* Corresponding author. Tel.: #44-01895-274000; fax: #44-01895-812556. E-mail address: hamid.bahai@brunel.ac.uk (H. Bahai). Finite Elements in Analysis and Design 37 (2001) 263}272 FEA modelling of visco-plastic behavior of metal matrix composites F.K. Shati,I.I.Esat,H.Bahai* Department of Engineering, Queen Mary and Westxeld College, Mile End Rd., London E1 4NS, UK Department of Mechanical Engineering, Brunel University, Uxbridge, UB8 3PH, UK Department of Systems Engineering, Brunel University, Uxbridge, UB8 3PH, UK Abstract A "nite element implementation of the uni"ed elastic}viscoplastic theory of Bodner for the analysis of metalmatrixcompositesispresentedinthispaper.Anoriginalmodelofcircular "bresembeddedinasquare arrayofmatrixmaterialhasbeenchosenforthepresentinvestigation.Theresultsofthepresentanalysisfor twoAluminiummatrixcompositeshavebeencomparedwiththeresultsofAboudi'scontinuumtheoryand the Halpin}Tsai equations.  2001 Elsevier Science B.V. All rights reserved. 1. Introduction The "nite element method (FEM) has been widely used in the elastic as well as inelastic modellingofvariousAluminiummatrixcompositesduringthelasttwodecades[1,2].Inallthese investigations, the inelastic behaviour of the composite has been characterised by the use of the classical theory of plasticity [3]. Thus, the problem becomes, simply, one of a. De"ningaspeci"cyieldcondition(stressthreshold)atwhichinelasticdeformationmayoccur. b. Calculatingthesizeandshapeoftheyieldsurfacessubsequenttotheinelasticdeformationby de"ning a speci"c hardening law. Althoughthese "niteelementmodelsofclassicalplasticityhavebeenusedbymanyinvestigators, theyhave,however,anumberoflimitationsfromboththephysicalandcomputationalviewpoints. To overcome some of these limitations, such as the need to specify a yield function, loading/ unloading conditions, etc. a new model was proposed by Bodner and his co-workers [4]. 0168-874X/01/$-see front matter  2001 Elsevier Science B.V. All rights reserved. PII:S0168-874X(00)00042-1