Effect of in-plane waviness in unidirectional CFRP composites – Mechanical behavior and failure considerations

초록

This work consists of an investigation of the effects of waviness in key structural properties of carbon fiber reinforced composites. Fiber waviness is a type of manufacturing defect commonly found in composite material parts. Finite element modeling using the commercial platform Abaqus® was performed to simulate unidirectional laminae containing in-plane graded undulations in the shape of sinusoidal waves. The peak misalignment angle was taken as sole influence parameter. Automated model generation was performed through the use of parametric Python scripting. Composites were subjected to in-plane loading and boundary conditions, with analyses being divided into tensile and compressive loads. Results proved that fiber curvature affects local stresses distribution, changing the normal longitudinal stress field and inducing the appearance of normal transverse and in-plane shear stresses. Initial failure was predicted by Hashin failure criterion, which distinguishes between fiber and matrix failure. A strength knock-down effect was observed as misalignment angle increased, favouring a matrix dominated failure mode. The influence on effective elastic modulus was less significant than on strength values. The goal was to provide a computationally efficient analysis framework to support decisions in quality control. © 2017 International Committee on Composite Materials. All rights reserved.

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