====== CREDAM ======
===== Description =====
Constitutive law for unilateral  mechanical contact with creep damage
==== The model ====
Creep damage analysis for polycrystalline materials. The contact and damage evolution conditions at the grain boundary are enforced via a penalty method. A threshold value is defined for crack propagation. When this value is reached, the interface and its foundation are no longer in contact
==== Files ====
Prepro: LCRDAM.F \\
Lagamine: CREDAM.F
===== Availability =====
|Plane stress state|YES |
|Plane strain state| YES|
|Axisymmetric state| YES |
|3D state| NO|
|Generalized plane state| YES |
===== Input file =====
==== Parameters defining the type of constitutive law ====
^ Line 1 (2I5, 60A1)^^
|IL|Law number|
|ITYPE| 290|
|COMMENT| Any comment (up to 60 characters) that will be reproduced on the output listing.|

====Integer parameters====
^Line 1 (1I5)^^
|NTEMP|number of temperatures at which CREEX, CREPA, SIGO and CADE  parameters are given (see hereafter)|
==== Real parameters====
^Line 1 (7G10.0)^^
|DGRAIN|mean grain size|
|SLIDE|grain viscosity parameter $\dot{\varepsilon}_{c}^{e}/\varepsilon_{B}$|
|CDIFF|boundary diffusivity|
|ATVOL|atomic volume|
|ACTIV|activation energy|
|FNUC|nucleation parameter|
|CADEN|cavities density for nucleation (not used because of temperature dependence of CADE, see hereunder)|
^Line 2 (5G10.0)^^
|PSI|cavities angle|
|AINI|initial cavity size|
|BINI|initial cavity distance|
|DLIM|rupture criterion (a/b)|
|CDMAX|factor of the cavities density for nucleation|
**if NTEMP = 1**
^Line 3 (4G10.0)^^
|CREEX|creep exponent  n|
|CREPA|creep parameter B|
|SIGO|normalisation stress|
|CADE|cavities density for nucleation|
^Line 4 (2G10.0)^^
|AKP|penalty coefficient on the contact pressure $K_P$|
|AKTAU| penalty coefficient on the shear frictional stress $K_{\tau}$|
**if NTEMP > 1**
^Line 3 (5G10.0) - Repeat NTEMP times^^
|TEMP|temperature (of the solid)|
|CREEX|creep exponent n at temperature TEMP|
|CREPA|creep parameter B at temperature TEMP|
|SIGO|normalisation stress at temperature TEMP|
|CADE|cavities density for nucleation|
^Line 3 + NTEMP (2G10.0)^^
|AKP|penalty coefficient on the contact pressure $K_P$|
|AKTAU| penalty coefficient on the shear frictional stress $K_{\tau}$|

===== Stresses =====
==== Number of stresses ====
3
==== Meaning ====
|SIG(1)| normal contact pressure|
|SIG(2)|tangent contact stress|
|SIG(3)| meaningless|
===== State variables =====
==== Number of state variables ====
17\\ These are the state variables related to the law, they are the first ones printed. After them, you find the state variables related to the contact geometry, their meaning is explained in the element section;
==== List of state variables ====
|Q(1)| = 0 if the current state is elastic (no sliding)\\ = 1 if the current state is elastoplastic (sliding at contact)\\ = -1 no mechanical, nor thermal contact|
|Q(2)| interface temperature|
|Q(3)| meaningless|
|Q(4)| accumulated damage d|
|Q(5)| accumulated interface sliding u|
|Q(6)| accumulated interface separation $\delta$|
|Q(7)| cavity volume growth rate $\dot{V}$|
|Q(8)| equivalent strain|
|Q(9)| equivalent strain rate|
|Q(10)| total cavity volume V|
|Q(11)| actual cavity density N|
|Q(12)| actual cavity size a|
|Q(13)| actual cavity distance b|
|Q(14)| mean stress|
|Q(15)| equivalent stress|
|Q(16)| total normal contact pressure|
|Q(17)| total tangent contact stress|