I’ve found that beams using PIPE with 0 ID (thickness = outer radius) is better than CIRC in *BEAM SECTION. Perhaps everyone should be advised to use PIPE for solid round bars?
Advantages of PIPE:
- Bending moment is more accurate.
- Doesn’t have the bug of rotational constraint being applied to the wrong DOF.
- Doesn’t have the bug of wrong deformed shape with prescribed rotation.
- Stress is more accurate.
- More accurate frequencies with *FREQUENCY, including twisting modes.
Advantages of CIRC:
- Looks like a circle.
Not quite a drop-in replacement because:
- *DLOAD uses different areas. Scale the pressure to compensate.
- Stress is only valid at the midside nodes of the ends, whereas for CIRC, it’s only valid at the corner and midspan nodes.
Have I overlooked any problems with PIPE?