Search Results

A redesigned 2005 Chevrolet Equinox rear cradle was optimized using metamodel techniques coupled with large scale finite element simulations. The rear cradle was redesigned to accommodate an electric drive system to convert the equinox to a hybrid as part of the General Motors sponsored student project Challenge X. The design optimization uses metamodels to represent the finite element responses of the cradle under multiple loading situations. The metamodels provide an optimization technique that reduces design time and the number of required simulations compared to the traditional, iterative type simulation based optimization. The result of the optimization was a 12% weight savings over the initial design with a higher confidence in safety. The optimization results were confirmed by an extra set of finite element simulations outside of those performed for the optimization process.

The Mississippi State University Formula SAE race car upright was optimized using radial basis function metamodels and an internal state variable (ISV) plasticity damage material model. The weight reduction of the upright was part of a goal to reduce the weight of the vehicle by 25 percent. Using an optimization routine provided an upright design that is lighter that helps to improve vehicle fuel economy, acceleration, and handling. Finite element (FE) models of the upright were produced using quadratic tetrahedral elements. Using tetrahedral elements provided a quick way to produce the multiple FE models of the upright required for the multi-objective optimization. A design of experiments was used to determine how many simulations were required for the optimization. The loads for the simulations included braking, acceleration, and corning loads seen by the car under track conditions.

Finite element models of vehicles have been increasingly used in component design and crashworthiness evaluation. As vehicle finite element models are becoming more sophisticated in terms of their accuracy, robustness, fidelity, and size, the need to compare different FEA codes has become more apparent. In this study, we compare finite element simulations of a 1996 Dodge Neon using LS-DYNA and PAM-CRASH codes with an effort to keep sameness of the material models, meshes and boundary conditions. The original Neon mesh and material properties were developed at the FHWA/NHTSA National Crash Analysis Center (NCAC) for LS-DYNA and subsequently modified for this study. The comparisons between test data and simulation results of the full-scale vehicle in terms of overall impact deformation, component failure modes, and velocity and acceleration at various locations in the vehicle show good correlations with only minor discrepancy.

We characterize the cyclic behavior of an AM30 extruded magnesium alloy. The micromechanisms of cyclic damage were studied by means of strain controlled experiments in both the extruded and transverse directions. A scanning electron microscope (SEM) analysis of the microstructure revealed that second phase particles were present in the Mg alloy that nucleated the cracks. However, crack initiation sites were observed to occur due to profuse twinning. Low cycle fatigue parameters were determined, and a microstructure-sensitive MultiStage Fatigue (MSF) model, which is able to capture mechanical and microstructure properties, was implemented to predict fatigue behavior and failure.

In this paper, a constitutive modeling of the metal powder compaction is presented as a first step of ongoing research of a multiscale and multistage mathematical based model concept for powder metallurgy component design and performance prediction using the finite element method. In recent years, techniques such as finite element analysis have received wide attention for their high applicability to powder metallurgy (PM) industry. These techniques provide a valuable tool in predicting density and stress distributions in the pressed compact prior to the actual tooling design and manufacturing process. However, the accuracy of FE prediction highly depends on the possibility to obtain appropriate experimental data to calibrate and validate the powder material model. Within the framework of continuum mechanics, the plasticity model depends on external and internal state variables such as temperature, stress, hardening, relative density and contact between metal powder particles.