准双曲面齿轮准静态接触分析和试验研究

建立了精确的准双曲面齿轮的轮齿面和过渡曲面数学模型;选择用平均接触椭圆长半轴、接触线方向角和传动误差曲线交点来评价齿面接触斑点和传动误差;以一个准双曲面齿轮副为计算实例,建立了适合准静态齿面接触分析的准双曲面齿轮传动系统有限元分析模型;通过准静态加载齿面接触特性分析,得到齿根弯曲应力、接触应力和传动误差的变化规律,分析载荷的影响情况,并比较了有限元结果与经验公式计算结果。开发了准双曲面齿轮试验台,进行齿面接触斑点和齿根弯曲应力检测,试验结果与仿真结果的一致性较好。     

基于MOPSO的斜齿轮传动几何参数多目标优化设计

斜齿轮作为机械设备传动装置中的主要零/部件,应用较为广泛。为了避免在使用过程中斜齿轮部分轮齿因强度低而发生提前失效的情况,综合考虑变位系数、齿数和模数等对齿轮强度的影响,建立以斜齿轮几何参数为设计变量,以斜齿轮副满足强度、重合度和齿顶厚度要求等为约束条件,以斜齿轮副齿根最大弯曲应力的差值最小、齿面接触应力最小为优化目标的数学模型,利用多目标粒子群优化(Multi-Objective Particle Swarm Optimization, MOPSO)算法编写相应的Matlab程序,对所建立的数学模型进行优化求解,并通过MASTA软件对优化前、后齿轮副进行仿真分析。结果表明,在满足设计条件的情况下,斜齿轮副弯曲强度差值与齿面承载能力均有所改善。该研究为斜齿轮宏观几何参数的优化设计提供了参考。     

考虑安装误差的弧线齿面齿轮承载接触分析

为获得弧线齿面齿轮副的精确啮合模型,采用展成方法加工仿真,并建立了安装误差下的齿面切触模型。应用弹性接触力学、有限元影响矩阵法、数学规划方法对弧线齿面齿轮进行承载接触分析,研究了在不同安装误差下面齿轮副载荷分布、齿面接触应力的变化规律。同直齿面齿轮副相比,弧线齿面齿轮副的重合度大、接触应力小、传动平稳、对安装误差的敏感性小、承载能力高。此分析方法为面齿轮副的设计、实验研究和实际应用提供了理论指导。     

非对称圆弧齿线圆柱齿轮建模与强度分析

为了提高圆弧齿线圆柱齿轮的强度,提出了双压力角非对称齿形设计。以双压力角铣刀盘为假想齿条,根据展成运动原理,推导齿面数学模型,获得齿面离散点坐标;在Pro/E中采用逆向建模的方法,建立高精度的非对称圆弧齿线圆柱齿轮模型;借助ABAQUS软件,分析工作载荷下两组压力角为25°/20°和25°/20°齿轮副的应力情况,提取出轮齿的齿面接触应力和齿根弯曲应力曲线。结果表明:大轮、小轮齿面的最大拟合误差分别为0.025mm、0.023mm;大压力角圆弧齿线圆柱齿轮能够显著提高轮齿的强度性能。     

弧齿线摆线圆柱齿轮副的几何参数与承载力分析

提出一种新型齿轮——弧齿线摆线圆柱齿轮,根据齿轮副啮合原理推导出齿廓曲线方程,并论述其基本几何参数,分析计算该齿轮副的重合度。设计该齿轮的三维造型,对弧齿线摆线圆柱齿轮副传动的接触应力和弯曲应力进行分析。结果表明:弧齿线半径在一定范围内时,弧齿线摆线圆柱齿轮副的接触应力和弯曲应力比渐开线圆柱齿轮副的接触和弯曲应力更小,其承载力比相同尺寸的渐开线圆柱齿轮更大。     

渐开线弧齿圆柱齿轮的应力分析

简要论述了渐开线弧齿圆柱齿轮的主要几何参数,从其齿面方程出发,分析渐开线弧齿圆柱齿轮副齿面接触线,并对其进行了重合度的分析,在此基础上提出了渐开线弧齿圆柱齿轮副齿面接触应力和齿根弯曲应力的计算方法,并通过有限元软件分析直齿轮、弧齿轮的应力。弧齿圆柱齿轮比直齿圆柱齿轮具有优越性。     

