Design by illusion

Posted on 10 Jan 2008 by The Manufacturer

Malcolm Wheatley explores the increasing use of simulation software to enhance the development of new products, solve complex development issues and push the boundaries of what is possible

When Cambridge-based industrial printing manufacturer Domino Printing Sciences was looking to improve the manufacturing yield of a recently introduced ink jet print head, it faced a number of challenges.

First, the ink jet itself was very small – too small, the company’s development engineers found, to be able to meaningfully investigate during operation through the use of probes. Second, it appeared that the parameters that were suspected to be the possible causes of the manufacturing difficulties were themselves too small to measure: tiny deviations from flatness, for example, measurable only in microns.

The only hope the company had of investigating further, it seemed, was to simulate the ink jet head through a computer model, using a technique called finite element analysis – a hope subsequently dashed when the modelling process proved too difficult.

Fortunately, Domino was able to call on the services of King’s Lynn-based Fine R and D, founded in 2002 by Dr John Clark and his wife Dr Jeannette Fine, who between them had 40 years’ experience of simulating industrial products and manufacturing processes in order to accelerate market launch and minimise cost wastage – including extensive experience of thevery finite element technique being tried at Domino.
“An ink jet print head is a complex object to model,” observes Dr Clark. “It contains piezoelectric actuators, solid parts, a reservoir of fluid, bolted joints, and contacting surfaces which might be out-of-flatness by up to five microns – all of which, in combination, present formidable challenges to the modeller.”

Nevertheless, Fine was able to develop a working model, which highlighted where the sources of product failure were. The result, explains Dr Clark, was that process yield went from a little over 50 per cent to around 90 per cent – a significant increase in anyone’s terms.

Look closely, in fact, and it’s possible to find complex simulation techniques – and software – being increasingly deployed in the battle to boost manufacturability and productivity. The logic is simple: by simulating the workings of a product or component inside a computer, it’s possible to do hundreds – or thousands – of ‘what if’ analyses in a fraction of the time it would take to attempt them in the laboratory. Even if, as Domino found to its cost, real world experimentation was physically possible in the first place.

Consequently, powered by ever more powerful computers and increasingly affordable software, more and more manufacturers are harnessing the power of simulation to cut time-to-market, cut development and production costs, and optimise manufacturing processes.

Take Sunderland-based Nissan, where demand for the company’s popular Qashqai model, which was introduced in December 2006, has exceeded all sales expectations. The result has been a switch to a four-shift pattern running 24 hours a day, seven days a week, and a major focus on squeezing additional manufacturing capacity out of existing resources.

This, however, presents something of a problem, explains Nissan industrial engineer Anthony Timmiss. Not only are many of the welding processes robotic – and thus screened off from traditional ‘stopwatch’ industrial engineering studies – but the very act of studying the manufacturing process and trying out more efficient ways of producing vehicles and vehicle components actually absorbs capacity, thus reducing output rather than increasing it.

The solution, he explains, has been to make use of a tool called Witness from Redditch-based simulation vendor Lanner Group. Originally buying just one Lanner simulation software licence back in 1999, Nissan now has 10, explains Timmiss, having seen its worth on tasks such as the challenge of boosting Qashqai production. “With no spare capacity at weekends to carry out industrial engineering studies to try and come up with improvements, we chose instead to simulate key processes,” he says. “Simulation lets you try things out in the computer before you make changes to the actual equipment.”

As a result, every identified improvement is virtually ‘cost free’, he notes, having been thought through and trialled without losing a second of actual production capacity. Nor are simulations necessarily always looking for ways of increasing output, stresses Timmiss. “The cost savings we’ve generated are huge,” he adds.

But ‘after the event’ simulations such as those at Domino and Nissan are only part of the story. Increasingly, simulation is being brought closer to the design process itself – and often undertaken in real-time, too.

“With recent developments in the software design world, simulation tools are becoming more accessible,” says Mike Lucas, northern Europe business development manager for manufacturing solutions at CAD vendor Autodesk. “With 3D design and analysis tools, users are not only able to visualise their designs before they are made – they can experience them, too. They can simulate a virtual prototype that actually behaves like the product they are creating. And importantly, they can do this in-house, to their own criteria and timescales and as an integral part of the design workflow.”

