The main use of FRC in automobiles, with the exception of a few specialized low volume vehicles, has been until now in semistructural parts. One of the most promising process in development today, that may play major role in future structural composite fabrication, is based on SRIM technology. The rapid and extensive introduction of this process goes also through the development of deeper theoretical knowledge of the process and the development of computer simulation to aid mold design and choice of proper processing parameters. To contribute SRIM advancement, a preliminary model has been developed for viscosity changes, extent of the reaction and temperature rises, associated with the mold filling stage, as well as a simple software to evaluate the pressure drop through different combinations of reinforcements.
In order to improve the design of drawn parts and to reduce the number of trial and error tests, Renault has undertaken the development and the validation of various finite element procedures and codes. This paper describes the function of each software and its level of integration into the design process. One of them is already an operational tool used be planners whilst the others are still in the validation phase. Selected examples show typical applications of the computer programs on automotive parts.
In this paper the socio-economic and technical problems of the handling of car wrecks are discussed. The recovery of metals as a goal for shredder operations will increasingly be supplemented with the recovery of other materials such as polymers. In order to deal economically and technically with polymer materials, it is necessary to know in advance which type of wreck handling will be used. Also optimization of shredder operations allow less freedom to incorporate a variety of materials when compared with selective dismantling or disassemble of cars. It is argued that various technical solutions have to be accompanied by increased cooperation along the firms that are connected to the handling of car wrecks. Cooperation between the scrap context and designers is essential, in order to optimize dismantling practices according to criteria of environmentally preferred solutions.
Compression molding of thermoplastic sheets, consolidated or non- consolidated, reinforced with glass fibers (GMT, GRT) is applied as an economic production process in the automotive industry. The aim of this work is to evaluate how the physical and mechanical strength characteristics depend on the presence or absence of ribs and how component performance may be changed by modifying the molding parameters, altering the content and orientation of the reinforcement fibers in the ribbed areas. For this purpose, two statistical designs will be considered, the first carried out on a box type component without ribs, the second on the same component with a set of internal ribs. Two different materials with a PP matrix will be tested, a GMT reinforced with continuous random glass fibers and a 12 mm random glass fibers composite.
The purely theoretical evaluation of critical compression loads seems complex and not very reliable in the case of honeycomb panels, on account of the numerous parameters in play and their complex interrelationships. This report provides the designer with a fast tool for preliminary calculations, consisting of a finite-element mathematical model with elastic-linear code (which can be processed using a PC), which makes it possible to obtain information very closely resembling the real situation.
The pending changes in European law enabling the use of plastic lenses on vehicle headlamps provide an opportunity for further advancement of vehicle styling, lighting performance and aerodynamic efficiency. Plastic lenses can also provide a useful weight saving and contribute to energy savings during the lifetime of the vehicle. This paper discusses the current requirements, technologies and solutions for plastic lenses, and indicates the way this advance can impact on the evolution of lighting products.
The replacement with plastic of an important component, formerly in steel, in the timing drive of a heavily duty diesel engine has been studied and realized. The substituted part is the toothed coupling connecting the injection pump to the timing drive. Torque that stresses the coupling has been measured with laboratory tests. The tooth stresses have been calculated with FEM analysis. Finally, fatigue tests have been carried out directly on the engine at different loadings. The test results are consistent with the predicted behavior of this component.
As a result of a phase transformation, shape memory alloys can change their shape when the temperature changes. This unusual effect can be utilized in actuation and fastening components for automotive applications. Springs made from Ni-Ti shape memory alloys change their rate in a predetermined temperature range due to a significant change in the elastic modules of the material. They can be used as sensor-actuators in pressures control valves or oil cooler by-pass valves in automatic transmissions or to compensate for oil viscosity changes in shock absorbers or thermal expansion of dissimilar materials in gear boxes. If the recovery is constrained, i.e., shape memory element is physically prevented from returning into its original shape, a potentially high stress is generated. This effect is used in fastener rings. Fasteners made from Ni-Ti alloys provide high reliability and easy installation for braid terminations, locating of shaft mounted components, connectors and hose clamps.
A data bank developed to give a concrete help to the designer concerned with fatigue-prone structures made of composite materials is described. The data bank not only collects the available results of fatigue tests on these materials, but also makes easy their statistical analysis and comparison for design purposes. It is then believed to constitute also an useful research instrument for the development of design rules for well defined classes of composite materials.
The paper summarizes the results of an experimental and numerical study performed on the rear door of a car of large production. It was carried out with a DMC ("dough molding compound") plastic material with short glass fibers. This technology makes strong the link between the production process and the mechanical properties of the component. Such properties really vary according to the fibers orientation, the distance from the injection points and the geometrical complexity of the different regions of the molded component. In some regions the fibers orientation is well defined, in others the orientation can be expressed only in average tendency terms, with a large scatter band. It is natural to think that the material modifies its behavior from region to region, showing marked orthotropic properties or, on the contrary, a compensation isotropic trend.
