一种具有强耦合作用的有限元单元刚度矩阵组装策略

讨论了对起重机械结构进行有限元静、动力分析时的一种特殊单元——钢丝绳单元的强耦合特性,研究了将钢丝绳单元刚度矩阵往总刚度矩阵组装时的策略,以方便地在现有的有限元分析程序中引进该单元。     

弹性钢丝绳理论研究进展

对弹性钢丝绳理论的研究现状进行了较为全面、系统的介绍和总结,重点概述了离散模型的发展情况,对其它模型如半离散模型,则作了简要介绍;将几种离散模型的计算结果与实验情况进行了对照研究,提出并讨论了目前钢丝绳理论的某些不足之处及今后的研究方向．     

钢丝绳捻制成形的空间几何模型与有限元分析

根据钢丝绳捻制成形原理，在考虑钢丝绳空间几何形状的基础上，建立了引入自扭转系数时钢丝绳的几何结构计算模型和钢丝绳捻制成形有限元计算边界条件模型。进而编制了相应的有限元建模程序，生成可被ANSYS直接调用的数据文件。分析了钢丝绳一次捻制和二次捻制的加工应力应变变化情况，并讨论了自扭转系数对加工应力应变的影响。     

轴向加载下不同捻向多股钢丝绳的力学行为研究

多股钢丝绳在工程结构中广泛应用，其中多数钢丝经过两次捻绕成为二次螺旋钢丝。基于Love弹性曲杆理论和变形前后钢丝绳结构状态分析，建立了轴向加载下考虑二次螺旋钢丝局部变形行为的多股钢丝绳弹性理论模型，并通过有限元模拟研究了钢丝绳的弹塑性力学响应。将弹性理论模型结果与有限元模拟结果、Costello模型进行了对比验证，进一步分析了不同捻向钢丝绳(顺捻、交互捻)整绳和局部钢丝的力学行为。研究发现二次螺旋钢丝的局部响应不同于单股绳一次螺旋钢丝，钢丝的弯曲和扭转变形沿钢丝绳截面周期性变化。整绳受拉伸载荷时，沿钢丝轴线的拉伸变形占主要部分，交互捻钢丝的弯曲和扭转变形均小于顺捻钢丝，且扭转变形的方向与顺捻钢丝相反。在通常弹性使用范围内，交互捻钢丝绳沿钢丝截面的最大拉伸和扭转应力均小于顺捻钢丝绳，且产生的反作用扭矩更小，因此优于顺捻钢丝绳。     

定、变载弯曲疲劳钢丝绳失效机理对比研究

为对比揭示定、变载弯曲疲劳钢丝绳断裂机理及磨损演化特性，运用自制钢丝绳弯曲疲劳试验机开展钢丝绳定载、变载弯曲疲劳试验，通过人工拆股统计法和VW-9000系列高速度数码显微系统对比研究钢丝绳断丝分布、断丝数、断口和磨痕形貌等断裂机理，对比分析钢丝绳未断钢丝和断丝的磨痕尺寸演化特性. 结果表明:与钢丝绳定载弯曲疲劳相比，变载弯曲疲劳钢丝绳断丝出现较晚，芯股、螺旋股外层断丝数分别较多、较少，芯股外层钢丝断口挤压变形较大，芯股各层钢丝断口裂纹扩展区占比较低，芯股和螺旋股的各层钢丝磨痕尺寸总体较小，钢丝绳更易达到报废水平.      

遗传算法在冲击隔振中的应用研究

借助泰勒级数给出了钢丝绳隔振器的一阶近似非线性数学模型, 选用遗传算法对系统固有频 率进行二进制编码; 然后建立了相应的冲击仿真模型, 并对冲击载荷作用下装有钢丝绳隔振 器的移动硬盘进行仿真实验. 理论分析与仿真结果表明, 采用遗传算法的仿真模型能够适应 脉冲宽度的多变性, 克服隔振效果与最大允许变形之间的矛盾, 良好地反演出钢丝绳隔振系 统的固有频率.     

钢丝绳隔振器的非线性动力学模型

基于非线性钢丝绳隔振器的静态力学特性,引入了频率软化系数,建立了非线性动力学隔振模型.基于该模型研究了钢丝绳隔振器对冲击激励与随机激励的动态响应,对结果进行了讨论.理论分析与数值模拟表明:引入频率软化系数的隔振模型比传统的线性动力学模型具有更好的隔振效果,更加符合实际情况.     

