基于有限元法的过盈配合接触特性分析

以某风力发电用齿轮箱为例,采用有限元法对斜齿轮与空心轴的三维弹性有摩擦接触问题进行了分析,针对不同工况、不同过盈量和摩擦系数下的过盈配合进行计算,获得了齿轮孔和轴之间接触压力和摩擦应力的分布随载荷、过盈量和摩擦系数的变化规律,为轴与轮毂之间合理过盈量的选择提供依据.     

多层高速旋转过盈配合圆筒的应力分析及径向尺寸优化设计方法研究

为了完善离心力作用下的多层圆筒过盈配合理论以及得到一定约束条件下较优的过盈配合设计方案,该文首先推导了多层旋转圆筒应力和变形分析解析公式以及多层旋转圆筒过盈配合设计公式,然后基于以上理论,以所定义的旋转圆筒最小安全裕度为适应度函数,采用遗传算法优化名义半径使圆筒的最小安全裕度最大化。根据优化并取整后的名义半径,采用有限元软件(ANSYS Workbench)建立磁悬浮轴承转子三维模型模拟了最大过盈条件下装配过程,并且比较了解析方法与有限元的等效应力结果。研究结果表明:所采用的名义尺寸优化方法提高了旋转圆筒的安全系数,增加了转子的安全性;本文模型中的最外层圆筒内壁为最危险环面,此处有限元方法所得最大等效应力比解析方法结果高18.72%,仅采用解析方法预测结果时应适当提高校核安全系数;所给出的解析方法与数值分析方法所得结果总体结果吻合良好,因此所提解析方法可以用于多层旋转圆筒的过盈配合初步设计、分析以及提供理论指导。     

多层圆筒过盈配合的接触压力与过盈量算法研究

为深入完善风电锁紧盘设计理论,首先基于厚壁圆筒受均布载荷作用下的位移表达式,推导了多层圆筒过盈配合各配合面接触压力和过盈量的计算公式;根据所得计算公式设计的某型号风电锁紧盘尺寸,采用ABAQUS软件建立了二维轴对称模型并模拟了其动态过盈装配;比较了两种方法的计算结果,并分析了两者误差产生的原因。结果表明,该文给出的解析算法与有限元数值方法所得结果吻合较好,可以为风电锁紧盘设计提供可靠的理论指导。     

双线性材料二次机械自紧厚壁圆筒的弹塑性分析

本文在文献［１］的基础上，针对作者首次提出的二次机械自紧技术，分析计算了双线性材料二次机械自紧厚壁圆筒的应力、位移、残余胀大量、过盈量与自紧度、冲头推力等二次机械自紧技术中的关键问题。结果表明厚壁圆筒二次机械自紧技术是可行的，理论分析与实验结果相吻合，满足了不同口径和材料性能厚壁圆筒的自紧要求。     

复合材料空心飞轮多环套装整体变形及应力简化精细分析

采用多环过盈装配是解决复合材料飞轮径向强度过低的有效途径之一。本文作者采用平面应力简化模型,提出了计及过盈配合后变形导致实际过盈量增大计算飞轮套装后的初终应力分布的方法;提出了基于叠加原理计算多环过盈装配旋转飞轮应力的方法;提出了保证飞轮旋转时配合界面不脱离的相关临界转速的概念和计算方法。算例分析表明:过盈配合后的变形对初终应力的影响不能忽略;过盈量和套装环数与飞轮的初终应力和相关临界转速有密切的关系。     

N层过盈联接结合压力算法研究

过盈联接作为联接件间的传统配合方式,具有结构简单、承载能力高等优点,在机械工程领域有着广泛的应用,其研究大多数局限在单层或3层以内的联接.随着机械设备中多层过盈联接应用逐步增多,为进一步完善多层过盈联接设计理论,以厚壁圆筒理论为基础,通过分析过盈联接中各圆筒的几何关系,推导出过盈联接中过盈量与圆筒内、外表面径向位移的变化关系,得到了N层过盈联接结合压力与过盈量的矩阵表达式;用推导所得的解析法和Abaqus数值法,对比分析了过盈联接结合压力和过盈结合面两端存在的应力集中现象.结果表明:N层过盈联接中最内层过盈的结合压力随着过盈层数的增加而增加,结合压力由内到外依次减小;解析法和数值法的计算结果基本吻合,中点相对误差均在4%之内,说明该解析法可以为N层过盈联接设计提供可靠的理论指导.同时,数值法计算中显示在结合面两端存在应力集中,不同模型最内层过盈面的理论应力集中系数差别较小,且各模型中理论应力集中系数由内到外呈现依次增大的规律.提出的算法和所得规律对N层过盈联接的设计研究工作具有一定的指导和帮助.     

