Università degli studi di Modena e Reggio Emilia

This contribution addresses the rotor design process of a Permanent Magnet-assisted Synchronous Reluctance Machine by adopting a multi-physics and multi-objective optimization algorithm. A Finite Element (FE) approach is employed to determine the electromagnetic and structural responses during the optimization. In particular, a detailed FE structural modeling is used, which often is based on simplifications and inaccuracies in the available literature. A genetic algorithm is adopted, with the objectives being the maximization of the mean torque, the minimization of the torque ripple and the minimization of the stress in the rotor. A parametric analysis of the geometric features precedes the optimization to establish the design variables which mostly affect the machine performance, and thus to reduce the computational cost of the optimization. The presented methodology consists of a useful tool for the final stages of the design process, and provides a rotor with a torque ripple reduced by 15.1% compared to an existing design used as a benchmark, while the mean torque and the maximum stress remain the same as the original configuration.

This paper deals with the adoption of composites in the design of the wheel rims of a sports car. With particular reference to cornering structural performance, the design of a composite wheel rim, produced via Resin Transfer Moulding (RTM) led to a reduction in mass and to an increase in bending stiffness. The adoption of alternatives to aluminium alloys allows the unsprung masses, as well as the total mass of vehicle to be contained. This paper provides a comprehensive view of the fatigue tests used for the wheel rim type-approval, followed by a rundown of wheel rims designed by Ferrari S.p.A from 2009 to present. These wheel rims have been classified in terms of mass and stiffness, and manufacturing process like casting, forging, or RTM. The failure modes of the reference Ferrari 488 GTB wheel rim were compared to those of the new composite wheel. In addition, the interpretation of the failures is supported by the results of Finite Element analyses. Though some initial defects led to a loss of stiffness of the wheel throughout the cornering fatigue test, the experimental results show that composite wheel rims are considered safe and they comply with the homologation targets and the Ferrari S.p.A. regulations.

Low-usage and rare earth free high-performance machines are in high demand, pushed by increasing costs and supply issues of rare earth materials. High torque density and high efficiency are key requirements in traction field. The challenge is designing propulsion systems which achieve such objectives while pursuing a global optimization logic in costs. This paper fits into this context by proposing a solution in which the same interior permanent magnet motor design is used for a four-wheel drive of a hypercar. A proper adaptation in axial length and magnets arrangement of the rear axle motor makes it suitable for the front axle requirements. Electromagnetic finite element analyses are performed to test different solutions with and without ferrite magnets. Torque, torque ripple, base speed, efficiency and rare earth reduction are the outputs under investigation. The best configurations are further studied via finite element structural analyses, as well as they are subjected to vibrational considerations. Different eligible solutions are found out with good performance while achieving a reduction in rare earth usage by 45.5%.

Is it possible to feel the difference in terms of comfort and handling between wheel rims having the same size but different weight in a sports vehicle? It is well known that reducing the unsprung mass has a positive effect both on vertical accelerations and forces transferred from the ground to the body of the vehicle. In the present study, a simplified quarter car model is exploited to quantify the real advantage of using composite wheel rim instead of aluminium one for a sports vehicle. Despite the common belief, a reduction of more than 12 kg of the unsprung mass leads to a reduction of less than 1% of the vertical force oscillation; unfortunately, this positive effect is not perceived by the occupants. The influence of the damping parameter on the dynamic response is critically discussed. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.