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This work compares the relative importance of material anisotropy in sheet forming as compared to other material and process variables. The comparison is made quantitative by the use of normalized dependencies of depth to failure (forming limit is reached) on various measures of anisotropy, as well as strain and rate sensitivity, friction, and tooling. Comparisons are made for a variety of forming processes examined previously in the literature as well as two examples of complex stampings in this work. The examples cover a range from nearly pure draw to nearly pure stretch situations, and show that for materials following a quadratic yield criterion, anisotropy is among the most sensitive parameters influencing formability. For materials following higher-exponent yield criteria, the dependency is milder but is still of the order of most other process parameters.

In many instances, automotive companies wish to create both a left-hand drive and a right-hand drive version of the same vehicle. When the vehicle has relatively low sales volumes, it is imperative to reduce investment costs wherever possible. One successful - if challenging - way is by producing the instrument panel system for both versions off the same tooling. This feat was accomplished in the case of the '97 Jeep® Wrangler, saving the company approximately $7 million.

Springback is one of the main problems in sheet metal bending operations. Theoretically, an accurate description of strain distribution and stress distribution is required in order to predict the springback behavior of a bending component. Prediction of strain distribution needs a good geometrical model while prediction of stress distribution needs both an accurate strain description and an accurate stress-strain relationship. In this paper, a new model is developed for strain calculation in plane strain bending. The displacement of the neutral surface, the thickness change, the stress and strain distributions over the sheet thickness, the bending moment and the springback curvature are examined using this new model and useful conclusions are obtained. The new model is also compared with Hill's pure bending model, the membrane theory (plus post-processing) and the shell theory. The application ranges and the limitations of the membrane theory and the shell theory are discussed.

The functional performance of the instrument panel has been changing dramatically since the late 80s, with FMVSS 208 legislation and its related impact on the addition of air bags and knee bolsters. In addition to addressing occupant safety legislation through more safety components, as well as navigation, security, comfort, informational and other systems are being added to the instrument panel as the consumers' desire for enhanced features continues. At the same time, consumers still want a product that is uncomplicated, affordable, aesthetically pleasing and - at the same time - doesn't limit valuable interior compartment space. The early efficient integration of these components (electrical, architecture, HVAC, steering) in the design, engineering and assembly process will be the areas of requirement that will have a primary effect on IP system cost in the future.

This article describes a fast design oriented tool to provide predictions of springback in automotive stampings. The new program, FAST_SPRINGBACK, utilizes the results of another membrane finite element code, FAST_3D, which performs a one step simulation of the forming process. The significant feature of the new springback tool is its ability to quickly predict the different modes of springback deformations as well as residual stresses that will affect the final shape and performance of the formed part. An important aspect of the program is its capability to integrate with existing CAD tools, thus enabling the designer to perform checks on the candidate part geometry in the early design stages.

In order to reduce fuel consumption light weight vehicles are in development. For this HSLA- steel, bakehardening- steels, stainless-steels and aluminum will be used for the body in white of personal cars. To form inner automotive parts of high dimensional accuracy out of steel with high strength or out of aluminum and to form automotive parts of high surface quality as well as of high dimensional accuracy a reproducible forming process is needed. For low volume cars tools and dies have to be as cheep as possible. The press has to be able to take over die functions and over the stroke steerable blankholder forces. Tools and dies for high volume parts can use expensive tools and dies like dies with nitrogen cylinders. In the future these cylinders will have the possibility to steer the pressure and so in turn the blankholder force over the stroke. See paper „Force- Stroke- Curve of Gas Springs” (State-of-the-Art Stamping) held on the same conference.

The robust operating window is a major problem during sheet stamping, but existing practical experience concerning process sensitivity is approximate and qualitative only. In this study, sensitivities of strain, punch force, and draw-in to the process and material parameters were calculated for a given part geometry. To ilustrate the influence and relative importance of n-value, anisotropy, friction, and restraining force selected results are presented, compared, and discussed. It was found that strain is the most sensitive, while punch force is least responsive. The restraining force has the strongest influence, and friction is relatively less important. Sensitivity responses are highly nonlinear, thus not allowing for extrapolation or generalization. The sensitivity calculations were performed following a proposed methodology, based on virtual experiments (numerical simulation). It allows variation of one selected parameter only, and keeps project time and cost lower.