超弹性材料过盈配合的轴对称平面应力解答

主要讨论了一种采用超弹性材料轴对称过盈配合的橡胶减震元件,推导了橡胶材料过盈配合平面应力的大变形解析解,并应用 ABAQUS 有限元软件进行数值模拟,分析和对比了解析解和数值解的结果,定量分析材料泊松比和体积刚度对问题的影响。     

一种根据膨胀位移计算橡胶圆筒弹性体膨胀内压应力的算法

根据薄膜壳体的无矩特性,提出了分析不同注水时刻,膨润土膨胀施加给橡胶膜的膨胀力的算法。该方法从橡胶膜的膨胀位移分析橡胶膜膨胀内压应力入手,根据橡胶膜微元体三维弹性状态下的柱坐标形式的物理方程和几何方程,以及橡胶膜圆筒横截面处截面的内力平衡方程,推导了橡胶膜膨胀内压应力在不同时刻和不同位置处的计算公式。应用编制的HSSA-EXCEL程序,计算分析了在不同注水时刻,膨润土的膨胀所施加给橡胶膜的膨胀内压应力。计算结果表明:与注水端的位置较近处橡胶膜的膨胀内压应力较大;与注水端的位置较远处橡胶膜的膨胀内压应力较小。膨胀内压应力随着时间不断增长。     

衬套松动检测方法简析

零部件座孔与衬套采用过盈配合安装。在产品使用过一段时间后需要检查衬套与座孔配合状况是否良好。目前采用"敲击方法"检测,由于此过程中敲击方式及敲击力不可控,并且存在冲击破坏配合状态的风险。本文提出新的衬套松动检测方法。该方法依据簿壁圆筒与厚壁圆筒弹性过盈配合的原理计算得出退卸衬套所需最小退卸力,然后采用检测装置对衬套施加相应压力,检测在该压力下衬套与座孔是否产生相对位移,以达到判断其过盈配合是否满足结构要求的目的。通过验证统计,新检测方法没有在检测过程中对衬套安装状态产生破坏,且检测合格的衬套能够满足使用要求。由此得出,该检测方法能够满足在不破坏前提下的检修要求。     

非拉梅问题的过盈配合结构装配应力的研究

对于经过盈装配而结成一体的构件,在装配过程中所产生的“装配应力”,往往与“工作应力”是同一数量级甚至在某些情况下大于“工作应力”。故而在对这类结构进行强度计算和结构设计中,装配应力是不容忽视的因素。因此,探究和获得装配应力可靠的计算方法具有重要的理论意义和实用价值。对于不同等长度的包容件,被包容件结成一体的过盈配合结构,其装配应力的可靠计算方法,一直未获得解决。作者对此进行了研究探讨、做了大量计算并经试验验证,满意地解决了对任意形状的轴对称过盈配合结构的装配应力计算问题。     

基于裂纹尖端应力比值的含裂纹功能梯度材料圆筒应力强度因子计算方法

由于功能梯度材料（FGM）性质的特殊性,现有含裂纹FGM结构应力强度因子计算方法难以避免复杂的矩阵运算以及数值积分。该文针对含外表面环向裂纹FGM圆筒,利用FGM圆筒与均匀材料圆筒裂纹尖端应力之间的比例关系,将复杂的FGM圆筒应力强度因子求解问题转化为简单的应力值提取问题以及经验公式计算问题,仅由均匀材料圆筒应力强度因子经验公式、均匀材料圆筒和FGM圆筒裂纹尖端应力比值即可得到任意含裂纹FGM圆筒应力强度因子。该方法仅需建立2D轴对称模型即可满足计算要求,在保证精度的基础上成功回避了传统方法中的复杂矩阵运算以及数值积分,且适用于不同FGM、筒体尺寸、裂纹深度等情况下的应力强度因子计算。通过多组算例对比分析,证明该方法计算精度高、计算过程简便,便于工程应用。     

Electromagnetic modelling of curved lossy dielectric surface and cylinder

A new electromagnetic model for curved dielectric surfaces and cylinder has been introduced. The model considers scatterers as a lossy dielectric body. The theoretical and simulation results have been compared with the literature and the model agrees with the published results of the hollow cylinder for which an exact solution exists. Figures of relative error versus ka and kT of hollow cylinder (a) single- (b) three-layered cylinder are used for the parameters. The curved dielectric scatterer is discretised to N small element, and then the contributions of each element are sum up coherently to find the total response. Finally, the simulations for curved cylinder and convex surfaces of arbitrary shape are presented.     

