THE APPLICATION OF COMPATIBLE STRESS ITERATIVE METHOD IN DYNAMIC FINITE ELEMENT ANALYSIS OF HIGH VELOCITY IMPACT

There is a common difficulty in elastic-plastic impact codes such as EPIC[2,3] NONSAP[4], etc.. Most of these codes use the simple linear functions usually taken from static problem to represent the displacement components. In such finite element formulation, the stress components are constant in each element and they are discontinuous in any two neighboring elements. Therefore, the bases of using the virtual work principle in such elements are unreliable. In this paper, we introduce a new method, namely, the compatible stress iterative method, to eliminate the above-said difficulty. The calculated examples show that the calculation using the new method in dynamic finite element analysis of high velocity impact is valid and stable, and the element stiffness can be somewhat reduced.

The Effect of Hydrostatic Pressure and Seismic Load on ITER Lower Cryopump Ports

The lower cryopump ports in International Thermonuclear Experimental Reactor （ITER） as a part of the vacuum vessel play many important roles. As the boundary of vacuum it must be ensured against structural damage. In this study a finite element model of the lower cryopump ports was developed by ANSYS code with a purpose to evaluate the stress and displacement level on it. Two kinds of loads were taken into account. One was the hydrostatic pressure including the normal operation pressure and test pressure. The other was the seismic load. The analysis results show that the peak stress does not exceed the allowable stress for either the hydrostatic pressure or the seismic load according to the ITER structural design criterion, which indicates that the structure has a good safety margin.

Structural Analysis of ITER Lower In-Vessel-Viewing Port

A finite element model of the International Thermonuclear Experimental Reactor （ITER） in-vessel viewing port was developed by the ANSYS code in order to evaluate the stress level of this structure. The thermal, elastic and modal analyses were made in succession based on the loads designated by the ITER International team. The designed loads include electromagnetic loads, seismic loads, pressure, temperature and gravity. The preliminary results of the finite element analysis （FEA） show that the stress intensity exceeded the allowable stress and the maximum stress was concentrated in the geometric discontinuous region of the shroud stub extension （SSE）. Therefore, the SSE has been modified recently. For the modified structure, we found that the stresses do not exceed the allowable value for all load combinations. In addition the modal analysis results show that the natural frequencies of the IVV port structure are located in the typical diapason of seismic excitation.

Structural Analysis of the ITER VV Lower Port Region

A structural analysis of the International Thermonuclear Experimental Reactor （ITER） vacuum vessel＇s lower port region was presented by means of a finite element analysis method. The purpose is to evaluate the stress and displacement level on this structure under various combinations of five designed loads, including the gravity of the vacuum vessel, seismic loads, electromagnetic loads, and possible pressure loads to ensure structural safety. The cyclic symmetry finite element model of this structure was developed by using ANSYS code. The re- sults showed that the maximum stress does not exceed the allowable value for any of the load combinations according to ASME code and the nine vacuum vessel （VV） supports have the ability to sustain the entire VV and in vessel-components and withstand load combinations under both normal as well as off-normal operation conditions. Stress mainly concentrates on the connecting region of the VV support and lower port stub extension.

Structural Design and Force Analysis for Equatorial Diagnostic Port Plug of ITER

The structural design of equatorial diagnostic port plug for international thermonuclear experimental reactor （ITER） was discussed in this paper. The induced electromagnetic （EM） loads of port plug and blanket shielding module （BSM） were presented. The finite element analysis （FEA） and numerical calculation of the system were performed under the maximum loads. According to the American Society of Mechanical Engineers （ASME） criteria, the EM stress is far below the admissible failure boundary, which indicates that the system can resist the cooperative action of EM loads and device deadweight. The analysis could provide technical data and references for further analysis and optimized design of the system.

Baking Analysis of the ITER Equatorial Diagnostic Port Plug

In this study both electric heating and fluid heating were proposed to bakeout the port plug structure being inserted in the middle of the international thermonuclear experimental reactor （ITER） vacuum vessel. The coupled thermal and structural analyses were carried out. The results, such as the distributions of the temperature field, thermal stress and thermal deformation of the port plug, were obtained. Based on the American Society of Mechanical Engineers （ASME） criteria, the reliability and feasibility of the heating technique were verified. The results provide detailed information on the selection of a preferable method for future engineering experiments.

Preliminary Thermal Mechanical Analysis of the Equatorial Thermal Shield for ITER

Thermal analysis of the equatorial thermal shield for ITER is conducted in order to confirm that the cooling tube design was reasonable under both the plasma operational and the baking operational conditions. The structural performance was analyzed by means of the finite element software ANSYS. A comparison of the results with design requirements shows that the results of the simulation are within allowable design requirements, which indicates the feasibility and reliability of the equatorial thermal shield structure.

