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。

Abstract: Bolt joints are widely used in many structures, they represent some nonlinearity subjected to different environment exciting generally. In order to study on their nonlinear characteristic, a bolt-joints system is designed, and the sin-sweep vibration tests are done on the system subjected to different base exciting. The resonant frequencies and the relative damping coefficients of the bolt-joints system are obtained by analyzing the test data, they show obvious nonlinear characteristic with the vibration level changing. In theory study, the system is simplified to be a single freedom degree mass-spring-damper model with nonlinear spring and nonlinear damper. The coefficients of the nonlinear equation are identified by the test data. Last, the main resonant frequencies and the relative damping coefficients of the system are obtained by the nonlinear equation. The theory results are coincident with the test results better, as shows that the nonlinear equation in the paper depicts the vibration characteristics of the bolt-joints better.