Abstract: A simple computational method for the vibration frequencies of a circular clamped baffled plate with an artificial crack in water is described. Under the conditions that water is incompressible, the plate vibrates in small amplitude and the modal deflection in water equals that in vacuo, the added mass density due to the water pressure is expressed using Rayleigh’s integral. Then the relationship among the vibration frequency of the plate in water and that in vacuo and the nondimensionalized added virtual mass incremental(NAVMI) is obtain by utilizing Rayleigh method. Based upon the data of modal analysis for the plate in vacuo by finite element method(FEM) and properly dealing with the integral at singularity, the value of NAVMI is obtained by discretizing the integral. Moreover the vibration frequencies of the plate is computed using iterative method, which begins with the in vacuo eigenfrequency and continues until in-water eigenfrequency converges. The present approach is validated by comparison the NAVMI computed here with the results of M. K. Kwak .

Key words: Circular plate with a crack, Finite element method, incremental, Nondimensionalized added virtual mass, Vibration frequency in water, Insertion force, Quality consistency, Robust design principle, Slash spring contact