Refine Your Search




Search Results

Technical Paper

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

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

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

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

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

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

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

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

The P2000 Body Structure

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

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

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

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

Front End Accessory Drive Program Management

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

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

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

Pedestrian Head Impact Time Estimate based on Vehicle Geometric Parameters

Pedestrian protection assessment methods require multiple head impact tests on a vehicle’s hood and other front end parts. Hood surfaces are often lifted up by using pyrotechnic devices to create more deformation space prior to pedestrian head impact. Assessment methods for vehicles equipped with pyrotechnic devices must also validate that the hood deployment occurs prior to head impact event. Estimation of pedestrian head impact time, thus, becomes a critical requirement for performance validation of deployable hood systems. In absence of standardized physical pedestrian models, Euro NCAP recommends a list of virtual pedestrian models that could be used by vehicle manufacturers, with vehicle FEA (Finite Element Analysis) models, to predict the potential head impact time along the vehicle front end profile. FEA simulated contact time is used as target for performance validation of sensor and pyrotechnic deployable systems.
Technical Paper

Full Scale Burn Test of Four Aluminum Body Ford F-150’s

Four full scale burn tests on aluminum body Ford F-150’s were conducted with four unique origins. The purpose of these burn tests was to determine if the origin of the fire could be accurately identified after the vehicle fires progressed to near complete burn (with near absence of the aluminum body panels). The points of origin for the four burn tests were: 1) Engine Compartment - driver’s side front of engine compartment, 2) Passenger Compartment - Instrument panel, driver’s side near the headlamp switch, 3) Passenger Compartment - passenger side rear seat, 4) Outside of Vehicle - passenger side front tire. Photographic, video, and temperature data was recorded to document the burn process from initiation to extinguishment. Post-fire analysis was conducted in an attempt to determine the origin of the fire based solely on the burn damage.
Technical Paper

Residual Effects of Metal Forming on Seat Belt Pull Analysis Results

Automotive industries are emphasizing more and more on occupant safety these days, due to an increase in awareness and demand to achieve high safety standards. They are dependent on simulation tools to predict the performance of subsystems more accurately. The challenges being encountered are designs which are getting more complex and limitations in incorporating all real-life scenarios, such as to include all manufacturing considerations like forming and welding effects. Latest versions of solvers are slowly introducing new options to include these actual scenarios. Ls-Dyna is one of the explicit solvers to introduce these possibilities. The process of including stamping details into crash simulation is already being performed in the automotive industry. However, for seatbelt pull analysis, this has not been explored much.
Technical Paper

Design of Automotive Structures Using Multi-Model Optimization

The use of structural optimization in the design of automotive structures is increasingly common. However, it is often challenging to apply these methods simultaneously for different requirements or model configurations. Multi-model optimization (MMO) aims to simplify the iterative design process associated with optimizing multiple parts or configurations with common design variables especially when conflicting requirements exist. In this paper, the use of MMO is demonstrated to evaluate the feasibility of an automotive door concept using an alternative material.
Technical Paper

Magnetic Tape and Servo-Hydraulics Applied to Truck Frame Testing

This paper discusses the possible impact of the FM tape recorder and servo-hydraulic actuators on the testing of automotive structures. The use of tape recorders and automatic data reduction systems will permit more accurate definition of service conditions and properly “set-the-stage” for laboratory testing. Servo-hydraulic strokers should encourage better laboratory simulation because of their great flexibility. Test set-up time is reduced, fixtures can be simplified and load control is more precise. Simultaneous multiple inputs can be controlled as to amplitude and phase relationships.
Technical Paper

Bending Process Optimization of Dual Phase 780 (DP780) Tubes for Body Structural and Chassis Applications

To reach safety, emissions, and cost objectives, manufacturers of automotive body structural and chassis components shape thin gauge, high strength steel tube with a bending, pre-forming and hydroforming process. Challenging grades and bend severity require a careful optimization of the bending procedure. A joint project between Ford and ArcelorMittal Tubular Products investigated suitable bending parameters for severe bends using commercially available thin-walled DP780 and HSLA350 tubes. This paper summarizes the measurement methods found to be capable of capturing small differences in bending formability and details the influence of bender variables such as boost, pressure die, center-line bend radius and bend angle on the wrinkling, thinning and springback of these tubes. As a result of this work, recommendations were made as to effective bender set-ups for these tubes.
Technical Paper

Use of Body Mount Stiffness and Damping In CAE Crash Modeling

This paper reports a study of the dynamic characteristics of body mounts in body on frame vehicles and their effects on structural and occupant CAE results. The body mount stiffness and damping are computed from spring-damper models and component test results. The model parameters are converted to those used in the full vehicle structural model to simulate the vehicle crash performance. An effective body mount in a CAE crash model requires a set of coordinated damping and stiffness to transfer the frame pulse to the body. The ability of the pulse transfer, defined as transient transmissibility[1]1, is crucial in the early part of the crash pulse prediction using a structural model such as Radioss[2]. Traditionally, CAE users input into the model the force-deflection data of the body mount obtained from the component and/or full vehicle tests. In this practice, the body mount in the CAE model is essentially represented by a spring with the prescribed force-deflection data.
Technical Paper

Nondestructive Evaluation of Adhesively-Joined Aluminum Alloy Sheets Using an Ultrasonic Array

Adhesive bonding technology has gained ever-increasing significance in automotive industry, especially with the growing use of aluminum (Al) alloy body structures. The variability in thicknesses of the metal and adhesive layers, as well as in joint geometry, of automotive components has presented challenges in nondestructive evaluation of adhesive joints. Though these challenges were recently overcome for steel-adhesive joints using an ultrasonic pulse-echo technique, the difference in acoustic impedances of steel and Al leads to a lack of robustness in utilizing the same algorithm for Al-adhesive joints. Here, we present the results from using a modified version of this technique to inspect Al-adhesive joints in both laboratory and production environments. A 15-MHz, 52-pixel, 10 mm × 10 mm matrix array of ultrasonic transducers was used to obtain ultrasonic pulse echoes from joint interfaces, analysis of which produced C-scan images of the adhesive bead.