Study On Identification Of Structure Modal Parameters Based On The Excitation Of Ship Operational Condition

The identification of structure parameters has great instructive in ship and marine design, especially in vibration attenuation design. Traditional identification method need to know the excitation signal, but it is extremely difficult to get from a huge structure like ship or marine structure. If we load the excitation on the structure in manual way, it is not only easy to harm the structure, but also very expensive.Operational modal identification method can identify the modal parameters well without the excitation signal by technical way. It has a high value in engineering practice. The excitation is very complicated in ship operational condition, but it can be considered as white noise combined with single frequency excitation. On the base of analysis the feature of the excitations which is on the ship operational condition, the author chose NExT and ERA technique to identify the structure parameters. And this method is precise and fast.To prove the feasibility of NExT and ERA technique in identifying the structure parameters on the ship operational condition, the author derived the theory in details, and discussed the feature of excitation on the ship operational condition.Then the author identified the parameters of a typical structure by using the programs. And the result is pretty good.At last, the experiment in the water with the ship modal which is designed by the author proved the feasibility of NExT and ERA technique in the field of identification of structure parameters.