螺栓连接非线性振动特性研究

摘要：在不同的外界激励下，螺栓连接常常表现出一定的非线性。为研究螺栓连接的非线性特性，设计了一个螺栓连接系统，并对其进行不同基础激励下的正弦扫频实验。通过实验数据的分析得到了螺栓连接的共振频率和相对阻尼系数，发现其随着激励量级的不同呈现出较明显的非线性特性。在理论模型研究中，将系统简化为非线性弹簧、非线性阻尼器、质量块的单自由度模型，并利用实验数据对非线性方程中的系数进行了识别。利用此非线性模型，求出系统的主共振频率和相对阻尼系数，它们与实验结果相比差别较小，说明文中所给的非线性方程能较好描述螺栓连接的振动特性。

Nonlinear vibrational characteristic of bolt-joints

Bolt-joints are widely used in many structures, they reveal some nonlinearity subjected to different envi- ronment excitations generally. In order to study their nonlinear characteristic, a bolt-joint system was designed, and sin- sweep vibration tests were done on the system subjected to different base exciting. The resonant frequencies and the rela- tive damping coefficients of the bolt-joint system were obtained by analyzing the test data, they showed obvious nonlinear characteristic with the vibration level changing. In theoretic study, the system was simplified as a single degree of freedom mass-spring-damper model with a nonlinear spring and a nonlinear damper. The coefficients of the nonlinear dynamic e- quation were identified using the test data. Last, the main resonant frequencies and the relative damping coefficients of the system were obtained by using the nonlinear equation. The theoretic results were coincident with the test results better, it indicated that the nonlinear dynamic equation deduced here can describe vibration characteristics of a bolt-joint system.