A concise finite element model for simple straight wire rope strand

Due to its complex geometry, a wire in a rope is subjected to the combined effects of tension, shear, bending, torsion, contact, friction and possible local plastic yielding when loaded. In this paper an accurate and general strand model using the finite element method (FEM) is presented. The model is capable of taking into account all the above effects and has been successfully used to predict the global behaviour of simple straight wire rope strand as well as the stress distribution within the wires under axial loads (tensile and torsional). In simplifying the finite element model, precise boundary conditions were developed. The finite element analysis results showed excellent agreement with the analytical theory of Costello and the experimental results of Utting and Jones. By using the model developed in this paper, localised highly non-linear phenomena such as contact stress, residual stress, friction and plastic deformation can be studied effectively.     

A concise finite element model for pure bending analysis of simple wire strand

A concise finite element model for simple wire strand under pure bending is presented in this paper. Accurate bending symmetric boundary condition has been developed and applied to the periodic artificial cross-sectional end boundaries of the wire strand finite element model. To achieve better analysis accuracy, full three-dimensional solid elements were used for structural discretization. For the global behaviour of the wire strand, i.e. bending moment vs. bending curvature, the finite element results showed good agreement with the analytical elastic strand model of Costello (Theory of wire rope, 2nd ed. New York: Springer-Verlag; 1997) in elastic loading regime. Furthermore, the finite element model can predict the detailed progressive nonlinear plastic behaviour of the wire strand.     

多层股钢丝绳直线张拉状态下接触磨损机理研究

为了解多层股钢丝绳内部接触磨损情况,通过不同方法对其在直线张拉状态下的力学特性进行了研究。基于Costello的普通钢丝绳弹性理论,建立了拉力作用下直线状态钢丝绳的受力模型,以18×7+IWS多层股钢丝绳为例,计算得出多层股钢丝绳不同层绳股的应力变化情况;根据钢丝绳的空间几何结构,分析钢丝在接触状态下的受力情况,研究了钢丝接触应力的大小和钢丝间的滑动位移量对钢丝接触状态和钢丝疲劳磨损的影响;利用Abaqus对钢丝绳进行有限元静力学分析,研究了绳股钢丝间的应力变形情况;最后在DIC-MTS试验台进行了钢丝绳直线状态下的拉伸实验,从力学角度分析了多层股钢丝绳疲劳损伤的主要原因,对上述理论分析进行了验证,并得出了多层股钢丝绳在使用中其失效先从内部磨损开始,继而扩展断裂的结论。     

捻距单股钢丝绳侧丝与股芯的应力场研究

基于SolidWorks-Ansys平台,以IWRC1×7线接触单股钢丝绳为研究对象,在侧丝与股芯之间建立一种新的凹凸匹配小面接触模型,对已建立的有限元模型施加合适的边界条件和载荷,对奇偶捻距侧丝以及多捻距侧丝与股芯进行应力场分析,从而得到侧丝以及绳股在单向拉伸载荷作用下各自的应力场分布。分析表明:捻距数目为偶数的侧丝应力集中的最大应力值要小于捻距数目为奇数侧丝的最大应力值;多捻距单股钢丝绳应力最大值发生在施加载荷端第一个捻距中部,一个捻距的应力最大值明显大于多个捻距的应力最大值,并且随着捻距数目的增加,最大接触应力值成波浪式下降趋势。     

基于ANSYS的多股螺旋弹簧有限元分析

简单分析多股螺旋弹簧的基本特性。以三股钢丝的多股螺旋弹簧为例,通过有限单元与接触单元的选取和网格的划分,建立多股螺旋弹簧有限元模型。然后对其进行静态受力分析和动态分析计算,分析冲击载荷质量和速度对多股螺旋弹簧性能的影响。结果表明多股螺旋弹簧在动态系统中具有内部振动波,并可能在中间产生并圈现象,为多股螺旋弹簧设计提供了依据。     

基于绝对节点坐标法的钢索-滑轮系统动力学模型与响应迟滞特性

钢索-滑轮系统间的非线性接触特性严重影响了长距离软式传动系统变形及动态响应迟滞效应的准确计算。基于绝对节点坐标法建立了三维高阶钢索单元模型。在此基础上,建立了钢索-滑轮系统的动态接触模型,应用Hunt-Crossley接触模型计算法向接触力,采用LuGre微变模型计算较低相对运动速度下的切向接触力,准确描述了钢索与滑轮接触由动摩擦向静摩擦的转变过程。仿真结果与准静态实验结果的对比验证了模型的准确性,分析了钢索材料参数和末端载荷对钢索-滑轮系统动态响应以及钢索末端位移的影响。结果表明,钢索-滑轮系统的动态响应延迟时间由钢索材料特性及末端载荷决定;钢索末端位移主要受钢索刚度及末端载荷影响。相同条件下采用小比重钢索材料,适当增加末端载荷以增大钢索结构刚度,可减小系统传动中钢索的末端位移,有效提高钢索-滑轮传动系统的传动性能。     

Research of numerical simulation method on vertical stiffness of polycal wire rope isolator

Wire rope isolator (WRI) is widely used in the power machinery and chemical equipment, and has a better dry friction damping and stiffness softening characteristics compared with other vibration isolators. The aim of this article is to create a simplified finite element model of polycal WRI and to avoid the use of overall model on the stiffness characteristic caused by the waste of time. The numerical simulation method used in this paper is to simplify the 1 + 6 +12 single strand into a single wire. The simplified WRI model subjects to the compression load by finite element analysis and obtained the vertical static stiffness characteristics which are consistent with the experimental results.     

