Failure behaviour of metal inserts embedded in CFRP subsequent to thermal, mechanical and cyclic pre-damage

Abstract

One of the most efficient implementations of lightweight design is the use of carbon fibre reinforced plastics due to their outstanding specific mechanical properties. With respect to multi-material-design, carbon fibre reinforced plastic parts have to be joined to other components such as load frames or functional elements. The use of embedded metal elements, so called inserts, is favoured to avoid drilling of composites. The fibre continuity is ensured and no local bearing stresses occur. In the work at hand the influence of impact damage on the quasi-static and cyclic strength was evaluated by pre-damaging the components by various impact energies. The components show only a minor reduction of the mechanical properties for impact energies up to 12 J. For impact energies between 12 J and 16 J, a loss in the mechanical properties is evident but final failure only occurred for impact energies above 16 J.Another aim of this study was to derive service-life-prognosis using multiple step tests and to validate these with experimentally determined S-N curves. Due to different damage mechanisms occurring under quasi-static and cyclic loads, a service-life-prognosis based on the multiple step tests was not feasible, however, a service-life-prognosis based on the experimental data is given.