Theoretical And Experimental Research On Parameter Identification Of Exponential Non-viscous Damping Model

Vibration problems are commonly found in the fields of machinery,civil engineering and aviation,and we are not only concerned with vibration itself,but also trying to reduce vibration through energy consumption by damping.So far,damping research has made a lot of results,but the damping of the physical mechanism of the study is still quite backward.One of the most important reasons is that,compared to mass and stiffness,the precise physical quantity to describe the damping force is not very clear.The recently developed exponential non-viscous damping model is considered to be a more g eneralized damping model,which takes full account of the damping effect of damping force and is valuable for its in-depth study.In this dissertation,the damping matrix decomposition method is extended to the exponential non-viscous damping model,and the damping coefficient matrix of the model is identified.At the same time,a new iterative calculation method of relaxation factor is proposed based on the BFGS(Broyden-Fletcher-Goldfarb-Shanno)method which is the most effective one of quasi-Newton methods.Finally,the new damping coefficient matrix recognition method and the relaxation factor iterative algorithm are verified by the shaking table test of a single-span and double-cross steel frame with additional viscoelastic damper.The concrete contents are as follows:Considering the incompleteness of the modal parameters of data extracted in the actual field,a new damping coefficient matrix recognition method for exponential non-viscous damping model is developed based on the damping matrix decomposition method.This method is able to consider the elemental distribution of the exponential damping coefficient matrix,and may apply the measured finite low-order mode to identify the damping coefficient matrix of the system more accurately.Furthermore,taking into account the insufficient research on the relaxation factor of the exponential non-viscous damping model at home and abroad,a new relaxation factor iterative algorithm is proposed by using the BFGS method in the quasi-Newton methods,based on the exponential proportional damping model.Finally,a single-span double-cross steel frame model with an additional viscoelastic damper with a similarity ratio of 1:4 is subjected to shaking table test,the non-viscous parameters of the integral steel frame model is calculated.Through the damping coefficient matrix decomposition method and relaxation factor iterative algorithm,the damping coefficient matrix and relaxation factor of the steel frame are identified,and the feasibility and correctness of the recognition methods proposed in this dissertation are investigated.