Mechanical Metrics of Virtual Polycrystals (MechMet)

Abstract

The details of polycrystalline microstructure often influence the early stages of yielding and strain localization under monotonic and cyclic loading, particularly in elastically anisotropic materials. A new software package, MechMet (mechanical metrics) provides a convenient finite element tool for solving field equations for elasticity in polycrystals in conjunction with investigations of microstructure-induced heterogeneity. The simulated displacement field is used to compute several mechanical metrics, such as the strain and stress tensors, directional stiffness, relative Schmid factor, and the directional strength-to-stiffness ratio. The virtual polycrystal finite element meshes needed by MechMet can be created with the Neper package or any other method that produces a 10-node, tetrahedral, serendipity element. Formatted output files are automatically generated for visualization with Paraview or VisIt. This paper presents an overview of the MechMet package and its application to polycrystalline materials of both cubic and hexagonal structures.

Designing Ti-6Al-4V microstructure for strain delocalization using neural networks

“…The first condition emphasizes the role of grain orientation or texture, while the second manifests the critical role of the grain neighborhood on slip localization and transmission in Ti-6Al-4V. In conclusion, experimental studies confirm that the development and connectivity of slip bands in titanium alloys, including Ti-6Al-4V, adversely affect their mechanical properties [4,20,21]. Motivated by these studies, a key question is what combination of microstructural features promote slip localization in Ti-6Al-4V and, perhaps more importantly, what ideal set of features would give rise to a delocalized accommodation of the applied strain in this alloy?…”

Recent Developments in Femtosecond Laser-Enabled TriBeam Systems

“…The segmentation of microtextured regions (MTRs) within Ti-6Al-4V allows for more accurate prediction of bulk mechanical response arising from these larger-scale structures comprising similarly oriented grains in a relatively equiaxed microstructure. 90,95 Identification of orientation gradients arising from base metal remelting during laser powder welding on oligocrystal substrates enables characterization of the solidification growth front direction, as well as the isolation of smaller, randomly oriented grains that nucleate later during solidification and form the bulk of the deposit.…”

Mechanical Analyses using Discrete Harmonic Expansions of Grain-Based Field Data

“…In this section we discuss the Neper instantiations of the three variants in terms of their grain diameter and grain sphericity statistics. The grain structure is presented for each sample variant along with maps of the single-crystal directional stiffness and Schmid factor defined in MechMet [5]. Mechanical attributes of the variants, evaluated using the sibling code, MechMet [5], are presented next for extensional loading.…”

“…The grain structure is presented for each sample variant along with maps of the single-crystal directional stiffness and Schmid factor defined in MechMet [5]. Mechanical attributes of the variants, evaluated using the sibling code, MechMet [5], are presented next for extensional loading. This is followed with presentation of the harmonic modes computed with MechMonicsand their associations with the grain axes.…”

“…The sample variants have relatively few grains and thus might be expected to show spread in their mechanical behaviors. The mechanical characteristics of the sample variants were examined with MechMet [5] to provide insight in this regard. The single-crystal elastic moduli correspond to AL6XN [7].…”