高密度聚乙烯塑料压力管道热板焊接头应力分布有限元分析

基于热粘弹性积分型本构关系,考虑材料性能依赖于温度变化及相变潜热的影响,利用AN SYS热-力耦合及载荷步功能模拟结晶型高密度聚乙烯(HDPE)塑料压力管道热板焊接过程,并对焊接接头的应力分布进行有限元分析,得到了环向、轴向以及径向瞬态应力分布的基本规律。采用盲孔法和锯切法测量焊后残余应力,实测结果与数值分析基本符合

纳米级微动平台的设计与实验研究

纳米级微动平台（以下简称微动平台）是微机电系统的重要组成部分，其技术涵盖多个领域的先进技术，其应用范围和领域也越来越广泛。微动平台是实现纳米尺度观测与操作的关键部件。纳米级微动平台的机械性能如力学和运动学特性，直接影响纳米作业系统的应用效果。本文以纳米级微动平台的设计开发为目标，采用CAD和CAE技术，以机械设计理论、有限元方法、显微视觉检测技术等为研究手段，较深入地研究了一种基于PZT驱动的非耦合2维纳米级微动平台的结构设计、结构力学特性以及运动精度等关键技术问题。为此类纳米级微动平台的设计、加工、组装与测试提供了基本理论依据和实现途径。主要工作如下： 1 针对非耦合纳米级微动平台的应用背景和技术要求，应用CAD和CAE技术完成了基于弹性筋板导向和压电陶瓷驱动的新型纳米级微动平台的结构设计。 2 研究采用有限元分析软件ANSYS和COSMOSWorks对所设计的纳米级微动平台进行了结构力学仿真分析，理论上证明了平台结构设计的合理性及可行性。 3 针对驱动器装配误差、导向筋板的加工误差对平台运动精度的影响问题，研究采用有限元仿真方法对平台的运动精度进行了定量的计算分析。 4 研究采用显微视觉技术和序列图像处理技术，完成了纳米级微动平台动态运动性能的检测，给出了平台的动态输入输出特性以及运动过程中平台边框的变形情况。

深海ROV铠缆绞车及主动升沉补偿装置设计研究

深海ROV是一种可以在深海进行观察和作业的水下机器人。其研究和开发，对海洋环境的调查，海洋资源的钻探以及军事应用方面都具有重要的意义。深海ROV收放在深海区域收放作业时，作业环境复杂，作业深度大，如果铠缆绞车采用单卷筒结构会存在驱动装置功率过大，卷筒的转动惯量过大，载体出水的瞬间铠缆外层压入内层等问题。另外，海面的海况条件比较恶劣，支持母船受风、浪、涌、流影响而产生较大幅度的升沉运动对有缆水下机器人正常作业和收放操作有较大的影响，ROV中继器的升沉运动甚至可以造成系缆的损害而使机器人本体丢失。为了提高ROV在恶劣海况下的安全性能，保护中继器与载体之间的系缆不受损坏，需要配备升沉补偿装置。所以深海ROV铠缆绞车及其升沉补偿装置的研究与设计，对实现深海ROV的收放及保障系统安全及各项关键技术的进一步研究具有重要的意义。 本文在863计划“基于母船升沉预测的深海装备主动升沉补偿测控单元的研究开发”资助下，结合7000m ROV收放操作和升沉补偿的要求，开展深海ROV铠缆绞车及其主动升沉补偿装置的设计研究。针对深海ROV收放作业时，ROV铠缆绞车需要具有ROV快速收放能力及升沉补偿能力，设计适合于深海ROV收放作业的铠缆绞车。本文重点研究适合于深海ROV铠缆绞车的双绞车结构形式；研究双绞车的受力分析，驱动装置的选型；设计深海ROV铠缆绞车的储存绞车和牵引绞车；设计用于深海ROV铠缆绞车的主动升沉补偿装置。本文的主要内容如下： （1）研究深海ROV铠缆绞车的结构形式。分析了如果深海ROV铠缆绞车采用单卷筒结构存在转动惯量过大，驱动装置功率过大，在出水的瞬间铠缆外层缆压入内层等问题，提出了双绞车结构。分析了双绞车的组成，布置及其作用原理，各部件的组成及作用原理。 （2）研究深海ROV铠缆绞车的受力及所需要的功率。利用微元分析，求解出深海ROV牵引绞车每个绞盘提供的摩擦力，从而求出各绞车驱动装置需提供的最大驱动力矩和功率，作为驱动装置的选型依据。 （3）设计深海ROV铠缆绞车。通过类比以前的绞车系统，理论计算，初步选定储存绞车及牵引绞车各个部件参数。采用SolidWorks进行三维建模后，采用ANSYS进行有限元分析，通过计算机仿真技术克服理论计算的缺陷，对各个部件进行强度校核及结构优化。 （4）设计主动升沉补偿装置。根据升沉补偿装置的技术指标，通过理论计算确定升沉补偿装置各个部分结构形式和参数，并进行了三维建模、通过有限元分析对各个部件进行强度校核，最后分析了超长缆释放时自身的张力对绞车定位的影响。 通过以上研究，设计出符合7000m ROV收放作业要求的深海ROV铠缆绞车及其升沉补偿装置，为7000m ROV的实现和收放技术的研究奠定了良好的基础。

