【作者】 袁建明；

【导师】 康宜华； 武新军；

【作者基本信息】 华中科技大学 ， 机械电子工程， 2012， 博士

【摘要】 拉索广泛应用于大跨度桥梁、大型建筑、游览设施,为确保其安全运营,在役定期检测十分必要。本学位针对拉索大直径、厚保护层的结构特征,对在役拉索金属截面积测量方法和关键技术进行系统、深入的研究,实现了拉索金属截面积变化量的精确测量和变化部位的准确测定。为解决拉索金属截面积变化量的测定问题,提出了一种基于导出磁通量的磁性测量方法。建立了该测量方法的磁阻分析模型,揭示出测量点处霍尔元件输出电压变化率与拉索金属截面积变化率成正比关系。然后,通过实验进行了验证。系统地分析了测量系统的标定、截面积变化的径向位置、磁化电流的大小、导磁磁路的数量、霍尔元件的放置位置、拉索的应力等对测量精度的影响。为确定拉索断面上金属截面积变化的部位,提出了一种基于磁通量离散阵列模型的测定方法。构建出金属截面磁通量离散阵列模型及测量方程组,并经过实验进行了验证。为满足在线实时定位测量的要求,引入粒子群优化算法解决模型参数的优化迭代计算,完成反演定位测量问题的快速求解。通过实验验证了该反演定位测量方法的有效性。针对拉索直径大、难以有效磁化的特点,采用有限元仿真计算,分析了拉索磁化线圈长径比、层数等参数对磁场分布的影响规律,给出了非均匀磁化时不同长径比、不同磁导率、整体磁化、局部磁化等条件下圆柱棒的退磁因子,研究了退磁场的作用规律,在此基础上,并通过圆柱棒和拉索钢丝束局部磁化效果的等效性分析,得到了可使拉索局部磁化效果最优的主路技术磁化方法,有效减小了磁化器的重量。为适应不同的应用需求,提出了分离式和可重构式两种爬行器结构,在现场进行了爬升实验,爬行器样机负载能力强、体积小、重量轻、拆装方便,能够适应不同直径拉索的在役检测。这两项技术是解决工程化在役拉索检测的关键。更多还原

【Abstract】 Cables are widely used in large-span bridges, large buildings and tour facilities. To ensure safe operation of the in-service cables, it is necessary to periodically test them. In this dissertation, for the cable’s structure with large diameter and thick protecting layer, the metal cross-sectional area measurement methods and key technologies are studied systemically in depth. Precise measurement of the variation of metal cross-sectional area of cable and the position of metal cross-sectional area change are achieved.To measure the variation of metal cross-sectional area of cable, a magnetic measurement method based on lead-out magnetic flux is proposed. The analytical model of the reluctance for this method has been established, which reveals the variation rate of the Hall elements output voltage at the measurement point is proportional to the variation rate of the cable’s metal cross-sectional area. Later, the model is verified by experiments. Analysis has been conducted systematically for the impacting factors to measurement accuracy, which include the calibration of the measuring system, the radial position of the cross-sectional area change, the magnitude of the magnetizing current, the number of the magnetic circuits, the placement of the Hall elements and the stress in cable.To determine the location of the cable’s metal cross-sectional area change, a method based on magnetic flux discrete array model has been developed. The corresponding discrete array model of magnetic flux in metal cross-section and mathematic equations have been constructed. The model is verified by experiments. To meet the requirements of online real-time locating measurement, the particle swarm optimization algorithm has been introduced to optimize iteration calculation of the model parameters, achieving the fast solution of the inverse problem of locating measurement. The effectiveness of this inversion locating measurement method is verified by experiment.On the cable’s features of large diameter and difficulty of being magnetized effectively, finite element simulation calculation is applied to analyze the impacts of the parameters such as the ratio of the length and diameter, number of layers of magnetization coil, etc. on the magnetic field distribution, and the demagnetization factors of cylindrical rod under the conditions of different ratios of the length and diameter, permeability, overall magnetization and local magnetization in non-uniform magnetization are achieved, and the effect of demagnetizing field is also studied. On this basis of the results above, by the equivalence analysis of local magnetization effect of the cylindrical rod and the wire bundle, the main road magnetization method has been obtained to optimize the cable local magnetizaiton. The method effectively reduces the weight of the magnetizer. Two crawler structures, namely separate and reconfigurable structures have been put forward to adapt to different application requirements. Climbing experiments have been carried in field. The crawler prototypes have strong loading capacity, small size and light weight, which is easy to dismantle and able to adapt to the testing of cables with different diameters in service. These two technologies are the key points to solve the problem of engineering testing of in-service cables.更多还原