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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.

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.