呼吸裂纹梁非线性动力特性研究  

Study on nonlinear dynamic response of a beam with a breathing crack

作　　者：胡家顺[1] 冯新[1] 周晶[1] 

机构地区：[1]大连理工大学海岸和近海工程国家重点试验室,大连116024

出　　处：《振动与冲击》2009年第1期76-80,87,共6页Journal of Vibration and Shock

基　　金：国家自然科学基金重点项目(50439010);教育部科学技术研究重大项目(305003)

摘　　要：疲劳裂纹是结构损伤的重要形式,是引起结构破坏的主要因素之一。建立了含非对称疲劳裂纹梁的非线性数值分析模型,采用奇异单元模拟裂纹尖端的效应,使用无摩擦的接触单元模拟疲劳裂纹的张开闭合特性,研究了结构在简谐荷载激励下的非线性动力特性。以悬臂梁为例分别分析了外部激励频率、裂纹深度以及裂纹位置等参数的变化对系统非线性行为的影响,重点讨论了系统的亚谐、超谐等共振现象,并且提出了系统频率的相对幅值用于辨识裂纹深度的方法。研究结果为裂纹结构的损伤识别提供了一定的理论基础和参考。Fatigue crack is one of main damages existing in structural members,it can lead to structure failure due to repeated loads.The nonlinear dynamic characteristics of a cantilever beam with a non-propagating asymmetric fatigue crack subjected to a harmonic load at its tip were studied.A breathing crack model was introduced to describe the nonlinear dynamic behavior of the fatigue crack and could be simulated as a frictionless contact plane problem.Meanwhile,a quarter-point element was used to simulate the crack tip effects.Based on the proposed model,the effects of various factors,such as,excitation frequency,crack depth and crack position on the nonlinear dynamic characteristics were discussed in detail.A relatively amplitude of the system frequency was proposed to detect the crack severity based on analysis of sub-harmonics and super-harmonics at the crack interface.The results provided theory and reference for damage identification of cracked structures.

关 键 词：呼吸裂纹 接触分析 亚谐共振 超谐共振 幅值谱 

分 类 号：TU311.41[建筑科学—结构工程]