The influence of die corner geometry on the attainable draw depth of rectangular parts was investigated using 3-D FEM and optimum rectangular blanks. Axisymmetric cup analysis was not adequate because a corner assist effect promotes corner draw. Guidelines for selecting corner radius were developed and the sensitivities of the maximum part depth to other process variables, such as drawbead restraint force; die clearance gap; friction coefficient; strain rate sensitivity; material anisotropy; and strain hardening exponent, were simulated. The results are much more conservative than handbook rules, which to not to take into account the details of blank size, drawbead restraint, die geometry, material properties, and friction.

The last few years have seen an enormous increase in the research, development and, especially, in the application of computer modeling of sheet metal forming operations. This increased industrial use is due to many factors, including: enhanced accuracy and robustness of forming codes, a growing sophistication in their use by engineers, common availability of CAD data for panels, and advances in hardware capability. This paper attempts to describe the current state-of-the art. We begin by offering a brief history of mathematical modeling of sheet forming, and then discuss some of the current formulations of finite element methods. We also speculate on some possible future accomplishments.

Robust operating window and subsequent quality of part is a major concern during sheet metal stamping. For a given part geometry, material, and lubrication conditions, the blankholder restraining force is the key parameter controlling metal flow, thus influencing formability and quality of the resulting part. Recent advances in press building provide capability of the blankholder force (BHF) variation during stamping stroke. In this study, a laboratory and numerical experiments were performed in an effort to better understand the effect of various BHF trajectories on stamping performance. The working numerical model using explicit LS-Dyna 3D code was successfully developed for time effective simulation of complex parts with variable binder force. Selected results of these numerical tests, showing strong influence and process design promise, are presented, compared to the experimental results, and discussed.

Ad-mixed nickel-molybdenum alloy powders currently present difficulties under conventional production conditions in that blending techniques may not produce material which are homogenous throughout.1 This problem can be solved through the water atomization of a low alloy (nickel-molybdenum) molten steel.2,3 In the production process of a water atomized molten steel, alloying elements such as nickel and molybdenum will become compounded during the steel melting stage, thus allowing for several improvements in physical properties when compared to an ad-mixed material. Most importantly, the homogeneous microstructures will allow for better sintered properties and performance characteristics. In this report, a low alloy nickel-molybdenum pre-alloy steel powder and its properties will be compared to conventional ad-mixed blends currently available.

The Sheet Metal Forming Simulation Research Group Japan, organized by the authors in September 1990 with the cooperation of Japanese car manufacturers, steel and aluminum producers and computer hardware and software companies, concluded its activities in September 1996. In this paper, the authors summarize the accomplishments of the group during the last 6 years. The paper consists of five parts. In the introduction, the historical background of FEM development is presented. Then, the situation of the Japanese automotive industry in the 1980's is described with emphasis on circumstances leading to the use of FEM in the design of stamping processes. Next, the motives behind the establishment of the Sheet Metal Forming Simulation Research Group in Japan are explained. Subsequently, the objectives and aims of the group activities are discussed. Then, examples of simulations done by members of the group. are presented.

The use of cerium oxide as an oxygen storage component in automotive three-way catalysis has been well established. More recently the need to thermally stabilize these materials against deactivation at higher temperatures has focused attention on doping of the ceria with a wide range of metal oxides. The role of these dopants in the stabilization mechanisms for ceria is not completely understood as they must perform the complex role of sintering inhibitor while promoting oxygen storage and release. The scattering of pulsed neutrons produced by a spallation source coupled with the Fourier analysis provides a powerful method to characterize the local atomic structure of complex systems such as mixed oxides. We demonstrate that by using this method it is possible to obtain valuable information on the local atomic structure of the CeO2/ZrO2 catalyst support that cannot be attained by the conventional diffraction methods.

We have prepared and tested laboratory scale monoliths wash-coated with 10, 20 and 30 wt% of either CeO2 or Ce.75Zr.25O2 (remainder is alumina). Wet impregnation was used to load the wash-coated monoliths with 50g/ft Pt:Rh at a 5:1 ratio. The catalyst were aged at temperatures between 825°C and 950°C using a cycled redox aging. The catalysts were then tested in a full-feed simulated exhaust laboratory reactor with air-to-fuel ratio (A/F) perturbations (frequencies at 1 and 3 Hz and amplitudes up to +/- 0.8 A/F). Even the lowest loading of Ce.75Zr.25O2 outperformed all three loadings of CeO2 over a full range of reaction temperatures, A/F perturbations, and catalyst space velocity (SV). Our data indicates that the ceria-zirconia catalysts can tolerate cycled redox aging at sustained bed temperatures at least 25°C higher (∼925°C vs. < 900°C) than can ceria. For the CeO2 catalysts aged at or above 900°C we observed an inverse correlation of catalyst activity to CeO2 loading.

