Characterization of flexible support systems of large outfitting components on cruise ships

Abstract

Modern cruise ships are required to have more specialized features and the design process to create them is also more specialized. The isolation of high-end entertainment deck amenities such as basketball courts and glass domes are not intuitive, and the survival of such features demands better characterization of the isolation structural members. Flexible mounting solutions are a viable option and are often characterized with equivalent dynamic stiffness properties to determine how well they survive. This thesis aims to determine the dynamic stiffness properties of two provided flexible mounting devices, one medium sized and one larger sized, by imparting marine-equivalent loads to them and developing the analysis methods to generate characterization information that can be used in further study or in the design of future marine systems.

The data was gathered using a load frame and load cell capable of producing the required frequency and amplitudes of oscillation while preloading the flexible mounting hardware per the marine environment. Preloads of 22.5 kN in compression to 15 kN in tension were performed with simultaneous 1.0 – 20.0 Hz oscillation frequencies at 0.02mm amplitude. This allows for a preview as to how the mounts would perform in a marine environment. The data is prepared for analysis through parsing, noise removal, high pass filtration, and removal of non-data entries before calculating the equivalent dynamic stiffness using the peak-to-peak slope of the recorded mount force and deflection.

A calibration study is performed, and the data collection method is optimized for each of the testing events. The equivalent dynamic stiffness is reported with values ranging from 15.316 – 41.107 kN/mm for the larger sized mount, and 5.645 – 11.170 kN/mm for the medium sized mount.

The two mounts appear to be made of different rubber materials due to the large differences in stiffness between the values calculated, and the larger mount likely approached an asymptotic limit in compression prior to the manufacturer’s stated maximum range. The effect of amplitude is briefly reviewed, and tensile loads appear to be more susceptible than compressive loads with respect to equivalent stiffness values. The characterization of the mounts yielded significant results, but also raised more questions as to the phenomena behind them.