Defining a Space System for the Plane
Defining a space system for the plane.
Once you have defined the plane, by one of the definition methods above, you need to define which space system it operates in.
This figure shows the Cut space system selection panel, showing the two possible systems. These are described below.
Section follows node(s) allows a cut section defined using 3 nodes, or a single node in the constant X/Y/Z cases, to be updated using the current coordinates of the node(s) at each state.
BASIC space systemIn this system the cut plane is calculated using the model's undeformed geometry, regardless of the current state in core. This means that the parametric coordinates of the cut positions on elements are calculated using the undeformed geometry, then applied to the current (deformed) in-core state. Therefore the cut plane will almost certainly not remain flat as the model deforms. This is a "lagrangian" cut: the cutting plane deforms as the element mesh deforms.
|
DEFORMED space systemIn this system the cut plane is calculated using the model's current deformed geometry. Therefore the cut position on elements, and indeed the elements which are cut, can change as the model deforms through the static plane position.
The plane will always remain flat, and will remain fixed in space relative
to the model coordinate system.
This is an "eulerian" cut: the cutting plane remains fixed while the element mesh can deform through it.
|
Note: Force and moment computation varies with section space.For compatibility with Ansys LS-DYNA the forces and moments computed in a BASIC space system are:
Whereas those computed in a DEFORMED space system are:
This is described in more detail in FORCES Computing forces and moments on the cutting plane below.
|