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This paper details the lightweighting efforts of the Ford Research & Advanced Transmission team as part of the Multi Material Lightweight Vehicle Project. 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 benefits and fuel consumption reduction.

This paper presents the final phase of a study to develop the modeling methodology for an advanced steering assembly with a safety-enhanced steering wheel and an adaptive energy absorbing steering column. For passenger cars built before the 1960s, the steering column was designed to control vehicle direction with a simple rigid rod. In severe frontal crashes, this type of design would often be displaced rearward toward the driver due to front-end crush of the vehicle. Consequently, collapsible, detachable, and other energy absorbing steering columns emerged to address this type of kinematics. These safety-enhanced steering columns allow frontal impact energy to be absorbed by collapsing or breaking the steering columns, thus reducing the potential for rearward column movement in severe crashes. Recently, more advanced steering column designs have been developed that can adapt to different crash conditions including crash severity, occupant mass/size, seat position, and seatbelt usage.

Structural adhesives are widely used across the automotive industry for several reasons like scale-up of structural performance and enabling multi-material and lightweight designs. Development engineers know in general about the effects of adding adhesive to a spot-welded structure, but they want to quantify the benefit of adding adhesives on weight reduction or structural performance. A very efficient way is to do that by applying analytical tools. But, in most of the relevant non-linear load cases the classical lightweight theory can only help to get a basic understanding of the mechanics. For more complex load cases like full car crash simulations, the Finite Element Method (FEM) with explicit time integration is being applied to the vehicle development process. In order to understand the benefit of adding adhesives to a body structure upfront, new FEM simulation tools need to be established, which must be predictive and efficient.

Optimal material selection for a part becomes quite challenging with dynamically changing data from various sources. Multiple manufacturing locations with varying supplier capabilities add to the complexity. There is need to balance product attribute requirements with manufacturing feasibility, cost, sourcing, and vehicle program strategies. The sequential consideration of product attribute, manufacturing, and sourcing aspects tends to result in design churns. Ford R&A is developing a web based material recommender tool to help engineers with material selection integrating sourcing, manufacturing, and design considerations. This tool is designed to filter the list of materials for a specific part and provide a prioritized list of materials; and allow engineers to do weight and cost trade-off studies. The initial implementation of this material recommender tool employs simplified analytical calculators for evaluation of structural performance metrics of parts.

Imposing tensile stress on an edge of a sheet metal blank is a common condition in many sheet metal forming operations, making edge formability a very important factor to consider. Because edge formability varies greatly among different materials, cutting methods (and their control parameters), it is very important to have access to an experimental technique that would allow for quick and reliable evaluation of edge formability for a given case. In this paper, two existing techniques are compared: the hole expansion test and the tensile test. It is shown that the hole expansion test might not be adequate for many cases, and is prone to overestimating the limiting strain, because the burr on the sheared edge is typically smaller than what is observed in production. The tensile test represents an effective alternative to the hole expansion test. Advantages and disadvantages of each case are discussed.

A uniaxial stress-strain curve obtained from a conventional tensile test is only valid up to the point of uniform elongation, beyond which a diffuse neck begins to develop, followed by localized necking and eventual fracture. However Finite Element Analysis for sheet metal forming requires an effective stress-strain curve that extends well beyond the diffuse necking point. Such an extension is usually accomplished by analytical curve fitting and extrapolation. Recent advancement in Digital Image Correlation (DIC) techniques allows direct measurement of full-range stress-strain curves by continuously analyzing the deformation within the diffuse neck zone until the material ruptures. However the stress-strain curve obtained this way is still approximate in nature. Its accuracy depends on the specimen size, the gage size for analysis, and the material response itself.

Finite element analysis (FEA) predictions of magnesium beams are compared to load versus displacement test measurements. The beams are made from AM60B die castings, AM30 extrusions and AZ31 sheet. The sheet and die cast beams are built up from two top hat sections joined with toughened epoxy adhesive and structural rivets. LS-DYNA material model MAT_124 predicts the magnesium behavior over a range of strain rates and accommodates different responses in tension and compression. Material test results and FEA experience set the strain to failure limits in the FEA predictions. The boundary conditions in the FEA models closely mimic the loading and constraint conditions in the component testing. Results from quasi-static four-point bend, quasi-static axial compression and high-speed axial compression tests of magnesium beams show the beam's behavior over a range of loadings and test rates. The magnesium beams exhibit significant material cracking and splitting in all the tests.

