beyond 60% is found to be counterproductive and is not recommended.

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