Downloaded from https://www.everyspec.com APPENDIX C MIL-STD-31000A Effects of condition on CAD data quality: Design or drafting: Cross sectional views may fail. Use of the small entity in a swept or lofted surface may produce tiny surfaces (G-SU-TI). Slight increase in model storage requirements due to unnecessary entities. Data exchange: Gaps or degenerate entities may be produced during data translation due to differences in tolerances between CAD systems. Faces may not trim properly. Finite element analysis: Unwanted mesh elements may be produced. Automatic mesh generation may fail. Numerically controlled manufacturing: May slow operation. Recommended correction:
Remove the tiny entity and extend or trim one or both entities to eliminate the gap. C.7.1.5. Indistinct curve knots (G-CU-IK). Definition: Two or more knot points on a spline curve positioned too close to each other. Measurement: distance between knot points, Δt Effects of condition on CAD data quality: Design and drafting: May cause an abrupt change in curvature. Data exchange: Differences in mathematical tolerances between systems may cause the number of segments in the spline to be reduced upon translation. May cause trimming problems with faces. Finite element analysis: May cause excessively fine mesh element to be generated. Numerically controlled manufacturing:
May cause tool path generation to fail. Recommended correction: Remove one of the knot points. If the CAD software does not permit knot removal, recreate the spline with the proper number of knots. 87