Augmented Lagrange方法在钢丝绳捻制成形磨擦接触数值模拟中的应用

钢丝绳中金属线间接触摩擦会影响捻制成形加工应力和结构强度.在经典的Coulom摩擦理论的基础上,本文采用Augmented Lagrange方法计算钢丝绳捻制过程中的法向接触力和摩擦接触力,并应用radial-return径向回映法修正摩擦接触力试算值.以钢丝绳一次捻制成形过程为例,分析并讨论了摩擦系数和自扭转系数对接触应力和加工应力应变的影响,为钢丝绳成形工艺和结构强度的合理设计提供依据.     

钢丝绳三维有限元建模及静态拉伸应力状态分析

钢丝绳由多根高强度钢丝捻制而成,具有强度高、柔性好、承载力强等特点,在矿山、码头、交通等领域得到了广泛的应用.根据钢丝绳的几何结构特点,建立了 7×7交互捻的钢丝绳三维有限元模型,并分析了钢丝直径、中心股捻距、外层股捻距和整绳捻距对钢丝绳周期性的影响.采用ANSYS进行优化参数的有限元模型进行静态拉伸载荷下的应力-应变...     

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。     

钢丝绳三维接触模型及丝间应力分布研究

建立了1×19IWS钢丝绳三维接触模型,该模型采用Splitting-pinball算法进行接触位置搜索,采用Augmented-Lagrangian算法进行接触载荷计算。对模型施加拉伸载荷,应用有限元进行了计算。分析计算结果,得出了钢丝沿轴线方向及在钢丝横截面内的应力分布规律;对照摩擦因数分别取0.10、0.11、0.12时的计算结果,得出摩擦因数对钢丝应力的影响规律,摩擦因数对钢丝切应力影响显著。分析了5个不同捻距倍数的钢丝绳计算结果,得出了捻距倍数对钢丝应力的影响规律,钢丝vonMises应力随捻距倍数增大而增大,但增大不明显,钢丝切应力随捻距倍数增大而减小,且在捻距倍数较小时变化幅度较大。进行了钢丝绳拉伸变形试验,试验结果与计算结果一致,说明所选用的模型是合理的。     

摩擦因数对钢丝绳有限元分析结果的影响

钢丝绳在使用过程中,钢丝之间的摩擦因数会逐渐增大。文中以某型起重机所用6×36+WS结构的钢丝绳为研究对象,仿真分析了其在不同摩擦因数下的应力和变形分布,探究了摩擦因数对其应力和变形的影响。利用Solid Works软件建立了钢丝绳三维模型,导入ABAQUS中,建立钢丝绳有限元模型。在相同的轴向荷载下,仿真分析了4种不同的摩擦因数对钢丝绳应力和变形的影响。结果表明,钢丝绳Von-Mises应力随着摩擦因数的增大而增大,变形量U随着摩擦因数的增大而小幅度减小,说明摩擦因数是影响钢丝绳寿命的重要因素,钢丝绳使用过程中应注意润滑。     

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。     

钢丝绳应力场与疲劳寿命研究

钢丝绳以独特的螺旋结构广泛应用于起重装备中,其应力与疲劳寿命特性是评价钢丝绳工作性能的重要指标。基于SolidWorks-ANSYS平台,运用空间扭曲特征建立一个完整捻距钢丝绳模型,结合虚拟疲劳寿命分析方法,对不同钢丝捻矩6×7+IWS型钢丝绳进行应力与疲劳寿命有限元分析。通过分析发现,6×7+IWS型钢丝绳芯股主要承担着轴向载荷的作用,钢丝捻距的大小影响着钢丝绳的应力分布特性,同时应力大小决定着钢丝绳的疲劳寿命,应力越大疲劳寿命越小。研究结果表明,选取合适的钢丝捻距值,直径、侧股捻距的6×7+IWS型钢丝绳采用钢丝捻距,能有效改善钢丝绳应力分布和提高疲劳寿命,更好的满足工作要求。     

金属捻线成形过程的弹塑性有限元模拟

提出考虑金属捻线成形过程中的大转动几何非线性的共转坐标系弹塑性有限元法,将此法用于金属捻线成形过程模拟,通过数值计算分析成形过程工艺参数对加工应力应变分布和残余应力的影响,为金属捻线成形工艺与结构强度的合理设计提供依据。     

