Search Results

This study is a joint development project between Chrysler Corporation and CFD Research Corporation. The objective of this investigation was to develop a 3D computational flow and heat transfer model for a vehicle windshield de-icing process. The windshield clearing process is a 3D transient, multi-medium, multi-phase heat exchange phenomenon in connection with the air flow distribution in the passenger compartment. The transient windshield de-icing analysis employed conjugate heat transfer methodology and enthalpy method to simulate the velocity distribution near the windshield inside surface, and the time progression of ice-melting pattern on the windshield outside surface. The comparison between the computed results and measured data showed very reasonable agreement, which demonstrated that the developed analysis tool is capable of simulating the vehicle cold room de-icing tests.

The purpose of this paper is to illustrate the use of Taguchi experimental methods as a development tool for designing a manufacturing process for inner door panels. Through analysis of experimental results, it was possible to identify critical manufacturing variables, as well as demonstrate inherent process capability.

The instrument panel (IP) is one of the largest, most complex, and visible components of the vehicle interior, and like most other major systems in passenger cars and light trucks, it has undergone considerable aesthetic and functional changes over the past decade. This is because a number of design, engineering, and manufacturing trends have been driving modifications in both the role of these systems and the materials used to construct them since the mid- '80s. This paper will trace the recent evolution of IP systems in terms of the trends affecting both design and materials usage. Specific commercial examples will be used to illustrate these changes.

The thermal performance of an automotive forward-lighting assembly is predicted with a computational fluid-dynamics (CFD) program. A three-dimensional, steady-state heat-transfer model seeks to account for convection and radiation within the enclosure, conduction through the thermoplastic walls and lens, and external convection and radiation losses. The predicted temperatures agree well with experimental thermocouple and infrared data on the housing. Driven by the thermal expansion of the air near the bulb surface, counter-rotating recirculation zones are predicted within the enclosure. The highest temperatures in the plastic components are predicted on the inner surface of the shelf above the bulb where airflow rising from the hot bulb surface impinges.

As the global auto industry wrote the final chapter on its first century, we saw the average thickness of an automotive instrument panel drop from 3.0 mm-3.5 mm to 2.0 mm-2.3 mm, as found in the 1999 Volkswagen Jetta and Golf. By reducing the wall thickness of the instrument panel, Volkswagen started an industry trend: both OEMs and tiers are investigating technologies to produce parts that combine a lower cost-per-part via material optimization and cycle-time reduction with the superior performance of engineering thermoplastics. The goal is to produce parts that are positioned more competitively at every stage of the development cycle - from design, to manufacturing, to assembly, to “curb appeal” on the showroom floor. The key to this manufacturing and design “sweet spot” is a technology called thinwall - the molding of plastic parts from engineering thermoplastics with wall thicknesses thinner than conventional parts of similar geometry.

The automotive industry is continually striving for opportunities to take additional cost and mass out of vehicle systems. Large parts such as an Instrument Panel retainer are good candidates because a small percent reduction in mass can translate into a significant material mass savings. Multiple requirements for a soft instrument panel including safety, stiffness, adhesion, etc. can make these savings difficult to achieve. This paper will describe how a new material and process development for the fabrication of a soft instrument panel can produce 50% weight savings with a 20% cost reduction potential. In addition, this new technology exhibits improved performance over existing materials during safety testing.

The Chrysler wind tunnel is a closed-circuit, single-return, semiopen jet facility used for performing engine cooling, transmission cooling, engine compartment airflow, underhood component temperature, air-conditioning, and other types of tests. It operates over a 0-120 mph speed range with 400 hp rear-wheel power absorption capacity. Special provisions have been made for idle, city traffic, and tail wind tests. Facility controls provide precise set-point capability, and comprehensive instrumentation and data acquisition systems permit measurement of many parameters and real time data reduction.

