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.

This paper discusses simplified lumped parameter thermal modeling of power train components. In particular, it discusses the tradeoff between model complexity and the ability to correlate the predicted temperatures and flow rates with measured data. The benefits and problems associated with using a three lumped mass model are explained and the value of this simpler model is promoted. The process for correlation and optimization using modern software tools is explained. Examples of models for engines and transmissions are illustrated along with their predictive abilities over typical driving cycles.

There is a major problem in maintaining the records of the more than 275 million vehicles presently registered throughout the world. Monitoring the life of a given vehicle from its fabrication to its destruction can best be accomplished by the inner facing of major computer programs and a uniform system for vehicle identification. The Vehicle Identification Number (VIN) is the legal identification of the vehicle. Every manufacturer has the responsibility of assigning a unique VIN to each vehicle, in compliance with numerous procedures, standards and laws. The VIN is attached to the vehicle, stamped and embossed on components, and printed on tamper resistant labels. It is printed on hundreds of documents and maintained in numerous files.

Chrysler Corporation Interior Electrical\Entertainment Department currently has three different mounting tab configurations on the radio escutcheon required by five platforms for radio installation. Prior to the re-organization into platforms, the corporation had one corporate mounting configuration. The reorganization into platforms encouraged diversification including different radio mounting locations. This however, requires three separate part numbers for the same radio unit, resulting in additional cost. How can we assure product diversification between platforms while controlling cost and managing complexity?

A selection of commercially available chromium and chromium-free post phosphate rinses along with a deionized water rinse were evaluated over several zinc and zinc-alloy coated sheet steels. The test specimens were pretreated and electrocoated on-line in an automotive assembly plant. The effect of the rinse treatments on the cosmetic corrosion performance of the substrates, after 5 years of exposure in an outdoor scab corrosion test was determined. After this exposure none of the rinse treatments had performed better than deionized water rinse on zinc and zinc-iron coated sheet. The zinc-nickel coating showed improved scribe creepage when treated with the Cr+6/Cr+3 rinse. Data is provided comparing the concentration of the treatments used vs scribe creepage and chipping corrosion paint loss.

A highly competitive market and increased emphasis on quality have gear designers searching for additional tools to produce accurate gearsets in a condensed timeframe. To meet this challenge, a Graphics Engineering method has been developed to enhance traditional gear design techniques. Graphics Engineering links interactive graphics, finite element analysis and solid modeling into a graphics/analysis development package. Starting with gear and cutter data derived by conventional techniques, it provides cutter paths and involute profiles for geometry, strength, and physical property analysis. The comprehensive data obtained through Graphics Engineering provides a powerful tool for the gear designer to increase gearset accuracy and reduce design iterations.

The object of this paper is to present an overview of the procedure leading to the selection of suspension system pivot points, show how to resolve terrain and maneuver loads at the tire contact patch to the vehicles' structure, illustrate the modeling technique used for stress analysis of suspension system components, and illustrate a few examples of suspension system models used to aid in the solution of ride and handling problems.

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 presents a method of accounting for sample variability and sample size in establishing the acceptable bogey levels. The technique makes use of the statistical tolerance theory which accounts for the variability of the sample mean and standard deviation by determining a K-factor adjusted for sample size. The result is a tolerance that is reasonably assumed to cover a specified fraction of the population of parts. The technique, although not as simple as a fixed bogey, does discriminate between designs with different levels of energy management robustness.

In recent years, strict weight reduction targets have pushed auto manufacturers to use lighter gauge sheet steels in all areas of the vehicle including exterior body panels. As sheet metal thicknesses are reduced, dentability of body panels becomes of increasing concern. Thus, the goal becomes one of reducing sheet metal thickness while maintaining acceptable dent resistance. Most prior work in this area has focused on quasi-static loading conditions. In this study, both quasi-static and dynamic dent tests are evaluated. Fully assembled doors made from mild, medium strength bake hardenable and non-bake hardenable steels are examined. The quasi-static dent test is run at a test speed of 0.1 m/minute while the dynamic dent test is run at a test speed of 26.8 m/minute. Dynamic dent testing is of interest because it more closely approximates real life denting conditions such as in-plant handling and transit damage, and parking lot damage from car door and shopping cart impact.

