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Simulation of Stable Crack Growth for Welded Joints Including Strength Mismatching

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Journal of Materials science & Technology 1999年第6期15卷 567-570页

作者： Jing, HY Luo, LX Zhang, YF Minami, F Tianjin univ Coll Mat Sci & Engn Tianjin 300072 Peoples R China osaka univ Osaka Japan

A 3-D computational method to simulate stable growth of a macroscopic crack under model condition is described in this paper. The Gurson-Tvergaard plasticity model for voided materials describes the damage process. Fixed-sized, computational cell elements (containing voids) defined over a thin layer at the crack plane simulate the ductile crack extension. Outside of this layer, the material remains undamaged by the void growth, follows the conventional J2 flow theory. The micromechanics parameters controlling crack growth are D, the thickness of computational cell layer and f(0), the initial void porosity. Calibration of these parameters proceeds through analyses of ductile tearing to match R-curve obtained from testing of deep notch bend specimens for welded joints. The effect of the strength mismatching on ductile crack growth for welded joints is simulated also.

关键词： Joints (structural components)

Elastic Energy and Elastic Interaction Ordering of Binary Solid Solutions

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Journal of Materials science & Technology 1996年第1期12卷 57-68页

作者： Ren, XB Wang, XT Shimizu, K Tadaki, T XIAN JIAOTONG univ COLL MAT SCI & ENGN XIAN 710049 PEOPLES R CHINA osaka univ INST SCI & IND RES IBARAKI OSAKA 567 JAPAN

A theory in the framework of continuum elasticity has been developed to calculate the total contribution of ''atomic size effect'' or ''strain energy effect'' to free energy of binary solid solutions. It is found that elastic free energy consists of two parts: elastic self energy (ESE), and elastic interaction energy(EIE). The former is a function of composition alone, the latter is also a function of atomic configuration. Minimization of total elastic free energy with respect to atomic arrangement results in an ordered arrangement of atoms, which is called elastic interaction ordering (EIO), as it originates from elastic interaction among atoms. EIO is a kind of local ordering within a ''characteristic range'', and it is found to be important in determining the state of solid solutions and structures of superlattices. The present theory also gives good explanation to the coexistence of ordering and decomposition which can not be understood in conventional theories.

关键词： Solid solutions

Effect of Elastic Energy due to Atomic Size Factor on Ordering and Decomposition Behaviour of Binary Solid Solutions

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Journal of Materials science & Technology 1996年第2期12卷 135-142页

作者： Ren, XB Wang, XT Shimizu, K Tadaki, T XIAN JIAOTONG univ COLL MAT SCI & ENGNXIAN 710049PEOPLES R CHINA osaka univ INST SCI & IND RESIBARAKIOSAKA 567JAPAN

A theory recently developed by the present authors is applied to the study of the effect of elastic energy due to atomic size factor on the transformation behaviour of binary solid solutions. It is found that elastic interaction energy (EIE), which is a part of the total elastic energy, plays a key role in both ordering elastic interaction ordering (EIO) and spinodal decomposition. The present study gives a reasonable explanation to the historical dilemmas, ''elastic energy paradox'' and ''atomic size factor paradox''. By solving these confusing problems, the coexistence of ordering (EIO) and decomposition, which has been regarded as impossible by conventional theories, can be well understood. The mechanism is as follows: lowering of elastic energy demands EIO, and such an ordering provides a driving force for spinodal decomposition. Therefore, in alloys with large atomic size factor, spinodal decomposition is preceded and induced by ordering. Ordering and spinodal decomposition are thus closely related processes to each other.

