Matrix Influence on the Impact Tolerance of Carbon Composites made of Non-crimp Fabric

Abstract

An efficient manufacturing solution for aircraft primary structures is the liquid resin injection/infusion (LRI) process with non-crimp fabric (NCF). Nevertheless, the main drawback of non-crimp fabric and liquid resin systems versus state of the art unidirectional prepreg tape (UDPT) is their poor tolerance to low velocity impact (compression strength after impact for the same indentation depth). The influence of the matrix properties (resin system and interlaminar toughening) on the impact tolerance of quasi-isotropic laminate manufactured with biaxial non-crimp fabric is studied. None of the liquid resin systems considered increased the impact tolerance of the NCF-Iaminate. The impact tolerance of UDPT could only be achieved by reducing the most critical impact failure mechanisms, delamination, thanks to an interlaminar toughening concept in the form of a veil positioned between each fibrous layer. The energy absorbed by the laminate during the impact could be qualitatively compared to an analytical estimation of the energy used for indentation and delamination.