Structural Design And Mechanical Analysis Of Wave Compensated Trimaran

With the development of the marine economy,ships,as necessary equipment for marine engineering,are no longer just tools for marine transportation,but also important carriers for the development of marine resources by carrying various mechanical equipment.The wave compensation platform is a displacement compensation device that counteracts the adverse effects of wave motion.Therefore,how to design a wave compensation device on the ship deck to have a larger area of wave compensation platform and achieve better wave compensation performance is the core exploration direction in the field of wave compensation.In this thesis,wave compensation devices are applied to the current popular trimaran ship types.With the unique structure of trimarans,wave compensation devices are configured on each hull and an upper compensation platform is formed.The stability of the upper compensation platform is ensured through the independent motion of the three hulls,and this structure is called a wave compensation trimaran.In this thesis,the structure of the wave compensated trimaran is designed,and its strength and dynamics are analyzed.Firstly,the three hull ships used for wave compensation structures were classified and compared,and the wigely ship type and triangular layout were selected for comparison.The main scale parameters of the ship model are determined and the base ship of the wave compensated trimaran is modeled.The structure of a wave compensated trimaran is explained and its structural advantages compared to traditional marine wave compensation platforms are analyzed.The overall degree of freedom of the structure is calculated,and the total degree of freedom of the wave compensated trimaran structure is 3,ensuring the rationality and feasibility of the compensation motion of the structure.Secondly,a finite element model is established based on the structure of the wave compensated trimaran,and the constraints and working conditions of the wave compensated trimaran are analyzed.The load is calculated based on different combination conditions,and the rolling and longitudinal waves encountered under uniform and non-uniform load distribution conditions are calculated and analyzed.The results show that the maximum stress of the wave compensated trimaran structure increases by 85.71% compared to the lateral load when encountering longitudinal rolling load.The maximum stress and strain of the wave-compensated trimaran structure under non-uniform load conditions are 149% and150% of those under uniform load conditions,respectively.The relationship between the natural frequencies of each order and the load response of the wave compensated trimaran structure is analyzed,and the harmonic response curve of the stress concentration point is further calculated.At the same time,the dangerous frequency range of external excitation and wave compensation for the resonance of a trimaran has been determined,and it is proposed that the natural frequencies of subsequent equipment installation should be below15.629 Hz and above 74.828 Hz to avoid the occurrence of common.Finally,the dynamic analysis of the wave compensated trimaran structure mainly involves the analysis of the driving force of the compensating oil cylinder and the analysis of the bow hull roll angle.The results show that the driving force of the compensation cylinder is not completely the same due to different positions,and the driving force of the compensation cylinder should exceed at least 11% of the ship’s displacement.When the stroke of the compensation oil cylinder is 0.5 times the unloaded discharge line of the trimaran,the maximum roll angle of the wave compensation trimaran is about 6°.