The Post-Failure Behavior's Prediction of CFRP Parts under Dynamic Loads 2015-01-0692

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. The particular problem to solve when using continuous carbon fiber composites is to take into account the strong anisotropy of the material, not only in terms of stiffness but also in terms of crack and damage propagation. This means the progressive failure model to define in each ply of the composite needs to include a specific damage law associated to simple fundamental loadings such as uniaxial tension and compression. This simplifies the calibration procedure and enables at structural level to cumulate these multiple damage behaviors when the structure is submitted to complex loads. The calibration of such material model requires only experimental testing at lamina level and allows then to predict accurately the behavior of geometrically complex structures.

This paper will address the very last enhancements of e-Xstream multi-scale material modeling strategy to the specific needs of post-failure behavior simulation of continuous fiber composite parts submitted to dynamic loads. This will demonstrate how simulation can be improved, for safety design simulations in particular, in the automotive industry, helping to reduce design delay, cost and weight of the structures.