Inversion Of Constitutive Parameters Of Viscous Damping Media Based On Experimental Data

The viscous damper is a type of energy dissipation device that can effectively reduce the dynamic responses of target structure.This technology has been widely used in various infrastructures,such as bridges,high-rise buildings,large-scale stadium,airports.The damping medium of viscous fluid damper is mainly power-law fluid dimethyl silicone oil.The theoretical calculation formula for the damping force of a silicone oil-based viscous damper has a similar derivation formula,but the derivation formula is derived based on the ideal power law fluid,provided that the constitutive parameters of the power law fluid are known.The existing methods for the determination of power law parameters and pore shrinkage coefficient are often complicated,because on the one hand too many variables involved in the formula,and on the other hand the rheological rate and pressure state of dimethicone in the viscous damper are particularly complex.Thus,constitutive parameters have become an important aspect of restricting the development of viscous dampers.This paper first analyzes the existing damper principle and structure type,and then theoretically analyzes the computational model of the viscous damper and corrects the hole shrinkage force.Secondly,the test data of various types of dampers that have been successfully developed are statistically analyzed,and the constitutive parameters of dimethyl silicone oil are obtained through the normalization processing of data and data fitting iteration.Finally,two new viscous dampers are designed,and the constitutive parameters obtained by fitting are applied to the design of new products,and are compared and verified by experiments with finite element simulation and formula calculation.The main research contents are described as follows:(1)The basic working principle of the viscous damper and the characteristics of the damping medium are analyzed,and then the damping force formula of the pore damper and the gap damper is analyzed.The pore shrinkage force formula corresponding to the classical local pressure loss is corrected according to the long-term test experience.(2)The damping force test data of a variety of different tonnage dampers that have been developed and successfully applied are sorted out,and the variable unification of limited test data is realized according to the relationship between pressure and flow.By using multiple iterative calculations between the travel force and the remaining pore shrinkage force in the initial stage,the constitutive parameters of the two types of dimethyl silicone oil are finally fitted.(3)A 165-ton pore damper and the small-bore and a 120-ton gap damper are designed and produced,and the mechanical strength of each component of the damper is calculated and verified.The results show that the mechanical strength of the designed damper structure meets the design requirements.(4)The finite element model of the small-hole damper is established,the constitutive parameters of the fluid medium are set to the power-law parameters obtained by the fitting of the data in this paper,and the finite element analysis of the damping force is performed,and the results illustrate the correctness of the finite element model.In particular,the finite element calculation method based on this constitutive parameter can guide the development of damper products well and provide a basis for the design and calculation of dampers with various complex special-shaped pore structures in the later stage.(5)The two dampers produced are tested for damping force on the dynamic stiffness loading tester.Then,the damping force is compared with the results obtained by formula calculation,finite element analysis and experimental test,which not only verifies the correctness of the inversion method and the constitutive parameters of the two types of dimethyl silicone oil,but also verifies the accuracy of the formula and finite element calculation.