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Sheet metal forming of automobile body panel consists of two processes performed in series: binder forming and punch forming. Due to differences in deformation characteristics of the two forming processes, their analysis methods are different. The binder wrap surface shape and formed part shape are calculated using different mathematical models and different finite element codes, e.g., WRAPFORM and PANELFORM, respectively. The output of the binder forming analysis may not be directly applicable to the subsequent punch forming analysis. Interpolation, or approximation, of the calculated binder wrap surface geometry is needed. This surface representation requirement is carried out using computer aided geometric design tools. This paper discusses the use of such a tool, SURFPLAN, to link WRAPFORM and PANELFORM calculations.

This report is a comprehensive investigation into the use of resin transfer molded glass fiber reinforced plastics in a structural application. A pickup truck cab structure is an ideal application for plastic composites. The cab is designed to fit a production Ranger pickup truck and uses carryover frame and front end structure. The cab concept consists primarily of two molded pieces. This design demonstrates extensive parts integration and allows for low-cost tooling, along with automated assembly.

Present models and methods for simulations of sheet metal forming processes are reviewed in this paper. Because of rapid progress of computer hardware, complex computations, formerly impossible to perform due to high computational cost, are now feasible. Therefore, more realistic and computational intensive models are suggested for finite elements, materials, and frictional forces. Also, simulation methods suitable for sheet metal forming processes are recommended. Four numerical examples at the end of the paper are presented to support the recommendations.

The bulge test in hydroforming is a simple fundamental experiment used to obtain basic knowledge in tube expansion. The results can be used to assist design and manufacturing of hydroformed automotive parts. It also can be used to develop a failure criterion for tubes in hydroforming. For these purposes, a section of a long unsupported tube with fixed ends was simulated numerically to obtain the mechanical states of the tube subjected to internal pressure. Steel and aluminum tubes are used. For the bulge tests, the internal pressure reaches a maximum and then decreases in value without failure while the stress, strain and volume of the tube keep increasing. A failure criterion for the bursting of a tube is proposed based on the stress-strain curve of the material.

One of the possibilities to fulfill the enhanced requirements on crash performance for new vehicles is the application of high strength steels (HSS) and even ultra high strength steels (UHSS). In order to achieve the strength, the strain rate sensitivity can be taken into account whereas the work hardening effect is difficult to be used. For UHSS with more than 500 MPa yield point the formability, spring back and weldability are important issues. In the present study the laser weldability of UHSS has been studied with positive results. Both Dual phase type and micro alloyed type LWBs showed high formability and good weldability and will satisfy the requirement of certain applications for body members. Stamping trials in the press shop under production conditions showed that the peak strain in certain parts can be reduced to avoid splits when LWBs were stamped. Simultaneously the spring back is reduced as well.

Current trends in the auto industry requiring tighter dimensional specifications combined with the use of lightweight materials, such as aluminum, are a challenge for the traditional manufacturing processes. The hemming process, a sheet metal bending operation used in the manufacturing of car doors and hoods, poses problems meeting tighter dimensional tolerances. Hemming is the final operation that is used to fasten the outer panel with the inner panel by folding the outer panel over the inner panel. Roll in/out is one of the main quality concerns with hemming, and keeping it under tolerance is a high priority issue for the auto manufacturers. Current hemming process technology, given the mechanical properties of current materials, has reached its saturation limit to deliver consistent dimensional quality to satisfy customers and at the same time meet government standards.

Recent advances in press and die building have provided the capability of restraining force (RF) variation during a sheet stamping stroke. Even though the commercial presses with VRF capabilities are now available, the full benefits cannot be attained because, for complex industrial stampings, it is difficult to select the VRF trajectory which will improve the stamping quality or achieve even more complex task of arriving at the desired design target. In this paper we demonstrate how numerical modeling can be used to select a proper VRF trajectory to achieve a postulated design target. The working numerical model using explicit LS-Dyna 3D code was successfully developed for time effective simulation of complex parts with variable binder force. Three case studies with the specific design targets of 1) springback, 2) punch force, and 3) maximum strain are presented and discussed. The results show strong nonlinear influence.

