Design and Modeling on Stranded Wires Helical Springs

A stranded wires helical spring is formed of a multilayer and coaxial strand of several wires twisted together with the same direction of spiral. Compared with the conventional single wire spring, the stranded wires helical spring has the notable predominance in strength, damping and vibration reduction, which is usually used in aircraft engines, automatic weapons, etc. However, due to its complicated structure, the precise computation of its strength and rigidity need be a correct mathematical model, which then will be imported to finite element analysis software for solutions. Equations on solving geometric parameters, such as external diameters of strands and screw pitches of wires, are put forward in the paper. It also proposes a novel methodology on solving geometric parameters and establishing entity models of the stranded wires helical spring, which provides foundation of computing mechanical parameters by FEA. Then mathematical models on the centre line of the strand and the surface curve of each wire, after closing two ends in a spring, are proposed. Finally, geometric parameters are solved in a case study, and a 3D entity model of a spring with 3 layers and 16 wires is established, which has validated the accuracy of the proposed methodology and the 3D entity mathematical model. The method provides a new way to design stranded wire helical spring.

Three-stage Method for Identifying the Dynamic Model Parameters of Stranded Wire Helical Springs

The dynamic behavior of the stranded wire helical spring is described by a modified Bouc-Wen model while the model parameters must be identified using an identification method and experimental data. Existing identification methods usually relies either solely nonlinear iterative algorithms or manually trial and error. Therefore, the identification process can be rather time consuming and effort taking. As a result, these methods are not ideal for engineering applications. To come up with a more practical method, a three-stage identification method is proposed. Periodic loading and identification simulations are carried out to verify the effectiveness of the proposed method. Noises are added to the simulated data to test the performance of the proposed method when dealing with noise contaminated data. The simulation results indicate that the proposed method is able to give satisfying results when the noise levels are set to be 0.01, 0.03, 0.05 and 0.07. In addition, the proposed method is also applied to experimental data and compared with an existing method. The experimental data is acquired through a periodic loading test. The experiment results suggest that the proposed method features better accuracy compared with the existing method. An effective approach is proposed for identifying the model parameters of the stranded wire helical spring.

A novel finite element model for single-layered wire strand

A new finite element model for single-layered strand was investigated for accurate and efficient mechanical behavior analysis.Mathematical model was created by sectional path-nodes sweeping and dynamic node-beam mapping.Geometric relations between nodes in center core wire and helical wires were deduced in tension and bending incorporating material elasticity theory and deformation geometrical compatibility.Based on Timoshenko beam theory,strand of a pitch length was modeled with specific material,geometric parameters and synthesized constraint equations defined in ANSYS software,and predetermined load cases were performed.The obtained results show that discrepancies between suggested method and Costello theory do not exceed 1.51% in tension and 6.21% in bending,which verifies the correctness and accuracy of the suggested finite element model in predicting mechanical behavior of single-layered wire strand.

Stress Analysis of Wire Strands by Mesoscale Mechanics

Steel wire ropes have wide application in a variety of engineering fields such as ocean engineering and civil engineering.The stress calculation for steel wire ropes is of crucial importance when conducting strength and fatigue analyses.In this study,we performed a finite element analysis of single-strand steel wire ropes.For the geometric modeling,we used an analytic geometry of space method.We established helical line equations and used the coordinates of the contact points.The finite-element model was simplified using the periodic law.Periodic boundary conditions were used to simulate a wire strand of infinite length under tensile strain,for which we calculated the cross-sectional stresses and inner forces.The results showed that bending and torsion moments emerged when the wire strand was under tensile load.In some cases,the bending stress reached 18%of the tensile stress,and the torsion stress reached 29%of the tensile stress,which means that the total stress was higher than the nominal stress.Whereas in ear-lier studies,a conservative prediction of nominal stress was not possible,the results of our strength and fatigue analyses were more conservative.

