摘要
提出了基于线调频小波时频分解的时变系统瞬时模态参数识别方法。该方法应用线调频小波对时变系统加速度响应信号进行时频分析,通过小波脊方法提取瞬时频率,再应用卡尔曼滤波进行自适应分解获得各阶响应的幅值信息;为了更精确地识别时变结构的阻尼比,该研究推导了基于幅值能量法的时变阻尼比识别方法;线调频小波相比传统小波对具有更高的能量聚集性,因此该方法具有更高的瞬时频率提取精度,此外传统的基于幅值的阻尼识别方法易受噪声干扰,能量法在短区间内基于幅值进行整体积分具有较强的抗噪性和更高的识别精度。仿真算例中,构造了一个三自由度时变结构来验证识别方法,通过与传统小波和时域峰值法作对比,验证了方法识别瞬时模态参数的精确性和抗噪性。
An instantaneous modal parameter identification method of time-varying systems based on the time-frequency decomposition of chirplet transform(CT)was proposed.First,the adaptive linear chirplet transform was applied in the time-frequency analysis of time-varying system acceleration responses,and the instantaneous frequency was extracted by using the wavelet ridge method.Then each order response was adaptively decomposed to obtain the amplitude information with a Kalman filter.In order to more accurately identify the damping ratio of the structure,a time-varying damping ratio identification method based on the amplitude energy was also proposed.It is found that CT has higher energy concentration than the traditional wavelet.Therefore,the method has higher instantaneous frequency extraction accuracy.In addition,the traditional amplitude-based damping identification method is susceptible to noise interference,while the energy method has strong noise immunity and higher identification accuracy based on the integral of the amplitude in a short interval.As a simulation example,a three-degree-of-freedom time-varying structure was constructed to verify the correctness and anti-noise capability of the method.The method can more precisely identify the instantaneous frequency and damping ratio,comparing with the traditional wavelet and time domain peak method.
作者
张杰
史治宇
赵宗爽
ZHANG Jie;SHI Zhiyu;ZHAO Zongshuang(State Key Laboratory of Mechanics and Control of Mechanical Structures,College of Aeronautics,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China)
出处
《振动与冲击》
EI
CSCD
北大核心
2020年第22期103-109,118,共8页
Journal of Vibration and Shock
基金
国家自然科学基金(11172131,11232007)
江苏高校优势学科建设工程。
关键词
线调频小波变换(CT)
时频脊提取
自适应滤波
时变系统
瞬时模态参数识别
能量法
chirplet transform(CT)
time-frequency ridge extraction
adaptive filtering
time-varying system
instantaneous modal parameters identification
energy method
