Mechanical part fault diagnosis method based on SVD and VMD

The invention relates to a mechanical part fault diagnosis method based on SVD and VMD. The method comprises the following steps: acquiring a vibration signal of a mechanical part; comparing the mechanical part with a fault-free mechanical part, and judging whether abnormity exists or not; performing singular value decomposition on the vibration signal, and calculating a difference value of adjacent singular values of a singular value sequence to obtain a difference spectrum; analyzing the differential spectrum, determining a reconstruction order, and reconstructing the vibration signal of the mechanical part; decomposing the reconstructed signal into modal components, and determining the optimal number of the modal components; carrying out variational mode decomposition on the vibration signal of the mechanical part subjected to original fault diagnosis; selecting a modal component with a relatively large weighted kurtosis index value for signal synthesis; generating an envelope spectrum by using the synthes