Slam and wave load response reconstruction in high speed catamarans using transmissibility on full scale sea trials

Abstract

In-service measurement of slam and wave load responses provide valuable information in the structural design and weight optimisation of high-speed catamarans. However, a limited number of measurements may be possible due to cost, and data may sometimes be lost or noise contaminated. This paper uses the transmissibility concept to reconstruct a set of unknown responses using a different set of known responses. Transmissibility functions and a transmissibility matrix based on linear response theory are derived from less than 12% of available data. The method is applied to full scale sea trials data on a 98 m high speed catamaran HSV 2 Swift, on which strain, acceleration, and angular velocity were measured. Responses are reconstructed for different vessel headings (head, port bow and starboard seas), speeds (15–35 knots), and sea states. The transmissibility matrix is tested on data from unseen sea states. Excellent agreement is achieved, particularly for larger loading events that would be of interest to structural designers. The study demonstrates the possibility to significantly reduce or build redundancy into the instrumentation.