Midas FX+ for Diana offers several methods to create interface elements. The next table shows which methods are available for point, line, and plane interface elements.
| Method | Point | Line | Plane |
| From element boundary | Yes | Yes | Yes |
| Manual Node ID Input | Yes | Yes | Yes |
| Convert Element | Yes | Yes | Yes |
| From Node Selection | No | Yes | Yes |
| From Free-Edge | No | Yes | No |
| From Free-Face | No | No | Yes |
| From Truss/Beam | No | Yes | No |
| From Plate | No | No | Yes |
| From Mesh-Set (T/X-cross Type) | No | Yes | No |
| Connect Closest Nodes | Yes | No | No |
From Element Boundary
When this method is used interface elements, either point, line, or plane interfaces, will be created on the boundary of the selected elements if these elements are connected to other elements. New nodes will be generated automatically for the interface using the from element boundary method. In the example below five line interfaces will be generated between the blue and the yellow elements. Note that no interfaces will be generated between the blue elements itself, because only the boundaries of selected elements will be checked for interface generation.
For quadratic meshes it is important that all regular elements are already made quadratic before the (quadratic) interface elements are generated. In case the interface elements would have been created from the linear meshes and afterwards all regular and interface elements are being made quadratic, the mid-nodes of the interface elements will not be duplicated and therefore result in an incorrect connectivity of the interface elements! In general it is advised to check the node numbers and connectivity of the generated interface elements.
Manual Node ID Input
When this method is used each interface element is created individually by specifying the node numbers of both sides of the interface elements. In this way the user has full control on the interface generation. For models containing many interface elements this method is very time consuming and there for less appropriate for large models. Note that both sides of the interface elements must have unique node numbers and that the node numbers must be provided in the correct order!
Quadratic interface elements can be either generated from quadratic regular elements by providing all the node numbers of both sides of the interfaces, or from linear regular elements and make all regular and interface elements quadratic afterwards as long as the mid-nodes do not share the same position. Note that the interface can be closed afterwards by moving the mesh without merging the nodes.
Convert Element
When this method is used a single layer of linear surface or linear solid elements is transferred to line or plane interfaces respectively. After the elements are converted the entire model can be made quadratic by changing the element properties of all elements, if necessary. Note that the interface can be closed afterwards by moving the mesh without merging the nodes. Next to the elements that need to be converted to interfaces, the base nodes of the interfaces can be defined by the user. Especially for fluid-structure interface elements this can be helpful to assure that the interface elements are correctly applied between the structural and flow elements.
From Node Selection
When this method is used point interfaces will be created at the location of the selected nodes.
New nodes will be generated automatically for the interfaces using the from node selection method.
From Free-Edge
When this method is used line interfaces will be created between two free edges if the distance between the edges is within the specified tolerance. This method can be used on both linear and quadratic meshes to generate either linear or quadratic line interface elements.
Note that the interfaces can be closed afterwards by moving the mesh without merging the nodes.
From Free-Face
When this method is used plane interfaces will be created between two free faces if the distance between the faces is within the specified tolerance. This method can be used on both linear and quadratic meshes to generate either linear or quadratic plane interface elements.
Note that the interfaces can be closed afterwards by moving the mesh without merging the nodes.
From Truss/Beam
When this method is used line interface elements will be created between the selected beam or truss elements and the attached regular elements. This method can be used on both linear and quadratic meshes to generate either linear or quadratic line interface elements. For quadratic meshes it is important that all regular elements are already made quadratic before the (quadratic) interface elements are generated. In case the interface elements would have been created from the linear meshes and afterwards all regular and interface elements are being made quadratic, the mid-nodes of the interface elements will not be duplicated and therefore result in an incorrect connectivity of the interface elements! In general it is advised to check the node numbers and connectivity of the generated interface elements. Note that in the example below 10 line interface elements will be generated: 5 between the beam elements and the blue elements and 5 between the beam elements and the yellow elements. This method can for example be used for modelling interface elements between soil and sheet pile walls.
From Plate
When this method is used plane interface elements will be created between the selected plate elements and the attached regular elements. This method can be used on both linear and quadratic meshes to generate either linear or quadratic plane interface elements. For quadratic meshes it is important that all regular elements are already made quadratic before the (quadratic) interface elements are generated. In case the interface elements would have been created from the linear meshes and afterwards all regular and interface elements are being made quadratic, the mid-nodes of the interface elements will not be duplicated and therefore result in an incorrect connectivity of the interface elements! Note that in the example below 50 plane interface elements will be generated: 25 between the plate elements and the blue solid elements and 25 between the plate elements and the yellow solid elements.
Optionally coupling nodes can be defined for this method. In the coupling nodes no additional nodes will be generated. Therefore, the interface elements cannot be opened at these coupling nodes. This method can for example be used for modeling plane interface elements between soil and sheet pile walls.
From Mesh-Set (T/X-cross type)
When this method is used line interface elements will be created between connecting elements of different mesh sets. New nodes will be generated automatically for the interface using this method. In the example below five line interfaces will be generated between the blue and the yellow elements. Note that no interfaces will be generated between the blue or yellow elements itself, because only the boundaries of mesh sets will be checked for interface generation.
For quadratic meshes it is important that all regular elements are already made quadratic before the (quadratic) interface elements are generated. In case the interface elements would have been created from the linear meshes and afterwards all regular and interface elements are being made quadratic, the mid-nodes of the interface elements will not be duplicated and therefore result in an incorrect connectivity of the interface elements! In general it is advised to check the node numbers and connectivity of the generated interface elements.
Connect Closest Nodes
When this method is used point interfaces will be created between two nodes if the distance between the nodes is within the specified tolerance. Note that the interfaces can be closed afterwards by moving the mesh without merging the nodes.
