SEDL / STP / STP1171-EB / STP18039S

Assessing a Material's Susceptibility to Constraint and Thickness Using Compact Tension Specimens

Smith, E
Professor, Manchester University, UMIST Materials Science Centre, Manchester,

Griesbach, TJ
Program manager, Electric Power Research Institute, Palo Alto, CA

Pages: 11    Published: Jan 1993

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Abstract

If the plastic component JDP of the deformation J integral JD for a nongrowing crack can be related, via a single eta factor, to the plastic work integral, using a single expression that is valid for all deformation levels, both JD and modified J integral JM crack growth resistance curves can be obtained from load, load-point displacement, and crack extension measurements using a single specimen. A theoretical analysis of a simulation model shows that the compact tension specimen, where the deformation is predominantly bending, satisfies this condition; it is not satisfied when there is significant tensile deformation. It is thereby argued that compact tension specimen JM (or JD) resistance curves provide an ideal basis for assessing the susceptibility of a material to thickness-induced constraint effects.