The recent trends of increasing driveline torque and use of traction control devices call for increasingly higher durability capacity from driveline components. Bench and vehicle durability tests are often used to validate designs, but they are not cost-effective and take months to complete. Traditional finite element analysis (FEA) procedures have been used effectively in the re-design of driveline components to reduce stress, and occasionally, to predict fatigue life. But in the case of certain rotating components, such as the Axle Differential Case, where the component sees large stress/strain fluctuations within the course of one complete rotation, even under constant input torque, historical fatigue analysis (when conducted) yields very conservative results. The axle differential case tends to be one of the weakest links in the rear axle assembly. Therefore, there is a crucial need for analytical methods to more accurately predict fatigue life to reduce testing time and cost.

Pump whine as well as other NVH issues related to power steering system can become customer concerns at the vehicle level. In order to avoid that, proposed treatment of the pump structure and its installation on the engine should be performed. This is particularly important because most vane pumps have a wide range of excitation that can reach 1000 Hz (30th order @ 6000 rpm). This requires maximizing the ‘as installed’ frequencies of the pump to avoid coincidence with the engine and other FEAD harmonics.

A stochastic simulation based on the Monte-Carlo method was developed to re-target gap bulk density (GBD) in ceramic catalytic converters. The combined effect of manufacturing tolerances, shell spring back and thermal expansion was analyzed by this model. Shell spring back during the canning process was calculated using Finite Element Analysis (FEA). Thermal shell expansion was obtained using can deformation data from the Key-Life Test (KLT). An example of optimized GBD that provides a robust and manufacturable design is also presented.

Machining fixtures are used to locate and constrain a workpiece during a machining operation. To ensure that the workpiece is manufactured according to specified dimensions and tolerances, it must be appropriately located and clamped. Minimizing workpiece and fixture tooling deflections due to clamping and cutting forces in machining is critical to the machining accuracy. An ideal fixture design maximizes locating accuracy and workpiece stability, while minimizing displacements. The purpose of this research is to develop a method for modeling workpiece boundary conditions and applied loads during a machining process, analyze modular fixture tool contact area deformation and optimize support locations, using finite element analysis (FEA). The workpiece boundary conditions are defined by locators and clamps. The locators are placed in a 3-2-1 fixture configuration, constraining all degrees of freedom of the workpiece and are modeled using linear spring-gap elements.

Drive shaft modelling effects frontal crash finite element simulation. A 35 mph rigid barrier impact of a body on frame SUV with an one piece drive shaft and a unibody SUV with a two piece drive shaft have been studied and simulated using finite element analyses. In the model, the drive shaft can take significant load in frontal impact crash. Assumptions regarding the drive shaft model can change the predicted engine motion in the simulation. This change influences the rocker @ B-pillar deceleration. Two modelling methods have been investigated in this study considering both joint mechanisms and material failure in dynamic impact. Model parameters for joint behavior and failure should be determined from vehicle design information and component testing. A body on frame SUV FEA model has been used to validate the drive shaft modeling technique by comparing the simulation results with crash test data.

A finite element analysis method has been developed to assess the design of an automobile body joint. The concept of the coefficient of joint stiffness and the force distribution ratio are proposed accordingly. The coefficient of joint stiffness reveals whether a joint is stiff enough compared to its joining components. In addition, these parameters can be used to estimate the potential and the effectiveness for any further improvement of the joint design. The modeling and analysis of the proposed process are robust. The coefficient of joint stiffness could be further developed to serve as the joint design target.

The use of die cast magnesium for automobile transmission cases offers promise for reducing weight and improving fuel economy. However, the inferior creep resistance of magnesium alloys at high temperature is of concern since transmission cases are typically assembled and joined by pre-loaded bolts. The stress relaxation of the material could thus adversely impact the sealing of the joint. One means of assessing the structural integrity of magnesium transmission cases is modeling the bolted joint, the topic of this paper. The commercial finite element code, ABAQUS, was used to simulate a well characterized bolt joint sample. The geometry was simulated with axi-symmetric elements with the exact geometry of a M10 screw. Frictional contact between the male and female parts is modeled by using interface elements. Material creep is described by a time hardening power law whose parameters are fit to experimental creep test data.