Although numerical simulation techniques for sheet metal forming become increasingly maturing in recent years, prediction of springback remains a topic of current investigation. The main point of this paper is to illustrate the effectiveness of a modelling approach where static implicit schemes are used for the prediction of springback regardless whether a static implicit or dynamic explicit scheme is used in the forming simulation. The approach is demonstrated by revisiting the 2-D draw bending of NUMISHEET'93 and numerical results on two real world stampings.

A mathematical model was developed to evaluate design options for control of road noise transmission into the interior of a passenger car. Both air-borne and structure-borne road noise over the frequency range of 200-5000 Hz was able to be considered using the Statistical Energy Analysis (SEA) method. Acoustic and vibration measurements conducted on a laboratory rolling road were used to represent the tire noise “source” functions. The SEA model was correlated to in car sound pressure level measurements to within 2-4 db accuracy, and showed that airborne noise dominated structure-borne noise sources above 400 Hz. The effectiveness of different noise control treatments was simulated and in some cases evaluated with tests.

For designing new products or developing new specifications, the reliability performance of systems and components experienced by the customer provides invaluable information for the engineer. This information, not only provides for the visibility of reliability requirements, but also an awareness of potential degradation of the systems and components during its life cycle. In this paper, a method is presented for predicting vehicle system and component reliability from vehicle fleet repair data. This method combines sampling stratification, computer data analysis and statistical modeling techniques into a reliability analysis procedure to provide reliability prediction. Specifically, published vehicle fleet data was used to provide the basis for predicting the vehicle system and component reliability at any mileage level.

An extensive program has been established to screen and evaluate heat- and corrosion-resistant alloys that may have some potential application in emission-control systems anywhere from the exhaust manifold to the tailpipe. The various phases of this program, which include tests conducted in air and controlled exhaust atmospheres at temperatures between 1300-2200°F are described. Some selected test data and the results of metallographic studies are presented to illustrate how representative alloys react to the various test conditions. The characteristics and functions of the basic emission-control devices are reviewed in light of their effect upon materials requirements.

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.

A method has been employed in the stamping facility to reduce scrap by correlating observations from the press shop with laboratory test results. This paper illustrates the successful use of this method for reducing formability failures. Correlation of observed coating behavior with laboratory adherence tests is also discussed.

MIL 3's OPNET simulator was used to model Chrysler's J1850 bus. Modeled were both J1850 bus characteristics and those portions of control modules (e.g., the engine controller) which communicate on the bus. Current Chrysler control module algorithms and proposed Chrysler J1850 message formats were used to design the control module models. The control module models include all messages which are transmitted at fixed intervals over the J1850 bus. The effects of function-based messages (e.g., messages to be transmitted on a particular sensor or push-button reading) on system load were investigated by transmitting an additional message with a fixed, relatively high priority at 50 millisecond intervals.

The impact response of foam is investigated using Finite Element Analysis (FEA). A procedure will be described for determining the material constants used in the FEA material models. The procedure uses compressive uniaxial, force versus displacement, and triaxial, pressure versus volume-change, data. After the material model is constructed using the uniaxial and triaxial data, FEA is used to predict the results of a free-moving-mass striking rigidly backed foam. The limitations of the current material models are also addressed.

A laboratory test fixture was designed and built to simulate seat belt assembly installations. The anchor positions of the retractor and pillar loop, and the engaged or free-hanging position of the latchplate can be varied to either simulate a vehicle's seat belt system geometry, or to optimize a proposed geometry. The required retraction forces for a simulated geometry are determined by replacing the retractor action with a motorized load transducer that measures the force required to stow the latchplate. The pillar loop, webbing, latchplate, and their relative positions can be varied until the minimum retraction force that successfully stores the latchplate is determined. The geometry of such a condition can then be applied to future designs of seat belt assembly components and their anchor positions.