低预紧扭矩螺栓连接悬臂梁的2倍谐振响应

为准确获得光电设备中螺栓连接对系统结构动态响应特性的影响,研究了装配连接环节导致的非线性振动特性。采用单螺对栓连接悬臂梁模型,对螺栓连接引起的结构振动特性的改变进行了研究和实验。利用接触有限元方法对低预紧扭矩下结构非线性振动特性进行了时域数值积分仿真分析,给出了不同激励量级周期受迫激励下的相轨迹曲线;结合快速傅里叶分析方法,指出此模型在低预紧扭矩下存在1/2频率激励下的谐振现象。基于激振器实验,给出了实验自由振动响应幅值和受迫振动响应幅值的变化,证实了仿真结果的准确性。数值仿真和激振器实验均表明:激励量级越大,螺栓连接引起的非线性振动中自由振动分量对结构动态响应的影响越大。该方法对开展后续连接结构的非线性振动特性的研究有指导意义。

Second super-harmonic resonance response of cantilever beam with bolt joint under low pretension

To obtain the effect of bolt-joint in a theodolite on the dynamic response of system ,the nonlinear property caused by assemble connection was researched .A single bolt connection cantilever model was used to analyze the change of structure vibration characteristics from the bolt-joint .Then , the finite element method was employed in the simulation analysis in time domain for the nonlinear vibration characteristics of cantilever model connected by the bolt joint under low pretension ,and the phase diagrams under different loads were obtained .With Fast Fourier Transfer method ,the super-harmonic resonances under 1/2 natural frequency excitation were pointed out . By an exciter experiment ,the response amplitudes by free vibration and forced vibration were given ,respectively , and the simulation results were verified .It shows that the greater the excitation magnitude is ,the greater the impact from the nonlinear term is .This method has guiding significance for research on nonlinear vibration characteristics of connection structures .