To obtain the equivalent damping ratio of the blade and its variation relationship with the response amplitude without acquiring detailed blade properties
a calculation method for the equivalent damping ratio of the blade based on traction loading is proposed. Based on vibration theory
the response characteristics of the blade under different periodic excitation are analyzed
and the mapping relationship among the equivalent damping ratio
deformation
and steady-state amplitude is constructed. Three large blades are loaded in steps using Tug Fatigue Testing system
and the equivalent damping ratios under various stages of amplitude are calculated
revealing the nearly linear relationship between the blade's equivalent damping ratio and the steady-state amplitude. At the full-load stage
the equivalent damping ratio of the blade reachs 2-3 times that under small amplitudes. Additionally
the calculated results are compared with those obtained from the free decay method
verifying the feasibility and applicability of the method for calculating the blade's equivalent damping ratio based on traction loading.
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references
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