It has been recently shown that (Ce, Zr)O2 mixed oxides provide improved catalytic performances compared to pure CeO2. Cerium oxide is the active Oxygen Storage Capacity (OSC) component in three way catalysts. However, higher performances, including OSC enhancement, can be achieved with thermally stable solid solutions of Ce and Zr oxides. In the present paper, we describe the structure and the advantages of Ce rich (Ce, Zr)O2 solid solutions and the improved catalytic properties of these materials when used in association with platinum. Various analytical techniques were used including thermo-reduction methods, OSC measurements, surface area measurements, XRD, HRTEM, XPS, and XANES/EXAFS.

Cerium oxide (CeO2) is known to have good oxygen storage capacity (OSC) and is used widely in three-way catalysts for automobiles, but it has a problem of inferior heat stability. In our previous work, cerium-zirconiumyttrium (Ce Zr-Y) oxide systems were investigated with the aim of improving the heat stability of CeO2-based oxide systems, and we found an optimum composition of Ce-Zr-Y oxide with platinum (Pt) showed good OSC even after high temperature aging. In this study OSC and thermal stability of Ce-Zr-Y oxide with varying the types of precious metals were investigated to evaluate the effect of precious metals. The results show that, Palladium (Pd) and Rhodium (Rh) are also available for Ce-Zr-Y oxide with precious metal system to improve OSC after thermal aging. In particular, Rh exhibited higher improvement than others at the composition of lower Ce content.

The tests described here have been used to provide a preliminary checkout of the control functionality of a prototype adaptive cruise control (ACC) system being used in a field operational test of intelligent cruise control. The results presented provide an initial characterization of the headway control performance of the ACC system. The inputs to these tests are the speed of the preceding vehicle. The results of the tests are based upon measurements of range, range rate, velocity, transmission shift commands, and velocity commands resident within the ACC system. Numerical performance measures are derived from these data and used to characterize system performance quantitatively. Results from these types of tests could be used in assessing differences in headway control characteristics associated with various ACC systems.

This paper describes the evaluation methodology for the Intelligent Cruise Control (ICC) Field Operational Test (FOT). The primary purpose of the evaluation is to assess safety impacts of the ICC system. Other benefits, such as convenience and comfort, as well as impacts of the system, e.g., fuel consumption and emissions, are also being assessed. The ICC system incorporates a forward looking sensor and a headway controller with a conventional cruise control system, to automatically maintain a headway (with accelerator and downshift control inputs) between the ICC-equipped vehicle and a vehicle that precedes the equipped vehicle. The FOT will collect daily usage experiences from up to 162 lay drivers, each of whom will drive one of 10 ICC equipped vehicles for periods of 2 or 5 weeks. Data collection is scheduled to last 12 months. Each of the 10 vehicles has a data collection system that will support the evaluation.

As Intelligent Transportation Systems (ITS) become more prevalent, the need to archive data from field tests becomes more critical. These data can guide the design of future systems, provide an information conduit among the many developers of ITS, enable comparisons across locations and time, and support development of theoretical models of driver behavior. The National Highway Traffic Safety Administration (NHTSA) is interested in such an archive. While a design for an ITS data archive has not yet been developed, NHTSA has supported the enhancement of the Test Planning, Analysis, and Evaluation System (Test PAES), originally developed by Calspan SRL Corporation for the U. S. Air Force Armstrong Laboratory, for possible use in such an archive. On a single screen, Test PAES enables engineering unit data, audio, and video, as well as a vehicle animation, to be time synchronized, displayed simultaneously, and operated with a single control.

This paper will review the role of zirconium oxide in automotive systems. Zirconium oxide has been used and been considered for use in many different applications within automotive systems. Examples include ceramics for engine liners, ionic conductors for oxygen sensors, piezoelectrics for a variety of sensors and as an ingredient of autocatalysts. In the first three examples, ceramics, ionic conductors and piezoelectrics, the known properties of zirconium oxide containing systems have been applied to solve problems in the automobile. In the last the use of zirconia here has created an interest outside automotive applications. This paper will also show how a knowledge of zirconia in one field can produce benefits in another and that through this synergy improved products can be brought to the marketplace