Definition by Three Nodes

In Tosca ANSA® environment, the button corresponding to the creation of a new coordinate system using three nodes is called CORD1 (Nastran), NODE (Abaqus) or CS (ANSYS®); in the latter case, only Cartesian coordinate systems are supported; in the other two cases, the type of the coordinate system is chosen in the drop down list.

In each case, after the command is chosen, the user selects three nodes from the model that are used as follows:

• the first node is the origin;
• the direction from the origin to the second node is the direction of the first axis that is x-axis (in case of NODES | RECTANGULAR (Abaqus), CS (ANSYS®) or ..._NODES_DYN (in selection window)) or z-axis (otherwise);
• the axis that follows after the first one (i.e., y- or x-axis) lies in the plane defined by the three nodes, perpendicular to the first axis and closer to the direction from the origin to the third node;
• the last axis is perpendicular to the first and the second one, forming a positively oriented basis.

The following figure shows the definition of coordinate systems using three nodes in Tosca ANSA® environment and in Tosca Structure.gui:

In Tosca Structure.gui, the IDs of nodes should be entered in the corresponding fields, and also the fields Axis (x-axis or z-axis) and Plane (X-Y plane or X-Z plane) should be specified. Then, the first chosen node (Node ID of Origin field) is the origin, the second node (Node on Axis field) defines the axis (specified in Axis field) as described above, and the third node (Node in Plane field) is needed to define the plane according to Plane field.