Downloaded from https://www.everyspec.com APPENDIX C MIL-STD-31000A Design and Analysis. Creation, viewing, and modification of the original 3D models, preparation of associated drawings, and analysis of models with techniques such as the finite-element method, boundary elements, computational fluid dynamics, and rigid body dynamics. Data used for design and analysis must be free of defects that would cause CAD system malfunctions and visual defects in drawings or models. Manufacturing. The production of physical prototypes or parts directly from 3D model data by methods such as numerically controlled milling and turning or additive freeform fabrication.
Manufacturing applications also include use of 3D models for inspection by optical scanning or coordinate-measuring instruments. Manufacturing data must maintain the highest positional accuracy of all surfaces because it is used to render of inspect working parts. C.5.2. Derivative model data. Derivative 3D models have been translated from their originating format to other formats. ISO 10303. An international standards organization format with a documented internal structure (also informally called the Standard for the Exchange of Product data or STEP). STEP may be used for long-term archival storage or as an intermediate medium for translation when the target systems are unknown.
Data translated to standard formats must maintain the highest levels of accuracy and freedom from defects because its ultimate uses are unknown. Visualization. Viewing of 3D models for design reviews, cost estimating by suppliers, and other applications in which the fidelity of appearance but not a high degree of manufacturing accuracy are required. Once data has been translated to a form for visualization, it should no longer be used for manufacturing. Visualization formats include 3D PDF, Siemens PLM Software JT, Parametric Technology’s Pro/View and Creo Visualization, and Autodesk’s DWF.
Models used for visualization must look right and the annotations associated with them must be accurate. Visualization models are subject to the least stringent validation criteria because it will not be used for manufacturing or engineering changes. Translation to Other Proprietary Formats. Data may be translated from one proprietary format to another for the purposes of manufacturing or because an organization is shifting from one brand of CAD software to another. Translated data may be modified by the receiving system and used for manufacturing and inspection applications. Translated data must be free from defects that would cause errors in the receiving systems.
Model tolerances must be within those required by the receiving system. The final decision about which types of errors are acceptable in 3D models and the values (such as gap width) that are acceptable must ultimately be determined by the parties who are sending and receiving data. In most cases these people will be the program managers for the Government and its contractors. The fundamental challenge of validating whether a derivative model is equivalent to its native 66