The effect of polyurethane structural foam on strength, stiffness, and energy absorption of foam filled structural components is investigated to formulate design directions that may be used in weight reduction and engineering functions of vehicle systems. An experimental/testing approach is first utilized using Taguchi’s DOE to identify design variables [foam density, gage, and material type], that are needed to determine the weight/performance ratio of structural hat-section components. An analytical CAE approach is then used to analyze the hat-section components using non-linear, large deformation finite element analysis. An accepted level of confidence in the CAE analytical tools is then established based on comparison of results between the two approaches.

Since doors are repeatedly used by vehicle owner, they have a great influence on his or her perception of vehicle quality. The door open overload is an abusive load requirement for customer usage. The doors must withstand loads which force the door open against its stop, leading to concern over the effects of permanent set to the functioning of the door system and the margins/ flushness. Traditionally, the CAE is utilized to objectively evaluate the deflections and permanent set at the door latch to evaluate door open overload requirement. In this study, the FEA methodology has been applied to expand the scope beyond traditional method to simulate door open overload condition. The change in the margin and flushness due to the permanent set are evaluated using nonlinear analysis (ABAQUS). The results show that the method helps designers to ensure the door meets the margin/flushness criteria for door open overload condition during early stage of the door design process.

Nonlinear finite element analysis has been applied to determine the conditions conducive to seal system aspiration. Aspiration noise occurs and propagates into the passenger compartment of a vehicle when there exists a gap between the seal and sealing surface due to pressure differential between the vehicle interior and exterior. This pressure differential is created by the vehicle movement which reduces the pressure acting on the exterior surface of the vehicle, and it is on the order of , where ρ and U∞ are the density of air and vehicle speed, respectively. The pressure difference is also created by turning on the climate control system which pressurizes the passenger cavity. Since aspiration increases door seal cavity noise level and creates a direct noise transmission path without any significant transmission loss, the presence of an aspiration noise source can dominate the vehicle interior noise level if it is close to the driver or passenger's ears.

This paper outlines the development process of a vibration isolation system for the timing chain guides of an internal combustion engine. It was determined through testing that the timing chain guides are a significant path by which the chain/sprocket impacts are transmitted to other powertrain components. These components radiate the energy as chain mesh order narrow band sound as well as wide band energy. It was found that isolation of the chain guides produced a significant reduction in radiated sound levels, reduced mesh frequency amplitudes, and improved sound quality. The development process utilized indirect force measurement techniques for simulation of the chain loading and FEA prediction of the resulting chain guide forces and displacements. The design of the isolation system involved material selection based on dynamic properties, frequency and temperature ranges, the operating environment, FEA geometry optimization, and durability testing.

In the current design process, the designer generates the detailed geometry of the component based on experience. Prototypes of this design are built and tested to verify the performance. This design - build - test iterative process is continued until performance targets/criteria are met. Computer Aided Engineering is often used to verify the design. This paper presents a new product development process to substantially reduce the number of design - analysis - build - test iterations. This Upfront Analysis Driven Design process incorporates several state of the art technologies in finite element structural analysis, optimization, and Computer Aided Design. This process ensures a near optimum design in the first design level itself.

Failure to provide consistent results in the parallel implementation of a crash simulation can render the simulation code unusable as a design heuristic. This paper describes a parallel implementation of a crash simulation package, FCRASH, which was designed from inception for parallel implementation. An example will be given which illustrates the variation a CAE crash analyst may encounter if the problem of parallel consistency is ignored. Techniques used in FCRASH to deliver consistent results in a parallel environment on a CRAY T90 parallel supercomputer will be discussed. This work has resulted in a robust crash simulation code that delivers consistent results in parallel environments on a variety of shared memory processors. Finally, problems remaining for delivering the same level of robustness in a distributed memory message passing version of an explicit crash simulation program will be examined.