不同基板预热温度对激光金属沉积成形过程温度场的影响

为降低成形过程的热应力,抑制成形过程裂缝的产生,减小成形过程试样和基板的翘曲变形,激光金属沉积成形往往需要进行基板预热,因此研究不同基板预热温度对激光金属沉积成形过程温度场的影响具有非常重要的意义.根据有限元分析中的"单元生死"技术,利用APDL编程建立了基板预热对激光金属沉积成形过程温度场影响的三维多道多层数值模拟模型,详细分析了基板未预热和分别预热到200,300,400,500,600℃时对沉积成形过程温度场和温度梯度的影响.通过中国科学院沈阳自动化研究所自行研制的激光金属沉积成形系统和基板预热系统,在与模拟过程相同的参数下,利用镍基合金粉末在基板未预热和分别预热到300,400,500,560℃时进行了成形试验,试验结果跟数值模拟结果吻合较好.

基板预热对激光金属沉积成形过程热应力的影响

为降低沉积过程的热应力,抑制成形过程中裂缝的产生,研究基板预热对激光金属沉积成形(Laser metal deposition shaping,LMDS)过程热应力的影响具有非常重要的意义。根据有限元分析中的"单元生死"思想,利用APDL(ANSYS parametric design language)编程建立多道多层激光金属沉积成形过程的数值模拟模型,深入探讨基板未预热和预热到400℃时对成形过程热应力的影响。计算结果表明,基板预热到400℃可以显著降低成形过程中试样的热应力变化波动性,试样的Von Mises热应力最大值可降低10%左右,其中x方向热应力最大值可降低8.5%左右,z方向热应力最大值可降低8.1%左右。在与模拟过程相同的条件下,利用自行研制的激光金属沉积成形设备进行了成形试验,成形试验的结果与模拟结果基本吻合。

