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Technical Paper

Weld Durability Analysis by Equilibrium-Equivalent Structural Stress Approach

Welding has been used extensively in automotive components design due to its flexibility to be applied in manufacturing, high structural strength and low cost. To improve fuel economy and reduce material cost, weight reduction by optimized structural design has been a high priority in auto industry. In the majority of heavy duty vehicle's chassis components design, the ability to predict the mechanical performance of welded joints is the key to success of structural optimization. FEA (finite element analysis) has been used in the industry to analyze welded parts. However, mesh sensitivity and material properties have been major issues due to geometry irregularity, metallurgical degradation of the base material, and inherent residual stress associated with welded joints. An approach, equilibrium-equivalent structural stress method, led by Battelle and through several joint industrial projects (JIP), has been developed.
Technical Paper

Heavy Vehicle Suspension Frame Durability Analysis Using Virtual Proving Ground

Virtual proving ground (VPG) simulations have been popular with passenger vehicles. VPG uses LS-DYNA based non-linear contact Finite Element analysis (FEA) to estimate fully analytical road loads and to predict structural components durability with PG road surfaces and tire represented as Finite elements. Heavy vehicle industry has not used these tools extensively in the past due to the complexity of heavy vehicle systems and especially due to the higher number of tires in the vehicle compared to the passenger car. The higher number tires in the heavy vehicle requires more computational analysis duration compared to the passenger car. However due to the recent advancements in computer hardware, virtual proving ground simulations can be used for heavy vehicles. In this study we have used virtual proving ground based simulation studies to predict the durability performance of a trailer suspension frame.
Technical Paper

Catalyst Converter Canning Simulation Studies

Canning is a very important aspect in the catalyst converter design, especially with the current trend of using more thin wall and ultra-thin wall substrates. This paper systematically investigated canning issues at different stages of converter manufacturing processes and operations. Commonly used converter canning processes, which include traditional clamshell style and tourniquet wrap, are included in the studies. Using a previously developed mat material model, visco-elastic behavior, as well as the unique expansion characteristic of the intumescent mat under high temperature, are included in the simulations. Lab testing of the mat material at different loading speeds was conducted to obtain the visco-elastic properties. These will allow the studies of the effect of closing speed on the peak pressures during canning processes, as well as the pressures during heating and cooling.
Technical Paper

Some Considerations in the Test Bogey Development for Automotive Components

Test bogeys are valuable tools in providing guidance in design iterations as well as serving as gatekeepers in laboratory endurance tests for product certification. In addition, test bogeys have been used to screen manufacturing process-induced performance variations. Typically, the endurance test specification consists of descriptions of parts to be included in a test setup, the minimum number of test samples of the target component, the load, and the number of cycles, block cycle repeats, or test time to exceed without failure. To define these test bogeys, however, is a special challenge for heavy and medium duty vehicle applications. Oftentimes, neither a representative field duty nor a well-developed proving ground test cycle is available. Furthermore, there are numerous vehicle configurations and broad variations of application. A test bogey that is adequate for one case might not be suitable for a seemingly similar case.
Technical Paper

Effective FEA for Product Development Support

Only products with high quality, low cost, and short concept-to-customer time will continue to have a high market share. For this reason, auto parts suppliers must strive to gain superior engineering capability. One key step in this pursuit is to implement widespread CAE (Computer-Aided-Engineering) in PDP (product development process) [1]. FEA (Finite Element Analysis), in particular, has been identified as a subject that deserves concentrated effort. Specifically, FEA needs to be used broadly and effectively in every phase of PDP ranging from concept evaluation and prototyping, to pre-production design and troubleshooting. However, resource requirement and process quality assurance are major issues in this undertaking [2, 3]. As a counter-measurement, developing product specific FEA guidelines has been identified as a priority strategic initiative. The focus of our presentation is on how to develop standard FEA procedures to guide FEA jobs.
Technical Paper

Predicting Drum Brake Noise Using Finite Element Methods

A method for predicting the propensity of a drum brake system to produce noise is presented. The method utilizes finite element models of the individual components of the drum brake system, which have been assembled into the system model of the brake assembly. An important step in this process is the tuning of the dynamic characteristics of the FEA model to ensure validation with experimental tests. Friction is the key element, which defines the behavior of the drum brake system. The system FEA model is assembled by coupling the lining and drum at the contact interface to simulate the friction interaction. This process produces an asymmetric stiffness matrix. A complex eigenvalue analysis identifies the system dynamic characteristics such as the frequency and damping for each vibration mode. The damping values reveal which modes are unstable and therefore likely to produce noise.
Technical Paper

Improved Drum Brake Performance Prediction Considering Coupled Thermal and Mechanical Effects

This paper presents a methodology for predicting drum brake performance using FEA (finite element analysis) models considering both the mechanical-structural compliance and thermal effects. The methodology for brake torque prediction with FEA models considering the structural flexibility of the brake components alone has been established [1]. The frictional heat generated during braking causes thermoelastic distortion that modifies the contact pressure distribution at the drum-lining interface. In order to capture this thermal effect, a transient thermal analysis is conducted to predict the transient temperature distribution on the brake components. In the thermal analysis, the heat generated at the drum and lining interface is based on the pressure distribution from the compliant mechanical model. Also, the mechanical properties of the brake components as well as the lining friction are dependent on the temperature distribution.
Technical Paper

Improved Drum Brake Shoe Factor Prediction with the Consideration of System Compliance

Effective linear and nonlinear drum brake system FEA (finite element analysis) models have been developed. Such models can help engineers understand many drum brake related issues, such as lining wear and mechanical and thermal instability. The pressure distribution at the drum and lining interface is an important piece of information in drum brake design. Besides the accurate prediction of the shoe factor, the models can be used to guide designs for improving brake efficiency, reducing component weight and enhancing durability. Progress is also being made in developing hybrid models that integrate FEA models with other analysis techniques. This approach offers engineers easy-to-use design tools. The integrated design and analysis approach will help product design and development by reducing cycle time, cost and improving product quality.