【作者】 冯坤；

【导师】 杨永春；

【作者基本信息】 中国海洋大学 ， 港口、海岸及近海工程， 2011， 硕士

【摘要】 本文综述了结构损伤识别与健康监测的意义、发展历程与研究现状。基于振动测试的全局性损伤诊断方法是当前研究的热点,基于此本文较为全面地介绍了现有的各种损伤识别方法,并对各种方法的优缺点进行了概述。受结构实验测试技术的限制,大型结构周边环境复杂以及测量过程中不确定干扰多等因素,导致结构响应的实测数据会受到噪声影响产生误差。而随着损伤识别技术及有限元应用软件的发展,很多结构损伤识别与健康监测方法已被应用于实际工程结构中。针对工程中实际情况,本文分别以简支梁、三维框架结构、Benchmark框架模型、海洋平台结构为分析对象,选择柔度差值曲率法、模态应变能法、改进后的模态应变能法和CMCM方法(交叉模型交叉模态方法)4种结构损伤识别指标,对其抗噪声性能进行了对比分析。对噪声的敏感性分析,需要综合考虑识别方法和结构自身的特点。分析结果表明,改进后的模态应变能法和CMCM方法对于一维结构和框架结构损伤定位均具有较好的抗噪声性能。这为今后工程化实施提供了筛选、检验、对比的方法。本文总结了国内外对模态应变能损伤诊断方法的研究现状,提出了一种基于轴向模态应变能比的损伤诊断方法。该方法仅需要测试结构损伤前后的前两阶模态信息,不需要结构转动自由度的测试信息。文中首先利用导管架海洋平台结构有限元数值模型对该方法进行了数值验证,随后对该方法进行了抗噪声性能的检验,最后通过导管架平台物理模型实验对该方法进行了实验验证。结果表明本文提出的损伤诊断方法能够有效地对结构的损伤进行定位,并可进行初步的构件损伤程度的评估,具有良好的抗噪声性能,有望在实际工程中得到应用。更多还原

【Abstract】 This paper reviews the significance,development and present situation of structural damage detection and health monitoring. Vibration-based global damage detection method is a hotspot of current research. This paper presents a comprehensive introduction to the various damage identification methods.The advantages and disadvantages of each method are outlined.As the experimental techniques of the structures are limited, the surrounding environment of large and complex civil engineering structures is complex, the uncertainty and the interference in the process of measurement and other factors, the measured data of civil structural response must be affected by noise. In view of this situation, considering the randomness of noise and damage stability characteristics, simply supported beam, three-dimensional frame, Benchmark framework model and offshore platform structure are analyzed to compare the ability to suppress noise interference among the flexibility difference curvature method, modal strain energy method, modified modal strain energy method and CMCM method by finite element numerical analogy. It is necessary to consider the recognition method noise immunity, but also need to consider the structure of its own characteristics. The results show that the modified modal strain energy method and CMCM method have good noise immunity for one-dimensional structure and frame structure. It provides screening, testing, comparison of methods for the implementation of engineering in the future.This paper systematically studies damage detection methods based on modal strain energy and summarizes the present situation of them in both home and abroad, axial modal strain energy ratio method is proposed on the basis of the existing methods. The major advantages associated with the new method are that it only makes use of pre- and post-damage modal natural shapes that are available for only the first and second-order modes. Additionally, the new method does not require the testing information of rotational degree of freedoms. First, numerical study of jacket offshore platform based on modal parameters generated from finite element models is carried out. Next, the new method is tested with the noise resistance. Finally, the new method is testified again with the physical model of offshore platform.According to the results, the new method is shown to be effective for the complex structural damage detection and has a good noise resistance. There is hope to apply it to practical application.更多还原