Finding the Restoring Force Finding the Restoring Force

The MOVE command is used to obtain the restoring force on a body as a function of either excursion or angle. The form of this command is:


     MOVE, BODY_NAME, -OPTIONS

and the available options are:


     -LINE, TH, DIST, NUMBER

     -ROTATE, EXCUR, TH_INC, NUMBER

where BODY_NAME is the name of the body to be moved. If this is omitted, the current body will be used. If no options are specified, then the default is the same as -LINE with no data.

The option -LINE is used to move the body in a line. Here, TH is the direction (deg.) in which the body will be moved, measured from the global X axis positive toward global Y, DIST is the total distance of the move, and NUMBER is the number of positions calculated. Notice that the position increment is the quotient of the distance and the number of positions. If only the body name is specified, then this command will move the body in thirty (30) equal increments in the direction TH from the initial configuration until a termination criteria is met. This criteria is when the most heavily loaded line has a horizontal force equal to the maximum in the table.

The -ROTATE option is used to move the body around in a circle. Here, EXCUR is the distance from the initial position (feet or meters) and this will be a constant. TH_INC and NUMBER are the angle increments (deg.) and the number of angles respectively. If these are omitted, 10 degrees and 36 will be used.

At each position, the X and Y components of the restoring force and the magnitude of the restoring force are reported. Also, the tension, the horizontal force, and ratio will be reported for the lines with maximum and minimum tensions. During this process, all other bodies are held fixed in their position in the initial configuration.