Longitudinal shear of a crack in a multi-material circular cylinder

This is an article dealing with the longitudinal shear of a crack contained in a circular cylinder, which is embedded in and fixed by perfect bonding to a composed hollow circular cylinder, consisting of a number of hollow sub-cylinders of different materials. A rigorous solution to the problem is developed. With the material and geometric constants of the composed hollow circular cylinder as parameters, numerical values of stress intensity factors for the crack are worked out. The delicate behavior in the variation of the stress intensity factors, when the number of the hollow sub-cylinders becomes large, is analyzed and discussed. The solution is developed by utilizing a simplified and improved technique using complex variables.     

Axisymmetric crack problem of a thick-walled Cylinder with cladding

The paper considers the elastostatic axisymmetric problem for a long thick-walled cylinder containing an axisymmetric circumferential internal or edge crack with cladding. The cladding is assumed to be bonded to inner wall of the hollow cylinder. Using the standard transform technique, the problem is formulated in terms of an integral equation of the first kind which has a generalized Cauchy kernel as the dominant part. The integral equation is solved numerically by using appropriate quadrature formulas. The related stress-intensity factors are calculated for the hollow cylinder with cladding under axial load. The influence of the geometrical configuration and the cladding on the stress-intensity factors is shown graphically.     

Extinction and scattering of a guided beam in a hollow dielectric waveguide.

We present a theoretical approach to the problem of mode scattering by a spherical object that is placed inside a circular dielectric waveguide. This approach is based on the separation-of-variables method for each subsystem, namely, the spherical inclusion and the circular dielectric cylinder, and on the concept of the generalized recursive T-matrix algorithm for multilayered structures. We apply the technique to the backward and the forward scattering of a quasi-optical beam in the form of the fundamental HE11 mode by a sphere inside a circular hollow dielectric waveguide. The results calculated for the perfectly conducting spherical objects inside the circular hollow dielectric waveguide are compared with corresponding measured data of the backward-and the forward-scattering characteristics at the 4-mm wave band.     

Axisymmetric problem of thermoelasticity for a hollow cylinder of finite length

The axisymmetric problem of heat conduction is examined for a hollow cylinder of finite length with mixed boundary conditions; a solution is given for the corresponding quasi-static problem of thermoelasticity.     

The torsional rigidity of a cylinder of curvilinearly aeolotropic material

Summary The problem of the simple torsion of a cylinder possessing aeolotropy defined relative to an orthogonal curvilinear coordinate net is formulated in terms of a stress function. The method of solution of the boundary-value problem for this stress function is indicated, and the torsional rigidity is obtained for both a solid and a hollow elliptic cylinder with a particular type of curvilinear aeolotropy.     

Stable crack growth in a surface compression-strengthened hollow cylinder

In this paper the static fatigue problem for a circumferentially cracked hollow cylinder is examined. For this particular configuration, stable crack growth, in the absense of any external forces, is determined for cylinders with axial components of residual stress which are compressive on the inner and outer radial surfaces and tensile in the cylinder wall. An initial surface crack which is deep enough to penetrate the compression strengthened surface region and enters the tensile zone may propagate in a stable manner until either sudden spontaneous failure occurs or the crack arrests. Since a portion of the crack near the cylinder surface will be closed because of the compressive residual stress field, an additional unknown in the problem is the extent of the crack surface contact. This crack surface contact length is determined by iteration on the integral equation which arises in the mathematical derivation for an embedded circumferential crack in a hollow cylinder. As an illustration of stable crack growth for this geometry with a realistic residual stress distribution, numerical results are presented for a hollow, soda-lime glass cylinder, based on crack growth rates in soda-lime glass exposed to water at 25‡ C. Using the fracture toughness and slow crack growth characteristics for soda-lime glass, the conditions for no crack propagation, crack propagation leading to crack arrest, and catastrophic failure are established.