Design & Analysis of Composite Impact Structures for Formula One Using Explicit FEA Techniques

Racecar safety has received an increased amount of attention in the motorsports industry. Along these lines, the use of composites in racecars has improved structural stiffness and crashworthiness, while reducing weight. Besides having high stiffness and low weight, composites are recognized to be very good materials for absorbing impact energy. However, the use of aerospace grade carbon fiber composites in passenger vehicles faces the issues of high cost and long manufacturing cycle times. The design cycle for developing composite impact structures has traditionally been based on experiments with guidance from some simplified empirical models. Recently, a new composite material model has been developed by Mechalog in the Radioss™ crash analysis code. This model takes into account the orthotropic material properties of the composite as well as the failure strains. To model the crushing mechanism, the code determines the stresses within each ply in an element, and deletes those that have reached their ultimate strength as determined by the Tsai-Wu failure criteria. This model has been applied to various composite tube structures of differing cross sections as well as materials. The results show that the mean crush force can be predicted within 15% of the experimental results. In addition, the model has been successfully used to predict the impact energy absorption of a nose cone structure and for evaluating chassis impact integrity for Jaguar Racing Formula One.