Computation of the Strand Resistance Using the Core Wire Strain Measurement

This paper proposes a method enabling to compute the prestressing strand resistance using the strain measured on only one core wire. Numerical analysis is conducted considering the pitch length of the strand and the diameters of the core wire and helical wires as parameters. The results verify that the relation between the stresses of the core wire and helical wires can be expressed in terms of the helical angle. Based on this observation, a formula computing directly the prestress force in the strand from the strain measured in the core wire is suggested. Owing to the recently developed measurement method for the core wire strain, the proposed formula can be exploited to determine the prestress of the strand.

新型CFRP索股锚固体系设计及试验研究

为改善CFRP索股锚固体系的锚固性能及CFRP索股受力不均问题,研制了锚具内壁面带凹槽的CFRP索股锚固体系,对其进行了试验测试,分析了锚固体系破坏模式、荷载-位移、锚固效率、CFRP索股应变变化规律,通过应力变异系数评估了锚具内壁面凹槽设置和预张拉对CFRP索股应力不均匀改善的效果。研究结果表明,锚具内壁面设置凹槽和对CFRP索股进行预张拉能够提高锚固体系的锚固效率,锚固效率可达99%以上;试验观察到CFRP索股存在受力不均现象,引起CFRP索股受力不均的原因主要与CFRP索股长度不一致和粘结介质的剪切变形相关;通过在锚具内壁面设置凹槽和对CFRP索股进行预张拉能够改善锚固体系CFRP索股的应力不均程度,锚具内壁面凹槽深度为2 mm、间距为5 mm,预紧力为10%名义极限荷载时,锚固体系在自由段中点和加载端处的平均应力变异系数分别降低了7.16%、3.86%。

基于整体与局部纹理特征加权融合的港机装备钢丝绳断丝缺陷检测研究

钢丝绳是港机装备的重要部件,由于作业工况环境恶劣,钢丝绳表面极易引起断丝等缺陷,影响港机装备作业安全。针对港机装备钢丝绳表面油泥严重、光照亮度不均,以及港机装备钢丝绳断丝缺陷能够在钢丝绳股顶钢丝椭圆形区域内有效体现的特点,提出了一种基于钢丝绳整体纹理特征与股顶钢丝椭圆形区域边缘轮廓纹理特征加权融合的钢丝绳断丝缺陷检测方法。首先采用图像降噪、增强、校正技术对钢丝绳原始图像进行预处理。然后采用图像平滑、阈值分割及边缘特征提取技术对股顶钢丝椭圆形区域边缘轮廓进行提取。接着采用局部二值模式(LBP)算子分别提取钢丝绳整体纹理特征与股顶钢丝椭圆形区域边缘轮廓纹理特征,并对钢丝绳整体纹理及边缘轮廓纹理特征进行特征加权融合。最后对加权融合后的特征向量进行主成分分析(PCA)法降维,并应用支持向量机(SVM)技术对钢丝绳断丝缺陷进行检测。研究结果表明:本文提出的方法对实际工况下重油泥、光照不均等钢丝绳断丝缺陷具有较好的检测效果,具有一定的工程应用价值。

输电线路断股捋回修复机器人设计

传统断股线路修复方法为人工高空修补,该方法工作强度高、风险大且效率低下。在现有断股线路修复装置的基础上,设计一种输电线路断股捋回修复机器人,通过PLC系统驱动机器人沿架空地线行走,在地线断股处通过驱动齿轮带动断股输电线路同环绕套筒旋转,并通过捋线套筒内弹簧圆柱件挤压断股电线,到输电线路凹陷部分,实现断股捋回与压接,从而修复断股输电线路。最终,通过实验验证了断股捋回修复机器人具有稳定与可靠的断股导线修复能力。

