Department of Civil, Environmental, and Geo-Engineering, University of Minnesota
Title: Mechanistic Mapping of Random Fields for Stochastic Finite Element Simulations of Quasibrittle Fracture Abstract: Continuum finite element (FE) modeling of damage and failure of quasibrittle structures
suffers from the spurious mesh sensitivity due to strain localization.
This issue has been investigated extensively for deterministic analysis
through the development of localization limiters. This talk will present
a mechanism-based model to mitigate the mesh sensitivity in stochastic
FE simulations of quasibrittle fracture. The present model is formulated
within the framework of continuum damage mechanics, and the spatial
randomness of material properties is represented by homogenous random
fields. Two localization parameters are introduced to describe the
evolution of the damage pattern of finite elements. These parameters are
used to guide the energy regularization of the constitutive law, as
well as to determine the mapping of the random fields of material
properties onto the finite element mesh. The model is applied to
simulate the stochastic failure of quasibrittle structures of different
geometries featuring different behaviors including both distributed and
localized damage. It is shown that the existing local projection and
local averaging mapping methods could lead to strong mesh dependence of
the predicted mean and variance of the structural load capacity. To
mitigate the spurious mesh sensitivity, the mapping of the random fields
of material properties must be tied to the damage pattern, which may
evolve during the loading process. This result has important
implications for the recent trends in the machine-learning approach for
constitutive modeling of quasibrittle materials.For more information, visit the AEM Mechanics Research Seminar website: