Dynamic Response Of ROV-cable System Under Random Excitation

With the exploitation of marine resources and the continuous development of marine science,Remotely Operated Vehicle(ROV)is being more and more widely used in recent years.However,because of the uncertainty of marine environment,loss of ROV that results from cable crack usually happens during operation.So it’s of great importance to analyze the dynamic response of ROV-cable system and to find out in which condition the cable is safe.Firstly,for the vertical heave motion,taking the nonlinear and non-smooth of drag force and cable’s tension into account,a single-degree-of-freedom model equation is deduced.Using the method of vibration theory,the non-dimensional equation is deduced.Solution of the equation under harmonic excitation is solved by numerical method to get in which area the cable is in taut-slack condition and analyze the period stability of ROV-cable system.Secondly,the response under random excitation is calculated.The non-dimensional random wave is deduced as excitation of the system.The area where the cable is safe during operation is analyzed and is compared with the result under harmonic excitation.Finally,this paper analyzes the response of passive heave compensator of the project: 4500 Deep Ocean System,under random excitation.The maximum tension and displacement of cable is simulated in different sea states and various operating depths,to get the efficiency and reliable of the compensator and thus to help improving the system.