The Research Of Beam Damage Identify Based On Structural Health Monitoring Theory

At the present time, the physical parameter identification method commonly considers the location and extent of element-level damage at the same time. It is very difficult to identify the damage and it often leads to wrong results of damage identification. The damage can be identified through two phases. That is we can identified the location of the damage at first and then identified the extent of the damage. The methodology, which is composed by the global identification and local identification, is an effective method to identify the structural damage in complex structures.Firstly, the differential equations of lateral bending free vibration of Euler-Bernoulli model and Timoshenke model are built. Then frequency equations of two different beams are derived with elastic rotation constraints at supports. According to the given boundary conditions, the natural frequencies of the beams are obtained.Secondly, the method to identify the flexural stiffness and boundary conditions with the frequencies is proposed. The feasibility to identify the stiffness and boundary conditions simultaneously is discussed. The accuracy of the proposed method and the effects of measurement errors are also studied. It can be concluded that at least 3 frequencies are needed to identify the flexural stiffness and boundary conditions in the case of beam with different constraints at supports, and at least 2 frequencies are needed in the case of beam with same constraints at supports. The numerical simulations also show that the identification results of flexural stiffness have high accuracy than those of boundary constraints, which requires the more accurate measurements of frequencies. It is noted that identification accuracy of the beam with strong constraints is more dependent on measurement accuracy, especially in the case...