*INITIAL STRAIN INCREASE

Keyword type: step

This option is used to define an increase of initial strains. The values are added to the initial strains already present in the model. The use of this option requires the previous use of *INITIAL CONDITIONS, TYPE=PLASTIC STRAIN or *MODEL CHANGE, TYPE=ELEMENT, ADD or *MODEL CHANGE, TYPE=ELEMENT, ADD=STRAIN FREE.

The resulting initial strain components are subtracted from the strain components computed from the displacement field. If thermal strains are relevant they are additionally subtracted. The resulting strain is used to compute the stress and tangent stiffness matrix using the appropriate constitutive equations.

Please note that the strains have to be provided in the GLOBAL (rectangular) coordinate system, no matter whether an *ORIENTATION card or *TRANSFORM card applies to the corresponding element.

First line:

• *INITIAL STRAIN INCREASE

Following line:

• Element number.
• Integration point number.
• Value of first initial strain increase component (xx) in the GLOBAL coordinate system x-y-z.
• Value of second initial strain increase component (yy) in the GLOBAL coordinate system x-y-z.
• Value of third initial strain increase component (zz) in the GLOBAL coordinate system x-y-z.
• Value of fourth initial strain increase component (xy) in the GLOBAL coordinate system x-y-z.
• Value of fifth initial strain increase component (xz) in the GLOBAL coordinate system x-y-z.
• Value of sixth initial strain increase component (yz) in the GLOBAL coordinate system x-y-z.
Repeat this line if needed. The strain components should be given as Lagrange strain components for nonlinear calculations and linearized strain components for linear computations.

Examples:

*INITIAL STRAIN INCREASE
20,5,0.01,0.,0.01,0.,0.,0.


increases the initial strain at integration point 5 of element 20 by a normal global x and normal global z component of 0.01, the other strains remain unchanged.

Example files: inistrain2.