直裂纹悬臂梁系统阻尼特性分析

以裂纹悬臂梁系统为研究对象,基于ANSYS软件采用梁单元、平面单元和接触单元,建立了一个直裂纹梁有限元模型.利用接触单元模拟裂纹的呼吸效应,并通过与文献测定的固有频率对比验证了模型的有效性.基于所提的模型,分析了冲击激励与正弦激励下,摩擦对系统振动特性的影响;在忽略摩擦的情况下,分析了系统阻尼比及固有频率随裂纹深度和裂纹位置的变化规律.研究结果表明:裂纹处的界面摩擦对系统振动影响不大,阻尼比在一定的程度上可以作为诊断裂纹程度的依据.

Damping Characteristic Analysis of Cantilever Beam with Straight Crack

Taking cracked cantilever beam system as the research project, a finite element model of straight-cracked cantilever beam was established on the basis of the ANSYS by using beam, plane and contact elements. The contact elements were used to simulate breathing effects of crack, and the effectiveness of the as-proposed model was verified by comparing with the natural frequency in the literature. Under impulsive and sinusoidal excitation, the effects of friction on vibration characteristics were analyzed based on the model. The change rules of system damping ratio and natural frequency with the crack depth and crack position were analyzed with ignoring friction. The results showed that the interface friction of crack has few effects on system vibration, and damping ratio could be used as a parameter of crack detection to some extent.