Investigations On Load Identification Method Of Continuous Structure Based On Houbolt Method

With the development of industry and the progress of the times,modern industry has put forward higher requirements for structural optimization,strength calculation,life calculation and reliability analysis of mechanical systems.The dynamic load identification method has great advantages for accurately obtaining the structural information and load distribution of the mechanical system.Especially in some special structures or environments,the load information received by the structural system cannot be directly obtained or the load information cannot be accurately obtained.At this time,the dynamic load identification technology,an indirect method of obtaining load information,shows great advantages.Therefore,the research in the field of dynamic load identification has very important engineering practical significance.In this paper,for a multi-degree-of-freedom linear elastic system,based on the modal truncation theory and the Houbolt numerical integration method,a method for identifying the dynamic load of the structure under non-zero initial conditions is proposed,and then a segmented load identification based on the continuous dynamic response of the structure is proposed.The method solves the problem of continuous load spectrum acquisition that cannot directly detect mechanical structures.The research content of this article is summarized as follows.(1)Using the Newmark-β single-step numerical integration algorithm,the initial three time-step numerical calculation formulas of the differential equations of the multi-degree-offreedom linear system are derived,which solves the problem that the Houbolt numerical integration algorithm cannot start automatically,and then derives the system dynamics based on the Houbort algorithm A four-step numerical integration method based on the study of equations is proposed,and a method for structural dynamic load identification under zero initial conditions based on the Houbort method is proposed,and verified by numerical simulation and experiments.(2)Aiming at the ill-conditioned problems in the dynamic load identification algorithm,combined with the traditional regularization method,an improved Tikhonov regularization method is proposed;based on the Morovoz compatibility principle,a pan-minimum function model and a model function of the regularization parameters are established,and a model function is given.Using the quasi-Newton iteration method to determine the regularization parameters,the problem of the selection of the regularization parameters is solved,and it is verified by numerical calculations.(3)Based on the modal truncation theory,an expression of the relationship between the non-zero initial conditions of the structure and its low-order modal parameters is established,and the combination of its low-order modal parameters and the system dynamic load are used as the system parameters to be solved,and the non-zero initial conditions are proposed The identification algorithm of the dynamic load of the lower structure;using the identification algorithm of the dynamic load of the structure under non-zero initial conditions,a segmented load identification method based on the continuous dynamic response of the structure is proposed and verified by numerical simulation.