内积加时间窗阻尼诊断新方法及在凸轮轴上的应用

New method for damping identification based on inner product calculation combining with time window and application on camshaft

提出一种采用内积模极值法和加时间窗技术相结合的方法进行阻尼诊断。首先利用频谱细化的傅里叶变换(FFT+FT)方法识别出信号频谱中峰值最高时所对应的共振频率,然后基于共振频率构造出指数衰减函数,用这个函数与响应信号做内积运算来初步诊断出衰减系数,以此衰减系数来构造时间窗函数,通过给原信号加上时间窗消减负频率项影响,来提高衰减系数的识别精度,得到准确的阻尼比。仿真算例验证该方法的有效性及准确性;同时,将其应用到凸轮轴的阻尼诊断上,证实该方法具有一定的工程实用意义。

A combinational method of inner product calculation and time window for damping identification is presented in this paper. It starts from using Fast Fourier Transform combining with Fourier Transfer refine （FFT＋FT） to obtain the resonant frequency of the most top spectral peak, then, use it to set a decay function. Inner product operation is conducted between the decay function and the response signal to get a rough value of decay factor which is used to set a time window function. This window function solves the problem of interference produced by the negative frequency item and improves the accuracy of damping ratio. Simulation examples verify that the identification is accurate, and the application of this proposed method in the camshaft test validate that this method is practical in engineering.