Initial Stress and Strain
You can add the Initial Stress and Strain subnode to the Linear Elastic Material, in order to specify the stress or strain state in the structure before applying any constraint or load. The values given are not initial values in the mathematical sense, but rather a contribution to the constitutive relation.
Initial stresses and strains can be included with Linear Elastic Material, Layered Linear Elastic Material, and Nonlinear Elastic Material. For the Layered Linear Elastic Material, the contribution can be applied to arbitrary layers in a multilayered membrane when the Composite Materials Module is available
In many cases Initial Stress and Strain and External Stress are interchangeable when prescribing stresses, but you can find some more options in the latter.
Shell Properties
This section is present only when the Initial Stress and Strain node is used under Layered Linear Elastic Material.
Select the layer or layers for which this stress or strain contribution is to be added.
When Use all layers is not selected.
If the initial stress or strain differ between layers, you will need to add several Initial Stress and Strain nodes with different layer selections.
If the same layer is selected in two Initial Stress and Strain nodes being active on the same boundary, the contributions will be added.
Coordinate System Selection
The given initial stresses and strains are interpreted in this system.
Initial Stress and Strain
Specify the initial stress as the Initial local in-plane force N0 and the initial strain as the Initial local in-plane strain ε0 (dimensionless). In addition, you can also provide the Initial out-of-plane strain, εn0.
If you know the stress, rather than the force per unit length, type in the stress multiplied by the membrane thickness mbrn.d. In a geometrically nonlinear analysis, the stresses should be interpreted as Second Piola-Kirchhoff stresses, and the strains should be interpreted as Green-Lagrange strains.
Prestressed Micromirror: Application Library path MEMS_Module/Actuators/micromirror
Location in User Interface
Context Menus
Ribbon
Physics tab with Linear Elastic Material, Layered Linear Elastic Material, or Nonlinear Elastic Material node selected in the model tree: