简支梁损伤定位的直接指标法应用

结构损伤诊断主要内容是对各种工程结构进行检测并对检测结果做适当的分析,从而确定结构的健康状况。损伤诊断要解决的关键问题之一是判断结构损伤的位置。结构损伤会对结构的物理特性如刚度,质量,阻尼等产生影响,从而使结构的模态参数如固有频率、振型等发生改变。研究结果表明应变相比固有频率和振型对局部损伤更加敏感。基于应变模态差分原理的损伤定位直接指标法ISMSD(Strain Mode Shape Difference)具有无需原始模态数据的优点。本文通过有限元方法计算得到非贯穿裂纹梁的位移模态，进而计算得到应变模态。再对经过三次样条插值的光滑应变模态差分曲线进行直接损伤指标值计算。对假定两处损伤的简支梁在几种不同损伤程度状况下进行数值仿真计算,直接根据直接指标值的大小正确地判定了损伤位置,尤其是损伤量较小时。

THE APPLICATION OF DIRECT INDEX METHOD OFSIMPLY SUPPORTED BEAM DAMAGE LOCATION DETECTION

The main contents of structure damage diagnosis are to determine the structure health status and analysis the research results.One key problem is to detect the damage location in the structure. Damage generally change the structure physical properties (i.e., stiffness, mass, and damping) corresponding with the modal characteristics of the structure (i.e., natural frequencies, modal shapes, and modal damping).The research results show that strain mode can be more sensitive and effective to local damage. The direct index method of damage location detection ISMSD is based on difference theory, without the modal parameter of the original structure. FEM numerical simulation to partial crack with different degree is also done. The criteria of damage location detection are obtained by strain mode difference curve through cubic spline interpolation. It has been possible to identify the damage to a reasonable level of accuracy.