Test Research Of Ni-Ti Shape Memory Alloy Wire Mechanical Characteristics Under Circulating Load

Shape memory alloy has special pseudo elasticity and shape memory effect, The material pseudo elastic make it has the characteristics of superior reset and energy-intensive. Therefore it can be used as energy dissipation and reset device in civil engineering structure vibration control. In structural vibration control, Shape memory alloy components the effect of dynamic load continuously, So it is necessary to research the history of stress and strain rate effect on mechanical properties of material. On the basis of previous researchs, In this article we research shape memory alloy mechanical properties as follows.Studied the circuit training times and loading rate effects on the relevant mechanical behavior of shape memory alloy. Based on the Ni-TiSMA wire test research of cycle training for many times under different loading rate, Analyses the number of times of circuit training effect on Ni-TiSMA wire related mechanical properties under different loading rate. Then further investigates the loading rate effect on the relevant mechanical properties of shape memory alloys after stability, Through the multiple sets of different rate of Ni-TiSMA wire under a load unload experimental study, Analysis the influence law of different loading rates on the relevant mechanical behavior of Ni-TiSMA wire. And then by the multiple sets of different strain amplitudes of Ni-TiSMA wire under a load unload experimental study, Analysis the influence law of different strain amplitudes on the relevant mechanical behavior of Ni-TiSMA wire. Finally, In order to study the stability of mechanical properties of Ni-TiSMA after training, through analyzed timeliness of shape memory alloy wire after circuit training, Analysis relationship between the related mechanical properties and time of the shape memory alloy wire after circuit training.Experimental study the specimen diameter influence on the tensile mechanical properties of shape memory alloy wire. By study the Ni-TiSMA of different diameter under different loading rate. Reveals the interaction between the size effect and strain rate and the influence laws on the relevant mechanical behavior of Ni-TiSMA materials.Through the test data of loading rate effect on the relevant mechanical properties after stability, Considering the stress-strain curve will present the phenomenon of hardening with the increase of loading rate. Then improve Graesser constitutive model and put the date into the improve Graesser constitutive model, Fitting stress-strain curve under the theory and compare with test stress-strain curve, To verify the applicability of the improve Graesser constitutive model. And considering the dynamic characteristics of Ni-TiSMA, establish the equations of the relationship between the stress increment and strain rate.