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Technical Paper

Lightweight Design of a Racing Motorcycle Wheel

Mass minimization is a key objective for the design of racing motorcycle wheels. The structural optimization of a front motorcycle wheel is presented in the paper. Topology Optimization has been employed for deriving optimized structural layouts. The minimum compliance problem has been solved, symmetry and periodicity constraints have been introduced. The wheel has been optimized by considering several loading conditions. Actual loads have been measured during track tests by means of a special measuring wheel. The forces applied by the tire to the rim have been introduced in an original way. Different solutions characterized by different numbers of spokes have been analyzed and compared. The actual racing wheel has been further optimized accounting for technological constraints and the mass has been reduced down to 2.9 kilograms.
Technical Paper

Lightweight Design and Construction of Aluminum Wheels

In this paper the lightweight design and construction of road vehicle aluminum wheels is dealt with, referring particularly to safety. Dedicated experimental tests aimed at assessing the fatigue life behavior of aluminum alloy A356 - T6 have been performed. Cylindrical specimens have been extracted from three different locations in the wheel. Fully reversed strain-controlled and load-controlled fatigue tests have been performed and the stress/strain-life curves on the three areas of the wheel have been computed and compared. The constant amplitude rotary bending fatigue test of the wheel has been simulated by means of Finite Element method. The FE model has been validated by measuring the strain at several points of the wheel during the actual test. From the FE model, the stress tensor time history on the whole wheel over a loading cycle has been extracted.
Technical Paper

Instrumented steering wheel for accurate ADAS development

The knowledge of the forces exerted by each hand of the driver at the steering wheel is useful for a better understanding of the driver steering action. This information is needed while developing haptic steering wheels useful for tuning Advanced Driver Assistance Systems (ADAS). The actual forces applied by the driver’s hands can be measured by means of a new Instrumented Steering Wheel (ISW), that, by using two six axis load cells, can measure the three force components and the three moment components exerted by the two hands, separately. Additionally, the instrumented steering wheel allows to measure the grip force, defined as the holding force applied by each hand on the handle. A full compensation of the inertia forces due to the vehicle acceleration guarantees an extremely high level of accuracy in the measure of the forces exerted by the driver. The resolution is just 0.1 N. The ISW has been already used for a couple of ADAS activities.
Technical Paper

Tire ply-steer, conicity and rolling resistance - analytical formulas for accurate assessment of vehicle performance during straight running

During straight-ahead running, the longitudinal axis of road vehicles - notably cars - is not parallel to road axis and sometimes a slight steering pull can be felt by the driver. This occurrence is general and is due both to road cross slope (road banking) and to tire characteristics, particularly ply-steer and conicity. In order to describe such a phenomenon, the paper introduces a new and relatively simple analytical model. Despite the linearity of the model, the solution provided is exact, since straight-ahead motion occurs with small angles and both the elastokinematics of suspension system and tire characteristics can be modelled by linearized equations. The validation of the analytical expressions is performed by using an MSC ADAMS full model of a car. By means of the new analytical formulae, the relationship between the tire ply-steer/conicity and the rolling resistance of the vehicle in studied.
Journal Article

Test Rig for Characterization of Automotive Suspension Systems

A test rig (named RuotaVia) is presented for the in-door testing of road vehicle suspension systems. It is basically a drum (ϕ 2.6 m) providing a running surface for testing the dynamic performance of a single tire or suspension system (corner). The suspension system is instrumented for the measurement of the forces and the moments acting at each joint connecting the suspension to the car body. A new 6 axis load cell was designed and manufactured for this purpose. The accelerations in various locations of the system (wheel carrier, suspension arms, …) and the wheel centre displacements in the longitudinal and vertical directions are monitored. The effect of the dynamic interaction between the test rig and the suspension system is discussed in the paper. The direct measurement of the forces and moments at the suspension-chassis joints is still an effective way for understanding the vibration and harshness (VH) suspension performances.
Journal Article

Optimal Robust Design Optimization with Application to a Piezoelectric Brake

A robust optimization approach has been applied to the design of a piezoelectric brake. The force generated by the piezoelectric actuator is transmitted to the pad shoe through a lever. The optimal design of the lever is crucial for obtaining the desired performance of the brake. Increasing the stiffness and reducing the mass of the lever is the key problem for such kind of mechatronic brake. A trade off between mass and stiffness of the lever must be obtained. Multi-objective programming (MOP) has been applied in order to achieve the best compromise. In addition to MOP, the optimal robust design method has been applied to perform the optimal design not only by considering the performance of the system (the stiffness and mass of the lever) but also by taking into account the robustness (the sensitivity to the uncertain system parameters).
Technical Paper

A Review of the State of the Art of Electric Traction Motors Cooling Techniques

This paper provides a review on state-of-art modern cooling systems employed for thermal cooling of electric motors for vehicle applications. In recent years, the pursue of a more sustainable and ecofriendly mobility has pushed the research towards the development of electric vehicle powertrain systems. Besides the evident advantages of the adoption of electric traction systems in terms of pollution and efficiency, the need of an effective cooling system for the electric machine components gained more and more importance in order to maintain high efficiency and ensure high durability. In fact, it is known that high temperatures can be harmful for the electric motor: besides the evident damages for mechanical parts, the influence on the permanent magnet properties is not negligible [1] [2]. In this fast-evolving environment, different solutions for the thermal problem have been researched and adopted, each one with its own pros and cons.