Downloaded from https://www.everyspec.com APPENDIX C MIL-STD-31000A Geometric Dimensions And Tolerances (GD&T). A general term for a system of applying dimensional annotations and tolerances to drawings or models defined by ANSI Standard Y14.5. Geometry. The surface shape of a mechanical part. Healing. The process of correcting errors in shape or topology to eliminate quality defects. History Tree. A hierarchical diagram of 3D model features that shows their relationships and the order in which they were created. Initial Graphics Exchange Specification (IGES).
The first standard format for describing 2D and 3D CAD data originally developed by the US National Bureau of Standards (now the National Institute of Standards and Technology). Jig. A structure similar to a fixture in that guides a tool to its correct position in addition to locating and supporting the work piece. Kinematics. The simulation and analysis of the motion of bodies without consideration of the forces necessary to cause the motion. Knot. One of a series of points lying on a spline curve or surface that partitions the curve or surface into a series of polynomial segments. Lifecycle Data.
Information that describes the state of the part within a control procedure for development, review, manufacture, logistical support, retirement, and disposal. Loop. A closed topological entity consisting of connected edges. Mid-Plane Geometry. The mid-plane is an offset from the solid surface which lies either on the inside outside or some distance between the inner and outer surfaces. It may also apply to tapered surfaces as the surface that lies equidistance between two surfaces. Mid-plane geometry is typically used to simplify models for analysis in which shell or surface elements are defined. Native (Model).
A 3D model in the (usually proprietary) format of the CAD system in which it was originally derived or modeled. Non-Manifold. A mathematical space that does not locally obey the properties of Euclidean (i.e. intuitive) 3D geometric space. NURBS (Non-Uniform Rational Basis Spline). A form of b-spline characterized by the use of weighted control points that enables it to exactly represent any conic section. Normal Vector. The vector at any point that is perpendicular to a surface or curve. 61