The study state of art and development trend of structural damage identification research is simply summarized in this paper . hilbert - huang transform ( hht ) is applied to the damage identification and intrinsic frequency confirmation of time - variable structures . furthermore , a kind of inverse calculation is presented to calculate structural stiffness . this method can solve three main problems : the time that damage occurred , the location and the degree of damage 本文简要总结了结构损伤识别领域的研究现状和趋势,围绕损伤引起固有频率变化这个特征,将希尔伯特?黄变换( hht )应用于时变结构的损伤识别和损伤前后固有频率确定上,并结合牛顿迭代法,对结构刚度进行反演计算,从而解决结构损伤识别领域所关注的三个主要问题:损伤发生时间、损伤位置以及损伤的程度。
Chapter two introduced the basic ideas of emd theories briefly , and then discussed the emd - based time - frequency analysis method ' s basic agrithom . the conclusion was deduced that the method is valid in the field of signals processing and fault diagnosis in rotating machinery by simulation and real signal analysis . chapter three discussed the origin of emd method ' s end effect , then studied the direct , time - series based and neuron network based data extention technologys to weaken the end effect 第二章介绍了基于emd时频分析方法的一些基本概念；阐述了emd方法和基于emd的希尔伯特变换的基本原理和算法；在此基础上，用基于emd的时频分析方法对仿真和实际信号进行了分析验证，结果表明把该方法引入旋转机械振动信号时频分析和故障诊断领域是有效的。
