Analysis of the effect of crack on the inherent frequency of blades
In order to study the effect of cracks on blade natural frequency,a finite element geometric model of blade was established,and the effects of crack location and crack depth on blade natural frequency were analyzed.The results show that:when the crack is in different positions of the blade,the decrease rate of natural frequency of the blade is 4.06%(transition arc)>1.08%(middle blade)>0.04%(near the tip of the blade).When the crack is in different depths,the decrease rate of blade natural frequency is 13.25%(40 mm)>8.12%(30 mm)>4.06%(20 mm)>1.35%(10 mm).In order to verify the validity of the simulation results,the experimental analysis was carried out,and the experimental results were basically consistent with the simulation results:the influence of cracks on the natural frequency at different positions of the blade was as follows:the transition arc>the middle of the blade shape>near the tip of the blade,and the natural frequency at the transition arc of the blade decreased with the increase of the crack depth.The research results can provide some reference for the prediction and detection of early cracks in blades.
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