New modelling technique could bypass the need for engineering prototypes

November 19, 2013
New modelling technique could bypass the need for engineering prototypes

A new modelling technique has been developed that could eliminate the need to build costly prototypes, which are used to test engineering structures such as aeroplanes.

The study, by Dr Róbert Szalai at the University of Bristol, is published in the latest issue of the Proceedings of the Royal Society A.

Most engineering structures, for example airplane landing gear, jet engines and gearboxes, involve friction and impact among their components. Traditionally these harsh phenomena are difficult to design for and introduce a great deal of uncertainty in the final product.

The new research offers an alternative view on this problem by providing a modelling technique that allows for more accurate predictions than methods currently available. The proposed method also offers a better understanding of contact mechanics, which might be used to achieve a better design.

Dr Róbert Szalai, Lecturer in the Department of Engineering Mathematics, said: "One of the greatest concerns of engineers is modelling friction and impact.

"Building prototypes to test engineering structures can be extremely expensive and this new modelling technique could mean a prototype does not need to be built."

Alan Champneys, Professor of Applied Non-linear Mathematics in the Department of Engineering Mathematics, added: "Strongly nonlinear behaviour, such as stick-slip motion and impact, are a huge cause of uncertainty in engineering systems.

"The findings from this paper provide a key breakthrough in research that is being pursued by a consortium of major universities and industrialists to address these problems as part of an EPSRC programme grant."

In the paper, the researcher has presented a general mechanical model and described a model reduction technique. The new model includes a memory term to account for effects that traditional models ignore. The study has also discussed the convergence of the method and its implications to non-smooth systems.

The derivation of the memory term is illustrated through the examples of a pre-tensed string and a cantilever beam. The paper has used the example of a bowed string and has demonstrated the properties of the transformed equation of motion, in particular its convergence as the number of vibration modes goes to infinity.

Explore further: Mathematical equation could reduce traffic jams

More information: Modelling elastic structures with strong nonlinearities with application to stick–slip friction, Róbert Szalai, Proceedings of the Royal Society A, 20 November 2013. rspa.royalsocietypublishing.or … .1098/rspa.2013.0593

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5 / 5 (1) Nov 20, 2013
If they can get a hold on slip-stick phenomena that would be huge. I've previously worked on finite element modeling algorithms nad whenever you get to these highly nonlinear situations the quality of the simulation suffers.
not rated yet Nov 20, 2013
The Dassault Falcon 5X has been entirely designed and engineered using computer software called CATIA, which was originally created by Dassault for this very purpose (although initially only to assist design and development) and is now sophisticated enough to design the entire aircraft. It has also become the industry standard and is used by all major aerospace companies.
In addition, test pilots have already 'flown' the virtual plane. All subsequent physical testing will be to satisfy the certification requirements of EASA, FAA etc.
So what is being proposed here that is new and beneficial?
not rated yet Nov 22, 2013
It sees to me as an aeronautical engineer, that the FAA requirements for civil aircraft safety by testing will never be changed. My experience with present-day structures, especially but not only landing gears--parts for which computer simulations have been carefully applied and used, shows that there remains sufficient doubt as to the quality of the computations. This applies to not only to static strength, also to dynamics from landing-impact or gusts and to fatigue. In other words, it will take a lot more experience and comparison between test and numerical analysis, before the public can reasonably expect flight safety to depend only on what one can calculate.

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