Abstract:

：The displacement and strain modal analysis of vibrating screen beam is studied, the results show that the modal frequency relative deviation between intact and damaged beam is minor, the displacement mode shapes have no obvious mutation, but the strain mode shapes have mutation peaks for the damaged beam. Thus a damage indicator is defined by using the strain modal variable ratio before and after damage, the strain modal variable ratio increases with the increase of damage degree, the strain modal variable ratio is obtained by the least squares fitting method of the strain modes. The initial fatigue crack size is determined by damage degree of the beam, then the residual life of fatigue crack growth of the beam is predicted by the Paris formula. The analysis results show that the strain modal variable ratio is a sensitive and reliable damage indicator for indicating the damage location and damage degree. The prediction of the crack propagation residual life can provide reference for maintenance forecast of the vibrating screen beam, which can ensure safe and reliable operation of the vibrating screen.

Key words: crack propagation, damage identification, residual life, strain mode, vibrating screen beam