Elastic-plastic fracture mechanics

Abstract

Deformation theory of plasticity is applied to generalise fracture mechanics concepts to nonlinear material behaviour. Special emphasis is put on the J-integral as energy release rate and crack-tip intensity parameter in perfect analogy to linear-elastic fracture mechanics. Its definition as path independent integral and calculation from experimental records is addressed. Requirements, extensions, applications, validity and limitations of J as “crack driving force” are discussed, in particular its application to ductile crack extension. The asymptotic J-dominated stress and strain fields at the crack tip are derived. Alternative fracture parameters like dissipation rate, crack-tip opening displacement (CTOD) and angle (CTOA) are introduced and procedures for structural integrity assessment based on these parameters are briefly introduced.