Aqua-ammonia absorption refrigeration cycle and R-134a Vapor jet-ejector refrigeration cycle for automotive air-conditioning were studied and analyzed. Thermally activated refrigeration cycles would utilize combustion engine exhaust gas or engine coolant to supply heat to the generator. For the absorption system, the thermodynamic cycle was analyzed and pressures, temperatures, concentrations, enthalpies, and mass flow rates at every point were computed based on input parameters simulate practical operating conditions of vehicles. Then, heat addition to the generator, heat removal rates from absorber, condenser, and rectifying unit, and total rejection heat transfer area were all calculated. For the jet-ejector system, the optimum ejector vapor mass ratio based on similar input parameters was found by solving diffuser's conservation equations of continuity, momentum, energy, and flow through primary ejector nozzle simultaneously.

THIS paper describes the springs, control system, and ride of the air suspension system on the 1958 Buick. The system is a semiclosed one, providing a variable-rate suspension, automatic leveling and trim control, and manual lift. The latter feature is a knob below the instrument panel which can be operated when necessary to cope with unusual clearance conditions. The car remains at the same height with loads of up to five passengers and 500 lb in the trunk. The authors describe the road-holding ability of a car with this suspension system as excellent.

Experimental study on a turbine housing with inner insulation structure has been conducted for rapid light-off of the catalyst unit, which is located at the downstream side of turbochargers. The turbine housing with feasible inner-insulation structures has been designed and prototyped. It is referred to as the inner-insulated turbine housing. The concept of inner-insulation structures is a combination of sheet metals and insulators. The turbine housing was built using metal additive manufacturing with powder bed fusion technique. The gas stand test demonstrates the inner-insulated turbine housing under cold start-up with high temperature and idle condition to evaluate the time reduction for activation of the catalyst unit. To acquire the thermal and flow characteristic of the catalyst element, sheathed thermocouples were installed in the catalyst element.

An evaporator which is one of important components of the automobile air conditioning system has been developed on the view point of increasing heat transfer coefficient and decreasing fluid pressure loss. To employ new configuration of refrigerant side heat transfer tube surface could improve heat transfer coefficient by 2.6 times of smooth surface heat transfer coefficient. A distribution adjustment pipe and optimized arrangement of heat transfer tubes were applied to achieve uniform refrigerant flow distribution. We tried to minimize the increase of refrigerant side pressure caused by employing turbulizers inside the heat transfer tubes. We studied on thermo-fluidic behavior experimentally and developed new high performance evaporator.

An automotive cockpit module is a complex assembly, which consists of components and sub-systems. The critical systems in the cockpit module are the instrument panel (IP), the floor console, and door trim assemblies, which consist of many plastic trims. Stiffness is one of the most important parameters for the plastic trims' design, and it should be optimum to meet all the three functional requirements of safety, vibration and durability. This paper presents how the CAE application and various other techniques are used efficiently to predict the stiffness, and the strength of automotive cockpit systems, which will reduce the product development cycle time and cost. The implicit solver is used for the most of the stiffness analysis, and the explicit techniques are used in highly non-linear situations. This paper also shows the correlations of the CAE results and the physical test results, which will give more confidence in product design and reduce the cost of prototype testing.

This paper describes the application of Statistical Energy Analysis (SEA) and Experimental SEA (ESEA) to calculating the transmission of air-borne and structure-borne noise in a mid-sized sedan. SEA can be applied rapidly in the early stages of vehicle design where the degree of geometric detail is relatively low. It is well suited to the analysis of multiple paths of vibrational energy flow from multiple sources into the passenger compartment at mid to high frequencies. However, the application of SEA is made difficult by the geometry of the vehicle's subsystems and joints. Experience with current unibody vehicles leads to distinct modeling strategies for the various frequency ranges in which airborne or structure-borne noise predominates. The theory and application of ESEA to structure-borne noise is discussed. ESEA yields loss factors and input powers which are combined with an analytical SEA model to yield a single hybrid model.

