PARAM, RBE3COL

Bulk Data Entry This parameter controls the handling of RBE3 elements.

Parameter Values Description
RBE3COL <ERROR, LINETRANS, LINEROTA, OFFSET> Controls the handling of RBE3 elements which satisfy the following conditions:
  1. All independent grids are collinear.
  2. All such collinear independent grid do not have rotational degrees of freedom defined (4,5,6).
  3. The reference grid (dependent grid) of the RBE3 element also lies in the same line as the collinear independent grids.
ERROR
RBE3 elements which satisfy conditions 1 and 2 mentioned above will lead to an error because there is no rotational degree of freedom to support rotations about the axis of collinearity (this was the default behavior in OptiStruct 2017.2.3 and earlier).


LINETRANS (Default)
RBE3 elements which satisfy conditions 1 and 2 mentioned above, and additionally satisfy the condition 3, will not error out.


If conditions 1, 2, and 3 are satisfied, the run will not error out if PARAM,RBE3COL,LINETRANS is specified in the model. There is no rotational degree of freedom about the axis of collinearity.
LINEROTA
For models wherein, an RBE3 element satisfies conditions 1, 2, and 3 mentioned above, and if PARAM,RBE3COL,LINEROTA is specified in the input file, then the model will not error out. The rotational degree of freedom about the axis of collinearity is available and it is automatically constrained out.


OFFSET
For models wherein, an RBE3 element satisfies conditions 1, 2 mentioned above, and if PARAM,RBE3COL,OFFSET is specified in the input file, then the model will not error out. The rotational degree of freedom about the axis of collinearity is available and it is automatically constrained out.

Comments

  1. For PARAM,RBE3COL,LINETRANS, the run will error out if condition 3 is not satisfied for any RBE3.
  2. For PARAM,RBE3COL,LINEROTA, the run will error out if condition 3 is not satisfied for any RBE3.
  3. For PARAM,RBE3COL,OFFSET the run will not error out if condition 3 is not satisfied for any RBE3. Therefore, it is important to be cautious when using PARAM,RBE3COL,OFFSET since it may lead to unexpected behavior when the dependent grid is away from the axis of collinearity of the independent grids.