船用重载钢丝绳隔振器性能的理论与试验研究

本文钢丝绳夺器的静压曲线出发，拟事钢丝绳振器的动刚度。并将隔振器的摩擦阻尼处理为等效粘性阻尼，对某船用主机隔振装置为对象，用龙格－－库塔法计算了机器隔持后的振动位移，结果与实测结果较为吻合。通过对实测信号进行分析，发现钢丝绳隔振器的非线性性明显，在推进工况１５００转／分下，机器的振动信号具有混沌运动的某些特性。     

基于ARCHARD磨损模型的WR-CVT非连续接触钢丝绳磨损研究

针对WR-CVT (Wire rope continuously variable transmission)弯曲段钢丝绳更易磨损问题,以6×7+IWS (Merallic wire strand core)钢丝绳为研究对象,基于Archard磨损模型结合自适应网格技术,建立WR-CVT钢丝绳非连续接触磨损有限元模型,研究磨损对钢丝绳接触压应力以及滑移幅值等接触参量的影响,并进行了试验揭示磨损机理.结果表明：随着磨损的作用,钢丝间接触区域不断增大.最大磨损深度出现在钢丝绳与绳槽边缘接触处,此处钢丝接触压应力较磨损前显著减小,滑移幅值和磨损深度在不断增大,接触压应力集中点沿钢丝轴向不断移动,接触区域形貌逐渐形成扁平状,磨损机理为磨粒磨损、黏着磨损和疲劳磨损.     

用重力弦振动分析法计算钢丝绳的负载

用重力弦一端悬吊重物Ｇ作为矿用铅直井提升钢丝绳的力学模型，导出了计算提升重量的公式，用该公式计算结果与实际吊重符合很好。     

A three dimensional approach to model steel wire ropes used in high energy absorber apparatus

The modeling method and dynamical characteristics of steel wire ropes has been researched for several decades. In the past, steel wire ropes were usually modeled as a two dimensional system, which was only suitable for the planar motion. Also, no kink-wave propagation was considered when steel wire ropes were used in relatively low speed engineering application areas. By contrast, a three dimensional approach to model steel wire ropes used in high energy absorber apparatus is presented in this paper. Three dimensional contacts between steel wire ropes and other objects and kink-wave propagation in steel wire ropes are taken into consideration when applying the new approach to model steel wire ropes. Compared to the two dimensional model of steel wire ropes, the proposed model regards steel wire ropes as a multi-body system consisting of identical cylindrical elements with 6 degrees of freedom connected by space constraints. Impact forces generated by three dimensional contacts between steel wire ropes and other objects are calculated and theories of elastic wave propagation are applied to analyze the kink-wave propagation when steel wire ropes are loaded with a sudden perpendicular impact by a high speed moving object. In addition, mathematical model of steel wire ropes is established and numerical simulation of the three dimensional model of steel wire ropes is implemented. By comparing the simulation results with the experimental data available, the model of steel wire ropes proposed in this paper is demonstrated to be valid and correct. Therefore, the proposed modeling method can be treated as a new approach in the research field of modeling steel wire ropes. The dynamical characteristics of the steel wire ropes based on this new modeling approach are addressed simultaneously and plots of the dynamics of steel wire ropes cannot only be regarded as a basis for the further comparative studies, but also can provide some significant and interesting results.     

Finite element modeling and optimization to prevent wire breakage in electro-discharge machining

One of the most important problems in wire electrical discharge machining is related to wire breakage. This research develops a simple finite element model and a new approach to predict the thermal distribution in the wire fairly accurately. The model can be used to optimize the different parameters of the system to prevent wire breakage. At any instant of time, the spatial heat distribution profile of the wire can be mapped on the transient analysis of any point on the wire traversing through all the heat zones from the top spool to the bottom end. Based on this principle, the finite element model and optimization algorithm are used to determine that the heat generated is the critical variable responsible for wire breakage. The model successfully predicts the thermal distribution profile accurately for various wire materials, for increased wire velocity and for reduction in heat transfer coefficient. This simple model is a precursor of development for 3-D finite element models that can describe the cross-sectional wire erosion as the workpiece cutting progresses. The modeling may lead to the development of a smart electro-discharge machining system with a sensor and feedback control to increase the cutting speed and minimize breakage.     

基于ASME应变限制准则的小冲杆试验等效断裂应变

为更清楚地了解阳江35kV服役导线的运行状态,从分析导线断线原因出发,通过对老旧导线的单丝断裂强度、弹性模量、应力应变曲线、拉断力、抗拉强度等综合指标的测试与分析,研究服役导线的力学性能,由试验结果得出：35kV老旧导线钢芯的直径变化对于架空导线的外径变化有直接的影响,老旧导线的铝线直径变化较小,其外径增大1.67％~4.24％;钢单线的拉断应力仍能达到标准中规定值的106%,且伸长率也满足要求;部分铝线的抗拉强度低于95%;绞线拉断力仍能达到95%的计算拉断力。但是相同规格下的老旧导线的抗拉强度比新导线的抗拉强度低2%~18%。结果表明：阳江地区服役三十年以上的老旧导线在力学性能上仍能继续承载。     

服役导线的力学性能退化研究

为更清楚地了解阳江35kV服役导线的运行状态,从分析导线断线原因出发,通过对老旧导线的单丝断裂强度、弹性模量、应力应变曲线、拉断力、抗拉强度等综合指标的测试与分析,研究服役导线的力学性能,由试验结果得出:35kV老旧导线钢芯的直径变化对于架空导线的外径变化有直接的影响,老旧导线的铝线直径变化较小,其外径增大1.67%~4.24%;钢单线的拉断应力仍能达到标准中规定值的106%,且伸长率也满足要求;部分铝线的抗拉强度低于95%;绞线拉断力仍能达到95%的计算拉断力。但是相同规格下的老旧导线的抗拉强度比新导线的抗拉强度低2%~18%。结果表明:阳江地区服役三十年以上的老旧导线在力学性能上仍能继续承载。     

