螺栓连接悬臂梁超谐响应特性试验研究

Super-harmonic resonance experiment about bolt connected cantilever beam

针对光电设备中广泛采用的螺栓连接形式,采用单螺栓连接悬臂梁模型,对螺栓连接引起的结构振动特性的改变进行实验。利用激振器和振动信号采集设备,结合快速傅立叶分析方法指出螺栓连接模型在一定条件下有超谐共振响应现象。模型的谐振频率随着扭矩的增大呈先增大后减小的现象。结构在相同扭矩下,第一阶谐振频率随着激励幅值的增大而减小,结构呈渐软非线性。给定1/2和1/3倍谐振频率下的正弦激励,系统能量随着激励幅值的增大而趋向于固有频率处。结构在低预紧扭矩下,非线性项中二次项对结构响应起主要作用;在较高预紧下,非线性项中三次非线性项对结构响应起主要作用。该实验结果对开展后续连接结构的非线性振动特性的研究有一定的理论和指导意义。

A single bolt connection cantilever model is used to analyze the difference of vibrational property due to bolt-joint which is widely used in optoelectronic devices.The phenomenon of super-harmonic resonance due to bolt joint connection is verified using the shaker experiment combined with the signal acquisition equipment.In the case that the torque incerease,the resonance frequency of the model increase first and then decrease.The first resonance frequency decrease when the excitation amplitude decrease and the nonlinear structure characteristic is soft nonlinear.The energy inclined to the natural frequency when the excitation amplitude become large while the system excited under the sinusoidal 1/2 and 1/3 times the resonant frequency.When the system is under low pretension,quadratic nonlinear terms in the structural response plays the major role;while at higher pretension,cubic nonlinear term in nonlinear terms of the structural response plays the major role.The results about research has some theoretical and guidance about subsequent nonlinear vibration characteristic calculation.