SEDL / STP / STP791-EB / STP37094S

A Perspective on R-Curves and Instability Theory

McCabe, DE
Senior engineer, Westinghouse Research and Development Center, Pittsburgh, Pa.

Ernst, HA
Senior engineer, Westinghouse Research and Development Center, Pittsburgh, Pa.

Pages: 24    Published: Jan 1983

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Abstract

Several aspects of elastic-plastic R-curve theory and instability analysis are discussed. It is shown how material flow property effects can be incorporated into the R-curve in place of the more common practice of incorporation into J crack drive. Formulas for deformation theory J that adjust for slow-stable crack growth in compact (CT) and center cracked tension (CCT) specimens are presented. For cases of extremely large crack extension where conditions of deformation theory J are violated, an expression for modified J also is presented. JR-curve data obtained from a 4T size compact specimen were used to predict instability in a displacement controlled CCT test for 2024-T351 aluminum.