Development of a fiber-reinforced plastic armrest frame for weight-reduced automobiles

This paper presents the design optimization process of a short fiber-reinforced plastic armrest frame to minimize its weight by replacing the steel frame with a plastic frame. The analysis was carried out with the equivalent mechanical model and design of experiment (DOE) method. Instead of considering the whole structure, it is divided into three simpler regions to reduce the complexity of the problem through examining its structural characteristics and load conditions. The maximum stress and deflection of the regions that carry the normal load are calculated by the analytical mathematical form derived from an equivalent model. The other regions loaded by contact stress are handled by FEM (finite element method), the DOE method, and the RSM (response surface model). To optimize the design variables in both cases, the object functions derived from these calculations are solved with a CAE (computer aided engineering) tool. This method clearly shows the mechanical and mathematical representation of structural optimization and reduces the computing costs. After design optimization, the weight of the optimum plastic-based armrest frame is reduced by about 18% compared to the initial design of a plastic frame and is decreased by 50% in comparison with the steel frame. Some prototypical armrest frames were also made by injection molding and tested. The research results fulfilled all of the design requirements.     

Design methodology of hybrid electric vehicle energy sources: Application to fuel cell vehicles

This paper presents a methodology to optimize the sizing of the energy and power components in a fuel cell electric vehicle from the driving mission (which includes driving cycles, a specified acceleration and autonomy requirements). The fuel cell and the Energy Storage System associated (battery or/and ultra capacitor) design parameters are the numbers of series and parallel branches respectively Nsi and Npi. They are set so as to minimize the objective function that includes mass, cost, fulfilling the performance requirements and respect the technological constraints of each power component through a penalty function. The methodology is based on a judicious combination of Matlab-Simulink® for the global simulation and a dedicated software tool Pro@Design®. Both are well suited to treat inverse problems for the optimization. An application for a fuel cell/battery powertrain illustrates the feasibility of the proposed methodology.     

Development of a new traction control system for vehicles with automatic transmissions

A traction control system (TCS) is used to improve the acceleration performance on slippery roads by preventing excessive wheel slip. In this paper, a new traction control system using the integrated control of gear shifting and throttle actuation is developed for vehicles with automatic transmissions. In the design of the slip controller, by means of a differential manifold transformation, a slip control system with nonlinearities and uncertainties is transformed into a linear system, and a sliding mode controller is applied for the purpose of increasing the robustness of the system. Next, to achieve the required driving torque, the optimal throttle and gear position, maps are constructed based on dynamic programming. The simulation results indicate that the present traction control system can improve the acceleration performance of an automatic transmission vehicle for various types of road conditions.     

Compensation factor method for modeling springback of auto parts constructed with high-strength steel

To more accurately manufacture an auto-body workpiece, a predictive compensation factor method was used to predict the workpiece’s springback, and the factors influencing springback are introduced. Based on this method, a numerical simulation was produced to simulate the springback compensation after distortion of the workpiece. After analyzing the simulation results, a compensation method was introduced to reduce the springback influence on an actual workpiece. Here, we used a fortified B-pillar, which is a kind of longitudinal stand-frame workpiece, made with a high-strength steel material (TRIP700). The simulation results indicated that the proposed method is feasible and can be efficiently used for predicting the distortion of springback compensation of an auto-body workpiece.     

Mixité sociale et choix modal : importance des dimensions symboliques dans l’attrait des transports collectives

Our understanding of transport mode choice is largely based upon functional attributes, such as travel time, cost or accessibility. It is important, however, to also look at symbolic and affective attributes. Indeed, one of the main differences between mass transit and private car use is strongly symbolic: public transport compels users to confront social diversity. Given a hypothetical choice between those modes, 200 residents of the Parisian region were asked five times to evaluate (measuring usage intention on a six point scale: ?3 meaning never and +3 meaning always, with no neutral point) the attractiveness of bus versus car-based transport, according to relative travel time and bus users’ population type. The results show that the symbolic dimension (the social mix) strongly contributes to the desirability of a transport mode, as does the functional dimension (travel time).     

