Alessandro Ferraris

XAM 2.0: from Student Competition to Professional Challenge

ABSTRACTIn 2012 the Team H 2politO from the Politecnico di Torino has taken part in the impressive Future Car Challenge, an international competition for electrical, hybrid and hydrogen vehicles. The most important car manufacturers such as Renault, Opel, Nissan, Jaguar, Mercedes and of car prototypes such as Gordon Murray Design cars were present at the competition. The Team H 2politO has always been in search of new technical, technological solutions and of concept of product nearer the market. This is why the Team H 2politO has been working for years in planning and carrying out low consumption prototypes such as IDRA and XAM, that took part to the international competition called Shell Eco-marathon. XAM 2.0 competed at the Future Car Challenge and it represents the number-plated evolution of the XAM vehicle (eXtreme Automotive Mobility), presented at the Politecnico di Torino on 13th June 2011. XAM 2.0 is road legal so it is capable to travel on the road and not on a motor racing track. Behind the Tea...

Static Design and Finite Element Analysis of Innovative CFRP Transverse Leaf Spring

This paper describes the design and the numerical modelization of a novel transverse Carbon Fiber Reinforced Plastic (CFRP) leaf-spring prototype for a multilink suspension. The most significant innovation is in the functional integration where the leaf spring has been designed to work as spring, anti-roll bar, lower and longitudinal arms at the same time. In particular, the adopted work flow maintains a very close correlation between virtual simulations and experimental tests. Firstly, several tests have been conducted on the CFRP specimen to characterize the material property. Secondly, a virtual card fitting has been carried out in order to set up the leaf-spring Finite Element (FE) model using CRASURV formulation as material law and RADIOSS as solver. Finally, extensive tests have been done on the manufactured component for validation. The results obtained show a good agreement between virtual simulation and experimental tests. Moreover, this solution enabled the suspension to reduce about 75% of the total mass without losing performance.

Design of the control strategy for a range extended hybrid vehicle by means of dynamic programming optimization

Electric vehicles (EVs) are attractive to reduce the pollution levels of urban areas thanks to their zero tail pipe emissions and to the possibility to rely on renewable energies for the electricity production. However, the market penetration of such vehicles is restricted by their limited range capabilities and by the lack of fast charging infrastructures. The Range Extended (R-EX) hybrid technology represents a valuable option to address these issues, since it offers the benefits of an EV, such as the electric driving for medium distances, while still maintaining the internal combustion engine, which can be operated at its optimal efficiency to recharge the battery, thus eliminating the drivers range anxiety. This article illustrates the design of the Energy Management System (EMS) of an R-EX Ultra-Light Vehicle (ULV), applying a heuristic approach based on the results obtained from the Dynamic Programming (DP) optimization, maximising the overall powertrain efficiency as function of trip information.

NVH Analysis of Automotive Components: A Carbon Fiber Suspension System Case

This paper presents the application of a modal parameter estimation technique, namely the Linear Identification by Polynomial Expansion in the Z-domain (LIPEZ) method, to automotive carbon fibre components. In particular, a leaf spring was chosen for its simple geometry and a door panel of an electric vehicle for its high influence in global NVH characteristics of vehicles. Both elements were experimentally tested with free-free boundary conditions under a random input force; the same test is reproduced at simulation level in order to perform a results correlation.

Modeling Li-ion batteries for automotive application: A trade-off between accuracy and complexity

This paper presents a fast and effective approach to Li-ion battery performance modeling, particularly suited for automotive applications (i.e. HEV, PHEV, BEV). A second-order electrical equivalent circuit model made up by one voltage source, one series resistor and two series RC blocks (dual-polarization model), is here selected as the best trade-off solution for the task, addressing both acceptable levels of accuracy and complexity. While a lithium-iron-phosphate cylindrical battery cell is chosen for the purpose of the study, the presented procedure has broader validity and is mostly independent of Li-ion chemistry and/or cell format. The battery model is parametrized through a low time-consuming current pulse test, performed during both charging and discharging, at different state of charge levels. The temperature and load-current effects on the battery performance are not considered for simplicity and lightness of the presented model. Validation is carried out by comparing measured and simulated results during the dynamic current pulse test, showing a high level of agreement between the two.

Moisture effect on mechanical properties of polymeric composite materials

The influence of moisture on the mechanical properties of fibre-reinforced polymer matrix composites (PMCs) was investigated. Four materials had been take into account considering: both 2×2-Twill woven carbon fibre or glass fibre, thermosetting matrix (Epoxy Resin) or thermoplastic matrix (Polyphenylene Sulfide). The specimens were submitted for 1800 hours to a hygrothermic test to evaluate moisture absorption on the basis of the Fick’s law and finally tested to verify the mechanical properties (ultimate tensile strength). The results showed that the absorbed moisture decreases those properties of composites which were dominated by the matrix or the interface, while was not detectable the influence of water on the considered fibre. An important result is that the diffusion coefficient is highest for glass/PPS and lowest for carbon/epoxy composite material. The results give useful suggestions for the design of vehicle components that are exposed to environmental conditions (rain, snow and humidity).

Experimental Characterization of Damped CFRP Materials with an Application to a Lightweight Car Door

This paper presents a complete design procedure for defining a dynamic model of a Carbon Fibre Reinforced Polymer (CFRP) component with an embedded damping material layer. The experiment to determine the mechanical characteristics of the materials is performed by the Oberst beam technique to provide precise material properties for a Finite Element (FE) model. The technique implemented, namely, the Linear Identification by Polynomial Expansion in the Z-domain (LIPEZ) method, is used to compare the experimental data with the numerical simulation results provided by the modal parameters to be compared with the numerical results. Two automotive components (a leaf spring and an outer shell of front door) have been tested. The research revealed the utter importance of a correct definition of the geometry for the numerical models. Finally, the positive effects for acoustic performance with a thin layer of KRAIBON® SUT9609/24 damping material, included in the stacking sequence of the CFRP component, are highlighted.

Function integration concept design applied on CFRP cross leaf spring suspension

In automotive systems, lightweight design is nowadays a mandatory target. Suspension systems, which are a safety system and contribute to overall vehicle performance (dynamic, comfort, noise and vibration, etc…), are one of the most complex systems in which to achieve lightweight targets. This paper discusses the development of a CFRP Cross Leaf Spring Prototype (TRL 6). The entire workflow, starting from kinematic design, multibody vehicle dynamics analysis, finite element method (FEM) structural analysis, prototype construction, testing and correlations is shown. Also studied in this project is the integration and applications of advanced continuous fibre reinforced thermoplastic polymer (CFRTP). This system, in comparison to traditional solutions, could guarantee: around 75% weight savings, suspension component optimisation, an optimisation of the suspension volume (resulting in more space for vehicle occupants), easy integration of advanced process using CFRTP, and a sustainable cost solution.