Three-dimensional effects on fatigue crack closure in the small-scale yielding regime - a finite element study

• Published in: Fatigue & fracture of engineering materials & structures Vol. 26; no. 8; pp. 663 - 673
• Main Authors: ROYCHOWDHURY, S., DODDS, R. H.
• Format: Journal Article
• Language: English
• Published: PO Box 1354, 9600 Garsington Road , Oxford OX4 2XG , UK Blackwell Science Ltd 01.08.2003; Blackwell Science
• Subjects: 3D finite element analysis; Applied sciences; Condensed matter: structure, mechanical and thermal properties; crack closure; Exact sciences and technology; fatigue; Fatigue, brittleness, fracture, and cracks; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Metals. Metallurgy; Physics; similarity scaling; small-scale yielding; Finite element method; Crack opening displacement; fatigue; Fracture mechanics; similarity scaling; Digital simulation; Theoretical study; Mechanical properties; crack closure; 3D finite element analysis; Fatigue cracks; small- scale yielding
• ISSN: 8756-758X; 1460-2695
• DOI: 10.1046/j.1460-2695.2003.00655.x

ABSTRACT Plasticity induced closure often strongly influences the behaviour of fatigue cracks at engineering scales in metallic materials. Current predictive models generally adopt the effective stress‐intensity factor (ΔΚeff = Κmax–Κop) in a Paris law type relationship to quantify crack growth rates. This work describes a 3D finite element study of mode I fatigue crack growth in the small‐scale yielding (SSY) regime under a constant amplitude cyclic loading with zero T‐stress and a ratio Κmin/Κmax = 0. The material behaviour follows a purely kinematic hardening constitutive model with constant hardening modulus. Dimensional analysis suggests, and the computational results confirm, that the normalized remote opening load value, Κop/Κmax, at each location along the crack front remains unchanged when the peak load (Κmax), thickness (B) and material flow stress (σ0) all vary to maintain a fixed value of . Through parametric computations at various K levels, the results illustrate the effects of normalized peak loads on the through‐thickness opening–closing behaviour and the effects of σ0/E, where E denotes material elastic modulus. The examination of deformation fields along the fatigue crack front provides additional insight into the 3D closure process.