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The automotive industry has a strong need for lightweight materials capable of withstanding large mechanical loads. Advanced high-strength steels (AHSS), which have high tensile strength and formability, show great promise for automotive applications, yet if they are to be more widely used, it's important to understand their deformation behavior; this is particularly important for the development of forming limit diagrams (FLD) used in stamping processes. The goal of the present study was to determine the extent to which anisotropy introduced by the rolling direction affects the local fracture strain. Three grades of dual-phase AHSS and one high-strength low-alloy (HSL A) 50ksi grade steel were tested under plane strain conditions. Half of the samples were loaded along their rolling direction and the other half transverse to it. In order to achieve plane strain conditions, non-standard dogbone samples were loaded on a wide-grip MTS tensile test machine.

This paper will provide an overview of the need, requirements, and constraints governing the development and application of polymer composites in automotive body components. It will discuss the efforts underway to lead and support the technology developments required for the cost-effective application of these new materials in mass-produced vehicles. The requirements and constraints of customer-driven, mass-produced, energy-efficient vehicles with uncompromised cost, capacity and performance, drive careful consideration of an injection-molded thermoplastic approach to a composite automotive body. Recent progress with this approach will be reported and some next steps examined.

Detail parts are approved during several different phases of the prototype build cycle. There is much pressure at all stages to meet strategic body quality targets. Parts stamped for assembly must meet a process capability requirement of Cpk>1.33. For final PSO (process sign off), as called out in the PPAP (Production Part Approval Process) manual, the requirement can be increased to meeting a Cpk>1.67. During the 2000 Neon part approval process, the PPAP requirements provided the guideline necessary for consistent buy-offs. However, on some critical parts the Cpk requirement made part approvals difficult to accomplish. Occasionally this caused resources to be focused in the wrong place. This paper will discuss how a requirement of Cpk>1.33 can make part approvals more difficult to achieve and change the entire application of a tolerance.

Thixomolding (1) is a relatively new process in which the metallic slurry is injected into a die cavity tool at semi-solid or liquid temperatures to form near net-shape products from the solid feedstock. As part of on-going research into Thixomolding technology, this study continues the work of a previous study, that concentrated on magnesium alloys AZ91D and AM60B. The test samples were made with high, low and zero percent fraction solid. The test results of the thixomolded samples of the various percent fraction solid are compared to conventional high pressure die casting samples and there is a discussion of the why the Thixomolding process produces superior properties. In addition, a comprehensive corrosion resistance study was completed utilizing uncoated corrosion plates in an salt spray environment (ASTM B117).

Frames are important structures found in many transportation applications such as automotive bodies and train cars. They are also widely employed in buildings, bridges, and other load bearing designs. When a frame is carrying multiple loads, it can potentially risk a catastrophic buckling failure. The loads on the frame may be non-proportional in that one force stays constant while the other is increased until buckling occurs. In this study the buckling problem is formulated as a constrained eigenvalue problem (CEVP). As opposed to other CEVP in which the eigenvectors are forced to comply with a number of the constraints, the eigenvalues in the current CEVP are subject to some equality constraints. A numerical algorithm for solving the constrained eigenvalue problem is presented. The algorithm is a simple trapping scheme in which the computation starts with an initial guess and a window containing the potential target for the eigenvalue is identified.

Modern engines are designed to operate at highly rated engine speed and load, which brings up challenges to the lubrication design of main and connecting rod bearings. Damages could occur on rod bearings due to high-speed relative sliding motion. Expensive cross drillings are often seen in today's engineering practice to ensure adequate lubrication in rod bearings. The objective of this study is to establish a methodology for predicting lubrication flows in rod bearings and use it to guide the engineering design. The high-speed nature of the crankshaft makes it difficult to acquire experimental data during its normal operation for better understanding the flow inside rod bearings and oil circuits. In the present study, the commercial CFD code, FLUENT, has been used to evaluate the flow characteristics within the rod bearings and oil passages connecting main bearing to rod bearing.

