Constraints and loads are defined in the Solution section. The symbol D is used for any general type of nodal constraint and the symbol F is used for any general type of applied nodal action. This derives from the concept of F = Kd. Distributed loads are defined with several different symbols. For example, SF is a surface force applied at nodes with SFBEAM for beams in particular.
The commands looks like this:
D,1,UY,0 ! constrain node 1 in y direction (roller) D,3,UX,0,,,,UY ! constrain node 1 in x and y direction (pin) D,1,ALL ! constrain node 1 all 6 degrees of freedom D,1,VOLT,20 ! voltage of node 1 is 20 D,2,TEMP,300 ! temperature of node 2 is 300
Constraints can be applied to a set of regularly spaced nodes by using the fifth and sixth options. As with the Load command, the fifth option is the last node number in the series and the sixth option is the node increment between the loads. For example, the lines:
nrows = 5 ! number of element rows D,1,TEMP,400,,(nrows*10+1),10 ! temp of inside nodes
constrain the temperature to be 400 at nodes 1, 11, 21, 31, 41, 51.
The commands looks like this:
F,1,FX,1000 ! force X direction at node 1 F,4,FY,-20e3 ! force -Y direction at node 4 F,1,MX,4e3 ! moment about X axis at node 1 F,2,MZ,42e3 ! moment about Z axis at node 2
Loads can be applied to a set of regularly spaced nodes by using the fifth and sixth options. The fifth option is the last node number in the series and the sixth option is the node increment between the loads. For example, the line:
applies a downward 1000 force at nodes 1, 3, and 5. Notice the double comma after 1000.
SFBEAM,1,1,PRES,60 ! uniform load 60 lb/in SFBEAM,1,1,PRES,0,60 ! tapered load 0-60 lb/in SFBEAM,2,1,PRES,60,0 ! tapered load 60-0 lb/in SFBEAM,ALL,1,PRES,60 ! uniform Load 60 lb/in
The first line creates a uniform load of 60 on the first element while the second gives a tapered load from 0 to 60 on the first element. The third command puts a load tapered from 60 to 0 on element 2 while the fourth command loads all selected elements uniformly with 60.
NSEL,S,NODE,,9,49,10 ! select top nodes SF,ALL,PRES,pressu ! load on upper surface NSEL,ALL ! reselect all nodes SF,ALL,CONV,0.2,70
the first NSEL command starts a new selection set with the S option. The second option specifies that nodes are to be selected. The next option is the default. The fourth and fifth options specify that node 9 is the first and node 49 is the last in the set. The sixth option increments the node numbers increment by 10. Therefore the selected nodes are 9, 19, 29, 39, and 49. The second command applies to the selected nodes, a pressure defined previously by pressu. The third command reselects all nodes. The fourth command applies a convection load to all selected nodes using a convection coefficient of 0.2 and a temperature of 70.
MENG 421 -- Source Program -- Ansys index -- Class assignments
Last revised: February 5, 2004 -- Copyright © 1997-2004 ARMiller