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Numerical Simulation of Microstructure Formation and Forecast of Mechanical Properties for spheroidal Graphite Iron

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Journal of Materials Science & Technology 2003年第Z1期19卷 13-16页

作者： Weimin ZHAO Shuping HOU Haipeng LI Aiwen HU School of Materials Science and Engineering Hebei University of TechnologyTianjin 300132 China Tianjin Commercial University 300400 China School of Materials Science and Engineering Hebei University of TechnologyTianjin 300132 China School of Materials Science and Engineering Hebei University of TechnologyTianjin 300132 China

The numerical simulation can overcome the hardship of mathematical analysis and experimental research, explicate the mechanism of microstructure shaping, predict mechanical properties and operating life of castings and then optimize technology and control microstructure formation to obtain the qualified castings. The finite difference method (FDM) is applied to the simulation of temperature field based on all kinds of nucleation and growth models on all stages of solidification of spheroidal graphite cast iron. Visual C++ is used to program the numerical simulation software, QTstructure-1 to simulate the solidification process of spheroidal graphite cast iron and the formation of all phases in solidification process. Finally, the result of simulation is well agreed with the experimental result.

关键词： spheroidal graphite iron, Numerical simulation, Finite difference method, Temperature field

Primary porcine hepatocytes with portal vein serum cultured on microcarriers or in spheroidal aggregates

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World Journal of Gastroenterology 2000年第3期6卷 365-370页

作者： Gao Y Hu HZ Chen K Yang JZ First Mil Med Univ Zhujiang Hosp Dept Hepatobiliary Surg Guangzhou 510282 Guangdong Provi Peoples R China

AIM To develop a culture mode providingdurable biomaterials with high yields andactivities used in bioartificial *** Hepatocytes were isolated from awhole pig liver by Seglen’s method of orthotopicperfusion with *** culture onmicrocarriers,primary porcine hepatocyteswere inoculated at a concentration of 5×10~7/mLinto the static culture systems containing 2 g/LCytodex-3,then supplemented with 100 mL/Lfetal calf serum(FCS)or 100 mL/L porcineportal vein serum(PPVS)*** aggregate culture hepatocytes wereinoculated into 100 mL siliconized flasks at aconcentration of 5.0×10~6/*** In culture on microcarriershepatocytes tended to aggregate on Cytodex-3obviously after being *** multi-cellular aggregated spheroids could be found inthe two systems 24 h-48 h after hepatocyteswere *** morphological charact-eristics and synthetic functions were maintainedfor 5 wk in FCS culture system and 8 wk in PPVSculture *** spheroidal aggregate cultureabout 80%-90% isolated hepatocytes becameaggregated spheroids 24h after cultured insuspension and mean diameter of the spheroidswas 100μ*** relationship among thehepatocytes resembled that in the liver in *** functions of albumin and urea of the spheroids were twice those of hepatocytescultured on *** As high-yields and high-activitymodes of culture on microcarriers or inspheroidal aggregate culture with portal veinserum are promising to provide biomaterials forbioartificial liver(BAL)efficiently.

关键词： porcine hepatocytes microcarriers cell culture spheroidal aggregate culture portal vein serum

Some paradoxical observations about spheroidal graphite degeneracy

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China Foundry 2018年第6期15卷 457-463页

作者： Jacques Lacaze Jon Sertucha CIRIMAT Université de ToulouseBP 44362F-31030ToulouseFrance Investigaeiòn y Desarrollo de Procesos Metalúrgicos IK4-AzterlanAliendalde auzunea 6E-48200Durango(Bizkaia)Spain

Differential thermal analysis experiments have been performed on samples machined from Y2-blocks cast with different high-silicon spheroidal graphite irons. Depending on magnesium, silicon, cerium and antimony content, the as-cast microstructure showed various levels of chunky graphite in the central part of the blocks. In contrast, the microstructure of the materials after remelting and resolidification during differential thermal analysis consisted of lamellar or compacted graphite. The formation of chunky graphite in the as-cast microstructure is rationalized using an index or silicon equivalent that has been recently suggested. The differences in the microstructures after differential thermal analysis are discussed in terms of available free magnesium. Emphasis is finally put on the striking differences in characteristic size of the microstructures made of compacted graphite as compared to lamellar graphite and chunky graphite. This leads to tentative conclusions about growth of compacted and chunky graphite which would be worthy of further experimental investigations.

关键词： high-silicon spheroidal graphite iron graphite degeneracy compacted graphite chunky graphite

维普期刊数据库

Fractal　Model　of　the　spheroidal　Graphit

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Communications in Nonlinear Science and Numerical Simulation 1996年第1期 19-21页

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关键词： the spheroidal Model Fractal Graphit

Thermomechanical Testing of GGG 40 spheroidal Graphite Cast Iron Alloy

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Materials Sciences and Applications 2017年第3期8卷 273-280页

作者： Marwan Faisal Eman El-Shenawy Mohamed A. Taha Mechanical Design and Production Department Ain Shams University Cairo Egypt Department of Plastic Deformation Central Metallurgical R&D Institute Cairo Egypt

spheroidal graphite cast iron GGG 40 was thermo-mechanically tested using thermo-mechanical simulator Gleeble-3500. Three deformation steps were successively applied on test-specimen at temperatures namely;900°C, 850°C and 750°C within the austenitic zone, at the same strain rate of 0.1 s-1. No cracks were observed, up to 50% deformation, after successive deformation steps. Stress-strain relationship obtained is correlated with previous work on SGCI with a different carbon equivalent. It was found that by decreasing the deformation temperature;for the same CE, young’s modulus, yield strength and strain hardening exponent increase. Microstructure of the deformed zone, for a specimen quenched after the final deformation step, reveals fine elongated ferrite and pearlite, as well as elongated graphite. While microstructure of the non-deformed zone subjected to the same treatment, includes coarser ferrite and pearlite with graphite spheres embedded in the matrix.

