Comparative evaluation of automotive oil pans fabricated by creep resistant magnesium alloy and aluminum alloy

A series of comparative tests were conducted on two geometrically-identical automotive oil pans, one produced from A380 aluminum - pulled directly from its high-volume production line - and a second produced in a casting trial using DSM's MRI 153M creep-resistant magnesium alloy. While the theoretical differences in mechanical behavior of cast aluminum parts versus cast magnesium parts are relatively simple to determine, very few quantified, experimental comparisons exist. Where these comparisons do exist, they are often performed on simple shapes. Therefore, the objective of this project was to compare the stiffness, modal behavior, natural frequencies, and damping ratios of the two materials in a complex, functional geometry. Stiffness, natural frequencies, and flexural modes were determined using holographic laser interferometry and finite element analysis. Natural frequencies, modal behavior, and damping ratios were determined via hammer-impact excitations. The push to reduce vehicle weight by applying magnesium to larger, automotive powertrain components requires the usage of a cost-effective alloy that exhibits creep properties similar to the incumbent material, A380 aluminum. Consequently, the creep behavior of the MRI 153M alloy was compared to A380 via determinations of the bolt load retention (BLR) on the sealing face of the oil pans. BLR was determined on-vehicle using ultrasonic measurement methods.