Elastic-plastic-brittle transitions using anti-plane elastic spring lattice model

Kale, Sohan

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https://hdl.handle.net/2142/42130 Copy

Description

Title

Elastic-plastic-brittle transitions using anti-plane elastic spring lattice model

Author(s)

Kale, Sohan

Issue Date

2013-02-03T19:16:40Z

Director of Research (if dissertation) or Advisor (if thesis)

Ostoja-Starzewski, Martin

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Elastic-plastic-brittle transitions
• Damage localization
• Strain localization
• Spring lattice model
• Fractals
• Random media

Abstract

The experimentally observed behavior in materials such as the size effect in failure strength, crack surface roughness and acoustic emission activity are directly related to the spatial material disorder present at the macroscopic and/or microscopic length scales. The classical continuum based theories fail to effectively address such issues and, therefore, spring-lattice models that can explicitly account for disorder are extensively used in statistical solid mechanics. The spring-lattice models reported in the literature over the past few decades have been used to study elastic-brittle and elastic-perfectly plastic transitions. The elastic-plastic-brittle spring lattice model proposed in this thesis is an extension of the existing spring lattice models that is more generalized and can simulate a wide range of material responses. The advantages of this model are demonstrated in this thesis by a thorough parametric study focusing on elastic-plastic transitions to understand the effects of the plastic hardening ratio and strength of disorder. The difference between elastic-plastic hardening and elastic-perfectly plastic behavior in anti-plane elasto-plastic medium is confirmed in terms of weak/strong nature of neighboring interactions and their implications in describing the problem as an uncorrelated/correlated percolation. Next, the damage localization in elastic-brittle transition is demonstrated and the roughness coefficient of the crack surface is estimated to be 0.7, which matches well with the previous studies. Absence of localization in the elastic-plastic transitions is attributed to the absence of stress concentrations near the yielded sites, as opposed to elastic-brittle transitions. Finally, usefulness of the proposed model is proved through a range of material responses that can be simulated controlled by the strength of disorder distribution in yield and failure limits of the given material.

Graduation Semester

2012-12

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http://hdl.handle.net/2142/42130

Copyright and License Information

Copyright 2012 Sohan Sudhir Kale

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