Coupling Characteristics Analysis Of Rigid Body Motion And Elastis Motion Of Impact Platform Under Explosion Load

In order to improve the continuous vitality of modern ships,the main equipment system of ships must pass the anti-impact assessment and meet the anti-impact standard of ship equipment before it can be put into practical use.It is usually the most reliable assessment method that the first part of a real ship directly passes the assessment of real explosion resistance to impact.In this paper,the formulas of explosion load are introduced,and then the finite element analysis model of typical ship is established.By comparing the ship impact environment with the platform impact environment obtained from the test,the problems existing in the assessment of ship equipment using the impact platform are clarified.In the process of ship equipment anti-impact assessment,there are different anti-impact standards according to the weight level,installation location and importance degree of the equipment.The weight of equipment represents the difference of installation frequency,the difference of impact environment caused by installation location,and the importance degree determines the necessity of impact resistance.In the process of using impact platform to assess equipment,a spectral velocity value is usually used as the assessment benchmark.However,according to the actual engineering practice,when the velocity of impact spectrum is the same,the trend of impact spectrum will be greatly different.In particular,the spectrum drop phenomenon caused by elastic vibration will lead to obvious difference in equipment response.In addition,there are great differences between the structure size and structural strength of the impact platform and the actual ship,so this paper analyzes the characteristics of the impact environment of the impact platform.The main content of the article is divided into the following parts.The structure of deck simulator is designed to expand the original spectral form of the impact platform after the problems in the assessment of ship equipment are clarified.The finite element simulation model of impact platform is established to further analyze the response characteristics of impact platform.The simulation calculation conditions of far-field explosion were set,and the measuring points were arranged in the deck simulator and the inner bottom plate of the impact platform.The displacement data and acceleration data of the simulation calculation results were extracted.The displacement response of the inner bottom plate was compared with the rigid-elastic coupling response characteristics of the deck simulator,and the basic response rules of the deck simulator were obtained.The acceleration data was plotted as impact spectrum.The rigid-elastic coupling spectrum of the deck simulator was compared with the rigid-elastic coupling spectrum of the inner floor rigid body displacement spectrum data to obtain the response law between the spectral displacement,spectral velocity and spectral acceleration under different impact factors.In order to further analyze the fundamental difference between the rigid body response spectrum and the rigid-elastic coupling response spectrum,the combined triangle wave transformation method in the German standard was used to obtain the combined triangle wave of the internal floor and deck simulator.By applying triangular wave directly to the boiler base,the response characteristics of two different triangular effects are obtained through finite element calculation,and the characteristics of the elastic impact environment on the deck simulator are defined.In chapter 4,the characteristics of underwater explosion loads are analyzed by using the excellent characteristics of ls-dyna explosion simulation calculation,and the differences of explosion loads under different water depths are compared.Then,the finite element simulation model of underwater double cylindrical shell is established,and the difference of the response between water medium and air medium is analyzed,and the response characteristics of double cylindrical shell under different medium conditions are obtained.The difference of bubble pulsating load in different water depth is analyzed.In chapter 5,according to the impact environment characteristics of the surface impact platform in chapter 3 and the response characteristics of different cylindrical shell structures in chapter 4 in the deep-water environment,the underwater impact platform and the deck simulator used to simulate the underwater elastic impact environment are designed.The finite element simulation model of underwater impact platform is established by using ANSYS.The structure of underwater impact platform is verified by using ABAQUS acoustic-solid coupling algorithm.At the same time,different working conditions of the underwater impact platform are simulated.The characteristics of the underwater impact platform under different water depths and different angles of attack are obtained.