新型摩擦搅拌焊电机齿轮传动有限元分析

齿轮折断和工作齿面磨损是齿轮的主要失效形式,细致分析动态啮合下齿轮的受力情况,对摩擦搅拌焊在工作过程中提高齿轮的使用寿命及防止轮齿的断裂有重要意义。以摩擦搅拌焊的电动机齿轮副为研究对象,基于有限元接触理论建立齿轮副动态啮合的接触分析模型,分析齿轮连续啮合时的应力分布。仿真结果表明:齿轮副在低速重载下,齿面接触应力远大于齿根弯曲应力;齿轮副在啮合时,齿面接触应力呈现出先增大后减小的变化趋势;齿轮进入下一齿啮合时会产生碰撞冲击,造成接触处较大应力。     

齿轮动态啮合过程应力仿真与分析

以渐开线圆柱齿轮副为研究对象,基于弹性动力学建立了齿轮副动态分析有限元模型并对齿轮副啮合过程进行了模拟。计算了齿侧主应力、齿面接触应力以及弯曲应力沿齿宽方向的分布,得到了齿轮啮合过程中各临界位置的齿根动态弯曲应力时域历程,就单双齿啮合变化对齿根动应力的影响作出了讨论。分析了负载及转速对齿轮的啮合状态、齿根动态弯曲应力的变化和动应力的影响,为齿轮传动系统的设计提供了理论依据。     

弧齿锥齿轮加载啮合特性有限元分析

基于齿轮啮合原理计算获得了弧齿锥齿轮精确的三维几何实体模型,并由此建立了齿轮加载啮合特性有限元分析模型,以赫兹接触解析法合理地确定了有限元的网格密度。根据弧齿锥齿轮副6齿对模型,获得了齿轮在啮合过程中的齿面接触应力和齿根弯曲应力最大值的位置,并绘制出了啮合周期内的应力曲线。分别以载荷和安装误差参数为变量,研究了弧齿锥齿轮加载情况下的接触斑点以及接触轨迹等啮合特性。研究结果对弧齿锥齿轮的设计和实际应用起到了重要的指导作用。     

全工序法准双曲面齿轮建模与有限元分析

研究了全工序法准双曲面齿轮,即大轮成形法、小轮螺旋成形法加工的齿面建模、加工切削仿真和有限元分析。借助坐标变换和空间啮合理论,推导小轮齿面方程;根据机床调整参数,在CATIA中模拟刀盘和轮坯的展成运动,进行切削加工仿真,建立高精度的齿轮副实体模型;利用有限元软件Abaqus对齿轮副进行接触分析,计算并提取整个啮合过程的齿根弯曲应力和齿面接触应力,为准双曲面齿轮的强度设计提供参考。     

A study of the development of the stress optic law of photoelastic experiment considering residual stress

Photoelastic experiment has two significant problems. The first problem is manufacturing a model specimen for complicated shapes of structures. The second problem is residual stress contained in the photoelastic model material. In this paper, the stress optic law that can be effecitvely used on photoelastic model materials with residual stress is developed. By using the stress optic law as developed in this research, we can obtain good results in photoelastic experiments using model material in which residual stress is contained. It is assured that the stress optic law developed in this research is useful. Therefore, it is suggested that the stress optic law considering residual stress can be applied to the photoelastic experiment for the stress analysis of the composite materials or bi-materials in which the residual stress is easily contained.     

Prediction of residual stress distribution in multi-stacked thin film by curvature measurement and iterative FEA

In this study, residual stress distribution in multi-stacked film by MEMS (Micro-Electro Mechanical System) process is predicted using Finite Element method FEMi. We develop a finite element program for residual stress analysis (RESA) in multi-stacked film. The RESA predicts the distribution of residual stress field in multi-stacked film. Curvatures of multistacked film and single layers which consist of the multi-stacked film are used as the input to the RESA. To measure those curvatures is easier than to measure a distribution of residual stress. To verify the RESA. mean stresses and stress gradients of single and multilayers are measured. The mean stresses are calculated from curvatures of deposited wafer by using Stoney’s equation. The stress gradients are calculated from the vertical deflection at the end of cantilever beam. To measure the mean stress of each layer in multi-stacked film, we measure the curvature of wafer with the left film after etching layer by layer in multi-stacked film.     

Boundary Lubrication with Tricresylphosphate (TCP). Importance of Corrosive Wear

The wear of 52100 steel in boundary lubrication condition is controlled by the formation of nonhomogeneous, thin films. When tricresylphosphate is used as an antiwear additive, the buildup of the film is due to a chemical reaction process involving the bearing surface and the lubrication on or near the bearing surface.

