Application of an effective SIMP method with filtering for topology optimization of motorcycle tubular frame

Optimal design of the motorcycle tubular frame is a complex problem due to the conflicting nature of the various main design criteria, namely, to reduce the frame mass, to increase torsional stiffness, to restrict bending stiffness and to minimize the maximum structural stress. Frame optimization is even more under the presence of different kinds of decision parameters: discrete (e.g., standardized tube diameters available in the market) and continuous (e.g., angles and fillets). Still nowadays optimal design of motorcycle tubular frames is the result of engineers’ creativity and experience, as well as further suggestions by test drivers. In the design workflow of tubular motorcycle frames Topology Optimization (T.O.) technique it is not a well-established practice. In this paper we aim to present the applicability of Solid Isotropic Material with Penalization (SIMP) method with filtering, to perform an effective topology optimization of motorcycle tubular frames. After the definition of an effective design domain boundaries, where by applying typical road excitation, the topology optimization of multi-load case is implemented with the objective of maximizing the set of weighted stiffnesses resulting from individual load cases. The case study of the “DUCATI 600SS” frame, made with three different cross-section tubes in chrome- molybdenum alloy steel, where the motor performs the stiffening function, provides the results to support the methodology by validating it with experimental data.