====== ELA ======
===== Description =====
Elastic constitutive law for solid elements at constant temperature
==== The model ====
This law is used for a mechanical analysis of elastic isotropic solids undergoing large strains.
==== Files ====
Prepro: LELA.F \\ \\
Lagamine: 
  * ELA2S.F (Plane stress state)
  * ELA2E.F (Plane strain state)
  * ELA2A.F (Axisymmetric and generalized plane state)
  * ELA3D.F (3D state)
===== Availability =====
|Plane stress state| YES |
|Plane strain state| YES | 
|Axisymmetric state| YES |
|3D state| YES |
|Generalized plane state| YES |
===== Input file =====
==== Parameters defining the type of constitutive law ====
^ Line 1 (2I5, 60A1)^^
|IL|Law number|
|ITYPE| 1 |
|COMMENT| Any comment (up to 60 characters) that will be reproduced on the output listing|
==== Integer parameters ====
^ Line 1 (2I5) ^^
|ISOL| = 0 : use of total stresses in the constitutive law |
|:::| ≠ 0 :  use of effective stresses in the constitutive law - see [[appendices:a7|appendix 7]] |
|NINTV| = 1  by default |
==== Real parameters ====
^ Line 1 (3G10.0) ^^
|E| YOUNG’s elastic modulus |
|ANU| POISSON’s ratio |
|RHO| Specific mass |
===== Stresses =====
==== Number of stresses ====
6 for 3D state \\ 4 for the other cases
==== Meaning ====
The stresses are the components of CAUCHY stress tensor in global (X,Y,Z) coordinates. \\
For the 3-D state:
|SIG(1)|$\sigma_{xx}$|
|SIG(2)|$\sigma_{yy}$|
|SIG(3)|$\sigma_{zz}$|
|SIG(4)|$\sigma_{xy}$|
|SIG(5)|$\sigma_{xz}$|
|SIG(6)|$\sigma_{yz}$|
For the other cases:
|SIG(1)|$\sigma_{xx}$|
|SIG(2)|$\sigma_{yy}$|
|SIG(3)|$\sigma_{xy}$|
|SIG(4)|$\sigma_{zz}$|

===== State variables =====
==== Number of state variables ====
7
==== List of state variables ====
|Q(1)|Element thickness (t) in plane stress state|
|:::| = 1 in plane strain state |
|:::| Circumferential strain rate ($\varepsilon_{r}$) in axisymmetric state |
|:::| = 0 in 3-D state |
|:::| element thickness (t) in generalized plane state |
|Q(2)| nothing|
|Q(3)| nothing|
|Q(4)| nothing|
|Q(5)| nothing|
|Q(6)|strain energy per unit volume|
|Q(7)|actualized specific mass RHO|