Design methods for mobility

Aluminium alloys are used extensively, whenever the advantages of high strength-to-density ratio, reduction of dead weight and corrosion resistance, make these alloys competitive with other materials. The major markets for structural application of aluminium alloys are civil engineering and the transport industry, in particular, aircraft construction and more recently, that of electric and low emission cars. One of the difficulties to be overcome in using aluminium alloys is the reduction of mechanical properties due to HAZ (Heat Affected Zone) deterioration caused by welding. The mechanical and microstructural characteristics of MIG welded joints in 6082-T6 plate alloy were investigated by means of tensile tests, fatigue bending tests, microhardness analysis, and optical and SEM metallography. The reduced hardness and tensile strength in the HAZ have been linked to the mechanisms of deterioration of constituents initially present in the alloy, originating from quenching and thermal ageing treatment. © 1997 Taylor and Francis Group, LLC.

Quite a lot has been written on active suspension, the topic being suitable for theoretical studies. Unfortunately only a few applications has seen the road and even less went into production; by now very few road cars equipped with a real active suspension system are available on the market, and the interest to this kind of application seems to be reduced, perhaps because of high costs and restrictive regulations applied to the race car world. For this reason this paper presents the results of a study conducted on the vertical dynamics of a two wheel car model with a semi active suspension system, a possible alternative way to a fully active system to considerably improve suspension performance. Here the damping force of each suspension is obtained by modulating its damping factor according to opportune functions of the system state variables. This allows to reach several of the objectives achievable with a fully active suspension, without the need of a big amount of energy. © Copyright 1996 Society of Automotive Engineers, Inc.

The top Formula 1 and Indycar teams make large use of computer simulation to improve the performance of their cars and make the set-up process quicker on the circuit. The paper aims to present a lap time simulation software dedicated to racing cars. It is based on the background of vehicle dynamics research developed at the University of Brescia, Italy (see [1]). It should be stated that racecar dynamics is strongly non-linear due to the fact that tyres are always very near the limit of adhesion. Moreover this makes the effect of lateral load transfer fundamental for the general balance of the car. Therefore Pacejka's Magic Formula has been used for lateral force/slip while longitudinal force computation is based on the assumption of a maximum longitudinal coefficient of friction μ. This is not only for simplicity but it is also due to lack of available data. The combined case is then based on the so-called "traction circle". Lateral and longitudinal load transfer and downforce as well as their effects on tyre load are taken into account. The vehicle model is capable of following a trajectory acquired with the on-board instrumentation. Also, the use of genetic algorithms enables the program to find the optimum cornering line for any given track. Some results are shown and compared with real world data. © Copyright 1996 Society of Automotive Engineers, Inc.

The time of the "magic touch" approach to race car design is nearly over, and modern engineering techniques are more and more employed in high-level racing. Finite Element Analysis, Computational Fluid Dynamics, Vehicle Dynamics are some of the computer-aided methods which are being successfully applied to improve engine performance, aerodynamics, structural effectiveness and driveability. People at the Department of Mechanical Engineering of the University of Brescia have been working on chassis and suspension modeling in co-operation with racing and sports car makers and leading-edge teams since 1989. Current research partners are the FIAT Research Centre (CRF), Dallara Racing Cars, the Scuderia Italia Touring Car Team, and others.