15×K6-EPIWRC多层阻旋转抗冲击钢丝绳研制

多层压实股钢丝绳阻旋转性能在一些应用场合有极其重要的意义,钢丝绳旋转超过相关要求会影响工作效率,甚至产生安全事故。为最大限度地克服阻旋转性差、断芯、外层磨损超标3大难题,新产品采用1-4+4/15结构形式,对绳芯进行注塑处理,以满足客户要求。26.0 mm钢丝绳研制完成后,实际破断拉力达到681.0 kN,钢丝绳各项指标均达到客户标准和EN12385标准要求,工艺设计合理,绳捻制紧密,抗旋转性能优良,抗冲击载荷性能好。

索道用钢丝绳轴向弹性模量有限元仿真研究

轴向弹性模量是索道用钢丝绳重要的力学特性,影响着索道设计中对钢丝绳的选用。应用微分几何理论推导每根钢丝的中心线参数方程,通过Creo建立一个捻距长度的钢丝绳三维模型,将三维模型文件导入Hypermesh中划分网格、设置边界条件,最后利用Abaqus计算得到不同轴向拉力下钢丝绳的变形与等效应力云图,得出钢丝绳拉力与等效弹性模量的关系。结果表明,在拉力较小时,钢丝绳等效弹性模量随拉力增大而增大,当拉力到达一定值后,等效弹性模量稳定在钢丝材料弹性模量的0.64倍。

三角股电梯曳引钢丝绳力学特性及失效分析

为进一步提升电梯曳引系统传动的安全性和可靠性,优化电梯曳引系统中受力部件钢丝绳与绳槽之间的受力情况。本研究首先分析电梯曳引系统的结构与失效形式,然后提出并建立新型电梯三角股曳引钢丝绳及其绳槽几何结构,最后建立电梯曳引三角股钢丝绳与绳槽接触受力的有限元模型,并进行仿真分析。仿真结果表明:当电梯载荷为1 kN,捻角分别为12°、16°和20°时,曳引三角股钢丝绳的最大接触应力分别为229.6 MPa、430.5 MPa和648.6 MPa,捻角越大,曳引钢丝绳接触应力越大,越容易磨损失效。该研究为三角股钢丝绳在电梯曳引系统中的安全应用提供了理论参考。

铝合金芯铝绞线断裂原因分析

高压架空电缆在输电过程中断裂是严重的安全事故。近年来,铝合金芯铝绞线已逐步替代钢芯铝绞线,但对其在输电过程中断裂的原因研究较少。借助扫描电子显微镜和能谱仪对失效的铝合金芯铝绞线断口的形貌和成分进行了观察和分析。结果表明:铝绞线断口存在明显的贝纹线和大量镁硅相。由于电缆长期发生微风引起的振动,在拉压应力的反复作用下,脆性镁硅相会割裂基体,其周围产生裂纹,并逐渐扩展形成贝纹线,即铝合金芯铝绞线断裂是合金元素偏聚形成了镁硅类脆性相导致的疲劳断裂。

预绞丝成型工艺研究与设备开发

预绞丝是特高压架空线路上的连接金具,能传递机械载荷、电气负荷以及保护电缆。预绞丝制造难点是成型张力不恒定,影响预绞丝尺寸精度,导致金具与电缆配合度降低,加剧磨损与松动,影响电气性能。从预绞丝成型工艺出发,对成型张力进行研究,分析成型条件,设计张力控制机构和系统;运用模糊神经网络算法对张力进行控制,研发出新型预绞丝成型设备并进行试验。试验结果符合控制技术指标,设备性能满足生产需求。

X光检测技术在输电检修作业中的应用

文章介绍了X光检技术在输电检修作业中,用来探究耐张线路压接管内部压接质量的重要作用,列举了在实际生产作业中发现的压接管典型缺陷;并对13353支压接管测量结果进行深入分析,得出耐热导线压接管钢芯断股断开、钢锚断裂的比例约为普通导线的84倍,且危急缺陷率为普通导线的6.4倍;随后通过机械性能(握力测试)、电气性能(温升、电阻测试)试验验证了通过安装备份线夹的方法处理钢芯断股、断开缺陷的可行性;最后针对X光射线源辐射剂量进行了检测,发现在正常工作中作业人员受到的辐射量为0.53~0.63 nSv/h,远低于工业标准规定2.5μSv/h,因此在日常检修作业中X光射线源辐射剂量对人体的伤害可以忽略不计。

