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An Enhanced Maximum-Entropy Based Meshfree Method: Theory and Applications

Citation

Kumar, Siddhant (2019) An Enhanced Maximum-Entropy Based Meshfree Method: Theory and Applications. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/0AP6-5F94. http://resolver.caltech.edu/CaltechTHESIS:05062019-043913897

Abstract

This thesis develops an enhanced meshfree method based on the local maximum-entropy (max-ent) approximation and explores its applications. The proposed method offers an adaptive approximation that addresses the tensile instability which arises in updated-Lagrangian meshfree methods during severe, finite deformations. The proposed method achieves robust stability in the updated-Lagrangian setting and fully realizes the potential of meshfree methods in simulating large-deformation mechanics, as shown for benchmark problems of severe elastic and elastoplastic deformations. The improved local maximum-entropy approximation method is of a general construct and has a wide variety of applications. This thesis presents an extensive study of two applications - the modeling of equal-channel angular extrusion (ECAE) based on high-fidelity plasticity models, and the numerical relaxation of nonconvex energy potentials. In ECAE, the aforementioned enhanced maximum-entropy scheme allows the stable simulation of large deformations at the macroscale. This scheme is especially suitable for ECAE as the latter falls into the category of severe plastic deformation processes where simulations using mesh-based methods (e.g. the finite element method (FEM)) are limited due to severe mesh distortions. In the second application, the aforementioned max-ent meshfree method outperforms FEM and FFT-based schemes in numerical relaxation of nonconvex energy potentials, which is essential in discovering the effective response and associated energy-minimizing microstructures and patterns. The results from both of these applications show that the proposed method brings new possibilities to the subject of computational solid mechanics that are not within the reach of traditional mesh-based and meshfree methods.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Meshfree methods; particle methods; updated Lagrangian; maximum entropy; tensile instability; finite deformation; severe plastic deformation (SPD); equal-channel angular extrusion (ECAE); multiscale modeling; phase Transformation; energy minimization; homogenization; nonconvex energy potential
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Aeronautics
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Kochmann, Dennis M.
Group:GALCIT
Thesis Committee:
  • Ortiz, Michael (chair)
  • Bhattacharya, Kaushik
  • Danas, Konstantinos
  • Kochmann, Dennis M.
Defense Date:18 March 2019
Funders:
Funding AgencyGrant Number
NSFCMMI-1254424
Record Number:CaltechTHESIS:05062019-043913897
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:05062019-043913897
DOI:10.7907/0AP6-5F94
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.cma.2018.10.030DOIArticle adapted for Chapter 2.
ORCID:
AuthorORCID
Kumar, Siddhant0000-0003-1602-8641
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11498
Collection:CaltechTHESIS
Deposited By: Siddhant Kumar
Deposited On:14 May 2019 21:40
Last Modified:15 May 2019 00:33

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