Research On Structural Nonlinear Damage Identification Method Based On Hilbert Transform

As an important engine for economic growth,infrastructure construction provides a steady stream of power for economic development.In addition to building new infrastructure,it is particularly necessary to perform damage detection and maintenance on the original infrastructure.Moreover,many old structures have been abandoned due to the lack of effective damage detection and life assessment,resulting in a waste of resources.Therefore,effective damage detection,damage type identification,safety warning and life assessment of the structure are very important..Damage detection is a complex reverse engineering,so some refined areas such as signal extraction,signal analysis,and accurate identification are derived.Among them,signal analysis and accurate identification have attracted the attention of many researchers.This article first focuses on nonlinear vibration response.The characteristics of the derivation of the formula,and through the numerical model analysis and physical model verification,effectively verify and identify the order of nonlinearity,and provide a reliable theory and method basis for the selection of nonlinear indicators in nonlinear damage identification.The main research contents are as follows:(1)The nonlinear vibration response function is derived from the formula,and the nonlinear single-free system with quadratic nonlinearity and cubic nonlinearity is analyzed.Through the perturbation solution,the nonlinear vibration response characteristics of the structure are obtained.(2)Establish a numerical model of the simple harmonic vibration of a single degree of freedom cantilever aluminum beam,analyze the structural vibration response through Hilbert transform,obtain the structural time-frequency characteristics,and use the time-frequency characteristics as the secondary signal to Fourier Leaf spectrum analysis.Through time-frequency analysis,the nonlinear order is identified,and the nonlinear softening and hardening and the influence of the nonlinear coefficient are analyzed.After that,a single free cantilever aluminum beam is also taken as an example to apply initial displacement to analyze its free vibration characteristics.(3)Extend this method to multi-degree-of-freedom systems,construct a10-degree-of-freedom spring-damping-mass system as a numerical example for simulation analysis,analyze its two different situations,simple harmonic excitation and free vibration,and conduct damage Position recognition.(4)The conclusions drawn from theoretical derivation and numerical examples are tested by physical model tests.The verification proves the correctness of the theoretical derivation,verifies the accuracy of the nonlinear order identification and the influence of the degree of nonlinearity on the vibration characteristics.