中文摘要：

针对变速齿轮箱中复合故障的故障特征提取，提出了一种基于阶次解调谱的变速齿轮箱复合故障诊断方法。先用线调频小波路径追踪算法从原始振动信号中提取转频曲线，再根据转频曲线对原始振动信号进行等角度重采样，将时域非平稳信号转化为角域周期平稳信号，最后对角域周期平稳信号进行能量算子解调分析，根据阶次解调谱中的调制信息进行变速齿轮箱复合故障诊断。通过算法仿真和应用实例对包含齿轮局部故障和轴承局部故障的变速齿轮箱复合故障进行了分析，结果表明，该方法在无转速计的情况下能有效地提取变速齿轮箱复合故障的故障特征。

英文摘要：

To solve the problem of extracting fault characteristics from variational-speed gearbox with compound faults, a com- pound fault diagnosis method for variational-speed gearbox based on order tracking demodulation spectrum is proposed. Since the rotation speed of variational-speed gearbox is time-varying, so are the fault characteristics because they are always related to the rotation rate. In the proposed method, the rotation speed is estimated from the original vibration signals by chirplet path following algorithm. In order to transform the non-stationary signal in time domain to the cyclostationary signal in angular do- main, the even angle resampling of the original signal is carried out according to the estimated rotation speed. The cyclostation- ary signal is analyzed by energy operator demodulation, and the compound fault diagnosis of variational-speed gearbox is per- formed according to the modulation information provided by the order tracking demodulation spectrum. The proposed method is applied to a variational-speed gearbox with compound faults including the gear local fault and the local hearing fault, and the results show that this method can effectively, in absence of tachometer, extract fault characteristics from the variational-speed gearbox with compound faults.