关键词： Thermo-Mechanical Behavior spheroidal Graphite Cast Iron Gleeble-3500

A New Integral Equation for the spheroidal Equations in Case of m Equal to 1

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Advances in Pure Mathematics 2014年第6期4卷 229-233页

作者： Guihua Tian University of Posts and Telecommunications Beijing China

The spheroidal wave functions are investigated in the case $m = 1$. The integral equation is obtained for them. There are two kinds of eigenvalues in the differential and corresponding integral equations, and the relation between them is given explicitly. This is the great advantage of our integral equation, which will provide useful information through the study of the integral equation. Also an example is given for the special case, which shows another way to study the eigenvalue problem.

关键词： spheroidal Wave Functions Integral Equation Green Function

Impact Properties of Austempered spheroidal Graphite Cast Irons

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Materials Sciences and Applications 2017年第13期8卷 948-958页

作者： Tohru Nobuki Minoru Hatate Toshio Shiota Faculty of Engineering Kindai University Hiroshima Japan Kindai University Higashiosaka Japan

This study aims to clarify the influence of external notch on impact characteristics of high toughness ductile cast irons prepared by austempering heat treatment. We produced ductile cast irons samples with various matrix microstructure tested by Charpy impact within five kinds of external notches whose stress concentration factors (α), with values taken from 1.0 (Un-notched) to 4.8. In addition, to clarify the initiation process of impact characteristics, we observed the evolution of microstructure surface during bending tests with a slow loading speed for the un-notched and the notched impact samples. The results showed that the impact fracture energy decreases strongly in the range of α from 1 to 2.3 but decreases slightly for α larger than 3. Moreover, the impact value of samples with austempered microstructure is sensitive to the external notch shape. The impact transition temperature increases with increasing the stress concentration factor. The fracture energy is decreasing with the external notch from the impact test since the crack initiation energy is directly affected by this later. This work contributes to get a better understanding in the basic theories of external notch effect on impact characteristics of austempered spheroidal graphite cast irons (ADI).

关键词： spheroidal Graphite Cast Irons Austempering Impact Characteristics Charpy Impact Value High Toughness

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基于PSWF的正交载波调制方法

系统工程与电子技术 2014年第12期36卷 2533-2537页

作者：赵志勇周恒军毛忠阳刘锡国海军航空工程学院电子信息工程系山东烟台264001

为了提高通信系统的能效,提出了一种高效正交载波调制方法。在该方法中,基于能效优先原则,采用频谱混叠、时域正交的椭圆球面波函数(prolate spheroidal wave function,PSWF)设计基带脉冲波形,通过正交的同频载波实现载波调制。理论分... 详细信息

为了提高通信系统的能效,提出了一种高效正交载波调制方法。在该方法中,基于能效优先原则,采用频谱混叠、时域正交的椭圆球面波函数(prolate spheroidal wave function,PSWF)设计基带脉冲波形,通过正交的同频载波实现载波调制。理论分析及数值仿真了该调制方法的差错性能、频域能量集中度。仿真结果表明,带内能量聚集度可达99.8%,该特性可大幅减小对相邻用户的电磁干扰,并有利于提高信号的抗干扰性能。

关键词：无线通信载波椭圆球面波函数正交 prolate spheroidal wave function (PSWF)

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Three-Dimensional Free Vibration Analysis of a Viscothermoelastic Hollow Sphere

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Open Journal of Acoustics 2012年第1期2卷 12-24页

作者： Jagan Nath Sharma Dinesh Kumar Sharma Sukhjit Singh Dhaliwal Department of Mathematics National Institute of Technology Hamirpur (HP) India Department of Mathematics Sant Longowal Institute of Engineering and Technology Sangrur India

This paper concentrates on the study of the three-dimensional free vibrations in a homogenous isotropic, viscothermoelastic hollow sphere whose surfaces are subjected to stress free, thermally insulated or isothermal boundary conditions. The use of governing partial differential equations is solved into a coupled system of ordinary differential equations. The equation for toroidal motion gets decoupled from rest of the motion and remains unaffected due to thermal variations. Matrix Fr?benious method of extended power series is employed to obtain the solution. The secular equations for the existence of various types of possible modes of vibrations in the considered hollow sphere are derived in the com- pact form. The special cases of spheroidal and toroidal modes of vibrations of a hollow sphere have also been deduced and discussed. In order to explore the characteristics of vibrations the secular equations are further solved by using fixed point iteration numerical technique with the help of MATLAB software tools. The computer simulated results have been presented graphically for copper material.

关键词： Toroidal spheroidal Isotropic Viscothermoelastic Vibrations Spherical Structures