Vibration damping of naval ships based on ship shock trials

Presently, the vibration damping mechanism of naval craft subjected to underwater shock is not well understood, and ship shock trials remain the most effective means of researching ship vibration damping problems. A damping modeling strategy for naval ship systems is presented for ship shock transient time-domain analysis. The total vibration damping ratios of a naval vessel under different shock conditions are calculated using the logarithmic decay rate based on measured shock trial data. The least-squares complex exponential method is used for the extraction of modal parameters in the time domain. The obtained modal parameters were employed to construct synthesized time histories, which compared favorably to the original time histories, verifying the proposed method. The structural damping is quantified and evaluated based on the extracted modal frequency and modal damping ratio, and Rayleigh damping coefficients and are experimentally obtained. The values of and presented in this work are respectively less and greater than those proposed for the U.S. Navy ship DDG-53.