A damage-based model for mixed-mode crack propagation in composite laminates

Abstract

A model for the off-axis crack propagation in laminated fibre reinforced polymer composites subjected to multiaxial fatigue loadings is presented. On the basis of several observations reported in the literature, the crack propagation phenomenon can be seen as the result of a series of micro-scale events occurring ahead of the crack tip within a process zone. The mixed mode loading condition defines the type of the micro-scale events which occur in the process zone and lead to fatigue crack propagation. Based on this evidence and by using a multiscale approach to determine the micro-scale stress fields in the matrix, two simple parameters are defined for predicting the crack growth rate through a Paris-like law. By extracting the proposed

Propagation of tunnelling cracks in composite materials under strain and force-controlled cyclic loading

“…Further, the propagation of tunnelling cracks can be represented through an equivalent ERR where two Paris-Erdogan like scatter bands cover the whole mode-mixity (MM) range. 17 Here, the mode-mixity is taken as MM=GII/(GI+GII). If the MM is less than a critical MM*, then the propagation of a tunnelling crack is taken to be governed by Mode I ERR only.…”

“…If the MM is less than a critical MM*, then the propagation of a tunnelling crack is taken to be governed by Mode I ERR only. 17 When MM is greater than MM*, then the tunnelling crack propagation is assumed to be governed by a mixed-mode or primarily Mode II (if Mode II>>Mode I) ERR (see equation (4)). 17 …”

“…Further, the propagation of tunnelling cracks can be represented through an equivalent ERR where two Paris-Erdogan like scatter bands cover the whole mode-mixity (MM) range. 17 Here, the mode-mixity is taken as…”

“…14 Especially in a multi-directional laminate, the propagation of tunnelling cracks occur under mixed mode. [15][16][17] Further, under force-controlled cyclic loading between a fixed maximum and minimum loads, a crack is anticipated to grow in steady-state. The maximum and minimum ERR will be the same and a constant crack growth rate is anticipated.…”

Durability sensor using low concentration carbon nano additives

“…Micro-damage in composites can propagate and develop into macroscopic cracks quickly [11,12] In order to avoid catastrophic failures, the identification of micro-damage should be detected in the early stage [13,14] The micro-damage is generally caused by stress concentration and materials' degradation [15]. Structural health monitoring (SHM) methods used for crack and deformation detection, are based on electrical, acoustic and optical principles [16,17].…”