Investigations on intrinsically manufactured FRP/metal composites - from embedded inserts to load-bearing hybrid structures

Fiber-reinforced materials offer a huge potential for lightweight design of load-bearing structures. However, the introduction of forces into such structures remains challenging since conventional joining techniques, e.g. screwing or bolting, are often accompanied by local damage and weakening of the material. In order to prevent this, hybridization can be used to introduce component loads in a non-destructive way. In this study, the intrinsic hybridization of a CFRP/metal structure manufactured using Resin-Transfer-Molding (RTM) is investigated. This enables to embed metal structures already during manufacturing of the fiber-reinforced material and, thus, avoids an additional process step, during which inserts or onserts are attached to an already manufactured CFRP structure.

In this project, the influence of intrinsic hybridization on the individual manufacturing steps and the impact on the resulting mechanical performance of the component are investigated. This begins with the preforming step, as the metal structure needs to be integrated into the stack of fiber textiles prior to molding. Depending on the geometry of the metal component, cutting of the fiber patches is required. ... mehrThis is demonstrated by using different geometries of the embedded structure. Moreover, a suitable preforming strategy is derived. During the subsequent mold filling stage, flow front propagation as well as formation of dry spots also depend on the design of embedded structure, which is demonstrated using mold filling simulations. As the process continues, process-induced residual strains develop due to chemical shrinkage during curing and temperature gradients during cooling of the finished part. Corresponding residual stresses are predicted using FEM simulations. The mechanical performance and failure behavior of the individual variants of the hybrid component is evaluated using quasi-static mechanical bending tests.