PSI - Issue 68

J. Köckritz et al. / Procedia Structural Integrity 68 (2025) 962–968 J. Köckritz et al. / Structural Integrity Procedia 00 (2025) 000–000

964

3

2. Materials and Methods 2.1. Topology Optimization and aerodynamic optimization of front wing attachments

The investigated components serve as the mounting of the front wing of a formula student (FS) race car, see Fig. 1 (a). They are loaded with a multitude of aerodynamical loads, must withstand the front wing bottoming out due to the low ground clearance as well as load cases required by FS regulation requirements in FSG (2024), but they also direct the air inflow for the aerodynamic components downstream. To achieve a structurally sound and aerodynamically favorable front wing attachment (FWA), a three-stage structural optimization is employed, consisting of initial topology optimization (TO), aerodynamical optimization and TO of the inner structure.

The TO are performed with HyperWorks® with the solver OptiStruct 2021.2. A first estimation of the required structure is achieved by a TO for maximum stiffness of the whole available design space shown in Fig. 1 (b). Sixteen load cases including aerodynamical loads, FS regulation load cases and track bump collisions, which dominate the TO result, are separately applied by beam elements. The load paths from the initial TO are utilized as an initial reference for the aerodynamic optimization of a closed outer shape of the FWA. The optimization is performed with a holistic approach, where a computational fluid dynamics model (CFD) is utilized to evaluate aerodynamic performance of several design stages. The CFD simulations are performed with the software STAR-CCM+ in accordance with best practice guidelines for external aerodynamics. The simulation results have been validated with on-track force measurements and the CFD load cases are based on significant driving states which represent 97% of the expected load cases during a FS competition. The result of the aerodynamical optimization is an adapted symmetrical airfoil and is employed as the basis for the last TO step, where bolted connections and the optimized outer skin of the FWA are set as non-designs, see Fig. 2 (a). Here, the inner structure is topology optimized for minimal mass, combined with constraints for displacement, yield strength YS and fatigue with a minimum of 10 5 cycles for the symmetric front bump collision. The previously described model with load cases and constraints is utilized, the FWA are modelled as shown in Fig. 2 (a) and tetra-meshed with an average element size of 0.5 mm. Finally, a fatigue analysis of the derived design in Fig. 2 (b) is performed. a Fig. 1: (a) Use case of the investigated front wing attachments with position and loading and (b) FEA model for initial and inner structure TO b

b Fig. 2: (a) Result of the aerodynamic optimization of the front wing attachment as basis for the topology optimization of the inner structure with Design (D) and Non-Design (ND) and (b) Topology optimization result of the inner structure, derived design and build direction (BD)