石墨金属波齿复合垫片力学性能的有限元分析

以DN50和DN80两种规格的石墨金属波齿复合垫片为研究对象,采用有限元分析方法分析了其在2.5 MPa压力作用下的应力分布,从而了解其密封性.结果表明:DN50比DN80轴向应力大50%左右,极值均出现在齿尖处,最大应力远小于材料的弹性极限;DN50比DN80变形大15%左右,计算出的DN50最大压缩率为0.925%,DN80的最大压缩率为0.921%,压缩率都在许用范围之内,DN50的压缩性能强于DN80.     

接触式盲插连接器在T/R组件中的应用

由于T/R组件高集成、小型化的发展需求,T/R组件内的空间利用率需要进一步提升,其内部互连设计也越来越要求小型化。文中介绍了T/R组件中插合式及接触式盲插连接器的应用现状以及新型接触式盲插连接器在T/R组件轻小型化设计中的优势,重点阐述了接触式盲插连接器在组件应用中的关键问题。结合某T/R组件中接触式盲插连接器的应用实例,对该新型互连方案的性能进行了验证。结果表明,接触式盲插连接器满足T/R组件的性能要求,可在工程应用中推广使用。     

基于Pro-E和ANSYS的超低温球阀数值模拟分析

对使用环境温度为-196℃、工作压力6.4 MPa的超低温球阀进行结构设计及数据计算,利用Pro-E软件对DN=150 mm球阀3D建模,通过ANSYS分析软件对其进行Steady-State Thermal、Statics-Structural分析,结果得出填料函底部温度,最大等效应力、应变,均符合要求,球阀结构设计合理,为实际生产制造提供理论支持。     

一种新型快捷销的设计研究

介绍了一种新型快捷销的结构原理及特点,重点论述了钢丝锁圈的弹性变形分析及受力分析,推导出快捷的锁紧力理论计算公式,并根据钢丝锁圈在最大弹性变形下的应力,得出强度校核的准则,这为系列化设计快捷销提供了理论依据。     

柴油机进气门颈部特征分析与结构优化

气门的颈部是杆部与盘部的过渡区域,也是应力集中的区域,结构不合理导致应力集中程度严重,促进疲劳源的产生,是疲劳断裂的主要原因之一。本文从优化气门颈部结构入手,利用有限元软件Abaqus对气门进行了热-应力耦合分析,对颈部应力集中程度和颈部结构对应力分布的影响进行了探究。利用SolidWorks对进气门的过渡锥角β和过渡圆弧半径R在允许范围内进行调整,再把新的模型导入到Abaqus进行分析,以最大应力最小,应力分布均匀为目标进行优化,研究了β和R对最大应力及应力分布的影响。由此得出:β=21°,R=21mm为最优结构,即过渡锥角为21°,过渡圆角半径为21mm。     

基于CROE的外圆车刀有限元分析及优化设计

本文以某90°外圆粗车刀为例,为探究车刀刃磨角度与刀具所受应力的关系,根据其实际的尺寸和角度在CROE中进行实体建模,并在实验室中用三向测力系统测得实际车削时的车刀受力数值,利用软件中内嵌的有限元分析功能对该外圆车刀进行有限元分析,得出车刀的后角关于刀具所受应力及最大变形的影响关系,通过设置后角的变化范围与最大应力的灵敏度关系,确定最大应力为优化目标,进而找到合适的车刀后角,实现对刀具的优化设计。     

圆弧导轨姿态模拟转台有限元分析

介绍了一种新型的的圆弧导轨姿态模拟转台,利用ANSYS Workbench软件建立了其有限元模型,并提出了一种适用于有限元程序的轴承等效处理方法。对转台进行静力学分析,得出最大应力和变形,为结构改进和轻量化提供了相关数据。对转台进行了不同姿态下模态分析,得出了固有频率和振型,验证了转台工作上的可靠性。     

新型风机叶片维修平台的设计与分析

目的通过对新型风机叶片维修平台受力分析,研究在四种工况下的应力变形,确定设计结构是否满足要求,为下一步结构优化提供数据。方法通过Solidworks三维软件对新型风机叶片维修平台进行建模,使用ANSYS软件进行结构应力分析,得出平台支架所受应力云图,并与许用应力进行比较。结果分析数据得平台最大应力为89.222MPa,最大应力变形为12.77mm,满足安全系数不小于2的设计要求。结论风机叶片维修平台采用三吊点结构设计可以降低各钢丝绳的受力,降低平台重量,安全系数大大提高;通过ANSYS分析可知,最大变形均出现在吊点附件的焊接点处,在实际生产中应注意加固,防止出现断裂。     