纳米铜丝尺寸效应的分子动力学模拟

采用EAM原子势函数对不同截面尺寸纳米铜丝拉伸性能进行了零温分子动力学模拟。研究表明截面变化对纳米丝拉伸性能有明显影响。由于表明原子弛豫，纳米丝存在表面张应力以及与之相平衡的内部应力。这种本征应力的存在是纳米丝尺寸效应的根源。纳米丝截面减小，则拉伸强度提高、屈服推迟、初始拉伸模量的软化程度增加。     

Critical effects of a spanwise surface wire on flow past a circular cylinder and the significance of the wire size and Reynolds number

An experimental study is conducted on flow past a circular cylinder fitted with a single spanwise wire on its surface. The work investigates the dependency of the critical wire locations on the wire size and Reynolds number, and examines the near wake and vortex shedding characteristics in an effort to advance the understanding of the critical wire effects beyond the existing literature. The Reynolds number is varied from 5000 to 30 000, and the wire diameter is varied from 2.9% to 5.9% of the cylinder diameter. All wires are larger than the boundary-layer thickness forming around a comparable smooth cylinder. Constant Temperature Anemometry and hydrogen bubble visualization are used as the flow diagnostic tools. The frequency and strength of the Karman instability are shown to vary with the wire location at any given Reynolds number nearly in an inverse fashion. For all the Reynolds numbers and wire sizes considered, two types of critical locations are shown to exist on the cylinder surface for the application of a wire. These locations are associated with the attenuation and amplification of the Karman instability, and in accord with the existing literature, are denoted as θ_c1 and θ_c2, respectively. The present work reveals that θ_c2 consists of a wide range of locations which remains unaffected from the wire size and Reynolds number, while θ_c1 is a relatively distinct location on the cylinder surface and depends on both the Reynolds number and wire size. For a given Reynolds number, increasing the wire size decreases θ_c1. For a given wire size, increasing the Reynolds number from 5000 to 15 000 increases θ_c1, and past 15 000, θ_c1 remains unaffected from the Reynolds number. When a wire is at θ_c1, even though, for the majority of the time the regular formation of Karman vortices ceases, the present data also reveals intermittent, short time periods where the regular shedding resumes.     

一种电力架空线垂度的简算方法

以输配电工程中带有绝缘子的电力架空线为研究对象, 简化绝缘子的力学模型, 采用纵横弯 曲理论推导了钢芯铝铰线的挠度方程, 计算了在自重和温度载荷共同作用下的架空线垂度和 水平张力. 计算结果表明, 文中算法简单有效, 架空线跨距和温度等是架空线垂度的主要 影响因素. 架空线垂度对温度的平均变率为2.55mm/$^{\circ}$C; 当跨距减 小1%时, 垂度增加近60%.     

Analytical procedure for modelling recursively and wire by wire stranded ropes subjected to traction and torsion loads

The aim of this article is to introduce a new theoretical procedure for modelling wire ropes subjected simultaneously to tensile and torsional loads. The procedure is based upon the beam assumption and takes account wire by wire of the double helical wires on the basis of general thin rod theory developed by [Love, A., 1944. Mathematical Theory of Elasticity. Dover Publications, New York]. The proposed kinematics are based on the assumption that wires are un-lubricated and therefore that no relative sliding between adjacent wires happens.     

Analysis of temperature and stress field in Al alloy’s twin wire welding

By analyzing the shape of twin wire welding’s arcs and the track of droplets’ transition, the phenomenon that the twin wire welding’s fore arc and rear arc all deflect to the middle of the two arcs is found. Based on this the double ellipsoid heat source model is amended, and a heat source model which can apply to calculate the twin wire welding’s temperature field is put forward. This model is testified by actual experiment of temperature sampling. By comparing the temperature field of twin wire welding and single wire welding, the results show that twin wire welding has slender weld pool the end part of which is ellipsoid, and its HAZ is narrower than that of single wire welding. So, twin wire welding can not only reduce the Al alloy generating hot crack, but can also weaken the “overaging” softened phenomenon of heat treated strengthening Al alloy. In the end, the evolving rules of 2219 Al alloy’s longitudinal and transverse stress when welded with twin wire welding are analyzed.     

Some dynamic properties of axially loaded wire ropes

Results are presented on the transverse damping, the transverse fundamental natural frequency as well as the longitudinal fundamental natural frequency for axially loaded wire ropes. Twelve different wire ropes are tested. During the test, a mass is centrally attached to the rope. The results indicate an increasing transverse damping with an increasing axial load. This damping is primarily attributed to a Coulomb damping. Although core material and construction influence the transverse damping of the wire rope, no relationships are found when comparing this damping with the structural strength, the number of wires used in the rope, the alloy composition or the heat treatment of the rope materials. The transverse and longitudinal fundamental natural frequencies of the axially loaded wire ropes with a mass centrally attached has been satisfactorily modeled.