Preliminary Design and Analysis of ITER In-Wall Shielding

ITER in-wall shielding （IIS） is situated between the doubled shells of the ITER Vacuum Vessel （IVV）. Its main functions are applied in shielding neutron, gamma-ray and toroidal field ripple reduction. The structure of IIS has been modelled according to the IVV design criteria which has been updated by the ITER team （IT）. Static analysis and thermal expansion analysis were performed for the structure. Thermal-hydraulic analysis verified the heat removal capability and resulting temperature, pressure, and velocity changes in the coolant flow. Consequently, our design work is possibly suitable as a reference for IT＇s updated or final design in its next step.

Numerical Analysis on Neutron Shielding Structure of ITER Vacuum Vessel

The neutron shielding component of ITER （International Thermonuclear Experimental Reactor） vacuum vessel is a kind of structure resembling a wall in appearance. A FE （finite element） model is set up by using ANSYS code in terms of its structural features. Static analysis, thermal expansion analysis and dynamic analysis are performed. The static results show that the stress and displacement distribution are allowable, but the high stress appears in the junction between the upper and lower parts. The modal analysis indicates that the biggest deformation exists in the port area. Through modal superposition, the single-point response has been found with the lower rank frequency of the acceleration seismic response spectrum. But the deformation and the stress values are within the permissible limit. The analysis results would benefit the work in the next step and provide some reference for the implementation of the engineering plan in the future.

基于ANSYS的ITER重力支撑结构有限元模态分析

为了分析ITER装置重力支撑结构的动态特性针对ITER重力支撑系统具有周期对称性的结构特点,应用有限元分析软件ANSYS建立了ITER重力支撑结构环向20度三维有限元分析模型,同时采用了精度比较高,而且规模又可以接受的单元网格划分方法,得到了网格划分图。在法兰之间的界面上定义接触单元。采用Block Lanc-zos方法对ITER重力支撑系统进行有限元模态分析,求出了ITER重力支撑系统的前10阶固有频率和振型。模态分析的结果对ITER装置的设计与改进具有一定的指导意义。

静载荷与地震载荷作用下ITER重力支撑系统有限元静力分析

针对ITER重力支撑系统的特点,提出了ITER重力支撑系统的有限元静力分析方法。应用AN-SYS软件,建立了ITER重力支撑系统三维实体模型。采用精度比较高,且计算规模又可以接受的单元网格划分方法,进行网格划分。在Volume之间的界面上定义接触单元。得到了支撑系统有限元模型。对同时受静载荷与地震载荷作用的ITER重力支撑系统进行了有限元静力分析。获得了支撑系统各零件的应力分布及最大应力,分析了这些零件的强度。结果表明:TF腿、韧性板、环形支撑和支撑圆柱的最大应力分别出现在TF腿与等效环向壳连接处、韧性板与其下法兰焊接的拐角处、环形支撑上端面与其内部加强筋的交接处、支撑圆柱的上端面,这些最大应力都小于其相应的许用应力,按照ASME压力容器评定标准,支撑系统各零件均满足强度要求。静力分析的结果为ITER重力支撑系统的设计或改进提供了可靠的理论依据。

基于ANSYS的ITER重力支撑系统特征值屈曲分析

针对ITER重力支撑系统的结构特点,应用有限元软件ANSYS,建立了ITER重力支撑系统的有限元模型。采用Block Lanczos方法对ITER重力支撑系统在静载荷与地震载荷同时作用下的稳定性进行了特征值屈曲分析,求出了ITER重力支撑系统的前3阶屈曲特征值和特征值屈曲模态。结果表明ITER重力支撑系统不会发生屈曲,韧性板是整个支撑系统中最易发生屈曲的零件。屈曲分析的结果对ITER装置的设计与改进具有一定的指导意义。

静载荷作用下的ITER重力支撑系统有限元静力分析

针对ITER重力支撑系统的特点,提出了ITER重力支撑系统的有限元静力分析方法。应用ANSYS软件,建立了ITER重力支撑系统三维实体模型。采用精度比较高,且计算规模又可以接受的单元网格划分方法,进行网格划分。在Volume之间的界面上定义接触单元。得到了支撑系统有限元模型。对受静负载作用的ITER重力支撑系统进行了有限元静力分析。获得了支撑系统各零件的应力分布及最大应力,分析了这些零件的强度。静力分析的结果为ITER重力支撑系统的设计或改进提供了可靠的理论依据。

