三峡升船机钢丝绳断丝与磨损检测原理与实现

根据三峡升船机钢丝绳的使用特点，提出了三峡升船机钢丝绳检测的原理与方法，采用周向多回路对钢丝绳轴向励磁，利用漏磁场原理检测钢丝绳断丝，磁桥回路检测钢丝绳磨损量，并实现在一个传感器中对断丝和磨损两种缺陷信息的综合检测。在信号处理方面设计了相应的电路和软件，实现了缺陷的定量分析。     

一种钢丝绳自动检测装置的设计

为了克服钢丝绳人为检测法误差大、判断不可靠的缺点,根据漏磁法和磁桥路检测原理,并在集成霍尔元件和LCD矩阵式键盘的基础上,开发了一种既可在线进行钢丝绳断丝位置、断丝根数判别,又可与PC机联机工作实现智能化检测诊断的高精度钢丝绳缺陷检测装置。     

基于弱磁的钢丝绳探伤技术研究

依据磁荷分析理论,建立了钢丝绳断丝磁偶极子模型,计算了单丝断口处漏磁场的分布规律。采用正交设计方法对激磁回路参数进行了实验研究,确定了弱磁磁化系统的基本结构与基本参数,实现了磁化与检测的一体化设计。依据弱磁激励情况下钢丝绳缺欠处的漏磁场强度,选择了高灵敏度MR01型磁阻式传感器;给出了多种断丝形态的实测曲线。实验结果表明,基于MR01型磁阻式传感器的钢丝绳磁检测系统,不仅能够实现对小尺寸断口缺陷的有效检测,而且可用于剩磁检测,为钢丝绳探伤技术的发展提供了有价值的科学依据。     

钢丝绳缺陷的微磁无损检测技术研究

为了探讨微磁检测技术在钢丝绳无损探伤领域的应用,采用有限元法,分析了无外加磁场激励状态下利用钢丝绳自身剩余磁场实现断丝缺陷检测的可行性。计算了钢丝绳缺陷处及周围空气中的漏磁场强度、分布规律及可测性;论述了地磁场的影响,为微磁检测技术提供了理论依据。通过对钢丝绳微磁检测方法的实验研究,得出了不同断丝状态下漏磁场的检测结果及变化规律。给出了钢丝绳金属截面损失与检测系统输出量的函数关系,验证了微磁无损探伤技术的可行性与可靠性。     

高噪下的钢丝绳断丝定量检测

研究高噪情况下的钢丝绳断丝定量检测信号处理。利用时域与频域相结合的处理算法实现断丝的特征提取，采用这些方法对高噪下的钢丝绳磁检测信号进行处理，能够清楚地区分噪声和损伤信号。该方法运算量小，适合于实时在线的钢丝绳检测。     

自激过程与非齐次Poisson过程用于钢丝绳断丝计数过程的建模与预测

对于钢丝绳集中断丝过程，提出了断丝自激点过程的建模方法；对于钢丝绳均匀断丝过程，提出了断丝非齐次Ｐｏｉｓｓｏｎ过程的建模方法。依据极大似然估计原理，给出了钢丝绳寿命预测方法和钢丝绳最佳更换期。     

自激过程与非齐次Poisson过程用于钢丝绳断丝计数过程的建模与…

对于钢丝绳集中断丝过程，提出了断丝自激点过程的建模方法，对于钢丝绳均匀断丝过程，提出了断丝非齐次Ｐｏｉｓｓｏｎ过程的建模方法，依据极大似然估计原理，给出了钢丝绳寿命预测方法和钢丝绳最佳更换期。     

基于主成分分析和BP神经网络的钢丝绳断丝定量检测方法

针对目前钢丝绳断丝定量检测中存在的问题,充分利用主成分分析与BP神经网络的优点,提出了基于主成分分析与BP神经网络相结合的钢丝绳断丝定量检测方法。采用主成分分析法对钢丝绳断丝信号的原始特征属性进行预处理,得到钢丝绳断丝信号主成分特征属性,并以此作为BP神经网络的输入,建立钢丝绳断丝信号主成分特征属性与断丝数目之间的关系,并对钢丝绳断丝数目进行预测;主成分分析方法减少了原始特征属性的维数,消除了属性之间的相关性;同时,主成分特征属性作为BP神经网络的输入,也简化了网络的结构。实例测试结果表明,基于主成分分析的神经网络钢丝绳断丝检测方法与常规BP神经网络方法相比,具有更高的检测精度和更少的计算量。     

小波分析在钢丝绳无损检测中的应用

目前钢丝绳无损检测中对断丝信号的处理仍比较困难，小波分析可以聚焦到信号的不同细节，于是本文将它应用于断丝信号的消噪平滑和奇异性检测，使得信号更加光滑，消除了干扰信号，避免断丝误判，同时使奇异点更加明显，有效地提高内外部断丝识别和定量检测的准确率，实验证明该方法效果明显。     

钢缆断丝NDT信号实时处理的一种有效方法

本文在分析钢丝绳断丝无损检测信号特点的基础上，经过试验，对比闻几种常用的信号处理方法，提出一种有效的能用于实时处理的方法，可以准确地识别钢丝绳断丝信号．     

悬索桥缆索钢丝损伤超声导波检测数值模拟

为了实现对大跨悬索桥缆索钢丝损伤的有效检测,采用理论分析和数值模拟相结合的方法,对超声导波无损检测技术进行研究。通过理论求解钢丝中导波的频散曲线,分析频散特性和波结构,选取中心频率为200 kHz的L(0,1)模态进行钢丝断丝损伤检测;利用有限元软件,研究了钢丝中导波的频散特性和波结构,通过二维傅里叶变换技术对钢丝中的低阶导波模态进行识别,进一步分析了缺陷尺寸和角度对L(0,1)模态缺陷反射系数的影响;最后,对L(0,1)模态在两根钢丝和七根钢丝的断丝处的缺陷回波进行了数值模拟。数值模拟与理论分析结果相吻合,说明低频L(0,1)模态可以有效地对缆索钢丝断丝损伤进行远距离检测。     

