Fibre reinforced plastics (FRP) are being increasingly used in automotive structure panels to reduce the weight due to their superior performance in specific stiffness, strength and energy absorption. On the other hand, the fail safe properties and prediction of failure must be strongly improved to meet all relevant requirements for structure parts.
At first a method for the selection or determination of vehicle components which is suitable for FRPs will be described. The method is based on the determination of the so called load anisotropy value (LAIV). The method was firstly developed by Durst for 2-dim. static load situations. Later Alberts proposed to extend it to 3-dim.l cases. The basic idea is to use the FEM results, select the relevant stress information and determine the major direction of loading which results in LAIV. Fang and Grote further developed the methods by adding the thickness effects and combine the clustering method proposed by Klein/Wartzak and Dlugosch etc.. In addition to the static load cases a superposition of crash load cases have been realized. A few examples for the determination of LAIV both for stiffness and crash load cases are given. On one example the design of a car part which is suitable for FRP, i.e. how to layout the composite layers and orientations for max. weight reduction and feasible manufacturing will be shown.
One of the most important conclusions which can be driven from the above mentioned results is that many car parts are not suitable for uni-directional or woven FRPs due to the so called fail safe requirements. Either metal (steel or aluminium) or metal-FRP composites may meet these requirements. A new method has been introduced in this work to determine a so called "bending value" to differentiate the appropriate parts for material with high energy absorption and load carrying capability in axial or bending direction.
In addition a FRP-metal hybrid forming method was invented to simultaneously form both sheet metals and thermoplastic FRPs in a single forming die in the same processing step and join them together. This novel method combines the principle of hydro-mechanical forming of metal sheets and the compression moulding of thermoplastic FRPs as well as adhesive bonding. The fail safe requirement can be met and this kind of FRP-metal composite can be used in wheel guiding chassis component with a weight reduction of more than 20%.