Publications

Meso-scale simulation of the shock compression response of equiaxed and needle morphology Al 6061-T6 powders

Fredenburg, David A.; Vogler, Tracy V.; Thadhani, N.N.

With component sizes approaching the mesoscale, conventional size microstructures offer insufficient homogeneity in mechanical properties, forcing microstructures to be reduced to the nanoscale. This work examines the effect of a nanocrystalline surface layer on the dynamic consolidation response of two different morphology Al 6061-T6 powders. Shock-propagation through equiaxed and needle morphology Al 6061-T6 powder beds initially at 73.5 and 75.0% theoretical density, respectively, is simulated at constant particle velocities ranging between 150 and 850 m/s. Shock velocity-particle velocity relationships are determined for powders both with and without the presence of a 2 μm high strength surface layer, which is representative of a nanocrystalline surface layer. Significant deviations in dynamic response are observed with the presence of the surface layer, especially at lower particle velocities. The equation of state (EOS) for both the homogeneous particles and those with a high strength surface layer are found to be best represented by a piecewise EOS. © 2009 American Institute of Physics.