In recent years, implementation of dual phase (DP) Advanced High Strength Steels (AHSS) and Ultra High Strength Steels (UHSS) is increasing in automotive components due to their superior structural performance and vehicle weight reduction capabilities. However, these materials are often sensitive to trimmed edge cracking if stretching along sheared edge occurs in such processes as stretch flanging. Tool wear is another major issue in the trimming of UHSS because of higher contact pressures at the interface between cutting tools and sheet metal blank caused by UHSS’s higher flow stresses and the presence of a hard martensitic in the microstructure. The objective of the present paper is to study the influence of trimming conditions and tool wear on quality of trimmed edge of DP980 steel sheet. For this purpose, mechanically trimmed edges were characterized for DP980 steel, sheared with six different cutting clearances (from 4% to 40% of the sheet thickness).

To correlate data collected at multiple sites when using flexible fixturing to position parts for a CMM (Coordinate Measurement Machine), there are additional factors to consider and coordinate than when using CMM Holding Fixtures.

In a vehicle NVH development and refinement phase, it is necessary to understand the source of the noise and vibration from various powertrain and drivetrain mechanisms. The noise and vibration generated by a drivetrain in a vehicle is a complicate but significant source of physical mechanism, which might become important issues in early or later phase of the vehicle development. For the diagnostic purpose of the drivetrain, a rear-wheel drive (RWD) vehicle in early development phase has been used to measure the bending and torsional vibration of the drivetrain, as well as the vehicle interior noise simultaneously, while the vehicle is running up and down under quasi-steady state on a chassis dynamometer. The lower frequency resonances of torsional and bending vibrations from the drivetrain are correlated with the vehicle interior boom or overall loudness.

The effect of forming strains on the fatigue behavior of an automotive mild steel, interstitial free steel, was studied after being prestrained by balanced biaxial stretch and plane strain. In the long life region, higher than 5×105 reversals, prestrain improves fatigue resistance. In the short life region, prestrain reduces fatigue resistance. At even shorter fatigue lives, the detrimental effect of prestrain diminishes. For plane strains, the fatigue behavior is anisotropic. In the direction perpendicular to the major strain, the steel exhibits much better fatigue resistance than in the direction parallel to the major strain.

During the initial vehicle design phase and as the first prototypes are built, extensive on-board instrumentation and data acquisition is required at the proving grounds (PG). The data is used for various types of testing and analysis. During this phase of development very few parts and assembly components are available for physical test. The objective is to develop a component test for the truck box. This test can be run without suspension parts during the early stages of the vehicle development. A further objective is to correlate the test to FEA models and actual Proving Ground full vehicle test results.

Styrene-Butadiene Rubber (SBR), a copolymer of butadiene and styrene, is widely used in the automotive industry due to its high durability and resistance to abrasion, oils and oxidation. Some of the common applications include tires, vibration isolators, and gaskets, among others. This paper characterizes the dynamic behavior of SBR and discusses the suitability of a visco-elastic model of elastomers, known as the Kelvin model, from a mathematical and physical point of view. An optimization algorithm is used to estimate the parameters of the Kelvin model. The resulting model was shown to produce reasonable approximations of measured dynamic stiffness. The model was also used to calculate the self heating of the elastomer due to energy dissipation by the viscous damping components in the model. Developing such a predictive capability is essential in understanding the dynamic behavior of elastomers considering that their dynamic stiffness can in general depend on temperature.

Sheet metal stamping involves a system of complex tribological (friction, lubrication, and wear), heat transfer, and material strain interactions. Accurate coefficient of friction, strain, and lubrication regime data is required to allow proper modeling of the various sheet stamping processes. In addition, non-intrusive means of monitoring the coefficient of friction in production stamping operations would be of assistance for efficiently maintaining proper stamping quality and to indicate when adjustments to the various stamping parameters, including maintenance, would be advantageous. One of the key sub-systems of the sheet metal stamping process is the draw bead. This paper presents an investigation of the tribology of the draw bead using a Draw Bead Simulator (DBS) Machine and automotive zinc-coated sheet steels. The investigation and findings include: 1) A new, non-intrusive method of measuring the surface temperature of the sheet steel as it passes through the draw bead.

