The optimization of the structural integrity for a CFRP wheel through the use of FEA

M.Ing. (Mechanical Engineering)Abstract: As part of the effort in reducing the weight of a lightweight solar powered vehicle, alternative options for lighter construction material for the wheel should be investigated. The aim of this dissertation is to evaluate the structural integrity of a carbon fiber reinforced polymer wheel by numerical analysis and verify the results through limited structural integrity tests on manufactured test specimens. A framework for the process of this investigation is drafted and verified during the course of this analysis. This framework can be utilised for similar analysis’s subject to a few limiting factors identified in the scope of the project mainly the anisotropic material properties and static failure modes for the part. These limitations form part of the recommendations for further study in order to expand on the flexibility of the framework for multiple scenarios involving carbon fiber reinforced polymer parts. Following the framework, a CAD model of the part was designed based on the part requirements and manufacturing process for such part. Tensile test samples were manufactured and tested in order to attain the material properties of the CFRP which would then be utilised to generate a custom anisotropic material in the FEA software. The simulations were setup and run in two different test variations based on common failures seen in commercially available CFRP wheels. This provided maximum static loadings and deformation which model could withstand. From the CAD model a two piece aluminium mould was CNC machined in order to provide an accurate manufacturing process which would allow the layup of test specimens which accurately represent the CAD model. Eight test specimens were manufactured, providing 4 samples per each of the 2 test variations. The samples were setup for the structural integrity testing and tested till failure with the load and deformation being measured The results from the structural testing and FEA simulations were compared, with FEA simulations measuring a maximum load possible on the model up to 20% greater than that of the test specimens and deformation up to a maximum of 25% greater. Accuracy limitations are attributed to imperfections in the manufactured test specimens. With these accuracies taken into account the simulations can be adjusted to allow for the improving of the overall design prior to manufacturing prototypes to be tested. Potential over engineering of the samples based on increasing the structural integrity of the model using the 20% loading accuracy and 25% deformation accuracy will have little impact on the final design