螺栓连接大变形梁非线性振动特性的实验研究

柔性机械臂、大型可展开天线等机械结构的动作精度受运动过程中大变形几何非线性和连接处接触非线性的影响十分显著。以含螺栓连接结构的大变形梁作为研究对象，针对动力学建模和振动特性开展了实验研究，通过数值计算验证了实验发现的非线性振动特性。搭建了含螺栓连接柔性大变形梁的实验台架，开展了敲击和正弦激振的实验测试。实验结果表明，螺栓连接的柔性梁较连续梁的（无螺栓连接）模态频率降低，阻尼增加，反映出随着激励能量增大，模态频率降低的非线性模态特征。改变螺栓连接位置会显著影响结构的模态频率，其变化规律可由求解线性矩阵特征值定性反映。

An Experimental Study on Nonlinear Vibration Characteristics of Large Deformed Bolted Beams

The operation accuracy of mechanical equipment such as flexible space manipulator, large-scale deployable antenna is significantly affected by the nonlinear vibration at the joints and the large deformations during its movement. This paper, taking the large-deformation beam with bolted joint structure as the research object, carries out experimental researches on its dynamic modeling and vibration characteristics, and verifies them through numerical calculation. An experimental bench with bolted flexible beams was built, and experimental tests of percussion and sinusoidal excitation were carried out. The experimental results show that the modal frequency of the bolted-connected flexible beam is lower than that of the continuous beam (without connection), and the damping is increased, which exhibits the nonlinear modal characteristics that the modal frequency decreases as the excitation energy increases. Changing the bolt connection position will significantly affect the structural modal frequency, and the influence law can be qualitatively reflected by solving the linear matrix eigenvalues.