Prediction of Process Forces in Fiber Metal Laminate Stamping

The stamping of fiber metal laminates (FMLs) at thermoforming temperature of the thermoplastic matrix is investigated. The studied FML types consist of a unidirectional carbon fiber-reinforced core that is attached to metal cover layers either made of a steel or magnesium alloy. An analytical model is established in order to predict the process forces during forming, which are the blankholder force required to make the metal covers yield plastically, the punch force, and the corresponding load distribution on the individual layers (outer layer, core layer, and inner layer). The global forces are primarily verified through experimental force measurements, while numerical simulations are mainly performed to assess the resulting load distribution with the help of strain distributions in the cover layers. The results show that the introduced model can be applied successfully if the stamp-forming process is dominated by friction-induced tensional loading rather than by bending.