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In order to take into account the local material non-linear elastic-plastic effects generated by notches, Glinka proposed the equivalent strain energy density (ESED) Criterion which has been widely accepted and used in fatigue theory and calculation for the last few decades. In this paper, Glinka's criterion is applied to structural optimization design for elastic-plastic correction to consider material non-linear elastic-plastic effects. The equivalent (fictitious) stress was derived from Glinka's Criterion equation for the commonly used Ramberg-Osgood and bi-linear stress and strain relationships. This equivalent stress can be used as the stress boundary constraint threshold in structural optimization design to control the elastic-plastic stress or strain in nonlinear optimization.

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.

Friction stir welding (FSW) shows advantages for joining lightweight alloys for automotive applications. In this research, the feasibility of friction stir welding aluminum for an automotive component application was studied. The objective of this research was to improve the Friction Stir Spot Welding (FSSW) technique used to weld an aluminum closure panel (CP). The spot welds were made using the newly designed swing-FSSW technique. In a previous study (unpublished), the panel was welded from the thin to thick side using both an 8 mm and a 10 mm diameter tool. The 10 mm tool passed various fatigue tests; however, the target was to improve performance of the 8 mm tool, especially to increase the number of cycle before the first crack appearance during fatigue testing. In this study fatigue tests and static strength was recorded for weld specimens that were welded from thick-to-thin with an 8 mm diameter tool.

Magnesium alloy extrusions offer potentially more mass saving compared to magnesium castings. One of the tasks in the United States Automotive Materials Partnership (USAMP) ?Magnesium Front End Research and Development? (MFERD) project is to evaluate magnesium extrusion alloys AM30, AZ31 and AZ61 for automotive body applications. Solid and hollow sections were made by lowcost direct extrusion process. Mechanical properties in tension and compression were tested in extrusion, transverse and 45 degree directions. The tensile properties of the extrusion alloys in the extrusion direction are generally higher than those of conventional die cast alloys. However, significant tension-compression asymmetry and plastic anisotropy need to be understood and captured in the component design.

Spot Welding is an important welding technique which is widely used in automotive and aerospace industry. One of the keys of checking the quality of the welds is measuring the size of the nugget. In this paper, the Shearographic technique is utilized to test weld joint samples under the thermal loading condition. The goal is to identify the different group of the nuggets (i.e. small, middle, and large sizes, which indicate the quality of spot welds). In the experiments, the sample under test is fixed by a magnet method from behind at the four edges. Thermal loading was applied in the back side and the sample is inspected using the digital Shearographic system in the front side. Results show the great possibility of classifying the nugget size into three groups and the measurement is well repeatable.