Local Stress and Damage Response of Polycrystal Materials to Light Shock Loading Conditions via Soft Scale-Coupling
- 55 Downloads
Accurately representing the process of porosity-based ductile damage in polycrystalline metallic materials via computational simulation remains a significant challenge. The heterogeneity of deformation in this class of materials due to the anisotropy of deformation of individual single crystals creates the conditions for the formation of a damage field. The work reported upon here is interested in the formation of porosity in the body-centered cubic metal tantalum. This chapter reports on the soft-coupled linkage between a macroscale damage model and mesoscale calculations of a suite of polycrystal realizations of tantalum. The macroscale model is used to represent a tantalum on tantalum plate impact experiment and predict the point in time in the loading profile when porosity is likely to initiate. The 3D loading history from the macroscale calculation is then used to define the probable loading history profile experienced within the experimental sample. Tantalum displays non-Schmid behavior in the motion of the dominant screw dislocations during deformation. This introduces directionality in the magnitude of stress required to propagate glide of these screw dislocations. A model is presented which provides representation of non-Schmid effects in tantalum. This model is employed in performing of meso-scale calculations of statistically equivalent microstructures of the tantalum material to provide local-scale stress condition at the time of the loading profile where initiation of porosity is anticipated. The results of these simulations suggest that non-Schmid effects significantly impact the local stress conditions within the microstructure and are very important to represent. The results also suggest that vonMises stress conditions at grain boundaries and grain boundary triple lines are highly variable close to those features but the variability is reduced with distance to the grain center. The computational results also suggest that the stress traction conditions at the grain boundary are a strong function of the orientation of each boundary with respect to the shock direction. Grain boundaries whose surface normal is parallel to the shock direction have a significantly higher normal tensile traction than other grain boundaries. Grain boundaries whose normal is at 45 or 135 degrees to the shock direction have relatively higher magnitudes of shear stress.
KeywordsDuctile damage Crystal plasticity Shock loading Porosity Metals Grain boundary Statistics Defects Nucleation Non-schmid effect Scale-coupling Dislocations
This work was performed at Los Alamos National Laboratory and funded through the Laboratory Directed Research and Development program via projects 20170033DR and 20150594ER. The authors also wish to acknowledge the assistance provided by Dr. M. Ardeljan in constructing the SVEs used in this study.
- 13.E.P. Busso, Cyclic deformation of monocrystalline nickel aluminide and high temperature coatings, Ph.D. Thesis, MIT, 1990Google Scholar
- 17.Dream.3D version 4.2, BlueQuartz Software, Springboro OH, USA, 2013Google Scholar
- 19.G.T. Gray III, Shock wave testing of ductile materials, in ASM Handbook, (ASM International, Materials Park, 2000)Google Scholar
- 24.G.T. Gray III, N.K. Bourne, V. Livescu, C.P. Trujillo, S. MacDonald, P. Withers. The influence of shock-loading path on the spallation response of Ta. in Proceedings of APS Topical Group of Shock Compression of Condensed Matter, Seattle, 7–12 July 2013Google Scholar
- 30.G.R. Johnson, S.R. Beissel, C.A. Gerlach, R.A. Stryk, T.J. Holmquist, A.A. Johnson, S.E. Ray, J.J. Arata, User Instructions for the 2006 Version of the EPIC Code (Network Computing Services Inc., Minneapolis, 2006)Google Scholar
- 36.U.F. Kocks, A.S. Argon, M.F. Ashby, Thermodynamics and Kinetics of Slip. Progress in Materials Science (Pergamon, Oxford, 1975)Google Scholar
- 40.P.J. Maudlin, E.N. Harstad, T.A. Mason, Q.H. Zuo, F.L. Addessio. TEPLA-a: coupled anisotropic elastoplasticity and damage, the Joint DoD/DOE Munitions Technology Program progress report, LA-UR-14015-PR (2003)Google Scholar