Downloaded from https://www.everyspec.com APPENDIX C MIL-STD-31000A C.7.6.5. Sharp face angle (G-SH-SA). Definition: Shell faces meet at angles below the recommended minimum. Effects of condition on CAD data quality: Design and drafting: Sharp edges are generally undesirable in products, with the exception of cutting tools or weapons. Sharp edges are prone to breakage. Sharp notches may promote cracking or fatigue failure. Data exchange: No problems with data exchange. Finite element analysis: Excessively fine local mesh may be generated. Numerically controlled manufacturing: Sharp edges are prone to breakage. Sharp notches may promote cracking during manufacture. Recommended correction:
Unless the design intent requires sharp edges, revised the shell to eliminate them. C.7.6.6. Inconsistent face in shell (G-SH-IT). Definition: Faces with normal vectors pointing in opposite directions share a common boundary. Or the shell normal vector orientation is opposite from the face normal vector. The criterion is true if no inconsistencies exist. Effects of condition on CAD data quality: Design and drafting: Offset operations may fail. Surfaces may appear to be missing from the shell. Data exchange: Faces may not be translated or may not sew properly following translation. Finite element analysis: No effect on FE applications. Numerically controlled manufacturing:
Tool paths may fail because surface offsets fail. 117