These elements are the simplest (geometrically speaking), and are efficient models, but are complex in usage (postprocessing - but is easier with PowerGraphics + /ESHAPE)
Beams give "general system performance," not localized behavior
Truss (spar) elements are a subset of beam-type elements which can’t carry moments (i.e., have no bending DOF’s). These are commonly called "two-force members", carrying only axial load. (p. 136)
Every node in a truss model is a pin joint (or hinge).
Use only one element between pins.
DOF’s: UX, UY, and UZ (in 3D)
Material Props: Modulus, Density, ALPX
Real Constants: Area, Initial Strain or Added Mass (180)
BEAM4, BEAM44, BEAM24 (3D)
BEAM188, BEAM189 (3D)
DOFs: UX, UY, ROTZ, and UZ, ROTY, ROTX (in 3D)
Material Props: Modulus, Density, ALPX, Shear Modulus,
Real Constants: Area, Moments of inertia, Thicknesses, Initial Strain, Orientation, Shear Constants, etc.
Special options: tapered sect., offset from nodes, moment release (p. 136)
Beam Coordinate systems (p.137) orient the element’s y- and z-axes for moments IYY and IZZ (could be: strong and weak bending directions)
The beam’s neutral axis is (default) along the line of nodes (element x-axis).
ONLY for the new 3D beams (BEAM188 & 189), ANSYS 5.5 has 11 predefined sections, or you can sketch your own.
Preprocessor > Sections > Common Sections
You must orient the cross-section. (p. 140)
ANSYS: uses an "extra" node (or keypoint) -OR- angle theta
Areas and lines: simple solid model of a machinery base plate
SHELL63 and BEAM188 model. BEAM188 with section shape and offset defined.
