*GEOMETRIC TOLERANCES

Keyword type: step

This option allows the specification of the geometric tolerances in a *ROBUST DESIGN analysis. It can be defined on a node-by-node basis and consists of a mean value and a standard deviation, both in length units. In a robust design analysis random field vectors are generated representing the geometric tolerances up to a specified accuracy.

There is one required parameter TYPE=NORMAL and there are two optional parameters HOMOGENEOUS and CONSTRAINED. TYPE=NORMAL specifies that the tolerances are normally distributed. Right now, this is the only distribution allowed. The parameter HOMOGENEOUS means that all tolerance does not vary across the structure. Finally, the CONTRAINED parameter enforces a smooth transition between those parts in the structure for which tolerances were defined and the remaining parts.

First line:

• *GEOMETRIC TOLERANCES
• Enter any needed parameters and their value

Second line:

• Node number or element set label.
• Mean value of the tolerance.
• Standard deviation of the tolerance.

Repeat this line if needed (only if the tolerances are not homogeneous).

Example:

*GEOMETRIC TOLERANCES,HOMOGENEOUS,TYPE=NORMAL,CONSTRAINED
N1,1.5,3.7

assigns normally distributed tolerances with a mean value of 1.5 length units and a standard deviation of 3.7 length units to all nodes in set N1. The random fields are constrained, i.e. a smooth transition of the random field vectors is requested between the nodes in set N1 and the remaining nodes in the structure.

Example files: beamprand.