Large damage capability of non-crimp fabric thin-ply laminates

Abstract

The residual strength of thin-ply non-crimp fabric laminates with large through-the-thickness cracks is investigated in this paper. Analysis methods such as the linear elastic fracture mechanics, inherent flaw, point-stress, average-stress and Finite Fracture Mechanics are used to predict large damage capability. Experiments show that thin-ply non-crimp fabric laminates exhibit high resistance to propagation of large cracks and a remarked crack-bridging effect. Due to the unsuitability of existing models to capture such bridging processes, large damage capability is systematically underestimated by the traditional analysis methods. By taking into account the R-curve of the material in the Finite Fracture Mechanics analysis good predictions of the notched response of laminated plates with large through-penetration damage are obtained using only independently measured material properties; in addition, the Finite Fracture Mechanics model does not require fitting parameters or complex finite element analyses.

Energy release rate of the fiber/matrix interface crack in UD composites under transverse loading: debond-debond and debond-free boundary interactions

“…Several experimental investigations on thin ply laminates have highlighted their main properties [7,8,9,10,11,12,13]: increased fiber content; more uniform packing of fibers; delay and even suppression of intralaminar cracking (called also transverse-, matrix-or micro-cracking) and delamination. A very insightful work documenting how these phenomena are affected by the morphology of thin-ply laminates is the microscopic study of Saito & al.…”

Simulation of the Mechanical Response of Thin-Ply Composites: From Computational Micro-Mechanics to Structural Analysis

“…For simple geometries and loading scenarios, analytical models can satisfactorily predict failure of composite laminates with smooth geometries [174,175,177] or notched configurations [11,16,31,36,46,69,76,115,116,191,193], as long as delamination is not the predominant failure mechanism. These models are particularly suited for material and lay-up screening and for preliminary design and optimisation of composite structures.…”

“…To overcome this limitation of the classical analysis methods, physically-based criteria [11,36,46,116] provide accurate predictions of the notched response of composite laminates without requiring fitting parameters or complex Finite Element Analyses (FEA). Only independently measured material properties are necessary, the laminate strength and the laminate fracture toughness or crack resistance curve.…”

“…This leads to unique features that can make thin-ply composites stronger, and consequently thinner and lighter. This includes woven [13] and non-crimp fabric reinforcements [8,11,14], which exhibit enhanced mechanical properties over conventional fabrics, allowing the development of advanced laminated composites using more competitive manufacturing techniques. Moreover, thin plies make laminate design more flexible.…”

Mechanical properties and drawing process of multilayer carbon-fiber-reinforced plastic sheets with various prepreg thicknesses

“…12 Moreover, the residual strength of thin-ply non-crimp fabric composites with large throughthickness cracks was examined, and experimental research on the mechanical response of a new series of advanced composite materials manufactured using thin non-crimp fabrics has been reported. 13 Tensile and compressive tests on both unnotched and notched specimens were performed using various lay-up processes. 14 The variation in mechanical properties in terms of the tensile strength and elastic modulus of CFRP, GFRP, and CFRP/GFRP hybrid composites exposed to different temperatures ranging from 25°C to 300°C was also studied.…”