Downloaded from https://www.everyspec.com APPENDIX C MIL-STD-31000A Face. A topological entity consisting of a portion of a surface bounded by a loop. Feature – In 3D CAD. A feature is a portion of an object defined by a procedure and controlled by parameters. Changing the parameters changes the feature dimensions. Examples of features include round holes, arbitrary cutouts, extrusions, volumes of revolution, sweeps, and lofts. Finite Element Method (FEM). A numerical technique for finding approximate solutions to systems of partial differential equations.
FEM is applied to calculations of stress, strain, and deflection, temperature distribution and heat transfer, electromagnetic and similar problems. FEM, also called finite element analysis (FEA), is characterized by the subdivision of solid objects into tetrahedral or hexahedral finite elements. Thin-walled objects may be approximated by two- dimensional shell elements having three or four sides. Fillet. A rounded shape connecting two surfaces which join at an angle less than 180 degrees to prevent the occurrence of a sharp (non-tangent) edge. The cross-section of the fillet may be a single radius, a conic or other smooth shape with ends tangent to the connecting surfaces. Fixture.
A custom device used to locate and in some cases hold a work piece during a manufacturing process such as milling or assembly. Gap. The distance between geometric entities that are defined to be topologically coincident but in reality are not. In general, gaps occur at the intersection of two spline-based surfaces (such as a NURBS) or other spline-surface and an analytical surface. In such cases, it may not be possible to define a single edge curve that lies on both surfaces at all points. Gauge. An custom fabricated inspection tool used to check that a work piece is within its allowable manufacturing tolerances. 60