文档介绍：、东南大学硕士学位论文自然激励条件下结构破损的无损检测方法研究摘要 r f|海载结构在使用寿命期间内不可避免会发生各种破损。由于破损的存在将导致结构承载能力的下降,从而导致整个结构的破坏。结果不仅缩短了结构的使用寿命,而且还威胁到生命和财产安全。因此无损地对结构进行检测以发现并定位破损及诊断出破损程度,无疑具重大的经济、安全价值。目前广泛使用动测技术来检测结构,但都存在各种局限,当缺少结构的健康档案时就难以应用到工程、\/ 实际。针对此种情况n本文提出了一种缺乏健康档案等基准对比数据、便于工程一应用的结构破损检测的称为动静法的新方法,它无需结构破损前的测试数据或用 FEM精确建模获得结构原型数据来作为基准数据,而是在环境激励下,将测得结构的动态响应,通过随机减量时域法获得结构在初始位移下的自由响应,利用傅立叶变换将时域响应转换到频域获得结构的频响函数。根据LTI系统频响函数的确定性就可求得结构在恒位移(恒载荷)下的表面切向应变分布。由分析可知, 结构存在破损时,在静载荷下结构破损区域内的应变分布会发生突变。据此现象, 根据结构的表面切向应变分布,从而判别结构破损与否,并定位破损及大致估计破损程度。在支腿上引入裂纹的框架式房屋模型上运用此方法进行破损检测,结果表明此方法能准确、方便地判别结构破损,并较大地减少了计算量和测试时间, 便于工程应用。关键词:模态分析无损检测动测技术随机减量时域法随机激励应变分布东南大学硕士学位论文 Research on Non-destructive Damage Detection Method of Structure Under Environmental Condition Abstract There are diversified damages happened on the structure undertaking loadS during itsservice damage on the structure willdecrease the CatTying capacity,which results in thedestroy oftheentirestructure,thus thall ever do harm tothesecurity ofpeople andwealth. detection on structure tofindand 10catethedamage and evaluate thedegree ofdamage has great economic and secure Value. Nowadays dynamic testingtechnique iswidely applied todetectdamage on structure,but ithassignificant practical limitations forapplications tothetype of structure detected the face of thisdifficulty,this Paper develops anew damage detectionmethod calleddynamic—statary·-method which needn,t datameasured before the occurrence ofdamage or theprior FEM accurate model ,by use ofstraingauge toobtain thedynamic response of structure under the environment condition,after transforming the stressdistributionof themeasured structure Can begained,and from which we can identifyand locatedamages and estimate thedegree demonstrate themethod on asteel--framed structure with result shows thismethod Can detectthedamage wellandtruly,anddramatically decreases the WOrk putation. Keyword: modal anal