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The development of new materials that are technically and economically viable is no small endeavor. The risks, costs, and time involved in research are usually so high that only governments or private consortia can bear them. And so it has been with the trajectory of carbon fiber reinforced composites, which are capable of providing the lightweighting needed for fuel efficiency, and the mechanical strength required for safety. After a long development cycle, this material is now being widely used by the military, in commercial aircraft, and in the automotive industry. Automotive Carbon Fiber Composites: From Evolution to Implementation, written by Dr. Jackie Rehkopf, senior researcher at Plasan Carbon Composites, gives a high-level summary on carbon reinforced fiber composites specific to the automotive industry in today’s market and its vision for the next 5 to 10 years.

A RIM material was selected for the rear bumper fascia of the Ford GT. As part of its performance criteria, the rear bumper fascia is required to withstand a 1.5 mph corner pendulum impact without sustaining permanent damage. Finite element modeling of this component was undertaken to predict whether the designed bumper fascia would meet the impact criteria. The mechanical properties of the material were required as input to the model, including the yield point and a representation of high strain rate behavior. The paper will present the testing methodology, the determined dynamic yield point, and a material model incorporating strain-rate sensitivity.

Polyurethane foams developed for interior automotive applications were tested to determine their mechanical responses to uniform dynamic compression. Specimens 50x100x100 mm were compressed to 25%, 50% or 75% strain at nominal strain rates of 0.14/s to 14/s. From 1 to 100 compression cycles were imposed on the specimens. A recovery period was provided between cycles. In all cases, the foam undergoes cyclic softening. The percent reduction in stress response varies with strain, and is greatest at the low strain levels within each compression cycle.