Crystal plasticity simulations of microstructure-induced uncertainty in strain concentration near voids in brass

Abstract

The uncertainty in mechanical response near a cylindrical hole in polycrystalline alpha brass was simulated as a function of variations in the crystallographic orientations of the grains near the hole. A total of 4 hole sizes were examined, including the case of a microstructure without a hole, and 45 simulations were performed for each case (yielding 180 simulations total) to acquire statistical data. For a hole larger than the grain size, the deformation resembles the homogenous solution but with perturbations due to the local microstructural environment. For a hole approximately equal to or smaller than the grain size, the deformation deviates substantially from the continuum behaviour, and depends strongly on the local microstructural environment surrounding the hole. Each population of simulations was analysed statistically to determine the effect of micro structural variability on strain localization near each of the four defect sizes. The coefficient of variation in the maximum plastic strain around microstructure-scale holes is about 37%, and the largest values of plastic strain are about twice those in the absence of microstructure. These results have significant implications for analyses of the margin of failure due to defects of this class (e.g. voids or small bolt holes).

Keywords:

• defects
• finite element analysis
• microstructure
• plastic deformation
• texture

Acknowledgements

The authors wish to thank Bonnie B McKenzie and Joel P McDonald for their valuable contributions to this work. Sandia National Laboratories is a multi-programme laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.