The transient response of a slant-cracked rotor system during shut-down has been analyzed while it is decelerating through the critical speed. Vibration response has been simulated by using finite element method (FEM) for flexural vibrations. An unbalance force and a harmonically-varying torque is applied on the rotor system. Subharmonic frequency components at an interval frequency corresponding to torsional frequency were found in the frequency domain (Fast Fourier Transform (FFT) plot). These peaks are centered on the critical speed of the rotor system when a slant crack is present and can be used to detect the crack. The fundamental mode shapes of the rotor bearing systems are wavelet transformed to identify the crack location. A peak is observed at the crack location in the spatial variation of the wavelet-transformed fundamental mode shape. A few suggestions for the detection of slant cracks in the rotor during shut-down are described.

已经分析了斜裂转子系统在停机过程中通过临界速度减速时的瞬态响应。通过使用有限元方法（FEM）来模拟弯曲振动的振动响应。在转子系统上施加不平衡力和谐波变化的转矩。在频域中找到了与扭转频率相对应的间隔频率处的次谐波频率分量（快速傅立叶变换（FFT）图）。当出现倾斜裂纹时，这些峰值集中在转子系统的临界速度上，可用于检测裂纹。对转子轴承系统的基本模式形状进行小波变换以识别裂纹位置。在小波变换后的基模形状的空间变化中的裂纹位置处观察到峰值。