Design and Experimental Analysis of an Adhesive Joint for a Hybrid Automotive Wheel

When it comes to lightweight design of automotive wheels, hybrid designs consisting of a carbon composite wheel rim and a metallic, e.g., aluminum alloy, wheel disc offer significant potential. However, the conventionally used bolted joint between the two parts is complex and requires compromises in lightweight design due to the additional mechanical elements. Within this research, an adhesive joint for a hybrid wheel is developed in order to demonstrate its performance and lightweight potential. The main challenges are the reliable resistance against high structural loads during different load cases, as well as the residual stresses in the joint due to different thermal expansion rates of the composite and aluminum material. The developed joint combines an adhesive bond with a form-fitted geometry while still enabling an assembling process of the wheel disc in rotational direction. In addition, adaptations of the fiber layup in the rim area significantly reduce the thermal residual stresses in the joint by 47%. Subcomponent specimens, which represent the joint of an aluminum spoke with the composite rim, are manufactured and tested at different temperatures and load cases. The test results show sufficient strength of the adhesive joint as well as an improvement of the developed form-fitted joint compared to a basic adhesive bond. The adhesively joined wheel offers a lightweight potential of 6% compared to the bolted wheel.