Edge traction
An edge traction acting on the edge of an element can be prescribed in any load case.
In the name.i2 file, a vector is first defined using a LV set:
LV set number T 9 V $l_x$ $l_y$ $l_z$
or
LV set number T 6 V $l_{x_h}$ $l_{y_h}$ $l_{z_h}$ $m_{y_h}$
and the set thus defined is then assigned to the edge of the selected elements:
AS load case number /$\dots$ /L set number E element number list L edge number /$\dots$
where
- $l_x,l_y,l_z~[\text{N/m}]$ are the components of the force in the direction of the global axes,
- $l_{x_h},l_{y_h},l_{z_h}~[\text{N/m}]$ are the components of the force on the edge of a semi-loof element in the direction of the local axes, see the Reference Manual,
- $m_{y_h}~[\text{Nm/m}]$ is the moment on the edge of a semi-loof element, see the Reference Manual.
Note
Edges and their local numbers are defined for 3D isoparametric elements and semi-loof elements, see the Reference Manual. For beam elements, distributed loading is specified in the form of a body force $Q=\text{edge traction}/\text{cross-sectional area}~[\text{N/m}^3]$. Similarly, for 2D isoparametric elements, distributed loading is specified in the form of a surface traction $q=\text{edge traction}/\text{thickness}~[\text{N/m}^2]$.
Note
More than one assignment of edge tractions to a single element edge may occur within a single load case. In that case, the force components are added together.
Note
The components of the vector can depend on the global coordinates $x,y,z$, using any of the available functional dependencies, see the Reference Manual.
Example
Let us consider a triangular shell element. The global node numbers follow from the specific numbering of the mesh.
According to the Reference Manual, the topology of the element is defined by the sequence of node numbers
22 24 77 23 44 43
and the orientation of edge 2 is as follows:
- the $x_h$ axis points outward from the element,
- the $y_h$ axis is oriented from node 24 toward node 77,
- the $z_h$ axis points upward (right-handed 22–24–77).
If the force is specified in the global system $x,y,z$ as $[l_x,l_y,l_z]$, knowledge of the edge orientation is not needed.
The assignment might, for example, take the form
AS <load case> /… /L <set> E 211 L 2/ …