Failure Analysis of Failed Wire Rope

Failure of an old rope from a stringing lattice transmission towers occurred in winter while the rope was being removed to make way for a new rope. Fracture took place around mid-span. At that time, ambient temperature was −22 °C. Wire rope was in service for nearly 50 years. We were given the mandate to determine the reasons for the fracture of the wire rope and also to suggest measures to prevent such failures from occurring. The study involved laboratory testing (mechanical and metallographic) of representative wire rope samples. The effect of low temperature (from room temperature to −40 °C) on the tensile behavior of wires and wire rope samples was evaluated. In addition, we designed an instrumented impact test to assess the effect of notches, low temperatures and dynamic loading on the fracture behavior; however, no standards were available for direct comparison. Optical metallography was used to judge the extent of corrosion and the nature of microstructure and the cleanliness of the steel. The fracture morphology of broken tensile and impact specimens was carried out using scanning electron microscopy to establish relations between test parameters and fracture modes. Results indicate that considerations have to be given to the occurrence of corrosion, notches, low temperatures, and dynamic loading conditions when replacing wire ropes and this may necessitate the replacement of wire rope earlier than the time dictated by the criterion of 10% loss in breaking strength. Results also indicate that impact testing is a better evaluator of the susceptibility of wire ropes to brittle fracture than tensile tests.     

Bending fatigue behaviour of bearing ropes working around pulleys of different materials

Nondestructive quantitative detection and artificial detection were carried out to study bending fatigue behaviour and failure mechanisms of wire ropes. When working around nylon pulleys, wire ropes exhibit a slowly increasing of fracture rate and total damage in one lay length. The bending fatigue life of wire ropes is twice longer than that of ropes working around steel pulleys. The primary failure mode of wire ropes working around nylon pulleys is fatigue fracture and the fracture surfaces of wires exhibit a wide crack propagation zone and narrow tear zone.     

Microstructural manifestations of fractured Z-profile steel wires on the outer layer of a failed locked coil wire rope

Locked coil wire ropes, by virtue of their unique design and construction, have specialized applications in aerial ropeways, mine hoist installations, suspension bridge cables, and so forth. In such specialty ropes, the outer layer is constructed of Z-profile wires that provide not only effective interlocking but also a continuous working surface for withstanding in-service wear. The compact construction and fill-factor of locked coil wire ropes make them relatively impervious to the ingress of moisture and render them less vulnerable to corrosion. However, such ropes are comparatively more rigid than conventional wire ropes with fiber cores and therefore are more susceptible to the adverse effects of bending stresses. The reasons for premature in-service wire rope failures are rather complex but frequently may be attributed to inappropriate wire quality and/or abusive operating environment. In either case, a systematic investigation to diagnose precisely the genesis of failure is desirable. This article provides a microstructural insight into the causes of wire breakages on the outer layer of a 40 mm diameter locked coil wire rope during service. The study reveals that the breakages of Z-profile wires on the outer rope layer were abrasion induced and accentuated by arrays of fine transverse cracks that developed on a surface martensite layer.     

Metallurgical Investigation of Failed Locked Coil Track Ropes Used in a Mining Conveyor

A locked coil track rope (LCTR) is essentially composed of wires (round and rail-shaped) laid helically in different layers. These wire ropes are sometimes used in conveyors carrying empty and loaded buckets in mining areas. During service, such wire ropes may fail prematurely due to disintegration/failure of individual groups of wires. To understand the genesis of LCTR wire failures, a detailed metallurgical investigation of failed rope wires was made and included visual examination, optical microscopy, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Two types of failed wires were investigated; one is from a 40 mm diameter locked coil track rope and the other from a 53 mm locked coil track rope. Optical microscopy of failed round wires in the 53 mm diameter rope clearly revealed fully decarburized layers at the surface and a few grain-boundary cracks. From the location of the failure, it was clear that apart from static tensile loads, the wire ropes had been subjected to bending and unbending loads near the saddle, as fully loaded or empty buckets traveled access the conveyor. The SEM studies confirmed that the fracture had been caused by initiation of fatigue cracks in the decarburized zone under conditions of repeated bending and unbending stresses superimposed on the static tensile load.     

Theoretical approach to the solutions of axially loaded complex ropes

Abstract

A rational analysis procedure consisting of a complete cycle of systematic calculations has been developed for the theoretical solutions of problems in describing the behavior of axially loaded complex ropes consisting of wires and strands, which were simulated as particle‐motion models. In essence, axial and rotational strains of a rope were specified. Constitutive relations of the loaded wires and strands were obtained through compatibility of motion requirements. Material law was then imposed to determine the internal force of each wire. Nonlinear equilibrium relations of wires were applied to describe the relationship among sectional stresses and external forces. The theory is used in the analysis of a 6 × 7 wire rope with an independent wire rope core (IWRC). Some solutions and comparisons to other research results have been provided. Results show that the recursive nature of the wire in the model enhanced the calculation of constitutive relations and made it easier to apply to the analysis of complex ropes having multiple orders.