Study of the Behavior of a Bell-Shaped Colonic Self-Expandable NiTi Stent under Peristaltic Movements

Table 1

NiTi material parameters which define its stress-strain curve. UMAT input material parameters for constitutive model implemented in Abaqus.

Parameter	Description	Value
𝐸A	Austenite elasticity modulus	52650 MPa
𝜈A	Austenite Poisson’s ratio	0.33
𝐸M	Martensite elasticity modulus	38250 MPa
𝜈M	Martensite Poisson’s ratio	0.33
𝜀L	Maximum transformation strain	8%
𝜎^AM𝑠	Start of transformation austenite-martensite stress	320 MPa
𝜎^AM𝑓	End of transformation austenite-martensite stress	360 MPa
𝜎^MA𝑠	Start of transformation martensite-austenite stress	200 MPa
𝜎^MA𝑓	End of transformation martensite-austenite stress	180 MPa
𝑇0	Reference temperature	22°C
𝐶^AM	𝜕𝜎^AM𝑠,𝑓/𝜕𝑇	6.7 MPa/°C
𝐶^MA	𝜕𝜎^MA𝑠,𝑓/𝜕𝑇	6.7 MPa/°C