Defining the Element Connectivity
The connectivity of a cohesive element is like that of a continuum element; however, it is useful to think of a cohesive element as being composed of two faces (a bottom and a top face) separated by the cohesive zone thickness. The element has nodes on its bottom face and corresponding nodes on its top face. Pore pressure cohesive elements include a third, middle face, which is used to model fluid flow within the element.
Three methods are available to define the element connectivity.
By Directly Defining the Element's Complete Connectivity
The complete connectivity of a cohesive element can be given directly (see Defining Cohesive Elements).
By Defining the Bottom-Face Element Connectivity and an Integer Offset
Alternatively, you can specify the connectivity of the bottom face plus a positive integer offset (see Defining Cohesive Elements) that will be used to determine the remaining cohesive element nodes.
Input File Usage
ELEMENT, OFFSET=n
Abaqus/CAE Usage
Element offsets are not supported in Abaqus/CAE.
Use with Displacement Cohesive Elements
The integer offset will be used to define node numbers of the top face of the cohesive element. Abaqus will automatically position the nodes of the top face to be coincident with those of the bottom face unless the nodes of the top face have already been assigned coordinates directly with a node definition (Node Definition).
Use with Pore Pressure-Displacement Cohesive Elements
When you define only the bottom face nodes, the integer offset will first be used to define the node numbers of the top face of the cohesive element, with the numbering of the top-face nodes offset from the bottom face node numbers. The integer offset will again be used to define the middle surface node numbers offset, with the numbering of the middle-face nodes offset from the top face node numbers. Abaqus will automatically position the nodes of the top and middle faces to be coincident with those of the bottom face unless the nodes of the top face have already been assigned coordinates directly with a node definition (Node Definition).
By Defining the Bottom- and Top-Face Element Connectivities and an Integer Offset
For pore pressure cohesive elements, you also can specify the connectivity of the bottom and top faces plus a positive integer offset (see Defining Cohesive Elements) that will be used to determine the middle face cohesive element nodes.
When you define the bottom and top face nodes, the integer offset will be used to define the node numbers of the middle face, with the numbering of the middle-face nodes offset from the bottom face node numbers. Abaqus will automatically position the nodes of the middle face to be halfway between those of the bottom and top faces unless the nodes of the middle face have already been assigned coordinates directly with a node definition (Node Definition).
Input File Usage
ELEMENT, OFFSET=n
Abaqus/CAE Usage
Element offsets are not supported in Abaqus/CAE.