Table 1 The parameters of the Ni–Ti material subroutine

Nitinol material density ρ (kg/m³)

6450

Elastic modulus of austenite phase E_A (MPa)

67000

Austenitic phase Poisson’s ratio V_A

0.33

Elastic modulus of martensite phase E_M(MPa)

26300

Martensitic phase Poisson’s ratio V_M

0.33

Transformation strain \(\varepsilon \) _L

0.067

(δσ/δT)_L (MPa T⁻¹)

63.8

Initial stress of loading\({\upsigma }_{\text{L}}^{\text{S}}\) (MPa)

200

End stress of loading \({\upsigma }_{\text{L}}^{\text{E}}\) (MPa)

300

Reference temperature T₀(°C)

73

(δσ/δT)_U (MPa T⁻¹)

8

Initial stress of unloading \({\upsigma }_{\text{U}}^{\text{S}}\) (MPa)

100

End stress of unloading \({\upsigma }_{U}^{E} \) (MPa)

50

\({\upsigma }_{\text{CL}}^{\text{S}}\)(MPa)

200