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McNair Scholars Program

Katrina (Lindsay) Alexander


Education: Bachelor of Science in mechanical engineering (December 2003)

McNair Project: Analysis of Frictional Coefficients on Metal Powder Compaction Using Finite Element Simulation (2000)

Mentor: Xiao Jiang Xin, Ph.D.

The compaction of metal powders is an important and cost-effective method for manufacturing complex metal parts with high strength-to- weight ratios. During compaction, friction between particles affects structural inhomogeneity and particle agglomeration, therefore its effects should be well understood in order to produce high quality parts. Yielding marks the end of elastic (or recoverable) deformation of a material; plastic (or unrecoverable) deformation occurs when the stress in the material reaches the yield point. Knowledge of the yield criterion (yield surface) for a material makes it possible to predict the onset of plastic deformation in practical engineering structures. Yield probing is the technique for obtaining the yield surface of a material during deformation. This process for powder compaction involves applying different pressure combination and finding the yield point. In the study, the effect of friction between metal particles on the yield surface was determined by using explicit finite element method (FEM). Yield surfaces of Fe-Al metal powder initially compacted to 96% density by bi-axial compaction with particle frictions of 0 and 1 were obtained. The results indicated densification and compact strength were greater for particle friction of 1. By obtaining the yield surface, better design and efficiency of the metal powder compaction process is possible.