Daniel Chindamo

The influence of suspension components friction on race car vertical dynamics

ABSTRACT This work analyses the effect of friction in suspension components on a race car vertical dynamics. It is a matter of fact that race cars aim at maximising their performance, focusing the attention mostly on aerodynamics and suspension tuning: suspension vertical and rolling stiffness and damping are parameters to be taken into account for an optimal setup. Furthermore, friction in suspension components must not be ignored. After a test session carried out with a F4 on a Four Poster rig, friction was detected on the front suspension. The real data gathered allow the validation of an analytical model with friction, confirming that its influence is relevant for low frequency values closed to the car pitch natural frequency. Finally, some setup proposals are presented to describe what should be done on actual race cars in order to correct vehicle behaviour when friction occurs.

Impact of reduced mass of light commercial vehicles on fuel consumption, CO2 emissions, air quality, and socio-economic costs

This study presents a modelling system to evaluate the impact of weight reduction in light commercial vehicles with diesel engines on air quality and greenhouse gas emissions. The PROPS model assesses the emissions of one vehicle in the aforementioned category and its corresponding reduced-weight version. The results serve as an input to the RIAT+ tool, an air quality integrated assessment modelling system. This paper applies the tools in a case study in the Lombardy region (Italy) and discusses the input data pre-processing, the PROPS-RIAT+ modelling system runs, and the results.

Reproduction of real-world road profiles on a four-poster rig for indoor vehicle chassis and suspension durability testing

Indoor testing should reproduce the real-world environment in order to be effective. In this article, an efficient methodology to reproduce road profiles on a four-poster rig is presented: such a method includes a complex rig control strategy based on an iterative process. Road profiles come from a purposely designed set of sensors fitted on the car which remains the same regardless of the vehicle or surface type. Particular stresses such as speed humps, potholes and manholes can be reproduced as well. Since there are no previous similar studies, a validation is provided by comparing road and rig data streams and using the maximum absolute error and root mean square error as performance indexes. Results show that the rig is able to reproduce road profiles and the related inputs to the vehicle successfully; hence, the method is reliable and effective.

Lightweighting in light commercial vehicles: cradle-to-grave life cycle assessment of a safety-relevant component

PurposeCurrently, the reduction of weight in automotive is a very important topic in order to lower the air pollution. In this context, the purpose of the present paper was to analyze a real case study through a comparison of the environmental sustainability between a conventional steel crossbeam for light commercial vehicles and an innovative lightweight aluminum one.MethodsFor both scenarios, a cradle-to-grave life cycle assessment methodology and a sensitivity analysis has been used through the study of the following phases: mineral extraction, component manufacturing, use on vehicle, and end of life. In particular, many primary data and a complete vehicle model simulation with three different European driving cycles have been used in order to reach the highest possible level of accuracy during the analysis.Results and discussionRegarding the manufacturing phase, the aluminum component’s production gave the highest impact because of the high energy required in the mineral reduction. Anyway, this stage of the analysis had a low effect on the entire LCA, because the benefit of weight reduction during vehicle use showed a strongly higher contribution. The urban driving cycle had the most relevant impact, as a consequence of the frequent start and stop operations and the longest time with engine at idle speed, while the extra-urban cycle is the less demanding due to its higher average speed and no start and stop.ConclusionsIn conclusion, the present research demonstrated the environmental importance of the lightweight for an actual case study in the commercial vehicles field.

High downforce race car vertical dynamics: aerodynamic index

ABSTRACT Race car performance is strongly affected by aerodynamics. Due to downforce generated by the vehicle floor (i.e. diffuser), vehicle ride heights are key parameters to improve performance, and the coupling of aerodynamics and suspension is one of the key points of race car setting. This work focuses on the suspension and aerodynamic coupling from the vertical dynamics point of view. Besides road holding performance, for race cars, aerodynamic performance and stability are major factors. Downforce decreases laptime (the main performance target) but pitch instability is a non-desired effect that can happen in high downforce race cars. A new vertical dynamic performance index is proposed through the use of simulation to improve aerodynamic performance and understand the pitch instability phenomenon. This new index uses all relevant vehicle nonlinearities related to vertical dynamics and can handle a specific track profile and vehicle speed range, allowing the analysis be conducted according to a circuit specification. A previously validated Formula 3 car model was used as an example.

Teaching automotive suspension design to engineering students: Bridging the gap between CAD and CAE tools through an integrated approach

The paper presents an integrated approach to suspension design with educational purposes. A dedicated design tool was created to instruct automotive engineering students in the whole process of suspension design across the various CAE tools involved, from early kinematics studies to CAD, vehicle dynamics simulations and FEM modelling. The tool has given birth to a proven design procedure that the authors would like to share in this paper with focus on the educational side, although suspension kinematics design is not certainly a novel subject in itself. The tool includes geometries like the widely used McPherson strut, complex five-link schemes for high-end road cars, and typical racing car geometries like the so-called push/pull rod systems used on Formula 1 and Le Mans racecars. It has been applied successfully to various projects developed by professionals as well as by students, including the latest three Formula SAE (FSAE) single-seaters of the University of Brescia (Brescia, Italy) team. The paper is structured as follows. The introduction describes the role student design competitions play in higher engineering education, and within the frame of the Automotive Engineering course at UniBS in particular. A selection of relevant bibliography on the topic is listed. The Educational scenario section deals with the specific case of the Automotive Engineering course at UniBS and the requirements posed by student competitions, also in the frame of the Dublin Descriptors, and shows how suspension design can play a pivot role in a FSAE project. The A tool for suspension kinematics: requirements, description, solution section presents the software tool in itself. The math underlying the user interface is outlined. Finally, the integration features towards other CAE tools are presented with the related advantages.

Mechanical steering gear internal friction: effects on the drive feel and development of an analytic experimental model for its prediction

The automotive steering system inevitably presents internal friction that affects its response. This is why internal friction phenomena are carefully monitored either by OEMs and by vehicle manufacturers. An algorithm to predict the mechanical efficiency and the internal friction of a steering gear system has been developed by the ZF-TRW Technical Centre of Gardone Val Trompia and the University of Brescia, Italy. It is focused on mechanical steering gear of the rack and pinion type. The main contributions to the overall friction have been identified and modelled. The work is based on theoretical calculation as well as on experimental measurements carried out on a purpose-built test rig. The model takes into account the materials used and the gear mesh characteristics and enables the prediction of the steering gear friction performance before the very first prototypes are built.