Damage
Use the Damage subnode to model damage and cracking in brittle materials according to various criteria. It can be used in combination with Linear Elastic Material.
Damage
Select the type of Damage model — Scalar damage or Mazars damage for concrete.
Scalar damage
Select the type of Equivalent strain — Rankine, Smooth Rankine, Norm of elastic strain tensor, or User defined.
The Activate damage in compression check box is available for the Rankine, Smooth Rankine, or User defined equivalent strain, and it is not selected by default. When selected, the damage evolution law is applied on the total undamaged stress tensor.
Select the type of Damage evolution — Linear strain softening, Exponential strain softening, or User defined.
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For Linear strain softening or Exponential strain softening enter the Tensile strength σts, the default is to take the value From material. Change to User defined to enter other value or expression.
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For User defined, enter an expression for the Damage evolution function d(κ).
For Linear strain softening or Exponential strain softening select the type of Strain softening input and enter the Fracture energy per area Gf, the Fracture energy per volume gf, or the Strain softening parameter εf accordingly.
Mazars damage for concrete
Select the type of Equivalent strain — Mazars, Modified Mazars, or User defined.
Enter the Shear exponent β, the default is set to 1.06.
Select the Tensile damage evolution — Linear strain softening, Exponential strain softening, Mazars damage evolution function, or User defined.
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For Linear strain softening or Exponential strain softening enter the Tensile strength σts, the default is to take the value From material. Also select the type of Tensile strain softening and enter the Fracture energy per area Gft, the Fracture energy per volume gft, or the Strain softening parameter εft accordingly.
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For Mazars damage evolution function, enter the Tensile strain threshold ε0t, and the Tensile damage evolution parameters At and Bt.
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For User defined, enter an expression for the Tensile damage evolution function dt(κ).
Select the Compressive damage evolution — Mazars damage evolution function or User defined.
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For Mazars damage evolution function, enter the Compressive strain threshold ε0c, and the Compressive damage evolution parameters Ac and Bc.
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For User defined, enter an expression for the Compressive damage evolution function dc(κ).
Regularization
Select the type of Regularization method — None, Crack band, or Implicit gradient.
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For the Crack band method select the type of Crack band calculation — Element volume/area, or Element size. Note that when the Crack band method is selected, only the Fracture energy per area is available as Strain softening input.
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For the Implicit gradient method enter the Internal length scale lint. If the Fracture energy per area was selected as Strain softening input, enter also the Characteristic size of the damage dissipation zone hdmg.
Advanced
Enter the Maximum damage. The default value is 0.99999.
The Damage subnode is only available with some COMSOL products (see http://www.comsol.com/products/specifications/).
When a Mixed Formulation is selected in the parent Linear Elastic Material, the damage model can give spurious results. The Implicit gradient regularization method is more stable in this respect, and it is recommended when using the mixed formulation.
See also
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Modeling Damage in the Structural Mechanics Modeling chapter.
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Damage Models in the Structural Mechanics Theory chapter.
Location in User Interface
Context Menus
 Solid Mechanics>Linear Elastic Material>Damage
Ribbon
Physics tab with Linear Elastic Material, node selected in the model tree:
Attributes>Damage