Research On Mechanical Properties Of A New Type Of Resilient Deformation SMA Damper

Structural vibration control technology has been widely used in the field of civil engineering,and energy-dissipation based vibration reduction technology is one of the most effective methods to achieve passive vibration control of structures and reduce seismic response of structures.When dampers are used for energy dissipation and vibration reduction of the structure,the traditional method requires the damper to have a large damping force and sufficient energy dissipation capacity to meet the needs of the energy dissipation and vibration reduction of the structure.However,with the development of structural control theory and social progress,traditional dampers have been unable to meet the new requirements,that is,new dampers not only require a large damping force and energy dissipation capacity,but also need sufficient resilient deformation capacity,referred to as RDC,to reduce the residual deformation of the structure and the accumulation of unnecessary damage.Having enough RDC has become one of the key parameters for the new type damper.Shape Memory Alloy(SMA)super-elastic dampers can be used to meet the needs of new types of dampers through appropriate improvements.This paper aims at designing and manufacturing a new type of SMA damper and performing theoretical and experimental research from three aspects of materials,components and structures.The main contents are as follows:First,at the material level,this paper performs a cyclic tensile test on three different diameters of superelastic SMA wire,explors the mechanical properties of different diameters of SMA wire under different loading rates and displacement amplitudes.The results show that the constitutive relationship of superelastic SMA wire has a flag shape property and the SMA wire for the diameter of 0.5mm has the most stable hysteresis property which can be used as the manufactural material of the damper.Second,at the component level,a new type of SMA damper is designed and manufactured by combining the SMA wire with the recentering spring.A cyclic loading test and a numerical simulation are performed for the new proposed SMA damper to develop the impact of different loading frequencies and displacement amplitudes on its mechanical properties,and a resilient model is also established.Meanwhile,a new kind of adjustable fixture for the SMA wire is put forward to solve the fixed problem of SMAs.The results show that the new SMA damper has a stable hysteretic performance under cyclic loading and has good recertering and energy dissipation capabilities.The numerical simulation results are in good agreement with the test results,and the correctness of the damper force model is verified.Finally,at the structural level,two sets of steel frames with new dampers and a four-bar linkage diagonal support system are designed and tested under pseudo-static loading to study the resilient functional performance of the new structural system.The results show that the new four-bar linkage diagonal support system can effectively transfer the inter-story drift to the SMA damper compared with traditional structures,avoiding the buckling of the connecting rod under compression forces.