Granular and other heterogeneous materials exhibit complex behaviors which are difficult to capture using classical continuum theories. Enhancements through higher order descriptions of the deformation such as micropolar or, most generally, micromorphic continuum have been proposed but suffer from difficulty in calibrating the numerous parameters. We here propose and demonstrate a variationally based method for computing, or “filtering,” the deformation and stress response of a Direct Numeric Simulation (DNS) to the micromorphic macro‐scale utilizing only the continuum equations of Eringen and Suhubi. Once determined for several DNS, we calibrate micromorphic finite deformation elastoplastic constitutive equations within the context of a surrogate‐based Bayesian uncertainty quantification framework and comment on upcoming extensions. 

About Nathan Miller

Nathan Miller, a research and development engineer at Los Alamos National Laboratory, has been a research and development engineer in Los Alamos National Laboratory's advanced engineering analysis group W‐13 since his graduation with a bachelor's and masters of science in mechanical engineering from Colorado State University in 2009 and 2010 respectively. He recently received his Ph.D. in Civil Engineering from CU Boulder with an emphasis on the application of micromorphic theory to elasto‐plastic materials undergoing finite deformation and is the lead developer of Tardigrade. His research focuses on the development of constitutive models for polymer bonded granular materials both at the phenomenological macroscale and the mechanistic micro‐scale and techniques for bridging those domains. Additional focus is placed on the development of uncertainty quantification frameworks for nonlinear problems using direct and surrogate based techniques.