Experimental and Numerical Determination of the Local Fiber Volume Content of Unidirectional Non-Crimp Fabrics with Forming Effects

Detailed knowledge of the local fiber orientation and the local fiber volume content within composite parts provides an opportunity to predict the structural behavior more reliably. Utilizing forming simulation methods of dry or pre-impregnated fabrics allows to predict the local fiber orientation. Additionally, during the forming process, so-called draping effects like waviness, gapping or shear-induced transverse compression change the local fiber volume content. To reproduce and investigate such draping effects, different manufacturing tools have been developed in this work. The tools are used to create fabric samples with pre-defined deformation states, representing the different draping effect. The samples are evaluated regarding the resulting fiber volume content. The experimental results are compared with the predictions of an analytical solution and of a numerical solution based on draping simulation results. Furthermore, the interaction of the draping effects at arbitrary strain states is discussed regarding the resulting fiber volume content.