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Technical Paper

Effects of Vehicle Windshield Defrosting and Demisting Process on Passenger Comfort

2001-05-15
2001-01-1729
This paper describes an investigation into the fluid flow and heat transfer on the windshield as well the effect of the air discharge from the defroster vents on passenger comfort. The investigation is both experimental and computational. Full-scale tests are conducted on a current vehicle model using non-intrusive diagnostic methods. The results presented are from numerical simulations validated by experimental measurements. The numerical predictions compare well with the experimental measurements. The locations of maximum velocity and pressure, as well as width and length of re-circulation regions, are correctly predicted.
Technical Paper

Material Damping Properties: A Comparison of Laboratory Test Methods and the Relationship to In-Vehicle Performance

2001-04-30
2001-01-1466
This paper presents the damping effectiveness of free-layer damping materials through standard Oberst bar testing, solid plate excitation (RTC3) testing, and prediction through numerical schemes. The main objective is to compare damping results from various industry test methods to performance in an automotive body structure. Existing literature on laboratory and vehicle testing of free-layer viscoelastic damping materials has received significant attention in recent history. This has created considerable confusion regarding the appropriateness of different test methods to measure material properties for damping materials/treatments used in vehicles. The ability to use the material properties calculated in these tests in vehicle CAE models has not been extensively examined. Existing literature regarding theory and testing for different industry standard damping measurement techniques is discussed.
Technical Paper

The Effect of High Mileage Spot Weld Degradation on Vehicle Body Joint Stiffness

2001-03-05
2001-01-0426
Joint stiffness is a major contributor to the vehicle body overall bending and torsional stiffness which in turn affects the vehicle NVH performance. Each joint consists of spot welds which function as load paths between adjacent sheet metal. Spot welds tend to lose structural integrity as a result of fatigue, loosening, aging, wear and corrosion of parts as a vehicle accumulates mileage. Experimental methods are used to identify potential degradation mechanisms associated with a spot weld. A CAE model which simulates a vehicle body joint generically is used to determine the effects of each individual degradation mode of a spot weld on joint stiffness. A real life B-pillar to roof joint CAE model of a production vehicle is then employed to examine the significance of weld distribution on joint stiffness degradation. The knowledge derived from this study can be used as a guidance in designing vehicle body structures with respect to spot weld distribution.
Technical Paper

An Assessment of a FEA NVH CAE Body Model for Design Capability

2001-04-30
2001-01-1401
Finite Element Analysis (FEA) models are routinely being adopted as a means of up-front design for automotive body structure design. FEA models play two important functions: first as a means of assessing design versus an absolute target; secondly they are used to assess the performance of design alternatives required to meet targets. Means of assessing model capability versus task is required to feed appropriate information into the design process. Being able to document model capability improves the credibility of the FEA model information. A prior paper addressed assessing the absolute performance of model technology using a metric based on a statistical hypotheses test that determines membership in a reference set. This paper extends the use of quality technology to determining the capability of the FEA model to span the design space using Designed Experiments.
Technical Paper

A New Experimental Methodology to Estimate Chassis Force Transmissibility and Applications to Road NVH Improvement

2003-05-05
2003-01-1711
The performance of structure-borne road NVH can be cascaded down to three major systems: 1) vehicle body structure, 2) chassis/suspension, 3) tire/wheel. The forces at the body attachment points are controlled by the isolation efficiency of the chassis/suspension system and the excitation at the spindle/knuckle due to the tire/road interaction. The chassis force transmissibility is a metric to quantify the isolation efficiency. This paper presents a new experimental methodology to estimate the chassis force transmissibility from a fully assembled vehicle. For the calculation of the transmissibility, the spindle force/moment estimation and the conventional Noise Path Analysis (NPA) methodologies are utilized. A merit of the methodology provides not only spindle force to body force transmissibility but also spindle moment to body force transmissibility. Hence it enables us to understand the effectiveness of the spindle moments on the body forces.
Technical Paper

Wind Noise and Drag Optimization Test Method for Sail-Mounted Exterior Mirrors

2003-05-05
2003-01-1702
An L18 Taguchi-style Design of Experiments (DOE) with eight factors was used to optimize exterior mirrors for wind noise and drag. Eighteen mirror properties were constructed and tested on a full size greenhouse buck at the Lockheed low-speed wind tunnel in Marietta, GA. Buck interior sound data and drag measurements were taken at 80 MPH wind speed (0° yaw angle). Key wind noise parameters were the fore/aft length of mirror housing and the plan view angle of the mirror housing's inboard surface. Key drag parameters were the fore/aft length of the mirror housing, the cross-section shape of the mirror pedestal, and the angle of the pedestal (relative to the wind).
Technical Paper

