EFFECT OF MANUFACTURING PROCESS INDUCED FIBER WAVINESS ON MECHANICAL PROPERTIES OF COMPOSITE STRUCTURES BY EXAMPLE OF A PREPREG FORMING PROCESS

In this paper an approach to include the effects of a forming process on preimpregnated fibers into the design of composite structures by analysis of the resulting fiber waviness is presented. Therefore the influence of the forming process and a measurement method for fiber waviness is discussed. Fiber waviness in formed composite parts is characterized by the power spectral density and the resulting fiber angle distribution. This modeled using a discrete inverse fast Fourier transformation. Subsequently the mechanical properties are calculated based on these fiber angle distributions in a finite element analysis. An additional comparative experimental analysis of a specimen manufactured with and without the influence of the forming process is presented. The measured fiber angle distributions are analyzed and resulting first ply failure for both cases is predicted using the presented method.