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

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

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

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

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

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

Validation of a Simulation Methodology for Thermoplastic and Thermosetting Composite Materials Considering the Effect of Forming Process on the Structural Performance

This research work investigated the influence of the press molding manufacturing process on the mechanical properties, both for thermoplastic and thermosetting fiber reinforced composite materials. The particular geometry of the case study, called Double Dome, was considered in order to verify the behavior of the Thermoplastic and Thermosetting prepreg in terms of shell thickness variation and fibers shear angle evolution during the thermoforming process. The thermoforming simulation was performed using LS-DYNA Finite Element Analysis (FEA) code, and the results were transferred by Envyo, a dedicated mapping tool, into a LS-DYNA virtual model for the structural simulation. A series of Double Dome specimens was produced with industrial equipment, and a bending experimental test was been carried on. Finally, a numerical-experimental correlation was performed, highlighting a significant forecast of the mechanical properties for the considered component

Study and analysis of advanced composite materials for automotive applications

Il lavoro di Tesi di Dottorato si è concentrato sui cosiddetti “Advanced Composite Material”, ovvero i materiali compositi rinforzati con fibra continua (tessuta o unidirezionale) e a matrice termoplastica anziché termoindurente, cercando di dare un contributo alla ricerca e alla loro sperimentazione. Questi materiali sono già abbondantemente utilizzati in ambito aerospaziale e militare, ancora poco negli altri campi, come quello automotive, in cui essi sono sicuramente molto innovativi e interessanti. In questa tesi infatti i materiali compositi saranno trattati soprattutto per applicazioni automotive, in cui a tutti i benefici dei laminati ottenuti da prepreg tradizionali si aggiungono i vantaggi e benefici della matrice termoplastica, tra cui la reciclabilità e la processabilità, fattori molto importanti soprattutto per le grandi produzioni di serie. Si si è scelto un caso applicativo automobilistico, in particolare un sistema sospensivo a balestra trasversale, che da una parte ha permesso di focalizzare il lavoro, dall’altra ha voluto essere un case study dell’attività svolta, della parte sperimentali e della validazione del modello virtuale di analisi strutturale. Il workflow delle attività è quindi consistito nel partire da una ampia caratterizzazione meccanica dei materiali selezionati e attraverso i dati sperimentali ottenuti costruire la Material Card per il solutore FEM. L’attività è quindi consistita nel disegnare, a CAD, il componente balestra e tutti i suoi attacchi al telaio automobilistico considerato. La successiva analisi effettuata per la Tesi ha portato quindi a definire i parametri ottimali per la realizzazione della balestra in termini di spessore, stacking sequence, numero di ply e geometria