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Testing times
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13/03/2009
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The Millbrook automotive test centre is looking to prove a point. Justin Cunningham reportsDeep within the natural hills and valleys of Bedfordshire lies Millbrook testing ground. The picturesque 700-acre site is home to a host of cutting edge technologies designed to push vehicles to the limit and beyond.
The site dates back to the late 1960's when General Motors opened it to support the test program of its vehicles built nearby at Luton. The site was chosen in particular because of the sweeping contours that the landscape naturally creates, which now make up a number of winding and undulating roads. The result is a plethora of quite amazing on road and off road tracks.
Millbrook now operates as an independent test facility. During the last 40 years it has seen every conceivable type of land vehicle, and probably some ill conceived ones. Everything from motorcycles, passenger cars, heavy commercial, military and off-road vehicles have passed through its gates at some point.
Its vast custom-built facilities provide tests and validation services that are required to get any new car on the road. But it also runs hundreds of other tests with the sole aim of development; from artificial buttocks to test the wear of seat materials to assessing the squeak and rattle of a dashboard.
The relationship between design engineers and test engineers is an interesting one. Designers are quick to point to errors in the set-up of accelerometers and test engineers are, of course, always adamant that the test results are accurate. Neither is always right.
But this is a vital part in the design cycle, and the results from physical tests have a direct and immediate effect on the design of a component or product going forward. The data gathered can point to a number of things that can improve a design, not just show that it works. Can it be made stronger? can it be made lighter? are the different materials compatible?: the design has to be fit for purpose and be no more, or no less, effective in its task than it needs to be.
In the automotive industry, physical tests can validate a concept and lead to optimisation and commercialisation, or expose potential flaws that can end projects.
"But it is more than just issuing a certificate with pass or fail on it," says Andy Eastlake, head of laboratories at the site. "We can do that, but we prefer to work with our customers on a consultancy sort of basis. "Quite often our customers don't actually know what they want in terms of testing. So we need to find out about the product so we can get behind it and understand what they are trying to achieve."
Over the years, Millbrook has conducted almost every type of test on virtually every type of vehicle imaginable. From tilt testing double decker buses to the effect an ejector seat has on the human body to the odd bit of motorsport. Whatever it is, Millbrook is sure to put it to the test with the view of proving and improving the predicted capability of a system or component.
And there is more to Millbrook than just a set of test tracks, although it has to be said, the tracks are something special. It gives the site the 'wow' factor and sets it apart, making it quite special when compared to similar sites in the UK and on the continent.
One such track is the 2-mile high-speed track. While hurtling around at exactly 100mph, head of business development Andy Beach decides to give a demonstration by taking his hands completely off the steering wheel.
"The camber of the track is banked at exactly the right angle," he says. "When we travel at 100mph, the centripetal force trying to throw the car outwards is equal to the camber effect of the road pulling the car inwards. As a result, the car behaves as if it is travelling at in a straight line, from tyre wear to the behaviour of the oil and lubricants."
But the site also houses a number of lab based facilities, from its crash laboratory that carries out a full range of frontal, side and rear impact tests to its exhaust emission facility, which can simulate temperatures of -30 to +50°C to test variations in emissions. Additionally, the accelerated corrosion testing facility is correlated to 'in-service' life to assess the accuracy of the tests. And the engine lab sees a number of engines undergoing various duty cycles to categorise emissions and assess efficiency.
"When we bring the engines in to test them, they can be difficult to get going," says Beach. "The reason is the engine management system is so good. It is looking for inputs and information from all the other systems that are normally on the rest of the car. But as it is just the engines it doesn't have these. Quite often we will be supplied a separate input box that will give false signals so the engine thinks it is in the car and we can test it.
"If you need data on some aspect of your vehicle design, chances are we have already done a test to do that. And if we haven't, we like a challenge and would probably be able to come up with something. The ultimate aim is to let customers know how a product will hold up in the real world."
The 'real world' is a rather clumsy term that cropped up frequently. The engineers don't like the term themselves. It really refers to the whole world and the everyday variability that it brings. From Greenland to the Sahara, the Dead Sea to Rocky Mountains, from the inner city to the most rural country; with the various driving styles and road conditions of different countries; the same car often has to cope with it all for the guaranteed life promised by the manufacturer.
"Quite often we get engineers conducting tests as a means to optimising a design," says Eastlake. "By carrying out a set of tests, it exposes a vehicle to conditions that are hard to model and quantify. Although a design engineer might have done all of his sums correctly and then carried out detailed computer models, until you do something to the vehicle physically, you can't be a 100% certain about how it is going to react.
"We are completely independent and impartial. As a result, we often have to give customers bad news, but strangely, they often like that as they then know what problems they have to address and work through."
You might think the Fords and GMs of this world would have all these facilities, and more, and do all own their own in-house testing. Well yes, they do. But, especially on new builds where time scales are now tighter than ever, they do not always have time or the resources to conduct lengthy R&D testing. Quite often they want, or need, experts to come in and do the work. So they come to Millbrook for that expertise which it provides.
"In terms of structure, vehicles are getting more and more similar," says Eastlake. "So it is more subjective stuff that is getting lots of focus and attention during development. Stuff like the squeak and rattle of the dashboard, the seat fabric, the durability of the dashboard. Once it is designed, it is quite difficult to quantify and test. We have seen a shift in our test facilities to increasingly look at these sorts of tests.
"And another common one is testing vehicles that come off the production line so you are assessing what has actually been manufactured as it would be released in to the market."
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Author
Justin Cunningham
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