# CSMm 2.5.Constitutive Laws

The constitutive law class is a core class of kratos. Located in kratos/kratos/includes/constitutive_law.h.

## ConstitutiveLaw derives from Flags

The flags that are in use right now are only used as options for the computation of the material response.

Current Avaliable Flags:

List of *LOCAL* flags, in will be used in the Parameters.mOptions:

**COMPUTE_STRAIN**

**COMPUTE_STRESS**

**COMPUTE_CONSTITUTIVE_TENSOR**

**ISOCHORIC_TENSOR_ONLY**

**VOLUMETRIC_TENSOR_ONLY**

**TOTAL_TENSOR**

**INITIAL_CONFIGURATION**

**LAST_KNOWN_CONFIGURATION**

**FINAL_CONFIGURATION**

**FINALIZE_MATERIAL_RESPONSE**

**AXISYMMETRIC**

Strain and stress working measures:

They are defined in to two * enum* arrays:

STRAIN MEASURES:

**StrainMeasure_Infinitesimal**, Infinitesimal strain measure related to small displacements

**StrainMeasure_GreenLagrange**, Green-Lagrange strain measure related to the reference configuration

**StrainMeasure_Almansi**, Almansi strain measure related to the current configuration

** true strain measures*:

**StrainMeasure_Hencky_Material**, Hencky strain measure expressed in the reference configuration

**StrainMeasure_Hencky_Spatial**, Hencky strain measure expressed in the current configuration

STRESS MEASURES:

**StressMeasure_PK1**, First Piola-Kirchhoff stress related to the reference configuration non-symmetric

**StressMeasure_PK2**, Second Piola-Kirchhoff stress related to the reference configuration

**StressMeasure_Kirchhoff**, Kirchhoff stress related to the current configuration

**StressMeasure_Cauchy**, Cauchy stress related to the current configuration