Computation of stress intensity factors (KI, KII) and T-stress for cracks reinforced by composite patching

Implementation of Virtual Crack Closure Technique for Damaged Composite Plates Using Higher-Order Layerwise Model

“…In order to see characteristic of behavior of patch repair, first, the patching effect is investigated in terms of nondimensional SIF of patched and nonpatched configurations as the crack length is increased from / = 0.1 to 0.8 as shown in Figure 9. The characteristic of patched plate with asymptotic values of SIF as a function of increased crack length compares well with the results of previous researches [17,18]. It is noted that the values of the nondimensional SIF are virtually unchanged even though the crack length is increased under the condition of suitable patch size.…”

Modelling fatigue crack propagation of a cracked metallic member reinforced by composite patches

“…Actual stress applied on the cracked member section, which is different but related to the nominal stress, will be decreased to improve the resistance of the cracked threshold stress intensity factor range for R = 0 Dr nominal stress range member to fatigue loading and to extend its fatigue life. In other words, a composite patch will cause the stress intensity factor at the tip of the crack of the cracked member to be reduced [8,13,15]. It should be pointed that the intrinsic fatigue properties of the metallic member do not change despite the bonding of the composite patch on the cracked member.…”

“…R c is used for a repaired cracked member to describe the relationship between the stress intensity factor and the length of a crack according to the principles of linear elastic fracture mechanics and average distribution of stress. Determination of the stress intensity factor for a repaired cracked member is a key problem in many numerical analyses [2,8,13,15,17].…”

“…The strain energy release rate at the crack tips is highly reduced [5,8], which results in the improvement of the fatigue life of the cracked member. Therefore, the stress intensity factor analyzed by numerical analysis [8,13,14] exhibits an asymptotic behavior as the crack length is increased and its value decreases considerably in comparison with an unbonded cracked member.…”

Analysis of cracked aluminum plates with one-sided patch repair using p-convergent layered model

“…But most of the studies were confined to very simple analyses and laboratory experiments. Subsequently, other researchers have undertaken more detailed numerical and experimental investigation of the problem to understand the effect of patch repair not only on stress and displacement, but also on other measures like SIF (stress intensity factor), and T-stress [3][4][5][6]. Especially, it was pointed out that SIF at the crack tip as fracture parameter is important for the prediction of the extent of improved performance of a bonded composite repair.…”