P. R. Ding
,
D. Y. Ju
,
T. Lnouc and E. de Vries( 1) MSC Japan Ltd.
,
Osaka
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Japan 2) Saitama Institute of Technology
,
Saitama
,
Japan 3) Kyoto Universily
,
Kyoto
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Japan 4) MacNeal - Schwendler (E. D. C. ) B. V.
,
Gouda
,
The Netherlands)
金属学报(英文版)
A method to simulate processes of forging and subsequent heat treatment of an axial symmetric rod is formulated in eulerian description and the feasibility is investigated. This method uses finite volume mushes for troching material deformation and an automatically refined facet surface to accurately trace the free surface of the deforming material.In the method,the deforming work piece flows through fixed finite volume meshes using eulerian formulation to describe the conservation laws,Fixed finite volume meshing is particularly suitable for large three-dimensional deformation such as forging because remeshing techniques are not required, which are commonly considered to be the main bottelencek in the ssimulations of large defromation by using the finite element method,By means of this finite volume method, an approach has been developed in the framework of "metallo-thermo-mechanics" to simulate metallic structure, temperature and stress/strain coupled in the heat treatment process.In a first step of simulation, the heat treatment solver is limited in small deformation hypothesis,and un- coupled with forging. The material is considered as elastic-plastic and takes into account of strain, strain rate and temperature effects on the yield stress.Heat generation due to deformation,heat con- duction and thermal stress are considered.Temperature - dependent phase transformation,stress-in- duced phase transformation,latent heat,transformation stress and strain are included.These ap- proaches are implemented into the commerical commercial computer program MSC/SuperForge and a verification example with experimental date is given as comparison.
关键词:
finite volume method
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Xiaobing REN and Xiaotian WANG (College of Materials Science and Engineering
,
Xi'an Jiaotong University Xi'an 710049
,
China)K.Shimizu and T.Tadaki (Institute of Scientific and Industrial Research
,
Osaka University
,
8-1
,
Mihoga-oka
,
Ibaraki
,
Osaka
,
567
,
Ja
材料科学技术（英文）
A theoretical study is developed on the evolution and mechanism of an ordering coupled phase separation, and on the origin of a resultant tweed microstructure. It is found that long-range elastic interaction among atoms with different atomic sizes plays a key role in the phase sep aration, and that the evolution of the phase separation is very similar to that Of conventional spinodal decomposition except that the separation is dependent on an elastic interaction order ing (EIO). This "EIO coupled spinodal decomposition" is shown to exhibit a periodical or tweed microstructure being accompanied by an EIO. It is also found that a large atomic size factor yields a large positive contribution of EIO to spinodal decomposition. Generally it is thermodynamically and kinetically favorable for the EIO to precede the onset of spinodal decomposition,though the former is not separable from the latter as a whole. We suggest that an initially disordered solid solution undergoes an EIO first, and then the partially ordered solid solution starts to decompose via a spinodal mechanism. Solute-enriched regions increase their degree of order along with an increase in solute content, and solute-depleted regions decrease their degree of order together with a decrease of solute content. The final microstructure is characterized by a periodical array of highly ordered solute-enriched regions and nearly disordered solute-depleted regions. The notion of EIO coupled spinodal decomposition is in general agreement with the transformation behaviour of a large number of alloy systems.
关键词:
H Y Jing
,
L.X. Huo and Y. F. Zhang(Tianjin University
,
Tianjin 300072
,
China)F. Mnami(Osaka Univeristy
,
Osaka
,
Japan)
金属学报(英文版)
A 3-D computationalframework was suggested to model stable growth of a macroscopic crack under model I condition. The Gurson-Tverpaaof dilatant plasticity model for voided materials describes the damage process. Fixed-sized, computational cell elements (containing voids) defined over a thin layer at the cmck plane simulate the ductile crack extension. Outside of this layer, the material remains undamaged by the void growth. The micro-mechanics parumeters controlling cmck growth are the thickness Of computational cell layen D, and the initial void porosity, fo. These parameters are calculated through analyses of ductile tearing to match R-curve obtained from testing of deep notch bend specimens for welded joints. The R-curve for the double edge notched tension specimens is eNctively predicted using these pammeters.The predicted R-curve gives a good agreement with the expemment results.
关键词:
ductile crack growth
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