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Title:A hybrid technique to extract cohesive fracture properties of elasto-plastic materials using inverse analysis and digital image correlation
Author(s):Gain, Arun
Advisor(s):Paulino, Glaucio H.
Department / Program:Civil & Environmental Eng
Discipline:Civil Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:M.S.
Genre:Thesis
Subject(s):cohesive zone model
inverse analysis
Park-Paulino-Roesler model (PPR)
Nelder-Mead scheme
Abstract:Current work utilizes cohesive zone modeling to study the fracture properties of metals. This study proposes a hybrid technique experimental/numerical to extract cohesive fracture properties of elasto-plastic material using inverse analysis and digital image correlation. Two approaches are suggested - a shape optimization technique and a parameter optimization for the PPR potential-based cohesive zone model. In shape optimization approach, CZM is obtained by piecewise interpolation of the optimized interpolation points whereas in parameter optimization for the PPR potential-based CZM, the CZM is obtained by using the PPR model which utilized the parameters coming from an optimization scheme. Unconstrained, derivative free Nelder-Mead scheme is used for optimization purpose. The bulk material is modeled as plane-stress J2 plastic material. The proposed schemes are verified for various plausible cases, such as different displacement field data, various initial guess and noisy displacement field data. As a proof of concept, both schemes are applied to Polymethyl Methacrylate (PMMA) quasistatic crack growth experiment, which is modeled as elastic material, to substantiate its utility. Near tip displacement field is obtained experimentally using DIC and used as input to the optimization schemes. Computationally predicted global responses of the PMMA specimen, using the CZMs extracted from the inverse analysis, shows good agreement with the experimental global response.
Issue Date:2010-05-18
URI:http://hdl.handle.net/2142/16010
Rights Information:Copyright 2010 Arun Lal Gain
Date Available in IDEALS:2010-05-18
2012-05-19
Date Deposited:May 2010


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