Material characterization of non-crimp braided CFRP for aeronautic applications

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Material characterization of non-crimp braided CFRP for aeronautic applications

Middendorf, P. / Broucke, B. van den / Geßler, A. / Maidl, F. / Metzner, C.

It is well known that the circular braiding technique provides an innovative and flexible method for the production of certain types of fiber reinforced polymeric parts. A major drawback of this production method is that it produces materials with possible largely crimped yarns, hence causing a non-ideal orientation of the fibers inside the structure. The mechanical performance of a braided part would be significantly lower than an equivalent non-cnmped fabric (NCF) draped or tape manufactured variant. However, recent developments performed at EADS Innovation Works have resulted in a non-crimped braided CFRP or so-called unidnectional braid (UD-braid) which solves the yarn crimp problem. The presented paper is organized in four different sections which describe different details of the non-crimped braids. An introduction describes the new manufacturing method itself and provides a comparison with other manufacturing techniques. Experimental investigations on the determination of geometrical, mechanical and damage characteristics are presented in the second part. Afterwards an overview of the meso-mechanical finite element model of a material tepresentative volume element is presented. This model is used in non-linear numencal simulations to investigate the mechanical as well as the damage behavior. In a last section, the paper shows the applicability of the method to aeronautic structures by means of a set of possible validation parts.