Through the conventional strength calculation of blade

the vibration frequency calculation

the finite element strength calculation

and finite element dynamic response analysis etc.

the analysed results of low-pressure blade rupture of steam turbine in one power plant show that the locations of blade fractures all are in the maximum dynamic stress zones resulted from resonance of axial first order vibration and torsional vibration.The fatigue fracture of blade mainly caused by steam flow excited vibration with frequency of 500~620 Hz

for this

the preventive measures

such as enhancing the corrosion resistant ability of blade material

adopting blade structure with crown-shaped ring

as well as low load low vacuum operation etc.

have been put forward.