Research On Low-frequency Impact Environment Test Of Ship's Far-field Underwater Explosion

With the development of modern warships towards high mechanization,automation and electronics,the reliability of shipborne equipment has played an increasingly important role in the completion of various tasks by ships.When attacked by enemy shipborne weapons,the strong explosion impact can easily cause the failure or damage of various types of mechanical and electronic equipment,causing serious consequences of the loss of combat effectiveness and even vitality of the ship.Therefore,the impact of shipboard equipment on the impact of ship designers and users is becoming more and more important,and the ship's impact environment is a basic work for the design and evaluation of shipboard equipment's impact resistance.At present,the most reliable way to obtain the ship's impact environment is actual ship explosion tests.In low-frequency impact environment test projects,special instruments such as low-frequency vibrators and reed instruments are usually used.These sensors have problems such as being bulky and difficult to install the instrument.Under this background,this paper proposes to modify the low-frequency impact environment by using the ship's total vibration strain method by the research on the characteristics of low-frequency impact environment of ships and actual ship explosion test tests.The specific work of this paper is as follows:First,this paper introduces the current research on the impact environment of ships and the status of low-frequency impact environment measurements on real ships.Then this paper studies the characteristics of low-frequency impact environments on ships,what's more,this paper introduces underwater explosion loads and impact spectra.The ship's shock spectrum has frequency band division characteristics.Combined with the ship's underwater explosion numerical simulation and empirical modal decomposition methods,the formation mechanism of the ship's low-frequency shock environment is studied.The proportion of the ship's total vibration to the ship's low-frequency response is analyzed.The low frequency stage is mainly based on the total vibration response,which provides a theoretical basis for subsequent correction of the low frequency shock environment through the ship's total vibration strain signal.Secondly,this paper analyzes the actual ship test data and finds that the ship's strain response is less affected by high frequencies after being impacted,so this paper proposes to use the ship's total vibration strain signal to modify the ship's low-frequency shock environment,so as to solve the problem of zero drift error that the acceleration sensor has when measuring the ship 's low-frequency data,and uses a combination of real ship explosion test and numerical processing.The ship's impact resistance problem involves theories of modal analysis and modal parameter identification.At the same time,numerical simulation and experimental examples are given to demonstrate the low-frequency impact environment modified by the ship's total vibration strain test method.The demonstration results show that the new method is feasible.Finally,based on the total vibration strain test method of the ship,this paper gives the recommendation of the measuring instrument in the real ship explosion test,and studies the number and placement of measuring points,and puts forward the corresponding testing principle.Finally,compared with the traditional method,it is concluded that this technology has advantages of simple sensor installation,low number of measuring points and large effective coverage of the length of the ship.This method has important reference value for low-frequency impact environmental testing of real ship explosion test.