Progressive cracking mastercurves of the transverse ply in a laminate

Abstract

In this study, progressive cracking of a transverse layer in a cross‐ply composite laminate subjected to tensile loading is considered. Using the results of a probabilistic cracking model, approximate relations for crack density as a function of stress are derived for initiation‐controlled and propagation‐controlled cracking. It is shown that the crack density evolution in the transverse ply can be represented by a mastercurve in suitably normalized coordinates. The mastercurve approach is applied to progressive cracking in glass/epoxy laminates. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Prediction of crack onset strain in composite laminates at mixed mode cracking

“…This is in agreement with previous findings regarding COS under on-axis tension (i.e. pure mode I conditions), that COS of relatively thin transverse plies agrees with critical ERR criterion of fracture [3][4][5][6]. It is seen in figure 3 that the COS is underestimated by (9) for relatively large off-axis angles, o 30 ≥ α .…”

“…By contrast, in cross-ply composites with relatively thick transverse plies, subjected to on-axis tension, the crack propagation criterion is met at lower strains than the initiation criterion, and COS of intact laminates is determined by ply strength [3][4][5][6]. Circumstantial evidence suggests that the same holds true also for complex loading involving both transverse tensile and shear stresses in the cracking ply.…”

“…The most frequently used laminate configuration in such studies has been cross-ply composite of lay-up [0 n /90 m ] s , subjected to tension along the 0º direction, and developing cracks along fiber direction of the 90º ply. It has been observed that the crack onset strain (COS) increases with reduction of the transverse ply thickness for relatively thin 90º ply while remaining constant for relatively thick transverse ply [3][4][5][6].…”

Thin-ply polymer composite materials: A review

“…This is a deterministic size effect that occurs at the meso-scale, known as the in-situ effect. The neighbouring plies cause a constraining effect on the embedded ply, reducing the available elastic energy and delaying damage propagation in the matrix [4,[70][71][72][73]. Therefore, the ply strengths cannot be treated as intrinsic lamina properties [22,74], but as in-situ properties that depend on the material and geometry of the laminate [23,69,75].…”

Finite fracture mechanics analysis of crack onset at a stress concentration in a UD glass/epoxy composite in off-axis tension

“…Hence both initiation and propagation criteria have to be fulfilled for a crack to appear at a given load in a confined, intact UD ply (see e.g. [36,47,48]). …”