Perversely, despite the apparent complexity entailed, this may serve to make simulation an easier ‘sell’ in terms of its take up by manufacturing companies. “Simulation is a huge opportunity – but very much an untapped one,” says Fine R and D’s John Clark, who performed the simulation at Domino. “Eyes glaze over at discussions of mathematical techniques, and it’s sometimes difficult to highlight how simulation can help. Are we talking to an engineering graduate, or someone who came through the apprenticeship route – or someone who doesn’t have an engineering background at all? For each, we have to craft a very different sales pitch: there’s no doubt, simulation is one of the toughest sales propositions there is.”
Except, perhaps, to designer engineers – already mathematically inclined, of course – who can see simulation’s potential to maximise a product’s performance at the design stage, rather than tweak it subsequently.

At Stourbridge-based Vee Bee Filtration, for example, computational fluid dynamics and finite element analysis simulation tools from specialist vendor Blue Ridge Numerics are used to develop cost-effective filtration solutions designed around the needs of specific customers – previously, says Vee Bee research and development engineer Napoleon Motaban, the company could only offer a range of standard products.
Until recently, explains Motaban, the development of specialist fluid flow systems such as Vee Bee’s filters and strainers had required a series of expensive and time-consuming analysis activities, including laboratory tests and complex calculations. But with Blue Ridge Numerics’ CFdesign simulation software fully integrated with Vee Bee’s Pro/Engineer CAD solution, “we’re able to run analyses and generate design models at the same time,” says Motaban.

“The CFdesign software reads the 3D CAD model directly, and you don’t need to be an expert in computational fluid dynamics to use it,” he adds. “Previously, I’d spend my time trying to generate the perfect 3D ‘mesh’, working out how to solve the mathematical problems, and getting the filtration loads or constraints right. With CFdesign, I don’t need to do any of that.”

Just as importantly, stresses Blue Ridge Numerics’ vice-president of marketing, Jim Spann, “there’s only one data model – so designs and simulations can’t get out of sync. Make a change in the CAD design, in terms of geometry, sizes, part names or parameters, and those changes are instantly reflected in the simulation model.”

What’s more, he adds, CFdesign – like most of today’s generation of simulation software – is written in computationally-efficient modern computer languages, meaning that simulations can be run on the PC desktop or workstation on which the CAD design is being carried out: “In the old days, you needed a language like Fortran, and a mainframe – now, those days are gone.”

And simulation software is not only being used to predict how products will perform – it is also being actively used to develop products that redefine the art of the possible. Even the humble running shoe has benefited, says Tim Robinson, a mechanical engineer with shoe company Adidas.

While shoe exteriors are largely fashion driven, focused around styles and colours, shoe interiors are a cutting-edge blend of increasingly esoteric technologies. Using materials science, biomechanics, and finite element analysis simulation technique, Adidas shoe designers are building motion-responsive, stress-reducing technologies – similar to ones found in earthquake-resistant buildings and car stability systems – into the heels and soles of modern running shoes.

Historically, explains Robinson, new athletics shoes have been based on a re-tooling of existing ones, necessitating time-consuming rounds of real-world prototype testing and redesign. Now, though, Adidas has short-circuited this process – and achieved a significant reduction in design cycle times – by coupling CAD systems on which new shoes are designed with finite element analysis simulation software – in this case, Abaqus from SIMULIA, a division of French firm Dassault Systèmes.
“If you were going to retool and test a whole new shoe, it could take six to eight weeks,” says Robinson. “But when you run simulations it only takes a few days. In terms of speeding up the entire development process, the finite element analysis software has proved invaluable.”

And again, says Tom Bianchi, SIMULIA’s head of marketing in the UK, the key to the Adidas success story is the sheer usability of today’s generation of simulation software. “Despite the fact that the calculations absorb a lot of computing power, the software can run on a PC, or on a server,” he says. “And for modern users, full integration with design and other systems is vital: Abaqus can interface with today’s leading packages like Pro/Engineer, CATIA and SolidWorks – but you can also feed it a legacy-style Fortran deck if you want.”

The lesson is clear: as such advances increasingly power the emerging simulation software category, expect to hear many more such tales.