竖井提升用三角股钢丝绳伸缩分析

竖井提升用6V三角股钢丝绳在投入使用后出现较大延伸和偶尔缩短现象,对竖井提升系统钢丝绳运行情况进行跟踪测量,并结合6V三角股钢丝绳的结构特性进行分析。钢丝绳延伸主要有初始结构性延伸、弹性延伸和永久延伸,钢丝绳使用初期和中期结构延伸较大,钢丝绳偶尔缩短属于弹性延伸,永久延伸阶段钢丝绳已经达到使用寿命末期或接近报废状态。钢丝绳载荷状态、预张拉效果以及设备运行情况等都影响钢丝绳的伸缩状况。钢丝绳进行预张拉处理非常重要,可以一定程度上消除结构延伸和捻制应力,使钢丝绳结构更加稳定。

一起500kV导线线夹过热缺陷案例分析

线夹作为导线连接的重要部件,在电力系统架空线路中被广泛使用,因导线断股、螺栓松动接触不良等导致的线夹过热现象时有发生。本文对一起变电站500kV主变变高开关上方引下线线夹异常发热的紧急缺陷案例进行分析,开展直流电阻试验、大电流温升试验、滑移试验、单线拉断力试验及解体检查,最终确定线夹过热原因为固定螺栓在投运时的紧固力矩不满足标准要求,垫片配置数量不统一,长期运行过程中导线受力导致线夹螺栓松动,致使线夹端部更易受潮腐蚀并进一步加剧接触不良,从而导致接触电阻增大,以及滑移试验与拉断力试验不符合要求。最后,提出对该批次导线加强红外监测的针对性运维策略。

大跨度后张拉缓粘结预应力结构施工质量控制

缓粘结预应力技术是有粘结、无粘结施工技术发展到一定阶段的创新,其施工工艺简单,质量容易控制,节点布置灵活,耐久性能优异,工程经济性强。但预应力专业施工单位一般规模不大,施工水平参差不齐,施工质量不易控制,因此,施工质量控制是缓粘结预应力施工的重点。

地震灾害风险管理和实施技术分析

围绕地震灾害风险管理与实施技术开展分析,提出构建震害信息管理系统,用于第一时间掌握地震造成的破坏程度,以此为后续救援管理提供数据支撑。同时,阐述最新的抗震加固设计方法,结合完善的地震保险制度,降低我国面对巨大自然灾害时的财政负担,加强风险转移,削减地震灾害造成的损失,保障人员生命安全,促进灾后重建工作的落实。

钢绞线用钢丝绳股表示之合理性商榷

虽然钢绞线和钢丝绳股同为钢丝一次螺旋捻制结构,考虑到ISO17893(E):2004 Steel wire ropes——Vocabulary,designations and classifications已明确给出钢丝绳股定义,且钢绞线和钢丝绳股之间确实存在诸多明显不同,分析认为,尽管国内外相关标准用钢丝绳股表示钢绞线似乎已成习惯,但其合理性值得商榷。

长寿命与环保港口钢丝绳制造相关问题研究

港口面临的环保压力越来越大,对钢丝绳的质量要求也越来越高。通过采用压实股组绳、钢丝绳内置含油纤维绳、钢芯聚合物包覆、增加外层绳股数、优化钢芯结构、精细结构参数设计与严格控制生产过程等措施以响应港口对钢丝绳的长寿命要求,通过使用高质量润滑油脂、重视润滑油脂对使用环境的适应性与实施润滑工艺标准化等措施以稳定钢丝绳润滑质量,最大限度满足港口减少海洋环境污染与实施清洁文明生产的需要。