Study On Magnetorheological Nanocomposite Bearings

In this paper,the materials,the design method and the application of magneto-rheological nanocomposites(MRNCs)bridge bearing are studied.Starting from the dynamic mechanical test of magnetorheological elastomers(MREs)and MRNCs materials.The MREs and MRNCs materials are studied and analyzed.Simulation of MREs and MRNCs materials using hyperelastic and viscoelastic material models in abaqus finite element software are studied and the ideal simulation results are obtained.Then,according to HDR(I)-320×320×176-G1.2 high damping rubber bearing in the specification of “High-damping vibration isolation rubber bearings for highway bridges”the Abaqus finite element model of MREs and MRNCs bearings is established.Dynamic shear simulation of bearing model is studied to obtain hysteresis curves of shear force and displacement.The hysteresis curve of shear force and displacement was analyzed to obtain the bilinear model parameters of MREs and MRNCs bearings.Comparing with HDR(I)-320×320×176-G1.2 high damping rubber bearings,the mechanical properties of the MREs and MRNCs bearings are greatly improved.In order to study the damping effect of the simplified bilinear model of the bearings,take the example of a fabricated bridge,the finite element model of the full bridge was established and the seismic responses under three kinds of bearings are analyzed.This article can be concluded as follows:(1)MREs and MRNCs are prepared.During the preparation process,the clusters of CNTs were effectively overcome by the high-speed stirrer and ultrasonic disperser.The Young's storage modulus,The variations of Young's energy loss modulus,Young's loss factor,shear storage modulus,shear energy modulusand shear loss factor of MREs and MRNCs under different loading conditionsare obtained through compression and shear tests.It was found that MRNCs have higher stiffness and damping than MREs under small strain conditions andalso have higher energy dissipation capacity.With the increase of the strain amplitude,the shear modulus appears a decreasing trend.The change trend of loss factor is not obvious.(2)The stress-strain hysteresis curves of the materials obtained from the experiments was analyzed.The Neo-Hookean model of Mooney-Rivlin model and the simplified Maxwell model were used to simulate the shear properties of MREs and MRNCs.The differences between the stress-strain curve obtained from the finite element simulation and the stress-strain curve obtained from the test are compared.The ideal hyperelastic material model and the viscoelastic material model parameters are obtained.(3)Taking HDR(I)-320×320×176-G1.2 high damping rubber bearing for reference and based on the MRNCs materials,the MREs and MRNCs bearings were designed,The theoretical calculations and Ansys finite element simulation of the magnetic circuit of the designed MRNCs bearings are proposed.The correctness and rationality of the magnetic circuit design are proved..(4)Based on MREs and MRNCs material models,the MREs and MRNCs bearing models were established.The hysteresis curves of the forces and displacements of the MREs and MRNCs bearings under dynamic shear are obtained.The hysteresis curves are crescent-shaped and elliptical-shaped,respectively which consistent with the actual situation and explain the correctness of dynamic shear simulation of the bearings.In addition,the hysteresis curves of the bearing force and displacement are analyzed and simplified as bilinear models.(5)The bilinear model was used to simulate the MREs and MRNCs bearings.The obtained bilinear model was applied to the seismic analysis of a prefabricated bridge.Comparing with HDR(I)-320×320×176-G1.2 high damping rubber bearings,MREs and MRNCs bearings have better damping effect,among which MRNCs bearings have the best damping effect.