考虑随机缺陷的网架结构损伤识别

发布时间：2018-04-17 23:10

本文选题：随机缺陷 + 网架结构　；参考：《河北科技大学》2014年硕士论文

【摘要】：大跨度空间网架结构由于其重量轻、结构合理、造型优美和力学性能好等优点,被广泛应用于大跨度公共建筑和民用设施。由于实际结构承受的荷载随机性较强且材料特性等具有各种初始随机缺陷,结构的几何特性、损伤演变机制和承载能力与设计的理想化模型往往会有所差异,因此原因发生损伤或者破坏的潜在危险较大,所以网架结构的随机损伤研究日益受到重视。另一方面,随着使用时间的增长,结构由于超载、周围环境变化、损伤累积等因素,损伤出现不可避免。并且结构的初始随机损伤也将会对结构损伤的检测带来影响。本文针对这些问题,从以下几个方面对有随机缺陷的网架结构损伤检测问题进行了研究:1)针对网架结构的模态特性和小波变换在信号处理方面的优势,采用基于曲率模态差和小波变换相结合的损伤识别方法对网架结构杆单元损伤进行检测,并通过对四种常见的网架结构(正放四角锥网架、两向正交正放网架、三向网架、蜂窝三角锥网架)进行数值模拟,验证了基于曲率模态差和小波变换相结合的损伤识别方法可以对多种网架进行杆单元损伤识别。2)假定结构随机缺陷的统计特征服从正态分布,采用ANSYS的PDS技术并结合结构模态分析确定结构响应的敏感参数。以四种常见网架结构为例,用MATLAB编程生成符合正态分布的随机数,写入ANSYS中构造具有随机缺陷的网架结构模型。3)以具有随机缺陷的网架结构模型作为初始结构,进行考虑缺陷的网架结构损伤识别。识别仍采用基于曲率模态差和小波变换相结合的方法,将随机模型与理想模型结果对比,表明在一定变异系数范围内,该方法可用于有随机缺陷网架结构损伤识别。
[Abstract]:Long-span space truss structures are widely used in public buildings and civil facilities due to their advantages such as light weight, reasonable structure, beautiful shape and good mechanical properties.Due to the randomness of the load and the material characteristics of the actual structure with various initial random defects, the geometric characteristics, damage evolution mechanism and load-carrying capacity of the structure are often different from the idealized model of the design.Therefore, there is a great potential danger of damage or damage, so the random damage of truss structure is paid more and more attention.On the other hand, with the increase of service time, structural damage is inevitable due to overload, environmental changes, damage accumulation and so on.And the initial random damage of the structure will also have an impact on the detection of structural damage.Aiming at these problems, the damage detection problem of space truss structures with random defects is studied in this paper from the following aspects: (1) aiming at the modal characteristics of grid structures and the advantages of wavelet transform in signal processing,The damage detection method based on curvature modal difference and wavelet transform is used to detect the damage of truss elements.The numerical simulation results show that the damage identification method based on curvature modal difference and wavelet transform can be used to identify the damage of various grid elements. 2) assuming that the statistical characteristics of the random defects of the structure follow the normal distribution.The sensitive parameters of structural response are determined by ANSYS PDS technique and structural modal analysis.Taking four kinds of common grid structure as an example, the random number that accords with normal distribution is generated by MATLAB programming, and the grid structure model with random defect is constructed in ANSYS. 3) the grid structure model with random defect is taken as the initial structure.Damage identification of grid structure considering defects is carried out.The method based on curvature modal difference and wavelet transform is still used to identify the damage of space truss structures with random defects. The results of random model and ideal model are compared. The results show that the method can be used to identify the damage of space truss structures with random defects in a certain range of coefficients of variation.
【学位授予单位】：河北科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU317;TU356

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