上下料直角坐标机器人机构研究

直角坐标机器人作为一种常用的工业机器人广泛应用于现代工业生产线中，其运动学和动力学特性关系整个生产线性能发挥。虚拟样机技术在复杂机械系统仿真中的成功应用不仅可以提高仿真精度，而且还可以缩短产品设计周期，对于工程实际具有重要的应用价值。通过虚拟样机技术，工程师可以通过机械系统运动仿真，在产品设计阶段发现产品设计中的潜在问题，并快速进行修改，减少了对于物理样机的依赖，这样不仅可以节省成本，缩短产品开发周期，而且还可以提高产品性能，增强产品竞争力。本文结合中科院沈阳自动化研究所现代装备研究设计中心的大型项目“激光拼焊生产线”，对生产线中从国外引进的上下料机器人进行研究分析，设计出一台可以满足“激光拼焊生产线”工业要求的上下料直角坐标机器人，来实现高性能上下料机器人的国产化。以设计出的上下料直角坐标机器人为研究对象，采用虚拟样机技术，以有限元法和多体系统动力学为理论基础，进行上下料直角坐标机器人机构的运动学和动力学分析仿真研究。其中研究了三维实体建模方法以及D-H方法，探讨了利用CAD/CAE软件SOLIDWORKS, ADAMS和ANSYS进行协同虚拟样机的建模、装配、数据共享、有限元静力分析以及刚柔耦合多体动力学仿真技术，研究成果对实际工程的运用具有一定的指导作用。本文主要的研究工作及其成果如下： 1根据工业生产线要求，确定高性能上下料直角坐标机器人总体机构设计方案，设计各个直线运动单元。 2利用CAD软件SOLIDWORKS对上下料直角坐标机器人进行3维实体建模，然后利用D-H方法，建立其运动学方程，最后利用MATLAB工具对运动学进行仿真。 3以有限元方法为基础，利用有限元分析软件ANSYS对上下料直角坐标机器人核心部件Y轴横梁静力分析，最后进行横梁结构优化。 4以多体系统动力学为基础，利用有限元软件ANSYS生成刚柔耦合多体动力学仿真所需的模态中性文件（MNF），同时结合运用ANSYS和ADAMS建立了上下料直角坐标机器人刚柔性耦合多体模型，并进行了动力学分析。

岩石类材料静态、动态拉伸弹性模量测试方法研究——以巴西圆盘试验和霍普金森压杆、效应为手段

As we all know, rock-like materials will absolutely show very different mechanical properties under the compressive stress and tensile stress respectively. Similarly, under the dynamic compressive stress or dynamic tensile stress, the characteristics of the dynamics showed by the rock-like materials also have great differences from the mechanical behavior under static force. Studying their similarities and differences in rock mechanics theory and practical engineering will be of great significance. Generally, there are compression modulus of elasticity and tensile modulus of elasticity corresponding to compressive stress state and the tensile stress state in the rock. Both the two kinds of elastic modulus play an extremely important role in calculation of engineering mechanics. Their reliability directly affects the accuracy and reliability of the calculation results of internal stress field and displacement field of engineering rock mass. At present, it is easy to obtain the compression modulus of elasticity in laboratory; but it is very difficult to determine the tensile modulus of elasticity with direct tensile test due to that direct tensile test is difficult to perform in laboratory in general. In order to solve this problem, this thesis invents and develops several indirect test methods to determine the static or dynamic tensile modulus of elasticity of rock-type materials with high reliability and good interoperability. For the static tensile modulus of elasticity, the analytical stress field solution has been given out for the Brazilian disc under the radial and linear concentration load with Airy stress function method. At the same time, the stress field has been modeled for the Brazilian disc test by using the finite element software of ANSYS and ADINA. The analytical stress field solution is verified to be right by comparatively researching the analytical stress field solution and the numerical stress field solution. Based on the analytical stress field solution, this thesis proposes that a strain gauge is pasted at the Brazilian disc center along the direction perpendicular to the applied force to indirectly determine the static tensile modulus of elasticity, and related measurement theory also has been developed. The method proposed here has good feasibility and high accuracy verified by the experimental results. For the dynamic tensile modulus of elasticity, two measuring methods and theories are invented here. The first one is that the Split Hopkinson Pressure Bar is used to attract the Brazilian disc to generate the dynamic load, make the dynamic tensile stress is formed at the Brazilian disc center; and also a strain gauge is pasted at the Brazilian disc center to record the deformation. The second is that, in the Hopkinson effect phenomenon, the reflection tensile stress wave is formed when the shock wave propagates to the free end of cylindrical rock bar and reflect, which can make the rock bar is under dynamic tensile stress state; and some strain gauges are pasted at the appropriate place on the rock bar to record the strain coursed by the tensile or compressive stress wave. At last, the dynamic tensile modulus of elasticity can be determined by the recorded strain and the dynamic tensile stress which can be determined by related theories developed in this thesis.

