High frequency traveling vibration of a fan casing may be excited by the wake of rotating fan blades.High vibration level of a fan casing was observed during the test of a turbofan engine

the causes were analyzed

and the vibration-absorbing measures were investigated.Then

a casing structural optimization method for reducing vibration was proposed.Vibration experiments for casings before and after optimization were carried out.The results indicate that the optimization method is very efficient.