Study On Optimization Of Anti-impact Characteristics Of Marine Main Engine Isolation System

In the underwater explosion environment,important equipment and devices such as ship main engine are easy to be damaged by impact and lose their functions.Their impact resistance performance directly affects the maneuverability and combat performance of ships,which is very important to the vitality of ships.The navies of various countries generally use vibration isolation technology to effectively isolate the vibration and impact of ship equipment.The starting point of this paper is how to grasp the parameter optimization direction of isolation elements on the basis of fully considering the mechanical characteristics of various isolation elements(isolators and limiters),so as to improve the impact resistance of main engine isolation system under complex impact excitation.Firstly,this paper analyzes the mechanical characteristics of isolation elements applicable to the main engine and obtains the complex impact environment of the main engine,so as to establish three nonlinear impact response analysis and optimization models of limit isolation system.Then,based on the theoretical model,the influence of various parameters of isolation elements on the impact resistance characteristics of the system is studied,and the parameter theoretical optimization strategy is proposed,Finally,the optimization algorithm is used to optimize the parameters of the isolation element,match the optimal solution of the parameters,verify the effectiveness of the theoretical optimization,and realize the optimization of the impact resistance of the main engine.The specific work of this paper is as follows:(1)Firstly,the nonlinear mechanical characteristics and parameters of rubber isolation element suitable for host impact isolation and metal spring isolation element for comparison are analyzed theoretically and experimentally.At the same time,the complex time-domain impact excitation of host is obtained by finite element simulation.On this basis,the practical impact response analysis and optimization theoretical model,nonlinear spring damping element finite element model and material entity finite element model of main engine limit isolation system are established.The impact simulation calculation is carried out under the same parameters,the effectiveness of the three models is verified,and the application scope,advantages and disadvantages of the three models are analyzed;(2)Then,based on the theoretical model of the limit isolation system,the impact resistance difference between the metal spring isolation system and the rubber isolation system and the influence of the installation of the limiter on the impact resistance of the system are analyzed.Furthermore,the effects of the damping ratio,stiffness,stiffness nonlinearity and limit clearance of isolator and limiter on the impact resistance of isolation system are explored.Considering the vibration isolation performance of the system and the maximum deformation requirements of the displacement sensitive element,the optimization strategy of the anti impact performance of the equipment body is proposed according to the parameters and the coordination relationship between the parameters,and the optimal parameter interval of the isolation element is found,which points out the optimization direction for the parameter design of the isolation element;(3)Finally,after integrating the theoretical optimization model of the limit isolation system with the optimization software ISIGHT,the multi Island genetic algorithm is selected to intelligently optimize the parameters of the isolator and the limiter.Taking the maximum absolute peak value of acceleration as the objective function,the variable value range and constraint function are determined according to the optimal parameter range of anti impact performance and the maximum relative displacement requirements of ship main engine,and the parameter sensitivity analysis is made.Finally,the overall optimal solution of the isolation element parameters is obtained,and the feasibility of the theoretical optimization strategy is verified.