Full- and Model-Scale Scrutiny of the Effects of Vehicle Windshield Defrosting and Demisting on Passenger Comfort and Safety

2003-03-03
2003-01-1082
Maintaining adequate visibility at all times, through a vehicle windshield, is critical to the safe usage of the vehicle. The ability of the windshield defrosting and demisting system to quickly and completely melt ice on the outer windshield surface and remove mist formed on the inner surface is therefore of paramount importance. The objectives of this paper are to investigate the fluid flow and heat transfer on the windshield as well the effect of the air discharge from the defroster vents on passenger comfort. The results presented are from numerical simulations validated by experimental measurements both carried out a model and full-scale. The numerical predictions compare well with the experimental measurements at both scales. The effects of the defrosting and demisting air on occupants' comfort and safety are examined.
Technical Paper

Design and Development of 25% Post-Industrial Recycled SMC Hood Assembly for the 1998 Lincoln Continental Program

1998-02-23
981019
This paper describes the process of incorporation of 25% post-industrial recycled sheet molded composite (SMC) material in the 1998 Continental Hood inner. 1998 Continental Hood assembly consists of traditional SMC outer and this recycled hood inner along with three small steel reinforcements. BUDD Plastics collects SMC scraps from their manufacturing plants. The scrap is then processed and made into fillers for production of SMC. Strength of SMC comes from glass fibers and fillers are added to produce the final mix of raw materials. This recycled material is approximately 10% lighter and less stiff than the conventional virgin SMC. This presented unique challenges to the product development team to incorporate this material into a production vehicle in order to obtain the desired goal of reducing land fill and improving the environment.
Technical Paper

Body Structure Joint Optimization: A Cost Driven Approach

1998-09-29
982280
Cross-section properties and joint stiffness properties of the body structure define its characteristic behavior. During the transitional product development process, body structure joints are optimized on an individual basis to reduce cost and weight. The objective of this paper is to present a methodology to analyze the entire body structure design by optimizing each body joint for stiffness and cost. This methodology utilizes joint sensitivity data from FEA, section properties, and cost/weight data. When the joint stiffness status does not meet the target during the design process, the methodology is an effective tool in making decisions regarding the gage increase/decrease for each part constituting body structure joints. Additionally, the methodology has been applied to body structure joints and door upper frame separately.
Technical Paper

Engineering Moveable Glass Window Seals of Automotive Door Using Upfront CAE

1998-09-29
982383
The traditional moveable glass window seal development process has relied heavily on physical prototypes for design verification. Due to frequent styling changes and an overall reduction in design time, physical prototypes for the glass window seals have proven to be inadequate. Utilization of computer aided engineering (CAE) tools is necessary in order to shorten lead time. CAE tools will help to decrease expensive prototyping, free up valuable manufacturing line time, and improve overall quality. A cross functional approach has been applied to expand the scope beyond traditional methods of moveable glass window seal design, such as wedged boarding, into new computerized modeling methods. The CAE was used to address major requirements of the glass window seals including glass velocity, glass stall force, sealing-ability, seal durability, seal assembly, seal appearance, and regulator motor current.
Technical Paper

The P2000 Body Structure

1998-09-29
982405
The objective of the P2000 body structure design was to provide a body structure with 50% of the mass of current mid-size production vehicles while maintaining all the safety, durability, NVH and other functional attributes. In addition, the design was to be consistent with the PNGV affordability objectives and high volume production by 2005. This paper describes the P2000 body structure including the structural philosophy, project constraints on the design, manufacturing processes, supporting analyses, assembly processes and unique material and design concepts which resulted in the 50% weight reduction from comparable production vehicles.
Technical Paper

Role of the Body Mount on the Passenger Compartment Response of a Frame/Body Structured Vehicle in Frontal Crash

1998-02-23
980861
A comprehensive strategy to investigate the role of the body mounts on the passenger compartment response in a frontal crash event is presented. The activities of the study include quasi-static vehicle crush testing, development of a component-level dynamic body mount test methodology, lumped-mass computer modeling, as well as technical analysis. In addition, a means of investigating the effects the body mounts have on the passenger compartment response during a frontal barrier impact is addressed.
Technical Paper

State of Knowledge and Current Challenges in Defrosting Automotive Windshields

1998-02-23
980293
Rapid and effective windshield defrosting has been the goal of various investigations by automotive engineers around the world. Car manufacturers have invested considerable resources to satisfy the thermal needs, safety requirements, and comfort demands of their customers. This paper addresses the climate control issues of defrosting automotive windshields. The paper summarizes the state of knowledge of the various approaches for improving defroster performance. Experimental as well as computational efforts, accompanied by heating techniques and heat boosters will be presented. The paper also features relevant measurement methods for airflow and thermal patterns, and discusses current challenges. Recommendations are made on where to focus engineering and design efforts given the state of present technologies.
Technical Paper

