MCOHED
Bulk Data Entry Defines the material properties for damage-based cohesive material models.
Format
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
MCOHED | MID | KI | KII | KIII | SFC | VED | RHO | MXDMG | |
DMGINIID | DMGEVOID | ||||||||
RAYL | ALPHA |
Example 1 (no damage, no Rayleigh damping)
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
MCOHED | 2 | 9000. | 3000. | 3000. | -1.0 | 1.0e-3 | 0.99 |
Example 2 (with damage, no Rayleigh damping)
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
MCOHED | 2 | 9000. | 3000. | 3000. | -1.0 | 1.0e-3 | 0.99 | ||
20 | 23 |
Example 3 (no damage, with Rayleigh damping)
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
MCOHED | 2 | 9000. | 3000. | 3000. | -1.0 | 1.0e-3 | 1.0e-5 | 0.99 | |
± | RAYL | 0.22 |
Definitions
Field | Contents | SI Unit Example |
---|---|---|
MID | Material
identification number. No default (Integer > 0) |
|
KI, KII, KIII | Elasticity modulus
corresponding to Mode I, II and III deformation, when the card
is used in cohesive elements. Penalty stiffness corresponding to Mode I, II and III deformation, when the card is used in cohesive contacts. 2 No default (Real) |
for cohesive elements for cohesive contacts |
SFC | Stiffening factor in
compression. This is applicable only for Cohesive elements. For Cohesive contact, the compression stiffness is controlled by the contact penalty.
Default = 1.0 |
|
VED | Factor for viscous
energy dissipation. 3 Default = 0.0 (Real > 0.0) |
|
RHO | Density (mass per
volume) Default = 0.0 (Real ≥ 0.0) |
|
MXDMG | Maximum damage index,
above which the cohesive element is excluded from
analysis. Default = 1.0 (Real ≥ 0.0) |
|
DMGINIID | Damage initiation
entry ID. 4 Default = blank (Integer > 0) |
|
DMGEVOID | Damage evolution entry
ID. 4 Default = blank (Integer > 0) |
|
RAYL | Continuation line flag for material-dependent Rayleigh damping 5 | |
ALPHA | Material-dependent
Rayleigh Damping coefficient for the mass matrix 5 Default = blank (Real ≥ 0.0) |
Comments
- The material identification number should be unique for all MAT1, MAT2, MAT3, MAT8, MAT9, MGASK, MCOHE, MCOHED entries.
- In cohesive contacts, it is recommended to use KII = KIII.
- In some cases, snap-back phenomena could appear in numerical models with cohesive elements. VED can be used to stabilize the solution.
- Cohesive material with traction
only can be defined by leaving the DMGINIID and
DMGEVOID fields as blank. In this case, cohesive
material behavior is linear elastic in nature. This is only supported for
cohesive elements.
DMGINIID and DMGEVOID must be specified with cohesive contact.
- For material-dependent Rayleigh
damping, the equivalent viscous damping,
, is defined as:
(1) Where,- Defined on the RAYL continuation line on the material entry
- Mass matrix
- Direct Frequency Response Analysis
- Modal Frequency Response Analysis
- Linear Direct Transient Analysis
- Linear Modal Transient Analysis
- Nonlinear Transient Analysis
- For additional information, refer to Cohesive Zone Modeling in the User Guide.