This research is focused on the four sides simply-supported damaged rectangular plate,using the equivalent stiffness in place of the damaged plate stiffness,and an elastic finite element plate model with several damage regions is established.Adopting the finite element method analysis the vibration characteristic of the plate,the angle displacement mode of the plate along its two directions is calculated by the Lanczos method.The angle displacement mode is analyzed as signal by db1 wavelet,the location of t...