The low noise and linear sound level characteristics of passenger vehicles are receiving increased scrutiny from automotive journalists. A linear noise level rise with increasing engine rpm is the first basic aspect of insuring an acceptable vehicle interior engine noise sound quality. In a typical case of structural response to engine vibration input, interior noise begins to rise with rpm, remains constant or even drops as the engine continues to accelerate, and then exhibits a noise period corresponding to the structure's natural frequency. Frequently this nonlinearity is bothersome to the customer. During the development process, Chrysler's Dodge and Plymouth Neon exhibited just such a nonlinear rise in noise level, heard within the passenger compartment, when the vehicle was accelerated through 4200 rpm.

To demonstrate that quantitative design criteria combined with computer analysis methods can facilitate the structural design of an automotive vehicle, two examples of computer aided preliminary design are given. The examples demonstrate analytical techniques applied at two different stages in the design process for a compact size (non-production) automobile. In the first example, analysis is applied to ensure that the front-end structure of the project vehicle is designed to withstand anticipated in-service loads. In the second example, structural dynamic analysis of the total vehicle system is performed to determine vibration response quantities in the passenger compartment. These quantities are compared with whole-body vibration criteria to assess passenger ride quality.

With parts consolidation and increasing systems performance requirements, instrument panel systems have become increasingly complex. For these systems, the use of predictive engineering tools can often reduce development time and cost. This paper outlines the use of such tools to support the design and development of an instrument panel (IP) system. Full-scale test results (NVH, head impact, etc.) of this recently introduced IP system were compared with predicted values. Additionally, results from moldfilling analysis and manufacturing simulation are also provided.

As the need for plastic components with high-performance and low systems cost continues to escalate, the issues associated with bringing applications to automotive market have become more complex. Automotive applications such as seamless integral Passive Supplemental Inflatable Restraint (PSIR) systems can have tearseams that are either molded-in or laser scored. Molded-in tearseams in seamless Instrument Panels (IP) eliminate the secondary operation of laser scoring, but they warrant thin wall molding conditions. This paper describes material characterization under thinwall molding conditions wherein the effects of processing on mechanical properties are explored. This paper also discusses results from a proprietary finite element code developed at GE to predict the processing parameters, which affect the mechanical properties of the material at the tearseam in a seamless IP system.

Hand dismantling of certain automotive parts has been an accepted process to remove high value materials, but in large scale recycling this may not be economical. In plastics, a pure non contaminated material stream is critical for maintaining high material values and this means designing plastic parts that can be machine separated. One candidate for separating the plastics in vehicle subsystems such as instrument panels and door trim panels is density separation. In order to better understand what processes are required to develop design requirements for automated plastic separation methods Chrysler and the Vehicle Recycling Partnership have undertaken a major materials separation study with MBA Polymers. In this paper, we describe the material separation methods and the application of these methods to three automotive interior assemblies.

To understand how the passenger compartment cavity interacts with the surrounding panels (roof, windshield, dash panel, etc) a numerical panel contribution analysis was performed using FEA and BEA techniques. An experimental panel contribution analysis was conducted by Reiter Automotive Systems. Test results showed good correlation with the simulation results. After gaining some insight into panel contributions for power train noise, an attempt was made to introduce beads in panels to reduce vibration levels. A fully trimmed body structural-acoustic FEA model was used in this analysis. A network of massless beam elements was created in the model. This full structural-acoustic FEA model was then used to determine the optimal location for the beads, using the added beams as optimization variables.

As automakers struggle to meet often conflicting safety, weight, styling, and performance requirements, engineering thermoplastics (ETPs) are making increasing inroads into applications that once were the exclusive domain of metals, glass, and thermosets. A good example of this is in the door systems area, where the performance, design flexibility, aesthetics, parts integration, and lower specific gravity offered by ETPs are allowing highly integrated and efficient modules to be created that, in turn, increase assembly efficiency and reduce mass, part count, warranty issues, and systems costs. This paper will use several case studies on innovative door hardware modules and door panels to illustrate the advantages offered by this versatile class of engineering materials.