Theoretical Comparison Between Different Configurations of Radial and Conventional Bogies

This article compares the dynamic behaviour of different configurations of radial and conventional two-axle bogies. In general, the design parameters for a better curve negotiation are not compatible with those for good stability. As the main target of this article is to compare the curving performances of different bogies under the same design basis, several bogie configurations with the same level of stability, obtained by choosing proper primary suspension stiffnesses, have been used. The comparison includes a conventional bogie and three radial bogies with differing self-steering and forced-steering principles in three different passenger services: High Speed, Regional and Mass Transit. The analysis has been concentrated on parameters such as stability, lateral wheel-track forces in curve and wheel wear indices. The results show that the radial bogie configurations studied do not make significant contributions in general applications with regard to a conventional bogie. It is only under specific running conditions and types of service that some radial bogie configurations provide advantages with respect to the conventional bogie.     

Relationships between characteristics of motorcycles and hydrocarbon emissions in Taiwan: A note

Taiwan’s inspection and maintenance (I/M) programs identifies high-emission motorcycles but, although these help reduce air pollution, they have been criticized for being cost-ineffective. This study examines the relationship between characteristics of motorcycles and hydrocarbon emissions in the Central Air Quality Basin of Taiwan. It is shown that engine size and type, age and manufacturer of a motorcycle significantly affect HC emissions. Larger-size engines emit smaller amounts of HCs; whereas older motorcycles emitted greater amounts. In addition, two-stroke-engine machines produced significantly higher HC emission levels than four-strokes. Variations in HC emissions testing are a result of various I/M testing locations and efficiency may be improved by modifying these.     

Design and optimisation of wheel–rail profiles for adhesion improvement

This paper describes a study for the optimisation of the wheel profile in the wheel–rail system to increase the overall level of adhesion available at the contact interface, in particular to investigate how the wheel and rail profile combination may be designed to ensure the improved delivery of tractive/braking forces even in poor contact conditions. The research focuses on the geometric combination of both wheel and rail profiles to establish how the contact interface may be optimised to increase the adhesion level, but also to investigate how the change in the property of the contact mechanics at the wheel–rail interface may also lead to changes in the vehicle dynamic behaviour.     

Automotive window seal design considering external aerodynamic load and surrogate constraint modeling

Installed between metallic DIW (Door in White) panel and nonmetallic door glass, automotive window seals has great influence on customers’ perception of NVH (Noise-Vibration-Harshness) performance. Recently, aerodynamic effect on ride comfort attracts increasing research interest. The external load causes unsteady pressure on glass, which is finally transferred to window seals and leads to complicated vibration and increases interior noise level. However, non-linearities of hyper-elastic material, rubber-glass contact and large deformation behavior make the construction of window seals constraint model much more difficult, thus impeding further analysis and optimization. A new window seal design method is proposed featuring in considering aerodynamics-induced load and nonlinear constraint. Firstly, by SST ? k ? ε (Shear Stress Transport) turbulence model, external flow field of full-scale automotive is established by solving three-dimensional, steady and uncompressible Navier-Stokes equation. With re-exploited mapping algorithm, the overall aerodynamic pressure is extracted and matched to local window as external loads for seals, thus taking into account high speed fluid-structure interaction. Secondly, based on functional equivalence and mathematical fitting, new surrogate constraint model is presented. The unitedseal CLD (Compression Load Deflection) curve is synthesized after translations and transformations from two semi-seal CLD experimental measurements of inner and outer lips. It is then fit to complex exponential function, making seal constraint equivalent to a surrogate elastic constraint with variable stiffness. Experiment is performed to verify the constraint surrogation effectiveness. Finally, case study of window seal design under high speed is investigated. After seal optimization based on the new method, windows seals’ maximal displacements have decreased. The improved seal-glass fitting status shows better NVH quality of window seal in high-speed condition.     

Two-port network based bilateral control of a steer-bywire system

Steer-by-wire (SBW) system which is characterized by variable steering feel, better active safety, unmanned drive, has been widely studied to realize a distinctive driving experience. Control strategy acts as a key part of SBW system to achieve the goals. In this paper, a control strategy by bilateral control structure for steer-by-wire system is proposed. To make SBW system has the same function of conventional steering systems, the controller is designed to realize desired tracking control and realistic road feel feedback. The control of position and torque for each actuator is taken as two ports for the control network. Based on different control loop, two kinds of bilateral control is investigated respectively. The hardwarein- the-loop experiment platform of SBW is developed by the reconfiguration of electric power steering system. The test results are compared to show the performance of different control loops.