Elasto-kinematics design of an innovative composite material suspension system

Abstract. In this paper, a lightweight suspension system for small urban personal transportation vehicle is presented. A CFRP (Carbon fiber reinforce polymer) beam spring has been used to efficiently integrate the functions of suspension control arm and anti-roll bar. Composites materials were chosen to tailor the required behavior of the beam spring and to reduce the weight. Furthermore, larger space for engine compartment has been provided thanks to the compact arrangement of beam suspension components. This suspension could be installed on electric/hybrid vehicles and conventional automobiles

Customer oriented vehicle dynamics assessment for autonomous driving in highway

Autonomous Driving is one of the main subjects of academic research and one important trend in the automotive industry. With the advent of self-driving vehicles, the interest around trajectory planning raises, in particular when a customer-oriented analysis is performed, since more and more the carmakers will have to pay attention to the handling comfort. With that in mind, an experimental approach is proposed to assess the main characteristics of human driving and gain knowledge to enhance quality of autonomous vehicles. Focusing on overtaking maneuvers in a highway environment, four comfort indicators are proposed aiming to capture the key aspects of the chosen paths of a heterogeneous cohort. The analysis of the distribution of these indicators (peak to peak lateral acceleration, RMS lateral acceleration, Smoothness and Jerk) allowed the definition of a human drive profile. These characteristics were then transferred to the simulation environment to create a pseudo-natural trajectory planning strategy, via polynomial fitting and spline optimization. This strategy differs from the standard approach of trajectory planning, where absolute minimums of cost functions are pursued. The polynomial and spline fitting techniques reached satisfactory results and are evaluated as valid procedures to imitate a natural human behavior in a simulation environment (also applicable to control the trajectory of AD systems) and raise a question about whether a human-like behavior can be subjectively perceived as better driving, despite not presenting optimized comfort indicators

Performance comparison between glass and basalt fibre-reinforced composites for an automotive seat backrest

In recent years, the automotive industry has been developing lightweight components in order to comply with stricter fuel consumption regulations. In fact, car mass reduction plays an important role in reducing fuel consumption and CO2 emissions. Composite materials are very promising solutions because of their potential to reduce mass by replacing traditional steel components, while ensuring safety requirements and structure reliability. However, they might present some issues in terms of sustainability and cost. This paper presents a methodology developed to carry out safety tests on a virtual automotive seat and then assess the structural practicability of using a more sustainable material, the Basalt Reinforced-Fibre Polymer (BFRP), as a replacement of the original material, the Glass Reinforced-Fibre Polymer (GFRP). The starting point of this study was the mechanical characterisation of both traditional and green composites. Then, the composite material formulation MAT-58 was optimised to correlate the simulated and experimental results. Finally, static and energy absorption simulation tests were performed according to the ECE R17 regulation. The seat model was compliant with the safety requirements in all cases studied, and both composites presented a similar structural performance

Enhancing Vibration Reduction on Lightweight Lower Control Arm

This paper describes the design procedure to enhance the damping properties of a multimaterial lightweight suspension arm for a C-segment vehicle. An innovative viscoelastic material has been used to join carbon fiber with steel that has a function of passive constrained layer damper and adhesive simultaneously. Therefore, the hybrid technology applied has been focused on reducing the LCA mass, diminishing the steel thickness, and adding a CFRP tailored cover without compromising the global mechanical performance. Particular attention has been paid to the investigation of the dynamic response in terms of vibration reduction, especially in the range of structure-borne frequencies of 0–600 Hz. Two different viscoelastic materials have been evaluated in such a way to compare their stiffness, damping, and dynamic properties. The experimental test results have been virtually correlated with a commercial FEM code to create the respective material card and predict the real behavior of the LCAs (original and hybrid). The experimental modal analysis has been performed and compared on both the arms highlighting a very good correlation between virtual and experimental results. In particular, the hybrid LCA allows an interesting improvement of damping ratio, about 3,5 times higher for each eigenmode than in the original solution

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

Feasibility Study of an Innovative Urban Electric-Hybrid Microcar

This paper presents the feasibility study of a new platform for electric-hybrid quadricycles, developed by addressing important concepts like passive safety and comfort, which often represent a shortcoming in this vehicle category. Starting from packaging of energy storage system and macroscopic subsystems as the main technological constraint, the study has been entirely developed in a virtual environment, with finite element verifications on preliminary models, and a subsequent cooperation phase between computer aided design and finite element analysis softwares, with a guideline for the main tests being that each could feasibly be carried out on a complete vehicle model in order to validate the original assumptions. The resulting design, with a body curb mass of less than 100 kg, was capable of integrating optimal static stiffness characteristics and crash performance, together with improved vehicle dynamics thanks to an innovative suspension archetype

Active Aerodynamics Design Methodology for Vehicle Dynamics Enhancement

This paper presents a workflow methodology for CAD design and Computational Fluid Dynamics (CFD) analysis of an active aerodynamic package for a sports vehicle. The objective is to provide a method in case of limited resources, such as time and computational power, in order to enhance the vehicle dynamic performances by the improvement of its aerodynamic characteristics. The use of the superposition principle is necessary to perform fast evaluation of the results having three different entities: base vehicle, active front splitter and active rear wing. The dynamic behavior of the vehicle is entangled with the properly made workflow. The results usefulness is related to the understanding of the improvements achieved on the baseline vehicle. The results point out the importance of the aerodynamic improvements connected to the vehicle dynamics enhancement of a sport vehicle

Modeling and simulation of Constant Phase Element for battery Electrochemical Impedance Spectroscopy

This paper presents a set of time-domain electrical equivalent circuit models for battery voltage prediction under arbitrary current profiles. The circuit model is composed by passive electrical components like resistance, inductance and capacitance. The constant phase elements are introduced in the model, which are usually used in electrochemical impedance spectroscopy analysis to describe the electrical property of double layer capacitors between electrode and electrolyte. The aim of the paper is the modeling in the time-domain of the constant phase elements. Two models are proposed. Model's accuracy and run speed are evaluated by comparing experimental results obtained by an appropriate testbed and simulation results obtained by the implementation and the execution of the model using Matlab software

Autonomous Driving Scenario Generation in Overtake Manoeuvres Through Data Fusion

For an effective study of specific driving scenarios, in particular related to overtaking manoeuvres, developing well-thought-out manoeuvre databases from the acquired data will greatly improve the analysis process. The key point being that identifying clearly the studied scenario and clustering the manoeuvres based on specific sub-cases of this will bring an extra dimension of information that allows to visualise existing correlations between a given set of conditions and the manoeuvres performed under them. This paper expands on how to obtain these databases starting from only from overtaken manoeuvres extracted from experimental data. Consisting in two main procedures, the manoeuvre classification itself, in which a hybrid-classifier that combines both supervised and unsupervised algorithms generates the scenario sub-cases, and the database compilation stage, in where it displays the different types of databases that can be created, based on the aim of the study