This year’s model

Posted on 3 Feb 2010 by The Manufacturer

Parametric modelling has advanced steadily since it gained widespread acceptance in the 1990s. Ruari McCallion looks at the current state of play and new developments.

An internet search for ‘parametric modelling’ is dominated by architectural applications.

They range from the seven star Burj Al Arab hotel in Jumeirah, Dubai, to discussions on M&E applications in commercial office buildings. One could be forgiven for thinking that architecture is the original and even the main ongoing application of the software, but that is far from the truth.

“The main industries that took up parametric modelling 10 to 15 years ago were aerospace and automotive manufacturing,” says Neil Dunsmuir, vice president of marketing, EMEA, for Siemens PLM Software. “They had the money available to invest in technology.”

The families of software products developed to meet and respond to these and other sectors’ demands are well known, and include Catia, SolidWorks, Autodesk Inventor, PTC — one of the early pioneers — and NX and SolidEdge, from Siemens PLM Software.

While business improvement tools, such as Lean manufacturing techniques, have been cornerstones in the automotive and aerospace companies’ business process development, parametric modelling and the broader package of applications of which they form part — product lifecycle management (PLM) — are essential components in the structure of these tools. Parametric modelling is a history-based function that requires the operator to use ‘design intent’. Essentially, he or she will be constrained by parameters imposed by the originator, the design owner.

Most, if not all, CAD tools on the market are now parametric. The relevance of this to manufacturers is that it means suppliers further down the supply chain can be entrusted with detailed design work, in the knowledge that they will not be able to come up with a brilliant idea that won’t fit the parameters.

It also means that components will be selected from a range that is approved and priced by the original equipment manufacturer. But it also means that creativity in problem solving is likely to be constrained. Furthermore, the leading design and modelling technologies don’t come cheap. Recently there has been advanced development of lower cost and mid-range parametric tools that are within the range and competence of small and mid-sized companies (SMEs).

“Siemens’ NX allows full CAD and CAE [computer aided enterprise] including parts ordering — it is seamlessly integrated into the PLM application,” says Dunsmuir, and the same can be said for the other leading solutions. “SolidEdge is a medium range modelling product; it’s sophisticated but not as much as NX. It is designed for Microsoft operating platforms and is within the reach of SMEs, who probably don’t need to go as deeply as the high end.”

Simultaneous collaborative design
There are two aspects to the collaboration of engineering design. When Ford Motor Company — the only one of the Detroit Three to avoid Chapter 11 bankruptcy in 2009 — designs a new car or platform, it needs to collaborate internally, to ensure everyone is working together simultaneously, without overwriting each other’s amendments to the design project.

Externally, through the tiers in the supply chain, the software needs to ensure people are working on the right version. Parametric tools allow suppliers to be brought into the overall PLM system with full access.

Loading all components onto the digital backbone allows everyone in the project to see the whole car assembly. If an item, such as a gearbox, is redesigned by one party, the new version will be shown to all and, vitally, how it affects the whole structure.

“One of the biggest challenges with collaboration on large projects is managing the interface between products,” says Paul Brown, global marketing manager for Siemens’ NX product. “One of our customers, Israel Aircraft Industries, appoints one person who ‘owns’ the design.” Using the digital backbone — TeamSensor from Siemens, Catia from Dassault Systèmes, and more software — enables people to work effectively. “At interface areas — such as areas where cables and hoses pass through airframe structures — designers can programme specific requirements into TeamSensor, which will have within it a command: ‘you shall not drill through this particular strut or rib’, which can be there for a key structural reason. People can work together, rather than going off on their own and then spending ages working out conflicts.” Digital backbones allow a lot more focus on underlying tools and enable design companies to focus on design.

When parametric design tools first emerged they were cumbersome. Integrating the application with the PLM backbone made them easier and facilitated a freer flow of information. Companies are now moving away from pure parametric technology to more intuitive solutions. ‘Direct’, ‘dynamic’, ‘freeform’, or ‘synchronistic’ tools provide the ability to edit parametric and non-parametric geometry without the need to understand or undo the design intent history. An operator doesn’t need to be a CAD expert in order to make some simple modifications quickly. They can import from nearly any format of CAD file, then edit and alter the geometry as if it was clay. US software developer PTC developed the earliest versions of direct modelling in the 1990s; its ease of use is seeing the popularity of direct modelling grow, with products like Autodesk’s Inventor Fusion.

Parametric in use: Case studies
South Wales-based Brick Fabrication, which makes brick arches and chimneys for the domestic construction industry, recently invested in both a new factory and 3D CAD, specifically Autodesk Inventor. It is now using the tool to develop its entire range of prefabricated building products including brick arches, chimneys and brick specials. This has helped the company to significantly reduce wastage and rework. Every job going through the factory now has a CAD drawing associated with it, together with key metadata to help engineers develop designs correctly at the first time of asking.

“We can now make changes rapidly without having to recreate the design from scratch with every modification,” says design and development manager David Rees. “It makes it much easier and quicker to produce associated parts lists and bills of material data. We have been able to reduce development time by 50 per cent.” The new Abu Dhabi Investment Council building is being designed by Aedas Architects in London using Digital Project (DP), which is based on Dassault Systèmes’ Catia platform.

“We used the Catia-based parametric solver in DP to construct complex dynamic components with all their parts to consider them in relation to the rest of the structure and the environment,” says Abdulmajid Karanouh, senior designer at Intelligent Systems. “The ability to iterate the façade and all its details relative to changes made to the main form [building] is a very powerful feature of this software.” Airbus recently deployed Delmia Quest to investigate a production scenario related to the use of lifting equipment for large wing parts. Various ‘what if’ scenario simulations were run via Microsoft Excel to Quest to discover the optimum manufacturing sequence and best return on capital equipment, and to identify where it was desirable to use a crane in conjunction with other production equipment to avoid delays and sequencing bottlenecks.

AeroTec Laboratories uses parametric solutions to develop collapsible fuel cells for Formula 1, World Rally Championship and DTM racing teams and Rogers Yacht Design have used it to create the new Artemis Ocean Racing 2 IMOCA Open 60 Vendée Challenge yacht, which not only has to be fast but also has to make the most efficient use of available space.

The objectives behind parametric technology are not new. Freeform or synchronised design is not entirely new either, but it seems to be the next step along the line to enable manufacturers to improve design effectiveness, shorten development times and reduce wastage.