Tests on the ductility of asymmetric part-through center cracks in plates

Welds, shoulders or other asymmetries may eliminate one of the shear bands of symmetrically cracked parts, giving less ductility than the corresponding symmetric specimens and increasing the stiffness requirements for stability. Experiments on part-through center cracks in plates of 1018 cold finished steel show that the growth displacement in the asymmetric case is about half that of the symmetric one. Unconstrained plane strain singly grooved asymmetric tests of the same material show less ductility by a factor of two to three. Expressions for theJ integral and the tearing modulus in both the asymmetric and symmetric cases are found and used to describe the growth resistance. To further understand the deformation, a macromechanical model represented by sliding off and fracture, based on an idealization of the underlying physical mechanisms, is applied to the test data.