基于SolidWorks和ANSYS直升机机翼有限元应力的对比分析

利用Solid Works Simulation软件对一种直升机机翼进行有限元应力分析,然后利用ANSYS Modal进行结构应力分析,初步得出Solid Works Simulation软件所得出的最大应力、最大位移、最大应变与ANSYS Modal的分析结果相比比较接近,因此,可以利用Solid Works Simulation软件进行一些简单的零部件进行应力分析,这样可以提高效率,减小工作量。     

基于ADINA的履带吊转盘轴承应力分布分析

通过ADINA有限元软件分析了履带吊转盘轴承在轴向载荷和倾覆力矩作用下的应力分布,结果表明,在其工况下最大应力值小于许用应力,验证了转盘轴承的悬臂环梁设计满足强度要求,并计算得出内外圈最大应力发生的部位及整套轴承最大应力发生的部位。     

基于拓扑优化和Kriging模型的前中盾结构轻量化设计

前中盾是盾构机的重要部件,其结构尺寸大、服役环境复杂,因此,在保证结构强度的前提下进行轻量化设计至关重要。针对某型号泥水平衡盾构机的前中盾,通过拓扑优化和尺寸优化实现轻量化。对现有前中盾结构进行拓扑优化设计,并根据拓扑优化结果进行二次设计;针对二次设计后的前中盾结构,构建尺寸优化模型,利用正交试验和方差分析筛选出对性能响应（前中盾质量、最大变形和最大应力）影响较大的结构参数作为设计变量,并通过最优拉丁超立方采样和有限元分析获得45组样本点,由此构建设计变量-性能响应隐式关系的Kriging代理模型;通过序列二次规划算法对前中盾尺寸优化模型进行求解获得最优的尺寸参数组合。验证结果表明,前中盾经过拓扑优化和尺寸优化后,质量减小约30 t,降幅达3.1%。     

Determination of mask opening size in creating a fluid hole on brittle material by double-side sand blasting

In creating a hole on brittle materials by double-side sand blasting, the rebounding sand particle flux during the process may result in underetching at the edge of the mask opening, and leads to a larger sized fluid hole than the desired one. Determination of the correct mask opening size was made mainly by trial and error in the past. In this paper, relationships between the mask opening size and desired size of a hole on both the front and the back sides of the substrate are derived. For the front side, by taking into account the underetching effect, an equation is derived based on the kinetic energy theory. For the back side, there is negligible rebounding sand particles, and the mask opening size is set to be equal to the desired size of the hole. Experiments were conducted to verify the derived relationships. It is found that the measured sizes of the eroded holes on both the front and the back sides of the wafer substrate are distributed normally. The desired hole sizes deviate slightly from the median of a normal distribution curve, and the maximum predicted errors are 2.4% and 3.0% for front side and the back side sand blasting, respectively. The very satisfactory result together with ANOVA and test of homogeneity of variance of the predicted errors for various hole size shows that the derived relationships is applicable for determination of the mask opening size in the sand blasting process.     

Determination of mask opening size in creating a fluid hole on brittle material by double-side sand blasting

In creating a hole on brittle materials by double-side sand blasting, the rebounding sand particle flux during the process may result in underetching at the edge of the mask opening, and leads to a larger sized fluid hole than the desired one. Determination of the correct mask opening size was made mainly by trial and error in the past. In this paper, relationships between the mask opening size and desired size of a hole on both the front and the back sides of the substrate are derived. For the front side, by taking into account the underetching effect, an equation is derived based on the kinetic energy theory. For the back side, there is negligible rebounding sand particles, and the mask opening size is set to be equal to the desired size of the hole. Experiments were conducted to verify the derived relationships. It is found that the measured sizes of the eroded holes on both the front and the back sides of the wafer substrate are distributed normally. The desired hole sizes deviate slightly from the median of a normal distribution curve, and the maximum predicted errors are 2.4% and 3.0% for front side and the back side sand blasting, respectively. The very satisfactory result together with ANOVA and test of homogeneity of variance of the predicted errors for various hole size shows that the derived relationships is applicable for determination of the mask opening size in the sand blasting process.     

Developing an optimal valve closing rule curve for real-time pressure control in pipes

Sudden valve closure in pipeline systems can cause high pressures that may lead to serious damages. Using an optimal valve closing rule can play an important role in managing extreme pressures in sudden valve closure. In this paper, an optimal closing rule curve is developed using a multi-objective optimization model and Bayesian networks (BNs) for controlling water pressure in valve closure instead of traditional step functions or single linear functions. The method of characteristics is used to simulate transient flow caused by valve closure. Non-dominated sorting genetic algorithms-II is also used to develop a Pareto front among three objectives related to maximum and minimum water pressures, and the amount of water passes through the valve during the valve-closing process. Simulation and optimization processes are usually time-consuming, thus results of the optimization model are used for training the BN. The trained BN is capable of determining optimal real-time closing rules without running costly simulation and optimization models. To demonstrate its efficiency, the proposed methodology is applied to a reservoir-pipe-valve system and the optimal closing rule curve is calculated for the valve. The results of the linear and BN-based valve closure rules show that the latter can significantly reduce the range of variations in water hammer pressures.     

