Methodology for characterization of internal structure parameters governing performance in NCF composites

Mechanical performance of non-crimp fabric composites is very dependent on their internal meso- and micro-structure which is defined by the manufacturing process of the fabric and composite processing conditions. This paper identifies the most important parameters which control mechanical properties of these materials. The identification is based on experimental observations and available theoretical findings. Characteristics of the internal structure of non-crimp fabric composites are analyzed in context of their significance for in-plane elastic and failure properties. Methodology for determination of most typical geometrical parameters of composites using optical observations of cross-sections of manufactured laminates is described. The methodology is applied to characterize cross-ply and quasi-isotropic composite laminates. These results are analyzed and a comparison between the laminates is performed.Discussion concerning advantages and disadvantages of the proposed methodology in terms of accuracy and usefulness along with practical recommendations of its application are presented.