Vibration Performance Analysis Of Small Unmanned Boats Based On Carbon Fiber Composites

As an intelligent ship,the unmanned surface vessel(USV)has the characteristics of fast speed,small size,high intelligence,stealth performance and unmanned,and the ship based on carbon fiber composite material is compared with the conventional unmanned boat.It has the advantages of light weight and high strength.Since carbon fiber composite material is a new material with excellent properties such as light weight,high temperature resistance,corrosion resistance,vibration reduction and noise reduction,the use of carbon fiber composite materials has become more and more extensive in the field of shipbuilding.Whether it is a steel ship or a ship made of carbon fiber composite material,it is inevitably affected by the free vibration of the ship and the internal vibration force of the main engine,the propeller,the jet pump,and the external vibration force caused by waves,etc.The vibration problem is the focus of research in the field of ships in various countries.This thesis is based on the carbon fiber composite small unmanned boat project of Guangzhou Ship and Ocean Engineering Design and Research Institute.The carbon fiber composite small unmanned boat is the research object,for the first-class sea state,the full speed rotation of the main engine and the three-level sea state,the cruising speed(rotation speed is 2600r/min),JQ excitation two kinds of working conditions for simulation,mainly to complete the following research work:1?The mechanical properties of the carbon fiber composites were tested to obtain the basic mechanical properties such as tensile,compression and shear of the composites.The material parameters were based on the vibration analysis of the unmanned boats based on carbon fiber composites.2?Carry out real ship test on unmanned boat,test the acceleration of these positions at the host 1000r/min,1930r/min,2000r/min,3000r/min and 3850r/min speed for the unmanned boat photoelectric forensics equipment,side sweep sonar and collision avoidance sonar,use Matlab software to summarize the test data,and finally draw the spectrum map.3?The finite element method is used to carry out three-dimensional modeling of the target ship,and the natural vibration characteristics of the ship are analyzed to obtain the natural frequency and mode shape.Then,using the surface force induced by the host as the exciting force,the ship vibration response prediction is performed.The speed and acceleration response amplitudes of the photoelectric forensics equipment,the side-scanning sonar and the collision avoidance sonar position under the five conditions of the host 1000r/min,1930r/min,2000r/min,3000r/min and 3850r/min are obtained;The numerical simulation under three working conditions of 1000r/min,1930r/min and 2000r/min was compared with the real ship test data,indicating that the numerical simulation based on finite element method of the unmanned vehicle was correct in a certain range.4?The outboard water pressure was used to simulate the pressure generated by waves on the bottom of the unmanned boat under the sea conditions of level 1 and level 3.Then the surface force induced by the main engine is used as the excitation force.The velocity and acceleration response amplitude of the positions of photoelectric forensics equipment,side-sweep sonar and collision avoidance sonar under two working conditions,namely,first-stage sea condition,full-speed rotation of the main engine and third-stage sea condition,main engine rotating speed of 2600r/min and JQ excitation,are obtained.And compared with the requirements of the CCS "shipboard vibration control guide",some suggestions are put forward to reduce the vibration of local structures that do not meet the requirements of the standard.