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Most of the carmakers show a clear interest in the replacement of metal by continuous carbon fiber composites to reach their targets in terms of lightweighting while keeping or improving the global performances of each new vehicle. Thanks to its complex heterogeneous microstructure this material provides a better ratio mass/strength than metal for this purpose, especially for crash objectives. One of the challenge to fully integrate this advanced material into the next vehicles structures is to be able to accurately predict its post-failure behavior in order to define the best optimized design. An efficient behavior prediction for crash performances is reached when the simulation is able to capture the correct dissipated energy and the associated damage not only globally but also locally.

Long fiber reinforced plastics (LFRP) have exhibited superior mechanical performance and outstanding design flexibility, bringing them with increasing popularity in the automotive structural design. Due to the injection molding process, the distribution of long fibers varies at different locations throughout the part, resulting in anisotropic and non-uniform mechanical properties of the final LFRP parts. Images from X-ray CT scan of the materials show that local volume fraction of the long fibers tends to be higher at core than at skin layer. Also fibers are bundled and tangled to form clusters. Most of the current micromechanical material models used for LFRP are extended from those for short fibers without adequate validation. The effect of the complexity of long fibers on the material properties is not appropriately considered. Thus, modeling of these materials is lagging behind the material manufacturing and design development, which in turn limits their further development.