Principle of Tailored Fiber Placement
A special characteristic of continuous fibre reinforced composites is their anisotropic properties. Only along the fibre direction exist the maximum properties. Already small differences between fibre orientation and angle of maximum stress reduce the load carrying capacity enormously. Therefore, designers attempt to arrange the fibres in such a way that they follow the stress field in the composite component under end-user conditions. This is what is meant by the term `tailor-made material´.
Using analytical and numerical calculation methods the stresses in components can be determined qualitatively and quantitatively. The example shows the calculated stress distribution in a torsionally loaded disc.
The FE-analysis generates a orientation plot of the principal stresses. The direction orientation indicate a stress field aligned fibre orientation along the two drawn curvilinear patterns which intersect in an angle of 90°. Such an optimal stress field aligned fibre orientation results in fibres being placed alternating under +45° and -45° over the whole disc area. In the centre area the loads are higher than at the outside so that the thickness of the disc should smoothly change from thick at the centre to thin at the outside edge. With conventional semi-finished reinforcements such as fabrics, multiaxial warp knitted fabrics and braids this is only partly possible.