| Due to its characteristics of transient and complexity,impact load has a very important impact on the stability and safety of the structure.Therefore,it is inevitable to study the dynamic characteristics in a wide frequency range.With the rapid development of space technology in recent years,more and more attention has been paid to the stability and reliability of its products.Especially for complex structures,the dynamic response characteristics in the frequency range have been widely concerned by scholars at home and abroad.The statistical energy analysis method developed in the 1960s can overcome the difficulties encountered by traditional modal analysis methods,but for impact load,it is difficult to study it accurately by using statistical energy analysis method because of its transient characteristics.Therefore,based on the basic theory of transient statistical energy analysis method,this paper carried out theoretical research and experimental analysis on the identification of impact load by conducting tests on typical components of deep submersible.First,the theory of statistical energy and transient statistical energy and the impact load identification theory are analyzed.In addition the equilibrium equation of transient statistical energy is derived and extended through a two-subcoupled system.Through matlab,the calculation formulas for the loss factor within the structure and the coupling loss factor were obtained.And the calculation formula of coupling loss factor of three sub-coupling system is derived.Then determine the test model of internal loss factor,coupling loss factor and impact load identification and detailed scheme design is carried out for the measuring and exciting points.Secondly,the inner loss factor and coupling loss factor of typical structure of deep submersible were tested.Three kinds of force hammers were used to stimulate the inner loss factor test.In the coupling loss factor test,according to the characteristics of the components,the components are divided into two sub-coupling systems and three sub-coupling systems for testing respectively.The internal loss factor values were processed and analyzed in detail based on the transient attenuation method of Hilbert transform and the coupled loss factor values were processed and analyzed in detail based on the principle of transient statistical energy and fluctuation method.In the process of data analysis,detailed steps of data processing are given,and comparative analysis of various working conditions is carried out.Finally,the values of internal loss factor and coupling loss factor of typical structure of deep submersible within the analysis frequency band of 100Hz～1000Hz are obtainedFinally,based on the basic principle of transient statistical energy analysis,combined with the measured loss factor value,the impact load identification of the cylindrical shell-transverse bulkhead coupling system is studied experimentally.Through comparative analysis of test data and identification data,it can be found that the identification data can roughly replace the measured data,which reflects the feasibility of this method.At the same time,the position of the impact load of the non-pressure shell-internal stiffened two-coupling system is identified.Through the comparison of the identification results and the analysis of the characteristics of the components involved in the test,the rule is summarized,and it is determined that this method provides a reliable identification method of the impact load for the shell,plate and other high modal density structures. |
