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Computational Methods for Debonding in Composites

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Chapter 10<br />

Elastoplastic Model<strong>in</strong>g of Multi-phase Metal<br />

Matrix Composite with Void Growth Us<strong>in</strong>g<br />

the Trans<strong>for</strong>mation Field Analysis<br />

and Govern<strong>in</strong>g Parameter Method<br />

Ernest T.Y. Ng and Afzal Suleman<br />

Abstract In this paper, we employ the comb<strong>in</strong>ed Trans<strong>for</strong>mation Field Analysis<br />

(TFA) method and the Govern<strong>in</strong>g Parameter Method (GPM) to predict the overall<br />

elastoplastic behavior of multi-phase fibrous composite materials us<strong>in</strong>g Gurson-<br />

Tvergaard yield criterion <strong>in</strong> order to account <strong>for</strong> the effect of void growth <strong>in</strong><br />

the matrix phase. For the homogenization scheme, we employ the TFA method<br />

with concentration factors determ<strong>in</strong>ed by the Eshelby-Mori-Tanaka (EMT) theory.<br />

Regard<strong>in</strong>g to the stress <strong>in</strong>tegration of the govern<strong>in</strong>g TFA equations, we employ an<br />

implicit <strong>in</strong>tegration scheme, namely the GPM. Furthermore, a necessary condition<br />

<strong>for</strong> the possible ranges of the govern<strong>in</strong>g parameters based on the GPM <strong>in</strong>tegration<br />

scheme is derived <strong>in</strong> a more general sett<strong>in</strong>g by <strong>in</strong>clud<strong>in</strong>g the rate of nucleation<br />

and coalescence with<strong>in</strong> the context of writ<strong>in</strong>g the expression of the rate of change<br />

of porosity. To validate our proposed approach, we compare our results to both<br />

numerical and experimental results provided <strong>in</strong> the exist<strong>in</strong>g literature.<br />

10.1 Introduction<br />

A metal matrix fiber-re<strong>in</strong><strong>for</strong>ced composite has many advantages over conventional<br />

eng<strong>in</strong>eer<strong>in</strong>g materials because of its light-weight and good <strong>for</strong>mability under fabrication.<br />

However, the <strong>in</strong>tr<strong>in</strong>sic <strong>in</strong>homogeneities of fibrous composite materials has<br />

made the prediction of the mechanical behavior of such a material a great challenge<br />

over the past three decades. As described <strong>in</strong> the preced<strong>in</strong>g paper by Ng and Suleman<br />

[19], the comb<strong>in</strong>ed TFA-GPM provided a good approximation of determ<strong>in</strong><strong>in</strong>g the<br />

Ernest T.Y. Ng<br />

Department of Mechanical Eng<strong>in</strong>eer<strong>in</strong>g, University of Victoria, British Columbia, Canada,<br />

e-mail: eng@me.uvic.ca<br />

A. Suleman<br />

Instituto de Engenharia Mecánica, Instituto Superior Técnico (IDMEC-IST), Instituto Superior<br />

Técnico, Lisbon, Portugal, e-mail: suleman@ist.utl.pt<br />

197

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