26.5.8 Two-dimensional cohesive element library

**Products: **ABAQUS/Standard ABAQUS/Explicit ABAQUS/CAE

You can define the element's initial constitutive thickness and the out-of-plane width. The default initial constitutive thickness of cohesive elements depends on the response of these elements. For continuum response, the default initial constitutive thickness is computed based on the nodal coordinates. For traction-separation response, the default initial constitutive thickness is assumed to be 1.0. For response based on a uniaxial stress state, there is no default; you must indicate your choice of the method for computing the initial constitutive thickness. See “Specifying the constitutive thickness” in “Defining the cohesive element's initial geometry,” Section 26.5.4, for details.

ABAQUS calculates the thickness direction automatically based on the midsurface of the element.

Input File Usage: | *COHESIVE SECTION |

ABAQUS/CAE Usage: | Property module: |

Distributed loads

Distributed loads are specified as described in “Distributed loads,” Section 27.4.3.

**Load ID (*DLOAD):** BX**ABAQUS/CAE Load/Interaction:** **Body force****Units:** FL^{–3}**Description: **Body force in global *X*-direction.

**Load ID (*DLOAD):** BY**ABAQUS/CAE Load/Interaction:** **Body force****Units:** FL^{–3}**Description: **Body force in global *Y*-direction.

**Load ID (*DLOAD):** BXNU**ABAQUS/CAE Load/Interaction:** **Body force****Units:** FL^{–3}**Description: **Nonuniform body force in global *X*-direction with magnitude supplied via user subroutine `DLOAD` in ABAQUS/Standard and `VDLOAD` in ABAQUS/Explicit.

**Load ID (*DLOAD):** BYNU**ABAQUS/CAE Load/Interaction:** **Body force****Units:** FL^{–3}**Description: **Nonuniform body force in global *Y*-direction with magnitude supplied via user subroutine `DLOAD` in ABAQUS/Standard and `VDLOAD` in ABAQUS/Explicit.

**Load ID (*DLOAD):** CENT^{(S)}**ABAQUS/CAE Load/Interaction:** Not supported**Units:** FL^{–4}(ML^{–3}T^{–2})**Description: **Centrifugal load (magnitude is input as , where is the mass density per unit volume, is the angular velocity).

**Load ID (*DLOAD):** CENTRIF^{(S)}**ABAQUS/CAE Load/Interaction:** **Rotational body force****Units:** T^{–2}**Description: **Centrifugal load (magnitude is input as , where is the angular velocity).

**Load ID (*DLOAD):** CORIO^{(S)}**ABAQUS/CAE Load/Interaction:** Not supported**Units:** FL^{–4}T (ML^{–3}T^{–1})**Description: **Coriolis force (magnitude is input as , where is the mass density per unit volume, is the angular velocity).

**Load ID (*DLOAD):** GRAV**ABAQUS/CAE Load/Interaction:** **Gravity****Units:** LT^{–2}**Description: **Gravity loading in a specified direction (magnitude is input as acceleration).

**Load ID (*DLOAD):** P*n***ABAQUS/CAE Load/Interaction:** **Pressure****Units:** FL^{–2}**Description: **Pressure on face *n*.

**Load ID (*DLOAD):** P*n*NU**ABAQUS/CAE Load/Interaction:** Not supported**Units:** FL^{–2}**Description: **Nonuniform pressure on face *n* with magnitude supplied via user subroutine `DLOAD` in ABAQUS/Standard and `VDLOAD` in ABAQUS/Explicit.

**Load ID (*DLOAD):** ROTA^{(S)}**ABAQUS/CAE Load/Interaction:** **Rotational body force****Units:** T^{–2}**Description: **Rotary acceleration load (magnitude is input as , where is the rotary acceleration).

**Load ID (*DLOAD):** SBF^{(E)}**ABAQUS/CAE Load/Interaction:** Not supported**Units:** FL^{–5}T^{2}**Description: **Stagnation body force in global *X*- and *Y*-directions.

