Modelling is the key to rapid success

Tom Shelley reports on the latest advances in the world of software modelling at different stages of the design process

Tom Shelley reports on the latest advances in the world of software modelling at different stages of the design process

Advances in modelling software and its use continue to improve productivity and effectiveness at all stages of the design and manufacturing process. New releases filter into the market on a regular basis. Here are a few of them.

A new player on the ‘UK block’, in terms of product performance modelling, is CFDesign V6.0, from Blue Ridge Numerics. The software is aimed squarely at improving the optimisation of fluid flow and heat transfer in a wide variety of products, especially for those users who do not want to be bothered with meshes.

The software reconstructs geometry prepared using standard 3D CAD packages such as ProEngineer, Autodesk Inventor, Solid Edge, SolidWorks and Unigraphics (Catia compatibility is in preparation). Complex models are not translated but directly reconstructed and simplified. The setup of which is performed by stepping through a series of buttons. The user picks a surface and sets boundary conditions with a bar on the surface indicating that this has been done. The user can then watch the software solving the problem and produce results. It is not necessary to wait for completion.

Users can also go back to the geometry and change it without having to re-enter boundary conditions and run the analysis again. The Design Review Center allows any number of design variations to be cycled through in a single window. Results can then be shared via PowerPoint, Word or a web browser and a free plug-in allows any user in a supply chain to view, rotate, zoom and pan results. Results which can be automatically prepared as an input desk to allow the calculation of flow and thermally induced stresses using packages such as Abaqus, Ansys, Mechanica and Nastran.

CFDesign’s capabilities include supersonic and two phase flows and heat transfer, conduction, convection and radiation calculations. Customers include IMI Norgren in the UK and Anheiser Busch and Debbie Cakes in the US. Target markets include designers of electronic packaging, automotive and fluid power products and plumbing. The UK reseller is IDAC. Cost is £3,000 to £20,000 for year one, and £3,500 to £5,000 in subsequent years, including all updates and support. It is also possible to lease additional solvers for $1,000 each per month for use on multiple PCs connected by LAN.

As well as innovative software developments, traditional CAD software is constantly being used in new ways and applied to new problems.
US firm, Guidant, has been using the freeform modelling capabilities of VX 6.11, from VX Corporation, to create organic shapes of the human heart and its arteries to achieve a high level of realism in its moulded anatomical models and to help the work of medical product designers.

David Wolf-Bloom, manager of in-vitro pre-clinical research and development at Guidant tells us: "Doctors want to avoid situations where a medical device has to be removed from the body because it doesn’t perform as needed. The life-like models that we create help physicians avoid this and help us to design and build devices that better address the clinical challenges they face."

In order to develop anatomical models to test new coronary products, Guidant begins with 3D medical images, typically models based on normal anatomy from a set of Computed Tomography (CT or CAT Scan) slices stacked up so that they reconstruct a whole organ. Guidant, in collaboration with outside research groups, then transforms the CT scans into IGES files that may be read into VX to produce mould ready surfaces.

Critical control points
Diseased organs, on the other hand, have different shapes, structures and tissue thicknesses, and Wolf-Bloom’s team uses VX to impose these effects on the 3D model to design devices that perform more effectively in diseased hearts.

In common heart disease for example, one of the chambers of the heart becomes damaged and enlarged, and the heart can no longer contract sufficiently to pump blood effectively. This enlargement may be modelled in VX by selecting and manipulating critical control points anywhere along a surface with the VX curve editor or lofting and filleting functions.

Guidant makes pacemakers, stents (the mesh tubes which keep open clogged blood vessels), implantable defibrillators (to monitor and regulate hearts that race out of control) and pumps and stabilisers that enable safe-beating heart surgery.

Feedback from physicians on the company’s newest devices and the surgical training with its moulded anatomical models has been uniformly positive. The new models are being used in a training facility in Brussels. Because they are easily portable, unlike patients or living animals, Guidant personnel can also use them to conduct training and testing in physicians’ offices and hospitals.

The hearts of industry can also benefit from computer modelling. Since adopting Delmia’s VNC system, the Hull office of Mayflower Aerospace believes that the need to produce prototype components is becoming increasingly limited. Such is Mayflower’s confidence, it has discontinued the practice of tape prove outs and fresh air test runs, thus saving its clients’ time and money.

Chris Smith, head of the Hull office, explained: “VNC utilises 3D models of machining tools, and emulates the machine tool controller and numerical control (NC) program to simulate and help eliminate on-the-floor manufacturing problems related to fixturing, tooling, program errors, and process setup.

"Our VNC results are checked by two different manufacturing engineers and the detailed analysis is intense. They check the depth of cut, the volumetric removal rate, collision detection and carry out a comprehensive method check. VNC also captures any problems there might be with peripheral elements, such as set up sheets and tooling. All this adds up to making all our prove-outs virtual, so that our customers are able to produce immediately only final specification parts. Our current right first time figure is 85%.

"We seek to be at the forefront technically and this has led us to be confident that a customer’s NC machine will never sustain damage and that no part material will be wasted. No company is too small to benefit from the savings that accrue when the NC machine is accurately mimicked." TS

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