Mechanical Engineering Faculty Research

Title

A Parametric Study of Mixed-Mode I/III Ductile Fracture in Tough Materials under Small Scale Yielding.

Document Type

Article

Publication Date

7-1998

Abstract

Mixed-mode I/III crack growth in high purity, tough materials under small-scale yielding conditions are studied using an elastic–plastic continuum model. The fracture process is controlled by the interaction of two mechanisms, the growth of the existing voids and the nucleation of new voids under increased plastic strain. Crack growth is constrained to occur only along the initial crack plane because of the symmetry conditions of load and geometry. The effects of mode mixity on mixed-mode fracture toughness are studied under different circumstances, and the effects of other factors, such as microstructural parameters, continuum properties of the solid and the crack-tip constraint, are also examined. The study indicates that mixed mode I/III fracture resistance, followed by some amount of ductile crack growth, displays a minimum at a critical phase angle [φ=tan−1(KIII/KI)] between 45° and 55°. This indicates a direction at which an initially flat mode I crack may reorient to cause slant fracture or formation of shear lips.

Publication Title

Engineering Fracture Mechanics

Volume

60

Issue

4

First Page

407

Last Page

420