钢丝绳股内钢丝应力—应变分布的计算模型及数值模拟

应用微分几何理论及利用ANSYS软件进行6×7IWS钢丝绳的几何建模和有限元建模,进行6×7IWS右同向捻和右交互捻两种钢丝绳模型对比,从几何结构上得出规律性结论,对两类钢丝绳确定相同的边界条件进行有限元计算。结果显示了两种捻向组合下钢丝绳股内钢丝应力分布及应力值的区别。对照几何模型的分析,得出相关性规律,同向捻制钢丝绳股内钢丝的应力变化幅度高于交互捻钢丝绳,应力变化周期同向捻高于交互捻,绳股中钢丝所处的位置不同,钢丝的应力也有很大差别,在一根钢丝中,应力分布与该丝所处的捻绕位置有很大相关性。通过试验验证分析结论,与模拟结果基本相符。     

钢丝绳弱磁探伤数值模拟及实验研究

在对绞线钢丝绳3D建模的基础上,采用有限元技术,分析了弱磁励磁状态下,钢丝绳复杂表面的磁场分布;对钢丝绳周围空气中的漏磁场矢量进行了仿真,研究了缺陷对钢丝绳表面及空间漏磁场分布的影响。仿真分析结果表明:在无缺陷状态下,钢丝绳周边空气中的漏磁场分布与其绳股形状相对应,其圆周方向的漏磁场呈周期性变化,周期为绳股节距;当缺陷存在时,漏磁场分布的周期性被破坏,且幅值大幅增加。依据理论分析结果,搭建了基于弱磁励磁的钢丝绳无损探伤实验平台,得到了不同断丝缺陷的漏磁场实测波形,实验结果验证了仿真分析结果的正确性。     

Elasto-plastic contact problem of laying wire rope using FE analysis

The three-dimensional elasto-plastic contact model, formulated with variational equalities, has been described for laying wire rope in this paper. The augmented Lagrangian multiplier method has been applied to calculate both the normal contact force and friction contact force, and the radial return mapping algorithm has been employed to handle stick/slip phases of friction. With a graphical user interface (GUI), a program for calculating boundary conditions of a three-dimensional finite element modelling is developed to create external files, which are in the format of the ANSYS parametric design language (APDL) and the external files can be accessed by ANSYS for nonlinear analysis. FE simulation of a simple wire strand has been given and the effects of friction coefficient and self-rotating ratio on the contact stress have been analysed. Also the effects of them on the forming stress and strain have been discussed.     

三角股钢丝绳应力平衡分析及提高捻制质量的研究

实施以应力平衡为主,消除应力为辅取代传统单一的消除应力的生产方式。研究发现三角股钢丝绳捻制应力产生的关键环节是三角股的捻制,利用捻制三角股的特殊装备,采取工字轮后翻身的方式,促成钢丝的正向预应力来平衡捻股产生的负向捻制应力,实现三角股捻制应力的有效控制。应用盘式成绳预变形器,采用一次预变形工艺替代传统两次预变形的生产方式,使三角股钢丝绳六股变形率一致性得以稳定提高。     

Bending fatigue characteristics of wire rope

Wire rope in elevators can become disconnected by tensile stress from friction between the rope and sheave, and by repeated stress including bending stress from various effects formed during contact between the rope and sheave. It is known that in designing wire rope, its strength is affected when wire disconnection occurs. However, insufficient related data is available. Therefore, fracture strength reduction and the effect of bending fatigue on wire rope life is difficult to evaluate. We considered the effects of wire rope diameter and tensile stress on fracture strength and wire rope life. We observed that fracture strength rapidly decreased when bending fatigue accumulated at the same time that the wire became disconnected. Moreover, bending fatigue was shown to be a crucial factor in decreased wire rope life.     

The response of wire rope strands to axial tensile loads—Part II. Comparison of experimental results and theoretical predictions

Carefully instrumented tests were performed on straight single steel strands of seven-wire construction subjected to axial loads and with various end restraints. The strands have a practical range of lay angles between 9.2 and 17.0° with core and helical wire diameters of 3.94 and 3.73 mm, respectively. A mathematical model of a strand was developed to explore the change of helix angle under load, Poisson ratio effects in wires, wire flattening under interwire pressure and the effect of friction between the core and helical wires. A companion article (Part II) [Int. J. Mech. Sci. 29, 621–636 (1987)] compares the theoretical predictions with previously published analytical work and with the corresponding experimental results reported in this article.     