Computer modeling of a micro-manufactured one-turn inductor

The results of a finite element computer modelling analysis of a micro-manufactured one-turn magnetic inductor using the software package ANSYS 10.0 are presented. The inductor is designed for a DC-DC converter used in microelectronic devices. It consists of a copper conductor with a rectangular cross-section plated with an insulation layer and a layer of magnetic core. The analysis has focused on the effects of the frequency and the air gaps on the on the inductance values and the Joule losses in the core and conductor. It has been found that an inductor with small multiple air gaps has lower losses than an inductor with a single larger gap

Wire bond reliability for power electronic modules - effect of bonding temperature

In this paper, thermal cycling reliability along with ANSYS analysis of the residual stress generated in heavy-gauge Al bond wires at different bonding temperatures is reported. 99.999% pure Al wires of 375 mum in diameter, were ultrasonically bonded to silicon dies coated with a 5mum thick Al metallisation at 25degC (room temperature), 100degC and 200degC, respectively (with the same bonding parameters). The wire bonded samples were then subjected to thermal cycling in air from -60degC to +150degC. The degradation rate of the wire bonds was assessed by means of bond shear test and via microstructural characterisation. Prior to thermal cycling, the shear strength of all of the wire bonds was approximately equal to the shear strength of pure aluminum and independent of bonding temperature. During thermal cycling, however, the shear strength of room temperature bonded samples was observed to decrease more rapidly (as compared to bonds formed at 100degC and 200degC) as a result of a high crack propagation rate across the bonding area. In addition, modification of the grain structure at the bonding interface was also observed with bonding temperature, leading to changes in the mechanical properties of the wire. The heat and pressure induced by the high temperature bonding is believed to promote grain recovery and recrystallisation, softening the wires through removal of the dislocations and plastic strain energy. Coarse grains formed at the bonding interface after bonding at elevated temperatures may also contribute to greater resistance for crack propagation, thus lowering the wire bond degradation rate

Computational Investigation of Inlet Distortion at High Angles of Attack

Lip separation is one of the primary sources of inlet distortion, which can result in a loss in fan stability. High angles of incidence are one of several critical causes of lip separation. There have been many studies into inlet performance at high incidence, including the resulting distortion levels when lip separation occurs. However, the vast majority of these investigations have been carried out experimentally, with little in the way of computational results for inlet performance at high incidence. The flow topology within an inlet when lip separation has occurred is also not well understood. This work aims to demonstrate a suitable model for the prediction of inlet flows at high incidence using ANSYS CFX, looking at both the performance of the inlet and the separated flow topology within the inlet. The attenuating effect of the fan is also investigated, with particular emphasis on the flow redistribution ahead of the fan. The results show that the model used is suitable for predicting inlet performance in adverse operating conditions, showing good agreement with experimental results. In addition, the attenuation of the distortion by the fan is also captured by the numerical model.

Thermal fatigue analysis of solar panel structure for micro-satellite applications

Thermal fatigue analysis based on 2D finite difference and 3D finite element methods is carried out to study the performance of solar panel structure during micro-satellite life time. Solar panel primary structure consists of honeycomb structure and composite laminates. The 2D finite difference (I-DEAS) model yields predictions of the temperature profile during one orbit. Then, 3D finite element analysis (ANSYS) is applied to predict thermal fatigue damage of solar panel structure. Meshing the whole structure with 2D multi-layer shell elements with sandwich option is not efficient, as it misses thermal response of the honeycomb structure. So we applied a mixed approach between 3D solid and 2D shell elements to model the solar panel structure without the sandwich option.

