As aerospace and defense manufacturing becomes increasingly digitized—from the earliest design stages to the factory floor and beyond—data accuracy is fundamental to realizing the speed, quality and repeatability promised by interconnected and automated computer systems and manufacturing machines.

Figure 1. Unique kernels of CAD packages can contribute to model variance during translation.

In parallel to such developments, OEMs and supply chains need to service aerospace and defense platforms that are likely to be in operation for decades, even as the tools and personnel that originally defined them change over time. Moreover, the industry differs from nearly all other fields in its unique requirements for safety, and inherent scale and complexity. Recognizing the critical importance of ensuring long-term system performance and business sustainability, aerospace and defense contractors are moving steadily toward Model-Based Definition (MBD) and the Model Based Enterprise (MBE).

These all-digital approaches demand software interoperability around an accepted master model that is passed from engineer to analyst, from supplier to supplier, and from the present to the future. The models must stay within approved specifications and not vary across time or place. Without a master model, different computer-aided design (CAD) programs, different versions of the same software, even just basic human error, can all contribute to variations and flaws that create significant roadblocks to productivity.

The Core Challenge

The CAD market, which includes computer-aided manufacturing (CAM), simulation (FEA) and product lifecycle management (PLM), has witnessed enormous innovation since its beginnings in the 1950s and robust growth in the 1990s. There are and have been many vendors and significant thirdparty contributors to the industry since then. One challenge is that these innovators generally have different and proprietary mathematical “recipes,” or kernels, that define how product geometry is represented and then communicated to other engineering disciplines and systems.

Figure 2. Shown above is Elysium's 3D PDF validation report detecting an engineering change in which a hole diameter has been modified from 40 mm to 52 mm. Associative geometry is highlighted for easy interpretation.

For instance, a cylinder shape or draft angle as represented in a CAD system that originated its own mathematical kernel will vary slightly from one vendor to another. So will the 3D annotations and attributes, defined as Product Manufacturing Information (PMI), that guide production machines in forming, cutting or growing parts. Those variations impact both OEMs and supply chains. When two separate software systems trade data between partners, say PTC Creo to Siemens NX, the geometry differences must fall within tolerance. Mating surfaces must meet manufacturing tolerances in order to join composite panels. Geometries need to be identical in order for FEA to accurately determine stresses around threaded holes and part interfaces. Innovation lives in the tool sets, but agreement between mixed tools is as important as geometry creation itself.

What People Think

Many engineering professionals in aerospace understand and embrace digital automation for its design and manufacturing benefits, and its capacity for management oversight. Engineers in general, however, naturally wish to design, test and produce. They are less interested in coding nuances within CAD/CAM/CAE that are not visible in their programs and that manifest problems in hard to determine areas. Nonetheless, the labor involved in manual fixes, and the potential for poor yields and missed deadlines, are increasingly driving companies to take note of inherent shortcomings in system interoperability. There is also a growing awareness that standard data translation through direct solvers and reengineering does not always provide enough accuracy for sensitive, highspec programs.

In seeking to take advantage of interconnected manufacturing work cells and integrated analyses, OEMs know that the hand-off of data to specialized suppliers and internal “consumers” must be solid for native-to-native programs, as well as disparate software systems. Those outside specialties include multiphysics such as Computational Fluid Dynamics (CFD), or margin-of-safety and manufacturability analysis of composites. The results from all of these programs must reside in a verified Master Model, be that Dassault Systèmes CATIA, PTC Creo, Siemens NX or another major system. In this way data can migrate to design, manufacturing and management via a translated 3D PDF, HTML, or other “digital twin” and remain as accurate in ten-plus years when needed for other, new product authoring and test approaches.

Data Interoperability, Repair, Translation and Validation

Figure 3. The Elysium Neutral File (ENF) uses the original Application Programming Interface (API) from each CAD system to ensure accuracy in translations. Use of the ENF is supported by quality checks on geometry, tolerances and topology.

Software quality tools for CAD should be thought of in the same way that the aerospace industry has come to accept hardware-based tools and methods for ensuring Six-Sigma practices on the factory floor. Interoperability software takes exchanged data between CAD systems and applies a menu of pre-chosen quality standards and checks, offering feedback, repairs and verification to the original digital model. The software also verifies that the data is not just valid mathematically for model exchange but also for manufacturability. There are specific checks increasingly available to ensure that the data is correct for mold making, machining, sheet-metal stamping, and industrial 3D-printing. Such capabilities get to the core business value of interoperability: saving time and preemptively fixing flawed models before they go downstream to manufacturing where scheduling, labor and material expense are affected.

Advanced interoperability and translation programs for accomplishing MBD/E provide:

  • Interactive geometry verification and healing for multi-CAD data exchange, geometry simplification for CAE, plus tools for Rapid Prototyping and Reverse Engineering;

  • Feature-based design conversion for remastering CAD and legacy CAD files and process control;

  • Secure, integrated solutions for ensuring data translation and exchange quality, managing design data and workflows, and integrating the supply chain;

  • Robust validations and clear reporting of differences between geometry, attributes, 3D annotations (PMI), and more, for any derivative formats, engineering changes, and CAD upgrades versus their respective master models.

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