【作者】 宋仙云；

【导师】 唐小兵；

【作者基本信息】 武汉理工大学 ， 结构工程， 2010， 硕士

【摘要】 工程结构在使用过程中由于自然、人为的原因会产生裂纹、松动、脱落等破坏。当其发展到一定程度而又没有被察觉处理时,有可能导致灾难性事故,严重威胁到人们的生命、财产安全。为了及时检测到损伤所在位置及程度,国内外学者做了大量研究,得到了一系列的损伤识别成果,其中目前研究比较多的是利用结构振动模态参数的变化判断结构损伤。本文论述了基于模态分析理论损伤识别的各种方法及其使用范围、优劣特性。详细地研究了损伤识别的模态频率法、模态振型法、曲率模态法、应变模态法、柔度差和柔度曲率法、模态应变能法的原理。以柔度法原理为基础对一空间杆系结构的损伤识别作了详细分析。由于空间结构自由度多,振型复杂,为简化分析并利用差分法求结构柔度斜率、柔度曲率,将空间问题转化为分析若干平面的问题。利用有限元动力学分析,得到结构前几阶的模态频率和模态振型,由模态参数计算结构的柔度,研究了结构损伤对于各个不同方向柔度的灵敏性；分析了结构各阶模态对于柔度的影响,柔度和结构的固有频率成反比,因此结构的低阶模态对柔度影响比较大,利用结构一阶模态得到柔度就能很好判断结构的损伤,当利用结构高阶模态计算柔度时往往不能准确判断结构损伤的位置；探讨了结构损伤程度对柔度曲率的影响。在有限元分析基础上对杆系结构做了试验分析,利用CRAS系统测量结构的模态参数,对测量振型作质量归一化处理,根据实测数据运用柔度曲率法对单个单元损伤的情况作分析,其在小损伤时候不是太灵敏,对于大损伤可以准确判断损伤位置。另外着重论述了基于频率改变方法的损伤识别,由有限元计算结构中每一单元在不同损伤程度时结构不同阶频率的改变量,根据计算结果建立损伤识别数据库,由实测不同阶频率的改变对比数据库中数据辨别损伤位置及相对损伤程度。柔度法、频率变化法在预测结构损伤程度上还存在不足,更达不到判断损伤对结构寿命影响的程度,因此要实际应用,还需做大量研究。更多还原

【Abstract】 Because of natural, man-made causes, engineering structures will occur cracks, loose and fall off damage. When it developed to a certain extent without being detected or treated, there may lead to catastrophic accidents, serious threat to lives and property of people. In order to timely detect the location of injury and extent, the domestic scholars have done a lot research for this, obtained a series of damage identification results, in which the most study is on the use of changing the modal parameters to diagnose structural damages.This article discusses the various damage identification methods based on the theory of modal analysis and their scope of use, advantages and disadvantages of features. Studied in detail the principle of damage identification base on the modal frequency method, mode shapes method, curvature mode method, strain mode method, flexibility and flexibility curvature difference method, modal strain energy principle.By the principles of compliance method, there are detailed analysis of the damage identification of a Structure in space. Because the spatial structure degree of freedom are many and more complicated modes, the space is transformed into a number of plane problems for sake of simplify the analysis and solve the flexibility slope, flexibility curvature by difference method. That finite element dynamic analysis get the structure the modal frequencies and mode shapes of the front steps. This calculated the structure of the flexibility by modal parameters and studied the structural damage cause the sensitivity of flexibility in all different directions; This has analyzed the mode regarding the flexibility influence.Flexibility and structure of natural frequency is inversely proportional.Thus the lower modes have the greatest impact on the flexibility. Flexibility can be a good estimate the damage useing the structure of the first modal, when using the structure of high model flexibility often can not be calculated accurately the location of structural damage; Also analyse structural damage to the flexibility curvature affect.The same frame structure made test analysis based on the finite element analysis. Using CRAS system measured modal parameters, then the measurement mode for the quality of normalization.Using flexibility curvature by the measured data calculateing analyse a single damage of element situations. This is not too sensitive in the small damage, for large damage can accurately determine the damage location. Another focuses on damage indentification methods based on the frequency change, finite element method calculated the frequency change by each element of the structure in different degree of injury. According to the calculated results established database, different frequency bands by the measured change in comparative data in the database to identify the damage location and relative degree of damage.There is still insufficient that predicted the extent of structural damage by compliance method, frequency method, and fail to determine the extent of structural life, therefore the actual application needs to do a lot of research.更多还原