Experimental modal analysis of a ship deck structure

The work focuses on a deck panel of a fast ferry and is aimed at characterising its vibrational behaviour in terms of modal shapes and frequencies. Surveys are performed on a full scale physical model of about 3 x 2.5 m tested in the DINAV structural lab. Accelerations in the direction normal to the deck plate surface are measured and frequency response functions are derived between the survey locations and the position where an impulsive excitation is applied. Records are post-processed in order to get modal characteristics (shape, frequency and damping inherent to each mode). The work is propaedeutic to an investigation on the influence of typical structural modifications (insertion of a reinforced beams, change in stiffeners spacing) on the vibrational behaviour. The long term target is to control noise transmission into the living areas placed above the deck by intervention on the modal characteristics of the panel.