Mechanical APDL Basic Analysis Guide - Ansys

• Transferred solid loads will replace nodal or element loads already present, regardless of the order in
which the loads were input. For example, DL,,,UX on a line will overwrite any D,,,UX loads on the nodes
of that line at transfer time. (DL,,,UX will also overwrite D,,,VELX velocity loads and D,,,ACCX acceleration
loads.)
• Deleting solid model loads also deletes any corresponding finite element loads. For example,
SFADELE,,,PRES on an area will immediately delete any SFE,,,PRES loads on the elements in that area.
• Line or area symmetry or antisymmetry conditions (DL,,,SYMM, DL,,,ASYM, DA,,,SYMM, or DA,,,ASYM)
often introduce nodal rotations that could effect nodal constraints, nodal forces, couplings, or constraint
equations on nodes belonging to constrained lines or areas.
2.5.2. Finite-Element Loads: Advantages and Disadvantages
Advantages:
• Reduced analyses present no problems, because you can apply loads directly at master nodes.
• There is no need to worry about constraint expansion. You can simply select all desired nodes and
specify the appropriate constraints.
Disadvantages:
• Any modification of the finite element mesh invalidates the loads, requiring you to delete the previous
loads and re-apply them on the new mesh.
• Applying loads by graphical picking is inconvenient, unless only a few nodes or elements are involved.
The next few subsections discuss how to apply each category of loads - constraints, forces, surface loads,
body loads, inertia loads, and coupled-field loads - and then explain how to specify load step options.
2.5.3. DOF Constraints
Table 2.1: DOF Constraints Available in Each Discipline (p. 27) shows the degrees of freedom that can be
constrained in each discipline and the corresponding ANSYS labels. Any directions implied by the labels
(such as UX, ROTZ, AY, etc.) are in the nodal coordinate system. For a description of different coordinate
systems, see the Modeling and Meshing Guide.
Table 2.2: Commands for DOF Constraints (p. 28) shows the commands to apply, list, and delete DOF constraints.
Notice that you can apply constraints on nodes, keypoints, lines, and areas.
Table 2.1 DOF Constraints Available in Each Discipline
Discipline
Degree of Freedom
ANSYS Label
Structural[1] Translations
UX, UY, UZ
Rotations
ROTX, ROTY, ROTZ
Hydrostatic Pressure
HDSP
Thermal Temperature
TEMP, TBOT, TE2, . . . TTOP
Magnetic Vector Potentials
AX, AY, AZ
Scalar Potential
MAG
Electric Voltage
VOLT
Fluid Velocities
VX, VY, VZ
Pressure
PRES
Turbulent Kinetic Energy ENKE
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2.5.3. DOF Constraints
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