Downloaded from https://www.everyspec.com APPENDIX C MIL-STD-31000A Recommended correction: Reverse the direction of the 3D curve if necessary. C.7.4. Edge loop criteria. C.7.4.1. Large edge gap (G-LO-LG). Definition: Distance between end points of adjacent edges is excessive (G 0 discontinuity). Curves may be separated by a gap or may overlap. Effects of condition on CAD data quality: Design or drafting: When edges are offset, gaps between segments may be enlarged or overlapping segments may intersect. Data exchange: Faces associated with edges may not trim properly. Finite element analysis: Unwanted mesh elements may be produced. Automatic mesh generation may fail.
Numerically controlled manufacturing: Gouges or abrupt changes in angle may occur when cutting curve surfaces. Recommended correction: Redefine the end points to reduce the gap to less than the recommended values. C.7.4.2. Non-tangent edges (G-LO-NT). Definition: Tangent angle changes at the common endpoint of adjacent edges, Δθ (≤ 90°) (G1 discontinuity). Effects of condition on CAD data quality: Non-tangent curves and line segments are not necessarily indicative of poor data quality. In some cases, such as square corners, chamfered, and beveled edges, non-tangent conditions are intended.
When curves are intended to be tangent, but aren’t, then G1 discontinuity is indicative or poor quality. Non-tangent conditions are usually visible to the unaided eye and can be felt by finger tips on physical models. 104