This report presents results of experiments to determine the effect of elevated temperature exposures on the mechanical properties of aluminum alloy materials. The two alloys studied, 5754 and 6111, are of the types which would be used in a stamped automobile structure and exterior panels. Yield strength, tensile strength, and total elongation are reported for a variety of test conditions. The material temperature exposures simulated a broad range of conditions which might be experienced during manufacturing operations such as adhesive curing and vehicle paint bake cycles. In addition, tests were conducted at temperatures to resemble in-service under-hood and under body (near the exhaust system) conditions. Materials were prestrained various amounts prior to temperature exposure to simulate metal forming processes. Results show that both materials react to temperature and aging times differently.

Creep-resistant magnesium alloys for automotive powertrain applications offer significant potential for vehicle weight reduction. In this study permanent mold casting, microstructure and creep behavior have been investigated for a series of ternary magnesium alloys (Mg-4Al-4X (X: Ca, Ce, La, Sr) wt%) and AXJ530 (Mg-5Al-3Ca-0.15Sr, wt%). A permanent mold was instrumented with twelve thermocouples and mold temperature was monitored during the casting process. Average mold temperature increased from 200°C to 400°C during a typical alloy casting series (fifteen to twenty castings). The cast microstructure for all alloys consists of primary α-Mg globular phase surrounded by eutectic structure which is composed of intermetallic(s) and α-Mg magnesium phases. The primary cell size of the AXJ530 increased from 18 to 24 μm with increasing mold temperature and a similar trend is expected for all alloys.

A method to predict gap distribution, can deformation and mounting force of catalytic converter during assembling and operation cycles has been developed using ABAQUS contact algorithm with user subroutine for material properties. Inherent in the methodology is the constitutive model for both vermiculite mat and wire mesh mounting materials, which is able to describe their nonlinear and thermal behaviors and shows good agreement with test results. A design optimization procedure is presented to achieve uniform gap design of can and substrate. The technology will enable engineers to generate robust converter can designs, substrate shape and stamping tools for minimum manufacturing failure rate and maximum durability performance once a mounting material is selected.

This paper documents the finite element (FE) analysis of a hot stamping process for high strength aluminum sheet. In this process a 7075 blank, heated above its solvus temperature, was simultaneously die quenched and stamped in a room temperature die to form a B-pillar outer reinforcement. Two modeling approaches have been investigated: an isothermal mechanical model and a non-isothermal coupled thermo-mechanical model. The accuracy of each approach was assessed by comparing the predicted strain and thickness distributions to experimental measurements from a formed panel. The coupled thermo-mechanical model provided the most accurate prediction.

In modeling of engine fuel-air mixing, it is desired to be able to predict fuel spray atomization under different injection and ambient conditions. In this work, a previously developed sheet atomization model was studied for this purpose. For sprays from a pressure-swirl injector, it is assumed in the model that the fuel flows out the injector forming a conical liquid film (sheet), and the sprays are formed due to the disintegration of the sheet. Modified formulations are proposed to estimate sheet parameters including sheet thickness and velocity at the nozzle exit. It was found that the fuel flow rate of a swirl injector satisfied the correlation well. Computations of correlation well. Computations of the sprays injected in an engine with a side-mounted injector were performed for conditions that duplicated a set of experiments performed in an optical engine. The computed results were compared with the spray images obtained from the optical engine using elastic (Mie) scattering.

Magnesium alloy extrusions offer potentially more mass saving compared to magnesium castings. One of the tasks in the United States Automotive Materials Partnership (USAMP) ?Magnesium Front End Research and Development? (MFERD) project is to evaluate magnesium extrusion alloys AM30, AZ31 and AZ61 for automotive body applications. Solid and hollow sections were made by lowcost direct extrusion process. Mechanical properties in tension and compression were tested in extrusion, transverse and 45 degree directions. The tensile properties of the extrusion alloys in the extrusion direction are generally higher than those of conventional die cast alloys. However, significant tension-compression asymmetry and plastic anisotropy need to be understood and captured in the component design.

