Numerical design of rotationally molded composite tie rods

Rotational molding constitutes a promising manufacturing technology for rotationally symmetric components made of thermoset matrix with continuous fiber reinforcement. The present study deals with the numerical analysis of a rotationally molded composite tie rod with metallic load introduction elements. For this purpose, the adhesive joint between carbon fiber reinforced plastic and metallic load introduction element was investigated in more detail. Different geometries of a spew fillet were evaluated to reduce the stress peaks occurring at the ends of the overlap. A design of experiments was used to determine the influence of the different parameters. An optimized geometry was derived and compared with a reference in terms of stress distribution. Subsequently, test specimens were rotationally molded and mechanically tested. The results of the study show that the maximum stresses within the adhesive layer can be reduced with an optimized spew fillet, and thus a higher mechanical tensile load of the composite tie rod can be achieved.