基于AMESim的石材叉装车工作装置运动特性研究

石材叉装车作为一种新型工程机械,需要具有较大的举升力和较强的运输性能,同时必须能够适应复杂的作业环境。由于现代矿山开采中叉装车的工况与装载机截然不同,因此传统的将装载机铲斗直接换成货叉的设计方法,使叉装车的举升性能未能得到较大的提升,不能满足使用要求。为获得结构合理、举升性能良好的叉装车工作装置,建立了工作装置动力学模型并分析比较了动臂液压缸铰接点水平和竖直位置变化对工作装置运动特性的影响规律,选取了动臂油缸最优铰接点位置。仿真结果表明,在同样举升30 t荒料的工况下,工作装置动臂液压缸最大压力减小了5 MPa,实现了叉装车性能的优化,为叉装车工作装置参数优化提供了依据。     

Stress distribution on the boundary of an elliptical hole in a large plate during passage of a stress pulse of long duration (major axis tangent to the wave front)

A solution to the problem of the stress distribution on the boundary of an elliptical hole in a large plate during passage of a compressive stress pulse of relatively long duration is presented. The major axis of the ellipse is tangent to the wave front. The solution was experimentally obtained by using a low-modulus model material in a combined photoelasticity and moiré analysis. The long-duration stress pulse was applied by loading a small region of an edge of the plate with a falling weight.

The results of the investigation indicate that the falling-weight loading generates a biaxial state of stress at every point in the plate, which varies with time. The maximum dynamic compressive stresses on the hole boundary can be computed with a fair degree of accuracy by using: (1) the equations of Inglis for the static-stress distribution on the boundary of an elliptical hole in any two-dimensional uniform and axial system of combined stress, and (2) the biaxial stresses, at the same instant of time, at a point, symmetric with respect to the center of the hole (free field stresses). The maximum dynamic tensile stresses on the hole boundary were always smaller than the values computed using the same procedure.     

马铃薯中耕机机架的有限元分析及改进设计

建立了以板壳单元为基础单元的马铃薯中耕机机架有限元模型,利用大型有限元计算软件ANSYS对其进行了计算分析。结果显示,中耕机工作时机架的最大应力分布在前后梁上,前梁应力分布均匀,后梁应力波动范围较大。以计算结果为依据对中耕机机架进行了改进设计。计算分析结果对中耕机的设计和使用提供了理论支持。     

受剪切应力作用的表面裂纹应力强度因子研究

应用改进的三维虚拟裂纹闭合方法研究了受远端剪切应力作用的有限大体半椭圆表面裂纹复合型应力强度因子分布,并讨论了整个裂纹前缘复合型应力强度因子分布随裂纹形状变化和结构参数变化的规律。研究发现在自由表面附近,Ⅲ型应力强度因子分布受角点应力奇异性影响较大,在自由表面附近出现转折,但转折现象与裂纹形状参数有关,当裂纹形状比a/c≤0.6时,应力强度因子分布曲线光滑,表现为经典的角点奇异性。     

Stress intensity factors for elliptical arc through cracks in mechanical joints by virtual crack closure technique

The reliable stress intensity factor analysis is required for fracture mechanics design or safety evaluation of mechanical joints at which cracks often initiate and grow. It has been reported that cracks in mechanical joints usually nucleate as corner cracks at the faying surface of joints and grow as elliptical arc through cracks, In this paper, three dimensional finite element analyses are performed for elliptical arc through cracks in mechanical joints. Thereafter stress intensity factors along elliptical crack front including two surface points are determined by the virtual crack closure technique. Virtual crack closure technique is a method to calculate stress intensity factor using the finite element analysis and can be applied to non-orthogonal mesh. As a result, the effects of clearance on the stress intensity factor are investigated and crack shape are then predicted.     

Quarter elliptical crack growth using three dimensional finite element method and crack closure technique

Shape evolution of a quarter-elliptical crack emanating from a hole is studied. Three dimensional elastic-plastic finite element analysis of the fatigue crack closure was considered and the stress intensity factor was calculated based on the duplicated elastic model at each crack tip node. The crack front node was advanced proportional to the imposed effective stress intensity factor. Remeshing was applied at each step of the crack growth and solution mapping algorithm was considered. Crack growth retardation at free surfaces was successfully observed. A MATLAB-ABAQUS interference code was developed for the first time to perform crack growth on the basis of crack closure. Simulation results indicated that crack shape is sensitive to the remeshing strategy. Predictions based on the proposed models were in good agreement with Carlson’s experiments results.