一种机械系统非线性类别辨识方法
Type Identification for Mechanical Nonlinearity

针对含刚度非线性连续体系统非线性类别辨识问题,提出了一种基于瞬时频率峰值检测的机械系统非线性类别辨识方法。该方法首先根据被测系统结构特点,分别建立含间隙、立方刚度等5种机械系统常见的刚度非线性系统简化模型;通过研究各模型自由衰减振动瞬时频率分布特点,建立不同非线性模型瞬时频率曲线库;结合图形匹配算法,匹配被测系统实测瞬时频率与曲线库曲线,以匹配结果作为辨识指标,实现非线性类别辨识。将基于瞬时频率检测的非线性类别辨识方法应用于含间隙非线性悬臂梁系统,仿真分析与实验计算表明:被测系统瞬时频率曲线与间隙非线性曲线库匹配较好,匹配值明显小于与其他非线性曲线库匹配结果,验证了该非线性类别辨识方法的有效性。
For type identification of nonlinear continuum systems with stiffness nonlinearity, a classification strategy with peak detection algorithm is put forward. According to the structure of under test system, simplified models with 5 kinds of stiffness nonlinearity are constructed. The nonlinearity types are particularly interested in structural diagnostic, such as clearance nonlinearity and cubic nonlinearity. An instantaneous frequency library is then set up by studying the free oscillations and instantaneous frequencies of different models. The shape？？matching algorithm is used to compare the real instantaneous frequency with the curves in the library. And the results are taken up to the index to identify the nonlinearity types. For a cantilever beam system with clearance, the matching value between the real instantaneous frequency and the curve of clearance nonlinearity measured in this strategy gets obviously smaller than the others, verifying the effectiveness