钛基复合材料好用

Finite element modeling of the deformation behavior of

semi-solid materials

Jong-Hoon Yoon a,Yong-Taek Im b,*,Nak-Soo Kim c

a Rocket Structures/Materials Department,Space Technology R&D Division,Korea Aerospace Research Institute,

52Oundong,Yusonggu,Taejon305-333,South Korea

b Computer Aided Materials Processing Laboratory,Department of Mechanical Engineering,Korea Advanced Institute of Science and Technology,

ME3227,373-1Gusongdong,Yusonggu,Taejon305-701,South Korea

c Department of Mechanical Engineering,Sogang University,Shinsoodong,Mapogu,Seoul121-742,South Korea

Abstract

In the current study,the deformation behavior of semi-solid materials was modeled using the von Mises yield criterion in which the semi-solid material was treated as a single phase material with the incompressibilitycondition in a global sense.The¯ow stress of the material was modeled as a function of strain in consideration of the solid fraction and the breakage ratio of dendritic structure.An algorithm based on mixture theoryand D'Arcy's law was developed to update the solid fraction,the distribution of which varies within the material due to relative velocitybetween the solid and liquid phases during deformation.The parameters involved with the proposed model were determined through a parametric studyin which numerous®nite element analy sis results were compared with the data from existing isothermal upsetting experiments for semi-solid Sn±15%Pb parison with experimental results showed that the current approach is improved compared to previous compressible approaches.The generalityof the current approach was examined through rigid±thermoviscoplastic®nite element analyses of the semi-solid forging of a ball-joint case under various preheating temperatures in consideration of the release of latent heat.The simulation results agreed well with the trend of the experimental®ndings but showed some quantitative errors.#2001Elsevier Science B.V.All rights reserved.

Keywords:Semi-solid material;Flow stress;Breakage ratio;Solid fraction updating algorithm;Solidi®cation

1.Introduction

The internal structure of a material in the semi-solid state

is composed of solid grains surrounded bya liquid phase.

Thus,the¯uidityof the workpiece is enhanced and near-net

shape manufacturing of complex shaped parts is possible.

However,the exact prediction of the material behavior of

semi-solids is extremelydif®cult due to factors such as the

mixed characteristic of solid deformation and liquid¯ow

and the change of microstructure during deformation.

n the last few decades manyefforts have been made to

characterize the deformation behavior of semi-solid materi-

als.Modeling for the deformation behavior of semi-solid

materials can be classi®ed according to the range of solid

fraction of the material.For low solid fraction materials,

Laxmanan and Flemings[1]and Hirai et al.[2]modeled

the characteristics of semi-solid slurrybyobtaining the

experimental relationship between shear rate and apparent

viscosity.For high solid fraction materials,Lalli[3]and

Charreyron and Flemings[4]characterized the deformation

behavior of semi-solid material with D'Arcy's law for liquid

phase¯ow and compressible plastic deformation theory

for solid grains.In particular,Kumar et al.[5]represented

the non-steadystate deformation behavior for low solid

fraction semi-solid materials byintroducing an agglomera-

tion variable into the apparent viscosityequation.Martin

et al.[6]proposed a new yield criterion that allowed

compressibilityof the solid phase and obtained experimen-

tallythe required variables byrelating a creep model with

the yield criterion.

Gebelin et al.[7],and Zavaliangos and Lawley[8]

analyzed the upsetting of semi-solid materials by the®nite

element method based on the above models and predicted

the internal distribution of solid fraction in the deformed

specimen.However,theyfailed to accuratelypredict the

change of stress or load and deformation mode in the

analyses.This was due to the fact that the models used

were veri®ed for onlya speci®ed range of solid fraction,

Journal of Materials Processing Technology113(2001)153±159

*Corresponding author.

E-mail address:ytim@mail.kaist.ac.kr(Y.-T.Im).

0924-0136/01/$±see front matter#2001Elsevier Science B.V.All rights reserved.

PII:S0924-0136(01)00677-X