A plane-on-plane-type tribometer using a 52100 steel specimen was used to determine the rate of wear and to follow the development of films by the use of the electrical contact resistance method. The results are correlated with the chemical analysis of the additive (polarographic method), with surface analysis of the film (AES and XPS spectroscopies) and finally with the surface topography (surface replicas and electron transmission spectroscopy).

During the mild wear test, several phases of wear are evidenced and the observed relation with TCP decomposition suggests a corrosive wear model proposed in the discussion. Explanations of observed phenomena are offered. (ECR increase, wear reduction, film formation).     

高精度薄壁轴承圈组件的加工应力变形分析及加工工艺

分析论述了轴承圈组件的加工变形问题。针对零件特点,从工艺安排上采取必要措施保证零件加工精度,通过控制工件热处理变形和加工应力变形,保证了淬硬层的硬度和厚度满足要求。通过设计专用球头测量仪,解决了组合件的测量难题。     

一侧有圆角过渡的矩形截面悬臂梁应力集中系数的计算

一侧带有圆角过渡的矩形截面悬臂梁受力时，圆角处存在应力集中现象。应力集中系数一般由实验确定或由弹性力学方法求出。文中通过对构件圆角处应力的分析，应用材料力学方法，推导出一种计算应力集中系数的方法，比弹性力学方法简便，并与实际相符。     

基于开槽法的毛坯内应力释放数值研究

为研究开槽法对毛坯工件加工变形的影响,分析了材料去除与加工变形的关系,解释了开槽法释放应力的基本原理。建立了开槽宽度、深度、位置等参数与释放变形量的表达式并进行了开槽参数优化。利用有限元法对优化的开槽参数进行了验证,仿真结果表明优化后的开槽参数能够比非优化的参数释放更多的应力。     

Finite crack propagation in a micropolar elastic solid

The dynamic propagation of a finite crack under mode-1 loading in a micropolar elastic solid is investigated. By using an integral transform method, a pair of two-dimensional singular integral equations governing stress and couple stress is formulated in terms of displacement transverse to the crack, macro and micro rotations, and microinertia. These equations are solved numerically, and solutions for dynamic stress intensity and couple stress intensity factors are obtained by utilizing the values of the strengths of the square root singularities in macrorotation and the gradient of microrotation at the crack tips. The motion of the crack tips and the load on the crack surface are not prescribed in the formulation of the problem. Therefore, the method of solution is applicable to nonuniform rates of propagation of a crack under an arbitrary time-dependent load on the crack surface. As an example, the diffraction of a micropolar dilatational wave by a stationary crack is considered. The behavior of the microrotation field and the dynamic couple stress intensity factor, influenced by microinertia, in addition to the dynamic stress intensity factor, are examined. The classical elasticity solution for the corresponding problem arises as a special case when the micropolar moduli are dropped from the present solution.     

超声振动时效可行性分析及实验研究

经过冷、热加工的金属零件表面和内部会存在残余应力,目前消除残余应力的振动时效技术主要是频率低于200Hz的低频振动,而对高频振动时效(大于1000Hz而小于15kHz)和超声振动时效(15kHz以上)的研究很少。对于固有频率较高的小型工件进行有效的时效处理成为目前亟待解决的问题之一。利用压力机对小型杆件施加集中荷载来模拟残余应力的形成,通过对超声振动激振应力计算和实验杆件中残余应力的计算,并从超声振动时效原理上进行实验的可行性分析。最后进行实验分析,即利用残余曲率计算出残余应力并进行时效效果分析,结果表明超声振动时效对小型工件的残余应力的消除有很明显的效果。为以后的超声振动时效研究奠定了理论及实验基础。     

FEM analysis of plasticity-induced error on measurement of welding residual stress by the contour method

The contour method relies on deformations that occur when a residually stressed component is cut along a plane. The method is based on the elastic superposition principle. When plasticity is involved in the relaxation process, stress error in the resulting measurement of residual stress would be caused. During the cutting the specimen is constrained at a location along the cut so that deformations are restrained as much as possible during cutting. With proper selection of the constraining location the plasticity effect can also be minimized. Typical patterns of longitudinal welding residual stress state were taken to assess the plasticity effect along with constraining locations.     

基于ANSYS的固定管板式换热器的热应力分析及评定

应用ANSYS有限元分析软件对固定管板式换热器进行热应力分析及评定。由应力强度云图可知最大应力强度发生在管板锻件的管程侧过渡圆角处。设定3条应力评定路径,进行线性化处理,在内压与热载荷作用下,对各路径上的一次加二次应力进行评定,得到应力评定结果。