开口裂纹梁振动特性参数分析  

Parametric Analysis of the Vibration Characteristics of an Open Cracked Beam

作　　者：李立新 赵桂欣 孟帅[2] LI Lixin;ZHAO Guixin;MENG Shuai(Hudong Zhonghua Shipbuilding(Group)Co.,Ltd.,Shanghai 200129,China;State Key Laboratory of Marine Engineering,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海沪东中华造船(集团)有限公司研发设计院,上海200129 [2]上海交通大学海洋工程国家重点实验室,上海200240

出　　处：《力学季刊》2023年第3期685-695,共11页Chinese Quarterly of Mechanics

基　　金：国家自然科学基金(51879161)。

摘　　要：开展仿真分析探究梁边界条件、裂纹位置、裂纹程度、梁几何尺寸对开口裂纹矩形梁振动特性的影响.采用等效刚度模型建立裂纹梁结构振动方程,并与试验比较完成验证.预报梁在简支、悬臂、固支三种边界下,在不同位置发生不同程度裂纹损伤时的固有频率.研究发现,裂纹梁固有频率特性与完好无损梁曲率模态相关.裂纹可使固有频率降低,且降低程度随损伤程度增加而愈显著.裂纹位置接近完好梁某阶曲率模态零点(无效位置)/极点时,该阶固有频率受到影响将会减弱/增强.开展悬臂裂纹梁在不同几何尺寸下曲率模态分析.研究发现,曲率模态在裂纹处发生尖角突变现象,且尖角峰值随着损伤程度的增加而增大.裂纹位置接近某阶曲率模态极点/零点时,该阶模态受裂纹影响更显著/不明显.在裂纹相对位置和损伤程度相同时,增加梁长度使裂纹处尖角峰值减小,改变梁宽度不影响曲率模态,增加梁高度可使尖角峰值增加.研究成果可为试验提供基础,为扩建数据库,探索一种在线检测方法,基于实时大数据和人工智能技术开展各项振动参数综合分析,为实现梁裂纹智能识别与定位提供依据.A parametric analysis is conducted to investigate the effects of boundary conditions,physical dimensions,crack location and severity on the vibration characteristics of an open cracked rectangle beam.At first,the dynamic equation of a open cracked beam is established employing an equivalent stiffness model,and is validated through comparison with the experimental data.Then,the natural frequencies of a cracked beam with different crack locations and severities at pinned-pinned,cantilevered and clamped-clamped boundary conditions are predicted.It is demonstrated that the natural frequencies of the cracked beam are related to the curvature mode of the intact beam.The natural frequencies of the beam are reduced owing to the crack damage,and this effect becomes more remarkable with the increase of crack severity.However,when the crack occurs near the zero points(or poles)of one curvature mode,the crack effect on the corresponding natual frequency is weakened(or enhanced).Finally,the cantilever beam is taken as an example to investigate the crack effect on the cruvature modes at different geometric dimensions.Phenomena of cusp catastrophe at the crack location are witnessed in the curvature modes,and a higher crack damage severity leads to a higher abrupt peak value.However,when the crack occurs near the zero point(or poles)of an curvature mode,the effect of crack on the corresponding mode is reduced(or enhanced).Morover,when the crack occurs at a fixed relative position with the same crack severity,the increase of beam length leads to a decrease of the abrupt peak value,the variation of the beam width has negligible effect on the curvature modes,and the increase of beam height gives rise to an increase of the abrupt peak value.This study aims to develop an approach for online crack identification and location detection based on vibration data analysis utilizing the real-time database and artifical intelligence.The current simulations provide a preparation for carrying out future experimental tests.

关 键 词：裂纹梁 等效刚度模型 固有频率 曲率模态 参数分析 

分 类 号：TU311[建筑科学—结构工程]