Hightech.NRW

Development of a CFRP engine hood

Within this project a CFRP engine hood in integral sandwich consruction based on the Ford Focus has been developed. Compared to the steel reference a weight reduction of 60 % has been realised with reasonable lightweight costs of approximately 15 €/kg. Thus with new manufacturing technologies and the development of practical simulation and design methodologies the potential of this material for higher production volumes of >10.000 units/year could be demonstrated.

Up to now the production of high-performance parts made of fibre reinforced plastics (FRP) has been associated with high costs. That is why the innovative gap impregnation process has been developed at the institute for plastics processing (IKV) at RWTH University has been developed. This wet impregnation process allows the fast automated production of FRP parts and thus offers the prerequisites for the series production of the CFRP engine hood.

The design has been conducted at ika by means of the finite-element method. Due to their complex anisotropic material characteristics fibre reinforced plastics demand special requirements to the virtual methods. Within the automotive development process the evaluation of the vehicle part properties under static as well as dynamic load cases has to be facilitated at appropriate time and costs. In addition to this the engineer has to be supported by specialised CAE methods to be able to control the numerous design parameters of FRPs and thus utilising the full lightweight potential of the material. The results of these methods developed at ika and their quality of prognosis have been verified based on real world tests. Design and optimisation of the engine hood have been conducted in close cooperation with the manufacturing technology experts to ensure a material and production appropriate construction. Here a main challenge was to solve the conflict between the functionally important stiffness of the part and the compliance needed for pedestrian protection. By combining high local stiffness and energy absorption of the sandwich construction it was possible to realise a pedestrian protection level in head impact situations comparable to the reference within the existing package and without the usage of active systems.