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/MAT/LAW71 - Superelastic Law for Shape Memory Alloy

Description

This law describes the behavior of superelastic materials. It allows modeling the behavior of the shape memory alloys (such as Nitinol). The particularity of these materials is that all of the strain is recovered upon unloading even when large deformations are reached. Besides, the material shows a hysteretic response in a complete loading-unloading cycle. The full recovery is due to phase change in the microstructure. The model is based on the work of Auricchio et al. 1997. This law is compatible with solid and shell elements.

Format

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/MAT/LAW71/mat_ID/unit_ID

mat_title

 

 

 

 

 

 

 

 

E

E_mart

 

 

 

 

EpsL

CAS

CSA

TSAS

TFAS

TSSA

TFSA

Cp

Tini

 
hmtoggle_plus1Flag Definition

Field

Contents

SI Unit Example

mat_ID

Material identifier

(Integer, maximum 10 digits)

 

unit_ID

Optional unit identifier

(Integer, maximum 10 digits)

 

mat_title

Material title

(Character, maximum 100 characters)

 

Initial density

(Real)

E

Young’s modulus

(Real)

Poisson’s ratio

(Real)

 

E_mart

Martensite Young’s modulus (only available for solid element)

Default = E (Real)

≠ 0: E is austenite young’s modulus.

Material parameter defining the start of phase transformation from austenite to martensite (AS) (Comment 1).

(Real)

Material parameter defining the end of phase transformation from austenite to martensite (AS) (Comment 1).

(Real)

Material parameter defining the start of phase transformation from martensite to austenite (SA) (Comment 1).

(Real)

Material parameter defining the end of phase transformation from martensite to austenite (SA) (Comment 1).

(Real)

Material parameter measuring the difference in response between tension and compression.

Default = 0  (Real)

 

EpsL

Maximum residual strain (Comment 2).

(Real)

 

CAS

Stress-Temperature rate during loading

Default = 0  (Real)

CSA

Stress-Temperature rate during unloading.

Default = 0  (Real)

TSAS

Initial temperature for transformation (AS).

Default = 0  (Real)

TFAS

Final temperature for transformation (AS).

Default = 0  (Real)

TSSA

Initial temperature for transformation (SA).

Default = 0  (Real)

TFSA

Final temperature for transformation (SA).

Default = 0  (Real)

Cp

Specific heat capacity.

Default = 1030  (Real)

Tini

Initial temperature.

Default = 360 K (Real)

hmtoggle_plus1Example

/MAT/LAW71/1

LAW71

#              RHO_I

             6.50E-6

#                  E                  NU              E_mart

               62500                  .3               51000

#            sig_sas             sig_fas             sig_ssa             sig_saf               Alpha

                 450                 600                 300                 200                0.20

#               epsL                 CAS                 CSA                TSAS                TFAS

               0.045                   1                   1                 383                 343

#               TSSA                TFSA                  CP                TINI

                 363                 403                 837                 360
hmtoggle_plus1Comments
1.The different stresses defining the start and the end of phase transformations, as well as the residual strain, correspond to the case of a uniaxial tensile test.
2.The parameter is computed from the initial value of the A symbol_arrow S phase transformation in tension and compression from the relation:

law71_transformation

List of Animation output (/ANIM/BRICK/USRI):

USR 1=  Martensite phase fraction

USR 2=  Loading function

USR 3=  Unloading function