Thermal fatigue analysis of small-satellite structure

The small-satellite thermal subsystem main function is to control temperature ranges on equipments, and payload for the orbit specified. Structure subsystem has to ensure the satellite structure integrity. Structure integrity should meet two constraints; first constraint is accepted fatigue damage due to cyclic temperature, and second one is tolerable mounting accuracy at payload and Attitude Determination and Control Subsystem (ADCS) equipments’ seats. First, thermal analysis is executed by applying finitedifference method (IDEAS) and temperature profile for satellite components case is evaluated. Then, thermal fatigue analysis is performed applying finite-element analysis (ANSYS) to calculate the resultant damage due to on-orbit cyclic stresses, and structure deformations at the payload and ADCS equipments seats.

Wave Interaction with an Oscillating Wave Surge Converter, Part 1: Viscous Effects

Bottom hinged oscillating wave surge converters are known to be an efficient method of extracting power from ocean waves. The present work deals with experimental and numerical studies of wave interactions with an oscillating wave surge converter. It focuses on two aspects: (1) viscous effects on device performance under normal operating conditions; and (2) effects of slamming on device survivability under extreme conditions. Part I deals with the viscous effects while the extreme sea conditions will be presented in Part II. The numerical simulations are performed using the commercial CFD package ANSYS FLUENT. The comparison between numerical results and experimental measurements shows excellent agreement in terms of capturing local features of the flow as well as the dynamics of the device. A series of simulations is conducted with various wave conditions, flap configurations and model scales to investigate the viscous and scaling effects on the device. It is found that the diffraction/radiation effects dominate the device motion and that the viscous effects are negligible for wide flaps.

Stress and Strain Distributions During Compressive Deformation of Titanium Alloy Affected by Microstructure

In the research of the microstructural influence on dynamic compression, an assumption that the α and the β phases in titanium alloys were linearly strengthened was proposed, and a two-dimensional model using ANSYS (ANSYS, Inc., Canonsburg, PA) focusing on the role of microgeometrical structure was developed. By comparing the stress and strain distributions of different microstructures, the roles of cracks and phase boundaries in titanium compression were studied.

Étude numérique des phénomènes transitoires dans une turbine axiale de type hélice durant l’emballement

Ce mémoire présente l’étude numérique d’un emballement de turbine hydraulique axiale à échelle modèle. Cet état transitoire est simulé du point de meilleur rendement jusqu’à l’atteinte de 95% de la vitesse d’emballement. Pour ce faire, une méthodologie numérique est développée à l’aide du logiciel commercial ANSYS CFX en utilisant une approche "Unsteady Reynolds Averaged Navier-Stokes" avec modèle de turbulence k-ε. Cette méthodologie numérique a été validée grâce à des mesures expérimentales de pression acquises en situation d’emballement sur les aubes d’une roue de turbine axiale étudiée au Laboratoire de Machines Hydrauliques de l’Université Laval. La validation des simulations numériques a été réalisée grâce à des comparaisons dans les domaines temporel et fréquentiel entre les pressions mesurées expérimentalement et calculées numériquement. Les analyses fréquentielles en transitoire ont été effectuées à l’aide de transformées en ondelettes afin de représenter l’évolution temporelle du spectre de fréquence. Des analyses qualitatives de phénomènes hydrauliques prenant place dans la turbine sont aussi présentées. Les analyses effectuées ont permis de confirmer le développement d’un tourbillon en précession par rapport à la roue dans l’aspirateur provocant les fluctuations de pression dominantes à des fréquences subsynchrones. La comparaison entre les données expérimentales et numériques a permis de valider une stratégie de simulation transitoire et d’en définir les limites en vue de prochaines simulations d’emballement. Des tests supplémentaires sont suggérés pour améliorer la précision ou le niveau de confiance de la méthode.