Integration of Chassis Frame Forming Analysis into Performance Models to More Accurately Evaluate Crashworthiness

1998-02-23
980551
For Body on Frame vehicles, the chassis truck frame absorbs approximately 70% of the kinetic energy created from a frontal impact. Traditional performance analysis of the chassis utilizes standardized material properties for the Finite Element (FE) Model. These steel properties do not reflect any strain hardening effects that occur during the forming process. This paper proposes a process that integrates the frame side rail forming analysis results into the FE crash model. The process was implemented on one platform at Ford Motor Company to quantify the effects. The forming analysis provided material thinout, yield strength, and tensile strength which were input into the performance model. With the modified properties, the frame deceleration pulse and buckling mode exhibited different characteristics. The integration of CAE disciplines is the next step in increasing the predictability of analytical tools.
Technical Paper

The Effect of Contact Surface and Bolt Torque Variations on the Brake Rotor Run-Out

1998-02-23
980596
Deformation of the hub, rotor, and the wheel results in lateral run-out of the rotor. The effect of contact surface variations and bolt forces on the deformation is investigated. It is analytically shown that the run-out due to deformation is caused primarily due to the radial and circumferential moments generated in the hub and the rotor due to bolt tightening. Case studies illustrate the interaction between hub, rotor, and the wheel for various surface conditions. Design guidelines are provided to reduce rotor run-out.
Technical Paper

Fundamental Issues in Automotive Veiling Glare

1997-02-24
970227
The veiling glare effect in automotive vehicles consists of diffuse and specular scattering of sunlight onto and from the windshield. This effect occurs over a wide range of solar elevation angles and increases with increased degree of inclination of the windshield. Thus its effect on visual acuity must be considered in automotive design. The present research on the subject of veiling glare only addresses scattering from a clean windshield and ignores the larger effect of scattering from dust, dirt or haze on the front and back faces of the windshield since the latter is operator dependent (can be removed by cleaning the windshield). In this paper, we present an analysis of autmotive veiling glare that takes into account windshield reflectivity without and with coatings, and the characteristics of dashboard cover materials.
Technical Paper

Front End Accessory Drive Program Management

1987-11-01
872227
Program Management organizes the different phases of new Front End Accessory Drive (FEAD) designs from inception providing lower cost, higher quality and shorter product development cycles. These outcomes are accomplished using a team concept to successfully incorporate simultaneous engineering, computer design/development methods, supplier input and other techniques.
Technical Paper

Soft Fascia Concept for 1979 Mustang/Capri Design and Manufacturing Considerations

1979-02-01
790331
A number of design and manufacturing requirements were considered in the development and application of a large, complex, RIM produced soft fascia for the 1979 Mustang and Capri front ends. The design and manufacturing process had to be closely coordinated to achieve the fit, functional and appearance objectives of this highly styled one piece soft part. The successful application of the 1979 Mustang and Capri soft flexible fascia demonstrates that the design and manufacturing capabilities exist and that the fascia concept will be a viable product/design consideration for future applications.
Technical Paper

Status and Update of MVMA Component Testing

1987-05-01
871116
At the Tenth ESV Conference, MVMA reported on the development of a component side impact test device developed for MVMA by MGA Research Corporation. Since that time, the test device has been modified by MGA to improve its biofidelity. Testing has shown that the modified device better meets the force-time corridors derived by MVMA from cadaver drop test data. The improved test device was used to test twelve 1985 Ford LTD doors at speeds of 25.7 and 37 km/h. The interior door surfaces were trimmed with either thin fiber board or foam padding identical to doors in vehicles tested by MVMA using NHTSA's full-vehicle test procedure. The tests showed that the MVMA device is simple to set up and run, is highly repeatable and easily discriminates between the unpadded and padded doors. A major issue for future research and development is how to select a priori a component test device impact speed which can account for differences in car size and side structure stiffness.
Technical Paper

The 1973 Ford Impact Absorbing Bumper System

1973-02-01
730032
The Federal government requires that all 1973 passenger cars be capable of withstanding a 5 mph front bumper and a 2.5 mph rear bumper fixed-barrier impact without damage to safety related components (lighting, latching, fuel, exhaust, cooling, propulsion, steering and braking systems). Two basic ways in which the impact energy can be handled are: (1) a thick flexible, external covering or large, flexible bumper guards attached to a rigid bumper-bar which is rigidly attached to the chassis by suitable supports; (2) a rigid reinforced bumper-bar attached to the chassis by means of compliant or compressible impact absorbing devices. While this general approach is used on most 1973 cars, the details of operation of the various systems are markedly different. Whereas, some of the systems utilize fluid-flow through an orifice to absorb energy, Ford Motor Company devices utilize shear deformation of rectangular rubber blocks.
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