ITER真空室中子屏蔽组件的热—静力学有限元分析

根据ITER(InternationalThermonuclearExperimentalReactor)真空室中子屏蔽组件的设计概念和结构特点,应用有限元分析软件ANSYS对结构组件进行静力学分析和热—结构耦合分析。有限元计算结果表明,等离子体中心破灭事件(centraldisruption27msec——CD27ms)下的巨大瞬间电磁载荷对其产生的应力与变形远小于真空室温度环境造成的应力影响,尤其在接触应力计算上表现最为明显。因此,根据强度分析的结果重新对中子屏蔽组件的结构方案进行修改,分析结果表明改进后的结构更加合理。

ITER Side校正场线圈端部大圆弧模压成形及回弹分析

利用大型有限元分析软件ANSYS分析了国际热核实验反应堆(ITER)Side校正场线圈(CC)端部三维大圆弧模压成形及释放模具后导体的回弹效应,研究了不同半径成形时导体内外表面的应力、应变的分布及释放模具后导体的回弹规律。设计了1套模压成形模具,通过修模的方式在该套成形模具上进行了不同半径成形试验,测得了不同成形半径时模压成形后的回弹量值。试验结果验证了所建立的有限元分析模型的正确性。有限元分析和试验结果表明:ITERSideCC端部三维大圆弧可通过模压成形达到所需的大半径要求,为ITER Side CC端部三维大圆弧成形提供了一种可行方案。

ITER真空室中子屏蔽组件的结构动力学有限元分析

为考察ITER真空室中子屏蔽结构组件对选址地法国Cadarache地震加速度频谱的单点响应情况,根据ITER真空室中子屏蔽组件的设计概念和结构特点,建立了组件结构的有限元分析模型。应用有限元分析软件ANSYS对组件进行了结构模态分析,并基于其结果进行了模态叠加。分析发现,组件结构的低阶振型与高阶振型有差异,且结构与低阶频率发生响应,但引起的位移与应力在允许的范围之内。结果表明,装配体结构更能适应结构抗震性的设计要求。仿真计算的结果为组件结构的优化设计和下一步的工程实现提供了可靠的依据。

ITER气体加料阀门箱磁屏蔽效能的有限元分析

通过Ansoft Maxwell有限元分析软件,用封闭圆桶模型对ITER送气系统阀门箱的磁屏蔽进行了计算。计算,获得了屏蔽层厚度、上端开孔及侧面狭缝对磁屏蔽的影响方式及规律,给出了一种具有合理参数的可能设计。

ITER部件转运车3自由度并联平台设计与有限元分析

针对ITER部件转运车的特殊需求,设计和分析了用于车厢姿态调整的3自由度并联平台。该平台由运动平台、固定平台、球形关节、虎克铰、连杆等组成,具有刚度大,结构稳定、承载能力强、误差小、位姿精度高等优点。论文详细论述了3自由度并联平台的机构设计、自由度计算和关键部件有限元分析。分析结果表明,该3自由度并联平台满足ITER部件转运车车厢对接需求。

管道连接装配型ITER增强热负荷第一壁的初步设计

中方承制的ITER第一壁采用大量焊接连接结构,冷却通道焊缝多,冷却水泄漏风险大,且存在焊接装配难以更换缺损部件等关键问题。在全尺寸原型件工艺认证阶段,需基于半原型研发基础,对其进行更改设计。设计重点在于手指部件采用前部燕尾槽和中部螺钉连接的固定结构,手指对采用前部管管连接、中部管连接件与中心梁焊接形成内部冷却通道回路。对初步设计模型进行了结构热及弹塑性分析。分析结果显示其温度、位移、强度均在可接受范围内,可以采用这种结构继续进行整个增强热负荷第一壁的详细设计。

Electromagnetic and Stress Analyses of the ITER Equatorial Thermal Shield

The ITER equatorial thermal shield is located inside the cryostat and outside the vacuum vessel, and its purpose is to provide a thermal shield from hot components to the superconducting magnets. Electromagnetic analysis of the equatorial thermal shield was performed using the ANSYS code, because electromagnetic load was one of the main loads. The 40 sector finite element model was established including the vacuum vessel, equatorial thermal shield, and superconducting magnets. The main purpose of this analysis was to investigate the eddy current and electromagnetic force in the equatorial thermal shield during plasma disruption. Stress analysis was implemented under the electromagnetic load. The results show that the equatorial thermal shield can accommodate the calculated electromagnetic loads.