1208 Advances in Constitutive Modeling Relating Microscale Heterogeneity to Macroscopic Performance in Structural Metals

Coleman Alleman, Sandia National Laboratories
James Foulk, Sandia National Laboratories
Hojun Lim, Sandia National Laboratories
Michael Stender, Sandia National Laboratories
Reese Jones, Sandia National Laboratories
Remi Dingreville, Sandia National Laboratories
This minisymposium focuses on recent efforts in computational solid mechanics to address the open issues surrounding the role of microscale heterogeneity, including polycrystal microstructure, defect fields, and residual stresses on the performance of structural metals at room to elevated temperatures and from quasistatic to dynamic strain rates.

Microscale heterogeneity in the internal state of a material induces heterogeneity in mechanical fields under deformation, and this plays a critical role in the localization of deformation. However, quantifying this effect is a challenging task.

To resolve the process of localization in the incipient stage of failure, it is necessary to accurately represent the effects of microscale heterogeneity while conforming to computational limitations that make it infeasible to explicitly resolve these fields in the entire domain. To accommodate these constraints, there are two main avenues of research being pursued. In the first, ensembles are studied to obtain aggregate material properties and performance characteristics, as in parametric homogenization. In the second, multiscale modeling methods are employed to resolve fields at the microscale in limited regions of interest, as in submodeling, FE^2, and domain overlap methods.

Conventional experimental techniques such as room-temperature quasistatic uniaxial tension tests relay insufficient information to accurately fit material parameters or to examine model form error. New experimental and model validation techniques are under development to address this challenge. The challenges from the modeling perspective are related to effective utilization of full-field (e.g., DIC) and multi-field (e.g., thermomechanical) experimental and characterization (e.g., EBSD) data, including the creation, simulation, and interrogation of realistic computational domains (e.g., polycrystalline microstructures, void distributions).

Ever-increasing model complexity means increasing difficulty in the computational evaluation of model behavior. Novel methods and innovations are required to address the difficulties surrounding the issues of ill-conditioning related to multiphysics treatment, stiffness of differential evolution equations, and efficient handling of large data sets, among others.

Topics covered include (but are not limited to):
-Models of the physics and micromechanics of metal plasticity
-Multiscale methods for simulation of heterogeneous deformation
-Numerical approaches for constitutive updating/integration
-Creation and meshing of domains with realistic microstructures
-Validation of simulation results with full-field and multi-field data
-Use of experimental testing and characterization as a means of discovery for model development