Effect of interface layer on fatigue crack growth in an aluminium laminate

Abstract

A B S T R A C T In order to study the effect of an interface layer on fatigue crack growth, a thin pure Al layer was sandwiched between two LY12 plates using explosive bonding. Experiment shows that as a fatigue crack approaches the interface a remote plastic zone appears in the soft Al layer. Energy dissipation in the interface leads to significant deceleration of crack growth rate. FEM analysis shows that crack arrest is associated with load and distance between the crack tip and the interface. The size of the plastic zone can be calculated and used to predict the reduction in crack growth rate. The predictions agree well with the experimental results.Keywords arresting; fatigue crack growth; interface layer. N O M E N C L A T U R Eσ 0Al = yield strength of Al a = crack length FEM = finite element method h 1 = thickness of one component of the bimetal lamella L c = critical distance from crack tip to the interfaceat which plastic deformation is initiated L (0−i) = distance from crack tip to the interface K = stress intensity factor range da/dN = fatigue crack growth rate r c = cyclic plastic zone (CPZ) size r p = monotonic plastic zone (MPZ) R pi = plastic zone size in the interface layer I N T R O D U C T I O NThe mechanical properties of laminate metal matrix composites have been studied in order to predict their endurance lives under different loading regimes. The main differences between composite and plain material are the presence of elasto-plastic mismatch and embedded interfaces. Most studies have dealt with static loading. Erdogen et al. studied the stress intensity factors of a crack approaching to and crossing over the interface. 1 He et al. predicted the direction of growth a crack approaching the interface at different angles using linear elastic analysis. 2 Delfin examined the difference in the elastic properties of metals on both sides of a crack growing normal to 2 Correspondence: J. W. He.

Modeling of crack path in layered architectures composed of dissimilar materials

“…For instance, different structures at different length scales are organized hierarchically to provide stiffness as well as fracture resistance in some biological systems 1 . Multi‐layered components comprising three main functional layers are applied in some moving mechanical systems within the internal combustion engine, which provide the combined properties of high mechanical strength, conformability, good wear resistance, and fatigue performance 3–5 . Multilayer metal films are used to endure large stretching, compressing, or twisting deformations to resist the occurrence of cracking and buckling in stretchable electronics, especially paper‐like electronic displays, wearable electronics, and prosthetic skin 6–8 .…”

“…1 Multi-layered components comprising three main functional layers are applied in some moving mechanical systems within the internal combustion engine, which provide the combined properties of high mechanical strength, conformability, good wear resistance, and fatigue performance. [3][4][5] Multilayer metal films are used to endure large stretching, compressing, or twisting deformations to resist the occurrence of cracking and buckling in stretchable electronics, especially paper-like electronic displays, wearable electronics, and prosthetic skin. [6][7][8] However, these varied advantages offered by layered architectures in the optimization of performance may be limited due to a lack of understanding of the failure mechanisms.A series of studies have been carried out on the mechanisms of fatigue of layered architectures, but most just focus on the effect of multiple layers on the crack growth behavior and note this extends the crack growth life in…”