A hydrocarbon trapping system for cold start emissions was constructed and tested using two types of carbonaceous adsorbents provided by Corning, Inc. One was made by combining activated carbon with an organic binder and extruding it into a honeycomb, and the other by depositing a carbon coating on a ceramic monolith. The tests were carried out on an engine in a dynamometer laboratory to characterize the performance of the carbon elements under transient cold start conditions. Performance was evaluated by continuously measuring exhaust gas hydrocarbon concentrations upstream and downstream of the trap, using conventional emissions consoles. Samples were also collected for off-line analysis of individual hydrocarbon species using gas chromatography to examine differences in adsorption of individual species. The speciated hydrocarbon data were used to distinguish between the mass trapping efficiency and a reactivity-based trapping efficiency of the adsorbant traps.

The Multi Material Lightweight Vehicle (MMLV) developed by Magna International and Ford Motor Company is a result of a US Department of Energy project DE-EE0005574. The project demonstrates the lightweighting potential of a five passenger sedan, while maintaining vehicle performance and occupant safety. Prototype vehicles were manufactured and limited full vehicle testing was conducted. The Mach-I vehicle design, comprised of commercially available materials and production processes, achieved a 364kg (23.5%) full vehicle mass reduction, enabling the application of a 1.0-liter three-cylinder engine resulting in a significant environmental benefit and fuel reduction. This paper reviews the mass reduction and structural performance of aluminum, magnesium, and steel components for a lightweight multi material door design for a C/D segment passenger vehicle. Stiffness, durability, and crash requirements are assessed.

Since 1997, General Motors Body Manufacturing Engineering - Die Engineering Services (BME-DES) has been working jointly with our software vendor to develop and implement a parallel version of stamping simulation software for mass production analysis applications. The evolution of this technology and the insight gained through the implementation of DMP/MPP technology as well as performance benchmarks are discussed in this publication.

A design of experiments is used to study the effect of laser weld parameters on formability of welded blanks for two different material combinations of cold rolled (bare) steel to cold rolled steel and cold rolled steel to hot dipped galvanized steel. Critical weld parameters influencing the formability of welded blanks are identified and the optimum weld set-up condition is obtained based on formability performance and consistency of formability for laser welded blanks. The results are applied to an automotive body side frame. The robustness of welded blank production is also assessed and the final welded set-up condition for the body side frame is obtained based on both the formability of welded blanks and the robustness of welded blank production. The body side frame is successfully made from the welded blanks with this final weld set-up condition.

The LDH (Limiting Dome Height Test) is widely used at Ford Motor Co. stamping plants laboratories to monitor the formability of incoming sheet materials. Although the LDH test is very easy to implement and interpret, variability of the results and poor reproducibility between laboratories limit its acceptance. In this investigation, some of the causes of variability and differences between plant laboratories are discussed. Much of the experimental work was done at plant laboratories and the results are directly applicable to quality control (QC) machines. It was found that the binder force and the binder shape have a big influence on the results, and they should be carefully controlled. The binder cleaning procedure is also relevant to the test variability. Punch temperature has a much greater influence on QC machines than on research machines and a method for controlling the punch temperature in QC machines is presented.

This work demonstrates the feasibility of hot stamping a B-pillar outer panel from aluminum alloy 7075. AA7075 is characterized by a high strength to weight ratio with yield strengths comparable to those of DP and TRIP advanced high strength steels. Applications using AA7075 have typically been limited to the aerospace industry due to the high variable cost associated with forming and joining of these materials. A primary key to implementation in the automotive industry is the development of metal forming methods that produce non-compromised stamped parts at automotive manufacturing volumes and costs. This work explores the feasibility of die quenching a hot blank within a cold die as a means of delivering high strength aluminum sheet parts. A die made from kirksite was used to evaluate the hot stamping process for a B-pillar outer. After the forming/quenching operation, the parts were subjected to an artificial aging process to regain the properties of the T6-temper.

For several years, a single-cylinder, spark-ignited engine without catalyst has been operated at Ford on single-component fuels that are constituents of gasoline as well as on simple fuel mixtures. This paper presents a review of these experiments as well as others pertinent to understanding hydrocarbon emissions. The engine was run at four steady-state conditions which are typical of normal operation. The fuel structure and the engine operating conditions affected both the total HC emissions and the reactivity of these emissions for forming photochemical smog in the atmosphere. These experiments identified major precursor species of the toxic HC emissions benzene and 1,3-butadiene to be alkylated benzenes and either straight chain terminal olefins or cyclic alkanes, respectively. In new data presented, the primary exhaust hydrocarbon species from MTBE combustion is identified as isobutene.