Research On Experiment Properties Of Viscoelastic Laminated Composite Dampers

The use of viscoelastic dampers for structural energy dissipation is an effective passive control method.Because it not only has the advantages of simple structure,convenient construction,low cost,but also has good energy consumption characteristics,which can effectively reduce the wind vibration and seismic response of building structures.At present,viscoelastic dampers have been widely used in seismic engineering.Different energy dissipation structures have different performance requirements for viscoelastic dampers.In a certain ambient temperature,the energy dissipation structures requires viscoelastic dampers to have obvious damping performance in the low-frequency vibration range to consume the energy input to the structure by external vibration;on the other hand,it requires viscoelastic dampers to be able to follow different elastic restoring forces are provided according to the change of structural displacement to meet the additional rigidity requirements of energy dissipation structures.However,it is difficult to optimize the stiffness and damping characteristics of the viscoelastic damper only by chemically modifying the viscoelastic damping material.This article focuses on the contradiction between the stiffness and damping characteristics of viscoelastic dampers.It introduces reinforcing phases into the matrix of viscoelastic damping materials based on composite material mechanics theory and composite material design methods to make viscoelastic laminated composite materials.And following the influencing factors and laws of the relative viscoelastic laminated composite material stiffness,a new viscoelastic damper--viscoelastic laminated composite dampers,which is composed of warp-knitted aramid mesh fabric and acrylic rubber.At the same time,the mechanical properties of the viscoelastic laminated composite dampers were tested under different loading conditions,and the influence of the reinforced materials content and the reinforced materials laying angle on their mechanical properties were compared and analyzed;And according to the characteristics of the experimental hysteresis curve,the Bouc-Wen-Baber-Noori(BWBN)model was extended,the model parameters were identified by genetic algorithm,and the recognition efficiency and accuracy of the BWBN model before and after the extension were simulated and compared.Based on the above studies and experiments,the following conclusions are obtained:(1)Based on the theory of composite material mechanics,the reinforcement material is introduced into the viscoelastic damping material,and the factors and laws affecting the mechanical properties of the reinforced relative unidirectional fiber reinforced composite material(unidirectional plate)are analyzed from the macroscopic and microscopic perspectives.The influencing factors and laws of the stiffness of the viscoelastic laminated composite material are analyzed by using the classic laminate theory.It is concluded that the mechanical properties of the viscoelastic laminated composite material are closely related to the content of the reinforcing phase,the laying angle of the reinforcing phase and the laying order of the viscoelastic unidirectional board.(2)Four types of viscoelastic laminated composite dampers were fabricated depending on the content of the reinforcing p hase and the different laying methods.The experimental research analyzed the influence rule of mechanical properties and energy consumption of the viscoelastic laminated composite dampers under the different ambient temperatures,frequencies,strain amplitudes,and fatigue loading cycles under large strains.It was found that the ambient temperature,strain amplitude,number of loading cycles under large strain amplitude,content of reinforcing phase and laying direction of reinforcing phase have significant effects on the performance of viscoelastic laminated composite dampers,and the effect of loading frequency is obvious.Therefore,when the external influencing factors cannot be changed,the performance designability can be achieved by adjusting the reinforcement phase content and the laying angle of the reinforcement phase of the viscoelastic laminated composite damper.(3)The characteristics of the hysteresis curve of the viscoelastic laminated composite damper are analyzed,and the source of the hysteresis curve is explored.On the basis of the characteristics of the hysteresis curve of the viscoelastic laminated composite dampers,the genetic algorithm was used to identify 12 control parameters in the BWBN model,the hysteresis curve was simulated,and the simulation results an d test results were compared and analyzed.The conclusion is BWBN model can well describe the softening effect,hardening effect,and pinch effect of the hysteresis curve of the viscoelastic laminated composite damper s.(4)According to the similarity of hysteresis curves of viscoelastic laminated composite dampers at the same strain amplitude,the Bouc-Wen-Baber-Noori(BWBN)model was improved so that it can reflect the softening effect caused by temperature and fatigue.The simulation results of BWBN mo dels before and after improvement are compared and analyzed.It is shown that the parameter recognition efficiency of the improved BWBN model is higher and the simulation results are closer to the actual test values.