Topology Optimization of Injection Molded Short-Fiber Reinforced Thermoplastic (FRP)-Metal-Hybrids

Lightweight design can be used to save resources and reduce greenhouse gas emissions. One way to implement lightweight design isto use short-fiber
reinforced thermoplastic (FRP)-metal-hybrids, which combine the advantages of
metal and FRP. These can be produced with injection molding by inserting a metal
insert into the cavity of an injection molding machine and then over molding it
with FRP. However, there is currently a lack of optimization methods to support
product developers in the design synthesis of such hybrids.
For this reason, a method for the topology optimization of FRP-metal-hybrids
is developed, which aims to increase the pull-out force of the metal insert from
the surrounding FRP without damaging the adhesive bond. A weight reduction of
the metal insert of such a hybrid structure is prescribed. To ensure that no cavities
are created between the FRP and the metal within a sensitivity-based topology
optimization, e.g. in Tosca, the method includes an iterative interruption of the
topology optimization. The FRP is adapted to the changed structure of the metal
insert and the contact pairs between metal and FRP are adjusted. ... mehrDepending on
the structure of the metal insert, the flow paths of the FRP also differ during the
injection molding process. For this reason, a mold filling simulation is performed
in each iteration of the topology optimization to account for the resulting locally
varying anisotropic material properties and residual stresses of the FRP in the
simulation model on which the topology optimization is based.
For a metal insert made of S700 and A3WG6 as FRP consisting of polyamide
6.6 with 30% glass fiber reinforcement, different designs result from the topology
optimization in Tosca with and without application of the described method. By
using the method, designs can be created that avoid premature failure of the cohesive zone. Compared to standard topology optimization in Tosca, higher reaction
forces can be achieved without cohesive zone failure.