Strain energy release rate associated with local delamination in cracked composite laminates

Analysis of delamination in laminates with angle-ply matrix cracks

“…In this case shear lag coefficients K 12 h K 21 ¼ 0 vanish, and equilibrium equations are reduced to two uncoupled second-order differential equations. Details of this case are given elsewhere (Kashtalyan & Soutis, 1999a, 2000aZhang et al, 1994b).…”

“…Better agreement of shear lag predictions for the Young's modulus reduction with the experimental data was observed, however, when the interaction between transverse cracks and delaminations was taken into account . Zhang, Soutis, and Fan (1994b) extended a modified 2-D shear lag approach (Zhang, Fan, & Soutis, 1992a) to analyse balanced [AEq m /90 n ] s laminates, damaged by transverse cracking and local delaminations growing from transverse crack tips. Consequently, closed-form expressions were derived for the reduced stiffness properties of the damaged 90 layer, representing them as functions of cracking density and relative delamination area.…”

Detection of delamination in laminated composites with limited measurements combining PCA and dynamic QPSO

“…It rarely occurs as an independent damage mode and is often associated with and triggered by other damage modes such as matrix cracking. The stiffness degradation due to matrix cracking and delamination has recently been investigated by several researchers [40][41][42][43][44][45]. Theoretical predictions reveal that transverse crack tip delaminations cause significant reduction in the shear modulus and Poisson's ratio of cross-ply and symmetric balanced ½AEh m =90 n s laminates.…”

“…This approach helps in avoiding cumbersome consideration of the repeated laminate element defined by the intersecting pairs of transverse cracks and splits. It also uses an improved 2D shear-lag analysis [41] to determine the stress fields in the explicitly damaged lamina and the In situ Damage Effective Functions to describe its reduced stiffness properties. Reduced stiffness properties of the damaged lamina are found to depend explicitly upon the crack density and relative delamination area associated with that lamina and implicitly upon two damage parameters associated with the neighboring lamina.…”

“…The complete formulation details of the related to the equivalent constraint model (ECM) can be found in Refs. [40][41][42][43][44][45].…”