Mechanical Heterogeneities in Structural Metals under Complex Environments: an Energy Landscape Approach Bridging Atomic-and Meso-scale Modeling
Abstract
The proposed research aims to provide a fundamental knowledge on the onset mechanisms of mechanical heterogeneities in structural metals under complex environments. The proposal consists of three scientific objectives: (i) Understand the key atomistic processes leading to the heterogeneous deformation (e.g. strain localizations and dislocation channelings), and identify the boundaries in thermo-mechanical space separating the heterogeneous deformation regime from the homogeneous regime; (ii) Probe the variations of critical resolved shear stresses for dislocation-obstacle interactions at different loading conditions, and quantify the negative strain rate sensitivity regime where mechanical instabilities could occur; and, (iii) Bridge the atomic- and meso-scale methods in a seamless manner, and obtain the constitutive relations of structural materials at complex environments without invoking many empirical assumptions and fitting parameters. To address these challenges, a novel algorithm based on the concept of potential energy landscape (PEL) will be employed, which can largely extend the timescale of modeling while still retaining the atomic details. By proactively sampling and exploring the system s underlying PEL, the key processes governing materials degradations will be obtained, which will enable the construction of deformation mechanism maps over a wide range of complex environments. Electron microscope characterizations and mechanical test experiments are also proposed to validate the predicted modeling results. The iterations of PEL-based modeling and experimental verifications will allow a fundamental understanding on the environmental effects on the origin of heterogeneous deformation and mechanical instabilities, which are critical for developing protection systems and improving the durability of materials under extreme environments and unanticipated event of stress fluctuations.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1810119
Entities
People
- Yue Fan
Organizations
- Army Contracting Command
- United States Army
- University of Michigan