6×7+IWS双螺旋钢丝曲率和挠率及其应力变化特性

为了掌握提升钢丝绳内部钢丝在波动载荷下的应力状态变化,针对典型钢丝绳6×7+IWS,推导轴向载荷下螺旋钢丝螺旋角变化量的显式表达式,给出钢丝绳侧股双螺旋钢丝的曲率、挠率和应力波动表达式.分析结果表明,钢丝绳在轴向载荷下,同向和交互捻制的钢丝绳中螺旋钢丝的螺旋角随载荷线性增加,其侧股螺旋钢丝的曲率和挠率随自身旋转角的变化呈360°周期变化;靠近独立股外侧时钢丝的曲率最大,而其挠率则最小,侧股内侧则相反;同向捻制钢丝绳侧股螺旋钢丝的曲率及其波动载荷下弯曲应力变化幅度远大于交互捻制钢丝绳.     

6×7＋IWS双螺旋钢丝曲率和挠率及其应力变化特性

为了掌握提升钢丝绳内部钢丝在波动载荷下的应力状态变化,针对典型钢丝绳6×7＋IWS,推导轴向载荷下螺旋钢丝螺旋角变化量的显式表达式,给出钢丝绳侧股双螺旋钢丝的曲率、挠率和应力波动表达式。分析结果表明,钢丝绳在轴向载荷下,同向和交互捻制的钢丝绳中螺旋钢丝的螺旋角随载荷线性增加,其侧股螺旋钢丝的曲率和挠率随自身旋转角的变化呈360°周期变化;靠近独立股外侧时钢丝的曲率最大,而其挠率则最小,侧股内侧则相反;同向捻制钢丝绳侧股螺旋钢丝的曲率及其波动载荷下弯曲应力变化幅度远大于交互捻制钢丝绳。     

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.     

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.     

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。     

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。     

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.     

The modelling of friction in polymer fibre ropes

Polymer fibre ropes are assemblies of in some cases half a million polymer fibres; this can in some circumstances be considered a ‘continuum’. However, the detail of these components results in a structure which is both inhomogeneous and anisotropic; the consideration of inhomogeneity is necessary since each component is distinct and there is no continuity of motion between them and anisotropy is the result of twist and braiding various subcomponents {yarns, strands, subropes} into a further component.This paper discusses the analysis of rope structures; it will survey the hierarchical approach in which the base component {fibres, filaments} are developed into a structure {yarns, plies}. This structure is then a component which forms the basis for the next higher structure, {strands, subropes, multiplies}. The progress in analysis and indeed in fabrication through the rope structure thus leads quite naturally to the hierarchical approach where the top is the rope and the bottom is the base yarn, the fibre or indeed for wire ropes, the wire. The assumptions used pertain to the detail of the contact between contiguous components; these are within a hierarchical level and pertain to contact within a layer or between layers; the contact friction must inhibit component sliding and the assumption of a friction force-contact force law must be made. Friction is identified in six modes: linear sliding, twist slip, sawing and scissoring between components and distortion and dilation within components. The effects of inter and intra friction are discussed and thus integrated into the analysis and model.This paper will first survey the various rope constructions. Then it will describe the analysis for rope deformations and loads which will yield also the loads and deformations of the internal components. Finally this paper will survey the mechanisms of component slip and show the analysis for the various friction modes.     

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。     

钢丝绳摩擦传动防滑计算的新方法

通过钢丝绳摩擦传动的受力分析，得出不打滑状态下的广义欧拉公式和接触弧内任一截面上钢丝绳张力的分布规律，提出了一种引入许用防滑角进行钢丝绳摩擦传动防没计算的新方法。     

摩擦提升机恒减速制动工况下的防滑特性

摩擦提升机是一种利用钢丝绳与卷筒之间的摩擦力来传动运动的矿井提升设备,其在紧急制动过程中容易出现钢丝绳打滑现象,严重威胁设备的安全运行。针对此问题,以恒减速紧急制动工况下的钢丝绳滑动为研究对象,提出利用加速度偏差对紧急制动过程中罐笼加速度进行归一化处理,以加速度偏差系数发生突变增大为钢丝绳发生临界打滑的判断依据,从而获得极限减速度。利用经过实验验证的摩擦提升机仿真模型和本研究所提出的方法获得了一系列恒减速制动工况下的极限减速度,经线性拟合后得到极限减速度预测模型,ax = -k1M + b1（下放工况）和ax=k2M+b2（提升工况）,该预测模型将有助于恒减速制动工作点范围的确定,从而可为摩擦提升机防滑策略的制定提供依据。