OOF: Finite Element Analysis of Microstructures
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Subsections
damisotropic
This is an isotropic element which can undergo ``damage'' when the
principal stress exceeds a user-defined upper limit or retrocedes
below a user-defined lower limit. The effect of damage is that all
components of the stiffness matrix are multiplied by a user-defined
knockdown value.
The damage does not take place until a mutation command is invoked, either explicitly with mutate (Section 3.1.4) or implicitly with the comp_equil (Section 3.1.3) command. An element can be re-mutated (i.e, re-multiplied by the knockdown factor) if the stress re-exceeds its bounds.
Elements which have mutated are drawn in black in the Mesh Drawer (Section 5.1), but are immediately redrawn with the new (unequilibrated) stresses or strains in the Stress Drawers and Strain Drawers. An additional equilibrate step is required to produce equilibrium after any elements incur damage due to a mutate command.
Parameters
- thermoelastic coefficients
- The thermoelastic coefficients young, poisson, and alpha are identical to those defined for the isotropic elements in
Section 4.5.1.
- max_stress
- The upper limit of stress. Elements whose largest principal stress
is greater than max_stress will mutate during a mutate
command (Section 3.1.4). [stress]
- min_stress
- The lower limit of stress. Elements whose smallest principal stress is
less than min_stress will mutate during a mutate command
(Section 3.1.4). Negative stresses are
compressive. [stress]
- max_knockdown
- The factor by which the entire element stiffness matrix is multiplied when
its largest principal stress exceeds max_stress. [dimensionless]
- min_knockdown
- The factor by which the entire element stiffness matrix is multiplied when its smallest principal stress is less than min_stress. [dimensionless]
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