关键词： Solid solutions

Origin of Ordering Coupled Tweed Microstructures in Alloys with Large Atomic Size Factors

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Journal of Materials science & Technology 1996年第3期12卷 166-174页

作者： Ren, XB Wang, XT Shimizu, K Tadaki, T XIAN JIAOTONG univ COLL MAT SCI & ENGNXIAN 710049PEOPLES R CHINA osaka univ INST SCI & IND RESIBARAKIOSAKA 567JAPAN

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 separation, 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 ordering (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： SPINODAL DECOMPOSITION TITANIUM ALLOYS TI ALLOYS TRANSFORMATIONS NICKEL LI

The possible relationship between hepatomegaly and release of HGF into plasma induced by clofibrate in rats

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World Journal of Gastroenterology 1999年第5期5卷 440-442页

作者： Xu W Wu SG First Mil Med univ Inst Pharmaceut Sci Guangzhou 510515 Peoples R China

INTRODUCTIONHepatocyte growth factor (HGF) is a newly discovered multifunctional growth factor, and the most potent mitogen known for hepatocyte[1]. It has been shown that recombinant human HGF can protect animal liver against the damaging action of carbon tetrachloride[2]. However, the generation of HGF is also associated with certain liver diseases and several extra-hepatic diseases[3-5]. For example, after partial hepatectomy or carbon tetrachloride poisoning, HGF level in rat plasma increases markedly[3,4]. Therefore, it is believed that HGF plays an important role in the restoration and regeneration of liver after injury.

关键词： clofibrate hepatocyte growth factors hepatomegaly rat

Density of Ni-Cr Alloy in the Mushy State

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Journal of Materials science & Technology 2003年第2期19卷 107-110页

作者： Feng XIAO1) Joining and Welding Research Institute, osaka university, osaka 567-0047, Japan2) School of Materials science and Engineering Tianjin university, Tianjin 300072, China Joining and Welding Res. Inst. Osaka Univ. Osaka 567-0047 Japan Sch. of Mat. sci. and Eng. Tianjin Univ. Tianjin 300072 China

The density of Ni-Cr alloy in the mushy state has been measured using the modified sessile drop method. The density of Ni-Cr alloy in the mushy state was found to decrease with increasing temperature and Cr concentration in alloy. The molar volume of Ni-Cr alloy in the mushy state therefore increases with increasing the Cr concentration in alloy. The ratio of the difference of density divided by the temperature difference between liquidus and solidus temperatures decreases with increasing Cr concentration. The density of the alloy increased with the precipitation of a solid phase in alloy during the solidification process. The temperature dependence of the density of alloy in the mushy state was not linear but biquadratic.

关键词： Ni-Cr alloy Density Molar volume Mushy state Modified sessile drop method

One-Pot Synthesis of N-Boc-2, 5-bis(trimethylsilyl)pyrrolidine

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Chinese Chemical Letters 2001年第12期12卷 1061-1064页

作者： Dong, JC Li, RT Cheng, TM Peking univ Sch Pharmaceut Sci Dept Bioorgan Chem Beijing 100083 Peoples R China

N-Boc-2, 5-bis(trimethylsilyl)pyrrolidine 4 was synthesized from the reaction of N-Boc-pyrrolidine 1 with trimethylsilyl chloride (TMSCl) at optional temperature in one-pot in good yield.

关键词： N-Boc-2 5-bis(trimethylsilyl)pyrrolidine trimethylsilylation one-pot

Chemistry 1,2,4-triazines--Mass spectrometry of 6-azapurines

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Chinese science Bulletin 1997年第8期42卷 652-655页

作者： Shi, XL Hu, CF Yue, BZ Cai, MS Cheng, TM BEIJING MED univ SCH PHARMACEUT SCIBEIJING 100083PEOPLES R CHINA

FOR the purpose of finding novel antitumor and antivirus medicines and understanding themechanism of the metabolic process involved,several 6-azapurine derivatives were synthe-sized from 1,2,*** spectrometry plays a k... 详细信息

关键词： triazine azapurine mass spectrometry splitting.

STUDIES ON THE SYNTHESIS OF NOVEL ISONUCLEOSIDE FROM D-GLUCOSE

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Chinese Chemical Letters 1995年第8期6卷 655-656页

作者： Yu, HW Ma, LT Zhang, LH Beijing Med univ Sch Pharmaceut Sci Beijing 100083 Peoples R China

A novel isonucleoside, 2,5-anhydro-4-(adenine-9-yl-)-L-iditol was synthesized from D-glucose through 9 steps.

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