Historically, pump noise can be a contributor to customer dissatisfaction with automatic transmissions. In this paper, a Shainin experiment was conducted to identify all probable root causes for pump noise on a production RWD transmission. Sample transmissions were selected following subjective evaluations. Noise was objectively measured in the lab using a microphone and an accelerometer. The study was conducted following a systematic Shainin statistical engineering methodology, which included the following major steps: selection of the test measure using the isoplot technique, selection of Best of Best (BOB) and Worst of Worst (WOW) transmissions, assessment of assembly variation, component search, and pair-wise comparisons. The study successfully highlighted the key variables on the drive gear involute profile, which are now being tightly controlled for improved noise characteristics.

As the use of electronic devices in automobiles increases, the reliability of such devices is becoming increasingly important. One possible failure is due to leakage resulted from imperfect hermetical seal in mircochips and microelectronic packages. This paper presents an optical technique referred to as shearography for rapid evaluation of hermetics seals. The proposed process of leaking testing is very fast and practical.

The springback behavior might be different due to different gap clearances between die and punch. A study using FEA simulation is done to investigate the die gap effect. A 3D brick element and an explicit-implicit method are employed to investigate a few simple problems. A draw form, a crash form with an upper pad and a flange form are investigated separately. Numisheet’93 2D draw bending springback problem is also investigated using an explicit dynamic code. Comparisons between springback simulation results on several different die gaps are illustrated. The Kirchhoff assumption of C° shell element and the Mindlin/Love assumption of thin shell element are also examined on different cases. A case study then is performed on a rail type panel. Conclusions and recommendations for future studies are summarized.

A Draw Bead Simulator (DBS), with modified draw beads, was employed in this study to understand the springback behavior of sheet metal subjected to multiple bending-unbending cycles. The investigations were carried out in both the rolling and the transverse rolling directions on four types of materials: Electro-Galvanized DQ steel, light and heavy gauge Hot-Dip Galvanealed High Strength Steels, and Aluminum alloy AL6111. The sheet geometries, thickness strains, pulling forces and clamping forces were measured and analyzed for the purpose of establishing a benchmark database for numerical predictions of springback. The results indicate that the springback curvature changes dramatically with the die holding force. The conditions at which the springback is minimized was observed and found to depend on the material properties and the sheet thickness. Analysis with an implicit FEM showed that the predicted and the experimental results are in very good agreement.

Traditionally, high-strength low-alloy (HSLA) steel is used for automotive vehicle weight reduction in the North American automotive industry. Dual phase (DP) high strength steel has gained great attention because it provides a combination of high strength and good formability. The main advantage of DP steel is the high ratio of tensile strength to yield strength, which provides more flexibility in stamping and higher energy absorption in a component crush event. This study compares the performances of DP and HSLA steel grades in stamping processes and component crush events, as shown in a typical automotive unibody inner rail. Simulation results show that DP steel offers more uniform strain distribution, improved formability, and better crush performance than conventional HSLA steel.

In the past several years there has been a significant effort to increase the reliance on CAE technology to guide the vehicle design process, with the accompanying effort to reduce or eliminate vehicle prototype testing during the early design phase. Since little or no representative hardware is available early in the design, a tool is needed which allows NVH Development Engineers to subjectively experience the results of NVH CAE model predictions in a realistic driving environment. This paper documents the development of a high fidelity NVH simulator, including both audio and vibration, and the integration of this simulator into an “operator-in-the-loop” Driving Simulator. The key development of this system is its ability to incorporate NVH CAE predictions into the simulated driving environment.

Hot Isostatic Pressing (HIP) has been routinely used to densify castings for aerospace and medical applications for over 30 years. While HIP is widely known to improve the toughness and fatigue life of castings through the healing of internal porosity, it has been perceived as too expensive for most cast aluminum alloys for automotive applications. Recent developments suggest that the cost effectiveness of certain special HIP processes should be revisited due to reductions in process cost and improvements in throughput. This paper will evaluate the Densal® II process applied to a front aluminum steering knuckle. Two casting processes representing differing levels of relative cost and quality were evaluated. The first was Alcoa's VRC/PRC process, a metal mold process with bottom fill, evacuation before fill and pressurization after fill. This is considered to be a premium quality, but higher cost casting process that is already qualified for this application.