A procedure adopted to verify and update the finite elements model of an electric powered car-body manufactured from composite materials is described. Experimental results, obtained from modal testing of the prototype, are used in order to identify and correct discrepancies in the FE model. The availability of a highly reliable FE model allows to simulate structural modifications by computer, optimizing the use of composites and reducing in the same time at minimum prototypes construction. The approach followed suggests a possible remarkable reduction in product development costs and duration. The work has been performed within a larger program for the development of thermoplastic composite materials, with particular attention to transportation market.
A wide variety of choices confront the potential user of finite element modeling (FEM) for sheet forming analysis. In the first part of this paper, a brief summary of the basic formulations available and sample references to them are provided. Several kinds of finite element models have been developed for analyzing sheet forming operations at OSU and in the Center for Net Shape Manufacturing. These variations began with in-plane FEM and grew into 3-D versions. In the second part of this paper, some key conclusions from these developments will be summarized. More recently, a section analysis program (SHEET-S) has been prepared and transferred to industry. The capabilities and limitations of SHEET-S will be presented in greater detail, including comparisons with experiments and industrial trials.
An inexpensive driving simulation system with sufficient fidelity has been developed. The system produces motion cues of four degrees of freedom, visual and auditory cues, and control feel on the steering wheel. This paper describes the features of this newly developed system and gives examples that demonstrate its effectiveness. The motion cues provided in this system are yaw, heave, and lateral and fore/aft accelerations. The lateral and fore/aft accelerations are simulated by tilting the simulator compartment. A computer-processed road image is given through a CRT monitor. The restoring torque of the steering wheel is produced by an electrical servosystem via a coil spring. Cruising sound is given in order to improve speed perception. Since the system uses digital computers, the vehicle characteristics are altered easily by merely rewriting the software. This enables us to simulate special vehicle dynamics such as front & rear wheel steering.
In this paper a computer simulation study on the effects of steering parameters on lateral dynamics of the guideway bus to contribute to a development practice of designing optimum steering control system are dealt with. A stability limit of vehicle lateral motion is analyzed and an emphasis is laid on the effects of moment of inertia of a conventional steering wheel and lateral elasticity of the guide rail which have proven to reduce the critical vehicle speed. It is pointed out conclusively that a normal bus equipped with additional simple guidance equipments can be guided smoothly on a simple guideway at adequately high vehicle speed.
Unsteady laminar flame propagation confined in a closed cylindrical combustion bomb is studied by numerical computation for an axisymmetric two-dimensional laminar flame. Computation includes complete two-dimensional unsteady Navier-Stokes equations of change for a chemically reacting propane-air mixture. Implicit Continuous fluid Eulerian, Arbitrary Lagrangian Eulerian finite difference technique, simplified reaction kinetics models, and artificial flame stretching transformation and inverse transformation were adopted in the calculation. Physically realistic flame behavior can be demonstrated even with rather coarse computing cell size, simplified reaction kinetics models, and personal computer level low power computing machines.
Synthesizing different customer and functional requirements into an acceptable design configuration within a given space constraints is a challenging task for design engineers. The principles for designing efficiency, noise levels, maneuverability, safety, durability, etc. into the product are well understood. However, designing for reliability, maintainability and quality turns out to be a long-drawn laborious process due to unavailability of simplified design procedures. The author in this paper develops the understanding of reliability, maintainability and quality design principles and methods for products, with specific reference to vehicle designs.
Over the last years, SEA has been recognized as a useful tool to model and analyze the high-frequency vibro-acoustic behavior of fully assembled complex structures. This paper discusses the experimental derivation of the loss factor model of a passenger car. The paper outlines the different steps which need to be taken to obtained a fully validated experimental SEA model. This includes the subdivision into subsystems, the PIM measurement campaign, the derivation of the loss factors and their associated confidence levels and the model validation. The paper further details how the experimental SEA model was used to quantify and investigate the airborne and structure-borne contributions to the interior noise level for a road noise test condition. The operational power inputs to the vehicle were indirectly determined from operational response measurements. A contribution analysis showed that airborne noise sources dominated structure-borne noise sources above 500Hz.
Statistical energy analysis is generally used to study the vibroacoustic response of systems with high modal densities. The most accurate predictions are obtained at high frequencies where the modal overlap is high and many modes contribute to the response in each frequency band. Under these conditions, the vibrational response is fairly uniformly distributed over frequency and over the spatial extent of the SEA subsystems. Validation of an SEA model at high frequencies can be accomplished by comparing the predictions of average subsystem response with an average formed from measured data at a relatively small number of locations. At lower frequencies, where the modal overlap is not high, the vibrational response shows significant variability over both frequency and location. Large variability makes validation of the models more difficult.