The response of wire rope strands to axial tensile loads—Part I. Experimental results and theoretical predictions

Carefully instrumented tests were performed on straight single steel strands of seven-wire construction subjected to axial loads and with various end restraints. The strands have a practical range of lay angles between 9.2 and 17.0° with core and helical wire diameters of 3.94 and 3.73 mm, respectively. A mathematical model of a strand was developed to explore the change of helix angle under load, Poisson ratio effects in wires, wire flattening under interwire pressure and the effect of friction between the core and helical wires. A companion article (Part II) [Int. J. Mech. Sci. 29, 621–636 (1987)] compares the theoretical predictions with previously published analytical work and with the corresponding experimental results reported in this article.     

新型电缆牵引机双摩擦卷筒应力分析与仿真

针对电力特种装备——新型自驱动式牵引机的关键装置双摩擦牵引卷筒设计缺乏设计依据等关键问题,采用微积分及有限元仿真分析结合的方法进行了力学分析,得到牵引钢丝绳沿双摩擦卷筒绳槽的张力变化函数关系,进而建立了卷筒的力学分析模型,研究在不同载荷条件作用下卷筒的应力状态与关系.最后,基于ANSYS软件对卷筒进行有限元建模分析,并将仿真结果与理论计算结果进行分析比较.结果证明了所采用的单元梁力学模型应用于卷筒的应力计算的可靠性与有效性,可为摩擦卷筒类零件的强度设计提供重要的理论依据,具有一定的工程意义.     

拉伸载荷作用下套管接头的应力分析

针对深井和大位移井中套管存在很大的轴向拉伸和压缩载荷的情况,采用弹塑性接触有限元方法对套管柱中最薄弱的螺纹接头部分进行分析计算,分析AP18牙圆螺纹套管接头在拉伸载荷作用下的应力情况,给出了负荷和各应力沿轴向的分布规律。     

Three-dimensional finite element analysis of the mechanical properties of helical thread connection

Conventional analytical and numerical methods for the mechanical properties of helical threads are relied on many assumptions and approximations and thus hardly yield satisfied results. A parameterized 3D finite element model of bolted joints with real helical thread geometry is established and meshed with refined hexahedral elements. The Von Mises plasticity criterion, kinematic hardening rule of materials and interfacial contacts are employed to make it possible for the suggested model be able to approach real assembly conditions. Then, the mechanical properties of bolted joints with different thread pitches, thread numbers and modular ratios are investigated, including the contact pressure distribution at joint interfaces, the axial load distribution and stress concentration in screw threads during the loading and unloading process. Simulation results indicate that the load distribution in screw threads produced by the suggested model agrees well the results from CHEN’s photoelastic tests. In addition, an interesting phenomenon is found that tightening the bolt with a large preload first and then adjusting the clamping force by unloading can make the load distribution more uniform and reduce the maximum residual equivalent stress in thread roots by up to 40%. This research provides a simple and practical approach to constructing the 3D finite element model and predicting the mechanical properties of helical thread connection.     

非对称齿廓齿轮弯曲疲劳强度理论分析与试验

为提高齿轮承载能力设计齿轮两侧压力角不等的非对称渐开线新齿形,推导双压力角非对称齿廓齿轮工作齿侧与非工作齿侧的渐开线齿廓方程和齿根过渡曲线方程,通过迭代计算和优化策略提出非对称齿廓齿轮疲劳强度解析法计算公式。编制生成非对称齿轮齿廓的参数化程序,在此基础上建立非对称齿廓齿轮有限元分析模型。通过解析法对不同压力角组合的非对称齿廓齿轮弯曲应力和危险截面位置计算得出,随着工作齿侧压力角的增大齿根最大弯曲应力逐渐降低,单齿啮合区向齿顶偏移;通过对有限元模型进行计算得出的结果与解析法一致,应用最小二乘法拟合出非对称齿廓齿轮齿根弯曲应力随工作齿侧压力角变化的计算公式。采用数控电火花线切割方法加工制造非对称与标准齿廓齿轮,在高频疲劳试验机上采用双齿脉动加载方法对其进行疲劳强度试验。试验结果表明,非对称齿廓齿轮在相同寿命下比对称齿轮极限载荷提高了50%,非对称齿廓齿轮的应力值变化趋势与前两种方法是一致的。     

起重机钢丝绳关键部位磨损失效机理研究

针对现有起重机钢丝绳的失效形式,从处于负载工作状态钢丝绳的三个关键部位-自由段、与滑轮接触啮合段和滚筒缠绕段-分析钢丝绳的受力状况,尤其分析钢丝绳受到的挤压力和摩擦力,导出钢丝绳内股与股和丝与丝之间、钢丝绳与滑轮之间、钢丝绳与滚筒上缠绕钢丝绳之间的摩擦磨损机理,为实际工作提供了指导的理论依据。