Research On Similarity Of Impact Response Between Floating Shock Platform And Real Ship Based On Nonlinear

The ability of shipboard equipment to resist extreme loads such as shock waves generated by underwater weapons during combat is of vital importance to ship survivability.Carrying out seaboard tests is the most effective and intuitive way to assess the impact resistance of equipment.However,the actual ship test is expensive,difficult to implement,and has a long test period.The test of light-weight and small-sized ship-borne equipment is usually carried out on the impact machine,and the large and medium-sized equipment,such as gas turbines,is checked by the floating impact platform.The research on floating impact platform has become more and more mature in recent years,and there are many specifications to provide reference.However,although these specifications stipulate the test conditions,they do not provide the corresponding conversion relationship between the platform and the impact environment of the actual ship,which has caused a lot of trouble to the impact resistance research of my country’s shipboard equipment.Therefore,according to the shock spectrum theory,this paper firstly studies the impact environment characteristics of real ships and floating impact platforms with different displacements and analyzes the Hurst exponent characteristics of the impact response,and analyzes the floating impact platforms and real ships from the perspectives of fractional Brownian motion and Hurst exponent.The similarity of impulse response.The specific work is as follows:First,the impact input of the underwater explosion load and the impact response of the ship’s plate frame are explained,and the basic theory of the impact environment of the ship under the action of the underwater explosion and the rounding and application of the design spectrum are introduced.Based on the analysis of the impact environment of traditional equipment,the concept of the non-linear characteristic parameter Hurst exponent is introduced,and the influence of different calculation parameters on the Hurst exponent of the underwater explosion shock response is analyzed.Secondly,combined with the finite element simulation software Abaqus,the underwater non-contact explosion simulation calculation of ships with different displacements,main dimensions and hull structures is carried out.Carry out research on the space characteristics of the ship’s impact environment under the action of underwater non-contact explosions at different impact factors,different angles of attack,and different burst locations.The Hurst exponent empirical formula is calculated on the acceleration data time-history curve of the whole ship with different displacements under the action of the underwater non-contact explosion,and the distribution characteristics of the Hurst exponent are analyzed.Next,the principle and data processing method of medium-sized floating impact platform,which is the commonly used anti impact test carrier of large shipborne equipment in China,are studied.The influence of different explosion attack angles,impact factors and different ballast equipment on its impact environment to impact response Hurst index is carried out.Based on the experimental data,the Hurst index of floating impact platform test and numerical simulation impact response is calculated,and the differences between them are analyzed.Finally,the fractional Brownian motion of the hull structure response under underwater explosion is discussed.Based on the Hurst exponent concept and Buckingham’s theorem,the Hurst exponent relationship between the prototype test and the model test of complete geometric similarity is derived and verified.The introduction of fractional Brownian motion proposes and verifies the conversion relationship between the floating impact platform and the actual ship impact environment.