Research In The Theory And Methods About Damage Detection Of Plate And Shell Structure

Damage detection of structure is a subject developed in the present years with the need of the engineering. Because of the serious injuries and deaths and the serious economic loss, and the increasing expenses with aging, fatigue and corrosion of structure, it is necessary for people to find the damage and maintain it in time. So it is significant to inquire the principle of the damage diagnos and the method of the damage detection.The main research is to analysis the damage character and to raise the damage detection method for the plate and shell structure. The research content includes:(1) Research on the influence of the local damage to the dynamic characteristic of the plate structure. Based on the continuous vibration equilibrium equation, the pulse function is used to present the material property, the influence of the local damage to the inherent frequency and the mode is deduced, especially the amendments function is advanced. The result shows that the influence to the mode is more serious than to the frequency, it is suitable to take the parameter related to the mode as the damage signature.(2) Research on the damage signature for the plate structure. Firstly the sensitivity of the frequency and the mode to the local damage is studied. Then the variation of the first mode is adopted as the damage signature, the sensitivity and the independent of normalization are certificated, and the advantage of which is listed. The result shows that the variation rate of the first mode is appropriate for the damage signature.(3) Research on the linear method for damage detection. Firstly the proposition of the variation rate of the first mode is proved. With the characteristic to damage localization, the detection for multiply damage is resolved through combined optimization of some single damage mode. And the new method can resolve the problem of model error.(4) Research on the use of the intelligence method in the damage detection. Because of the damage localization of the variation rate of the first mode, the scale of the network and the search range are reduced greatly. And the advantage...