Identification of damage on ship's cross stiffened plate panels using vibration response

This paper describes a scheme for identifying damage on a cross stiffened plate of a tanker ship model. Two damage locations were investigated. One was located at the intersection between the longitudinal and the bulkhead. The other was located at the intersection between the longitudinal and the web frame. The amplitude of a function containing the natural frequency, the damping ratio and the response was used as an indicator for damage. The function was obtained from a simulation using a neural network technique which inputs were the model's response. Simulation results obtained using response from numerical and experimental investigations are discussed. It was observed that even when the natural frequencies and the damping ratios did not show any definable trend due to the presence of damages, the amplitudes of the function showed consistent trends as the damage became more severe.