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。     

基于漏磁原理的钢丝绳无损检测励磁结构设计与优化北大核心CSCD

为提高钢丝绳无损检测装置的励磁效果,基于漏磁原理在不改变永磁体总体积前提下,增加轴向永磁体,通过改变永磁体充磁方向,增加磁路横向磁感线密度,同时在轴向充磁永磁体之间安装电磁屏蔽器避免形成干扰磁感线;使用有限元分析对装置参数进行优化设计后,钢丝绳最大磁化强度提高约8.8%,饱和长度提高约24%,励磁效果优于已有励磁结构。     

舰载机柜钢丝绳隔振器试验研究

基于振动数据采集器和单轴加速度传感器,使用理论和试验方法对某舰载机柜的钢丝绳隔振器进行正弦振动试验研究,通过数据采集器分析软件计算所得的振动传递率曲线对钢丝绳隔振器的动力学特性进行探讨分析,采用不同安装形式下的钢丝绳隔振器对其一致性特性进行研究。试验结果表明,舰载机柜钢丝绳隔振器振动传递率特性满足钢丝绳隔振器国军标规范文件的要求,钢丝绳隔振器的一致性较好,可为其他舰载机柜钢丝绳隔振器选型优化设计提供理论和试验依据。     

矿车与柔性车挡碰撞过程仿真分析

多盘摩擦吸能器与柔性车挡联动,可以有效地将矿车的动能转化为摩擦热。钢丝绳是多盘吸能器的重要组成部分,其受力是多盘吸能器设计的重要参数。为了准确分析钢丝绳受力的变化规律,建立了相应的非线性仿真模型,从而分析了矿车与柔性车挡之间的碰撞规律。     

小型磁化器条件下的变励磁MFL检测新方法

为解决常规储罐和管道的漏磁检测(MFL)方法中磁化器体积大、耗能多的缺点,提出了一种小型磁化器条件下的变励磁MFL检测新方法。首先,分析了小磁化器条件下被测钢板磁化状态随外部励磁强度的变化特性,推导了偏置磁化条件下励磁通变化量与漏磁场变化率的关系模型;其次,根据所建立的关系模型,设计了一种新型变励磁MFL检测探头,并给出变励磁MFL法的系统实现方案;再次,结合实现方案,搭建了变励磁MFL相应的实验平台;最后,在该平台上,开展了一系列的物理实验并对实验结果进行了深入讨论。实验结果表明,所提变励磁MFL法无需对被测钢板进行局部饱和磁化,适合小型磁化器条件并具有较高的灵敏度。变励磁MFL法为漏磁检测领域提供了一种新的检测思路。     

DLT微机励磁装置在电站中的应用

分析了DLT6000励磁装置的工作原理和系统功能单元,并对DLT6000调节器在中小型水电站励磁系统改造中所带来的效果进行了详细的分析总结.     

钢丝绳电动葫芦导绳器的研究及相关检验标准的探讨

对钢丝绳电动葫芦导绳器的种类及作用进行了研究,分析了检验中存在的问题,并对电动葫芦导绳器相关的检验标准进行了探讨。     

基于物联网的客运索道安全监测系统研究

近年来,随着客运索道总条数、总长度的增加,乘坐人数不断增长,客运索道安全成为索道管理的重中之重。2022年冬奥会将在我国北京市和张家口市举行,雪地客运索道作为主要载人特种设备,保障索道设备运行安全至关重要。本文通过对客运索道设备关键部件进行分析,对钢丝绳结构进行实时损伤在线监测,提出了利用漏磁探测技术,在钢丝绳运动过程中对其轴向进行励磁,使钢丝绳磁场达到饱和,撤去磁场后对钢丝绳上的极限剩磁进行检测。同时,分析了对客运索道关键节点安装传感器,对关键参数等信息进行数据采集,可以实现基于物联网云平台的客运索道全方位安全监测。     

一种转轴式钢丝绳隔震器

介绍了一种转轴式钢丝绳隔震器,它不但具有普通钢丝绳隔震器的优点,而且其结构设计了可转动的转轴,在受力变形过程中,钢丝绳两端转动,不承受弯矩。可使隔震系统在冲击载荷作用下由第一刚度迅速降低为第二刚度,提高了隔震系统的隔震率。     

对电梯上行超速保护装置技术的探讨

根据GB7588-2003<电梯制造与安装安全规范>中关于上行超速保护装置的技术要求,讨论了数种常用电梯上行超速保护装置,探讨改善钢丝绳夹绳器可靠性的途径,提出了可供参考的钢丝绳夹绳器检验方法.     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....