**Load ID (*DLOAD):** SP*n*^{(E)}**ABAQUS/CAE Load/Interaction:** **Pressure****Units:** FL^{–4}T^{2}**Description: **Stagnation pressure on face *n*.

**Load ID (*DLOAD):** VBF^{(E)}**ABAQUS/CAE Load/Interaction:** Not supported**Units:** FL^{–4}T**Description: **Viscous body force in global *X*- and *Y*-directions.

**Load ID (*DLOAD):** VP*n*^{(E)}**ABAQUS/CAE Load/Interaction:** **Pressure****Units:** FL^{–3}T**Description: **Viscous pressure on face *n*, applying a pressure proportional to the velocity normal to the face and opposing the motion.

Distributed loads

Surface-based distributed loads are specified as described in “Distributed loads,” Section 27.4.3.

**Load ID (*DSLOAD):** P**ABAQUS/CAE Load/Interaction:** **Pressure****Units:** FL^{–2}**Description: **Pressure on the element surface.

**Load ID (*DSLOAD):** PNU**ABAQUS/CAE Load/Interaction:** **Pressure****Units:** FL^{–2}**Description: **Nonuniform pressure on the element surface with magnitude supplied via user subroutine `DLOAD` in ABAQUS/Standard and `VDLOAD` in ABAQUS/Explicit.

**Load ID (*DSLOAD):** SP^{(E)}**ABAQUS/CAE Load/Interaction:** **Pressure****Units:** FL^{–4}T^{2}**Description: **Stagnation pressure on the element surface.

**Load ID (*DSLOAD):** VP^{(E)}**ABAQUS/CAE Load/Interaction:** **Pressure****Units:** FL^{–3}T**Description: **Viscous pressure applied on the element surface. The viscous pressure is proportional to the velocity normal to the element face and opposing the motion.

Stress, strain, and other tensor components available for output depend on whether the cohesive elements are used to model adhesive joints, gaskets, or delamination problems. You indicate the intended usage of the cohesive elements by choosing an appropriate response type when defining the section properties of these elements. The available response types are discussed in “Defining the constitutive response of cohesive elements using a continuum approach,” Section 26.5.5, and “Defining the constitutive response of cohesive elements using a traction-separation description,” Section 26.5.6.

Cohesive elements using a continuum response

Stress and other tensors (including strain tensors) are available for elements with continuum response. Both the stress tensor and the strain tensor contain true values. For the constitutive calculations using a continuum response, only the direct through-thickness and the transverse shear strains are assumed to be nonzero. All the other strain components (i.e., the membrane strains) are assumed to be zero (see “Modeling of an adhesive layer of finite thickness” in “Defining the constitutive response of cohesive elements using a continuum approach,” Section 26.5.5, for details). All tensors have the same number of components. For example, the stress components are as follows:

S11 | Direct membrane stress. |

S22 | Direct through-thickness stress. |

S33 | Direct membrane stress. |

S12 | Transverse shear stress. |

Cohesive elements using a uniaxial stress state

Stress and other tensors (including strain tensors) are available for cohesive elements with uniaxial stress response. Both the stress tensor and the strain tensor contain true values. For the constitutive calculations using a uniaxial stress response, only the direct through-thickness stress is assumed to be nonzero. All the other stress components (i.e., the membrane and transverse shear stresses) are assumed to be zero (see “Modeling of gaskets and/or small adhesive patches” in “Defining the constitutive response of cohesive elements using a continuum approach,” Section 26.5.5, for details). All tensors have the same number of components. For example, the stress components are as follows:

S22 | Direct through-thickness stress. |

Cohesive elements using a traction-separation response

Stress and other tensors (including strain tensors) are available for elements with traction-separation response. Both the stress tensor and the strain tensor contain nominal values. The output variables E, LE, and NE all contain the nominal strain when the response of cohesive elements is defined in terms of traction versus separation. All tensors have the same number of components. For example, the stress components are as follows:

S22 | Direct through-thickness stress. |

S12 | Transverse shear stress. |