4891

4595

كارشناسي ارشد

سازه

اصفهان: دانشگاه صنعتي اصفهان، دانشكده عمران

1388

ده، 85ص:مصور، جدول، نمودار

ص.ع. به: فارسي و انگليسي

بيژن برومند

محمد مهدي سعادتپور

15/10/88

حميد هاشم الحسيني، بهروز كوشا

مهندسي عمران

ID4595

به فارسي و انگليسي: قابل رويت در نسخه ديجيتال

Finite element modeling of materials with incompressible behavior in elastic and plastic regimes Ruhollah Moradi Roohallah moradi@yahoo com 29 July 2009 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language Farsi Supervisor Dr Bijan Boroomand boroman@cc iut ac irAbstractIn the first part of this research we focus on improving the recently introduced volumetric forces method while addressing the possibility of confronting instability in the solution oftwo dimensional plane strain elastic problems with incompressibility behavior The methodis based on an iterative procedure for elimination of displacement modes responsible forvolume change i e in each step a series of forces which cause volume change in theelements are evaluated and adversely applied to the system to remove the modes This isperformed by considering an artificial compressibility to the original problem Since thewell known Babu ka Brezzi condition is not satisfied while using linear triangularelements locking effect may be seen in the solution one must employ a series of suitablecontrol volumes in place of the original elements in order to calculate the forces As thismethod does not apply constant volume condition directly on the elements its results donot show locking effect In this part of the thesis a new approach has been proposed fordefining the control volumes so that the final solution shows stability and convergenceafter a large number of iterations This paves the way for the use of the method innonlinear plastic problems In the second part we consider the extension of the aforementioned method to 2D planestrain problems with elasto plastic material behavior obeying von Misses yield criterion Inthis way the method is employed to eliminate displacement modes responsible for plasticvolume change while considering an artificial volumetric plastic strains in the process ofthe numerical plastic solution i e in each equilibrium Newton Raphson iteration themodes which produce plastic volume change in the control volumes are removed To thisend some simple amendments are proposed to the well known numerical plasticityroutines The method has been tested on some benchmark problems and excellent resultshave been obtained Key WordsPlasticity Incompressibility Von Misses criterion plane strain Finite Element Method Volumetric Forces Method

بيژن برومند

محمد مهدي سعادتپور

حميد هاشم الحسيني، بهروز كوشا