Re-design and structural optimization of a Carbon Fiber Retractable Hard Top cover frame for a spider sport car

This thesis project has its origin in a customer’s company request that ask to evaluate the structural performance of a Retractable Hard Top Cover frame of a spider sport car and, in particular, to analyze its structural frame made of Aluminum and to design a new alternative structure, realized in carbon fiber composite material, evaluating the possible performance advantages. Although this kind of component could seems a trivial case of study, in reality there are many different aspects and situations that must be taken into account. In particular, the Retractable Hard Top is responsible not only of the structural integrity of the esthetical external body shell but it has to withstand some different situations: •??It must resist to aerodynamics loads both in its closed and opened position. In this case, it’s fundamental to take into account that the overture of the Retractable Hard Top must be ensured also when the vehicle is moving, until a speed of roughly 50 Km/h. •??When the mechanism is closed, the Retractable Hard Top must ensure a specific pressure in the supports fixed on the body in order to both avoid vibration and ensure the correct functioning of the seals. This case is referred as “Coupling” load-case. •??The structure must ensure a vibrational behavior compliant with the passenger acoustic comfort requirements; •??Considering durability, we must avoid any kind of plastic deformation that could alter any of the previous requirements. All these parameters were investigated using specified load-cases with relative constraints that will be analyzed in details during the course of this thesis project. These load-cases will takes into account all the operational loads and are employed to determine frame static stiffnesses, in particular: •??Bending stiffness; •??Torsional stiffness; •??Coupling stiffness; •??Local stiffnesses. The stiffness value measured for the aluminum frame will be used as target for all the following optimizations. In particular, topological optimization was used to obtain a general component layout suggestion since it allow us to understand which are the load path in the material. The output of the topology optimization will represent the first guideline for the definition of the new frame shape and, after the realization of a 3D geometry, a 3 phases optimization process was adopted in order to determine all the parameters required to define the laminate layout considering all the required manufacturing constraints. All the performances evaluation are addressed using the Finite Element Method, relying on the Altair suite. In particular, Hypermesh is adopted to build the model and conduct all the pre-processing phase, while OptiStruct is used as solver. The 3D design of the new structure was realized using CATIA V5 as software.