MET 415 Lecture Notes

**** PROJECT 1 Notes (ANSYS, not WBE)****

• What element type ? What element options are needed ?
• What are ‘Real Constants’ and are they needed ?
• Where will you get material properties ?
• Necessary Features + Symmetry
• Use Working Planes to cut ‘areas’ - turn WP on edge to cut
• A Cylindrical Coordinate System is needed for pin support B.C.
• Rotated node coord. systems allow support like the OD of a rigid shaft
• Creating a fillet in 2D is a ‘Line Fillet’ (in 3D we use ‘Area Fillet’)
• What are ATTRIBUTES ?
• Assign ATTRIBUTES to the model BEFORE meshing:
• If Attributes are not assigned, defaults are used.
• Initially, defaults are: MAT = 1, TYPE = 1, REAL = 1
• ADD, GLUE, MERGE of model entities
• ADD: removes internal boundaries (i.e., lines) between areas
• GLUE: keeps internal boundaries
• MERGE: replaces coincident entities with one

NODAL COORDINATE SYSTEMS

Every node in the FEA model has its own "nodal coordinate system".  The nodal coordinate system "orients" the DOF directions at each node.

Loads and Displacement constraints are applied in the nodal coordinate systems: FX, FY, FZ, MX, MY, MZ; UX, UY, UZ, ROTX, ROTY, ROTZ.

By default, nodal coordinate systems are parallel to the Global Cartesian.

If needed, you can change the orientation of the nodal coord. system:

1. by Modifying the node with known angles or direction cosines
2. by "rotating" the node directions into the currently active coordinate system (Cartesian, cylindrical, spherical).
3. sometimes, a symmetry boundary condition will automatically rotate the nodal directions to produce the symmetry B.C. (If the symmetry edge of the model is not parallel to one of the global coordinate directions.

For Project 1:

• Create/Activate a cylindrical coordinate system at the center of the pin
• Select the nodes on the edge for the pin boundary condition
• Modify the nodes by rotating them into the active coordinate system
• Apply the constraint in just the radial direction