MCOHE

Bulk Data Entry Defines the material properties for potential-based cohesive material models.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
MCOHE MID MODEL
COHE CRTOD MAXOD BETA EXP VED SFC

Example 1

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
MCOHE 2 1
20.0 0.02 0.2 1.0e5

Example 2

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
MCOHE 2 2
10.0 0.03 0.5 1.0e-3 -1.0

Example 3

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
MCOHE 2 3
20.0 0.03 2.0 1.0e-4 SOFT

Definitions

Field Contents SI Unit Example
MID Material identification number.

No default (Integer > 0)
MODEL Indicates the traction-separation relationship profile type.
1
Bilinear
2
Exponential
3
Linear-Exponential

No default (Integer)
COHE The energy per area that can be absorbed by the cohesive elements. It is the area under the traction-separation curve.

No default (Real > 0.0)

 [ N m ] or [ J m 2 ]
CRTOD Critical opening distance.

No default (Real ≥ 0.0)

 [ m ]
MAXOD Maximum opening displacement (bilinear model only).

No default (Real > 0.0)

 [ m ]
BETA Coefficient on the shear opening for mode mix based on displacement.

Default = 1.0 (Real ≥ 0.0)
EXP Exponential decay factor (linear-exponential model only).

No default (Real > 0.0)
VED Viscous energy dissipation factor.

Default = 0.0. (Real > 0.0)
SFC Stiffening factor in compression.
Positive value (= Real > 0.0)
Directly prescribed stiffness.
Negative value (= Real < 0.0)
Defines a stiffness scaling factor. The stiffness scaling factor is equal to |Real < 0.0|. The scaling is applied to the initial stiffness in separation condition.
SOFT
Takes the maximum diagonal value in the global stiffness of the numerical model multiplied by 1.0E2 as the compression stiffness.
HARD
Takes the maximum diagonal value in the global stiffness of the numerical model multiplied by 1.0E6 as the compression stiffness.
AUTO
Takes the maximum diagonal value in the global stiffness of the numerical model multiplied by 1.0E4 as the compression stiffness.

Default = -1.0

Comments

  1. The material identification number must be unique for all MAT1, MAT2, MAT3, MAT8, MAT9, MGASK, MCOHE, and MCOHED entries.
  2. In some cases, snap-back phenomena could appear in numerical models with cohesive elements. VED can be used to stabilize the solution.
  3. For additional information, refer to Cohesive Zone Modeling in the User Guide.