Experimental Study On Shock Absorbing Performance Of SMA-Piezoelectric Friction Composite Shock Absorber And Reactor Structure

Ordinary friction shock absorber has simple structure and good dissipation ability,and it is one of the commonly used energy shock absorber in engineering structures.However,as a passive shock absorber,the device does not have the ability to adapt.At the same time,the device can not actively change its friction according to structural damping needs to achieve better structural shock absorption effect.In this paper,combining with the characteristics of Shape Memory Alloy(SMA),piezoelectric stack and ordinary friction shock absorber,a kind of SMA-piezoelectric friction composite shock absorber was developed and the corresponding mechanical performance test was carried out.Based on the fuzzy control theory,the simulated sElsmic shaking table test was conducted on the reactor structure to test the damping control effect after the integrated SMA-piezoelectric friction composite damping system.The main contents are as follows:(1)Through the physical and mechanical properties test of domestic austenitic SMA wire,the effects of the number of cycles,strain amplitude,loading rate on the mechanical properties and energy dissipation capacity of SMA materials were studied,and the corresponding stress-strain constitutive model was established.The above work provided the basis for the development of piezoelectric friction composite shock absorber.The results showed that the energy dissipation performance of SMA was mainly related to the strain amplitude,which is not affected by the loading rate.The constitutive model established in this paper can well reflect the constitutive characteristics of SMA material,so SMA can be used for the development of SMA-piezoelectric friction composite shock absorber.(2)In order to make up for the shortcomings of the existing SMA passive damping device and the piezoelectric friction semi-active damping device,a new SMA-piezoelectric friction composite shock absorber is developed in combination with the characteristics of SMA and piezoelectric materials.The working principle is that the SMA in the composite shock absorber is driven by the SMA in the small earthquake,and the SMA wire is driven by the passive energy dissipation.The piezoelectric friction semi-active damping device in the composite damping device is actively participate in the work in the large earthquake,and it could adjust the voltage to achieve hybrid semi-active control of shock absorber.(3)The mechanical performance test of SMA-piezoelectric friction composite shock absorber was carried out by using HT97711 dynamic/static material testing machine and special driving power source.The effects of input voltage,loading frequency and displacement amplitude on the shear stiffness,unit cycle dissipation energy and equivalent damping ratio of the shock absorber are analyzed.The results showed that the composite shock absorber had a large force in two-way and full hysteretic curve of the good symmetry.Meanwhile,the working performance of the device is not affected by the frequency of loading rate.It means that the working performance of SMA-piezoelectric friction composite shock absorber developed is stable.The application range is wide and the energy dissipation capacity is better.(4)According to the theory of fuzzy control,a double input single output fuzzy controller is designed to adjust the real time input voltage of the SMA-piezoelectric friction composite shock absorber.The input-output calculation model of SMA-piezoelectric friction composite shock absorber was established by using Simlink module in MATLAB.The numerical simulation of a 3 layer frame model structure under uncontrolled,passive control and hybrid control was carried out to discuss the corresponding damping law and damping effect.The results showded that the SMA-piezoelectric friction composite shock absorber could effectively reduce the sElsmic response of the structure,and the effect of the hybrid damping effect is better than that of the passive damping effect.In general,the passive damping effect of structural displacement and acceleration response was about 30%,and the effect of hybrid damping could reach 40-50%.(5)The structure model of a dry air reactor with a similarity ratio of 1:2 is designed.Using the fuzzy control theory,a series of shake table tests of reactor structure under uncontrol,passive control and hybrid control was conducted to analyze the damping effect and damping law of the reactor under different working conditions.And sElsmic wave used El Centro wave and Jiang You wave.The results showed that the damping effect of SMA-piezoelectric friction composite shock absorber was obvious.In general,the passive damping effect of structural displacement and acceleration response could reach 40%,and the effect of hybrid damping could reach 50%.It means that the device could improve the sElsmic reliability of the reactor structure...