I wrote a couple of weeks ago about ‘Our last DIMES’ meetings (on September 22nd, 2021). They were hybrid meetings with about half the participants attending in person and the remainder on-line. When the pandemic started we had to master the skill of conducting discussions via our laptops while sitting on our own. Now, we are learning how to include everyone in a discussion when only half of the participants are in the physical room. One of our first steps was to re-equip our meeting rooms with higher quality video conferencing facilities so that we can see and hear one another more clearly. Unfortunately, our new equipment revealed the poor quality of the video clips we have produced during the DIMES project. Nevertheless, if you have never been present during a wing-bend test or a fatigue test on a large composite panel then you might find these clips interesting (see also the video of ‘Noisy progressive failure of a composite panel’ on June 30th 2021). We also produced an introductory video for the DIMES project which was to be first in a series of video shorts but the pandemic intervened and we have never been in the same place as our camera crew so we have not made anymore. Maybe that’s a good thing because 500 hours of video are uploaded every minute to YouTube so you will not have time to watch our DIMES videos 😉.
Thirty-three months ago (see ‘Finding DIMES‘ on February 6th, 2019) we set off at a gallop ‘to develop and demonstrate an automated measurement system that integrates a range of measurement approaches to enable damage and cracks to be detected and monitored as they originate at multi-material interfaces in an aircraft assembly’. The quotation is taken directly from the aim of the DIMES project which was originally planned and funded as a two-year research programme. Our research, in particular the demonstration element, has been slowed down by the pandemic and we resorted to two no-cost extensions, initially for three months and then for six months to achieve the project aim. Two weeks ago, we held our final review meeting, and this week we will present our latest results in the third of a series of annual workshops hosted by Airbus, the project’s topic manager. The DIMES system combines visual and infrared cameras with resistance strain gauges and fibre Bragg gratings to detect 1 mm cracks in metals and damage indications in composites that are only 6 mm in diameter. We had a concept design by April 2019 (see ‘Joining the dots‘ on July 10th, 2019) and a detailed design by August 2019. Airbus supplied us with a section of A320 wing, and we built a test-bench at Empa in Zurich in which we installed our prototype measurement system in the last quarter of 2019 (see ‘When seeing nothing is a success‘ on December 11th, 2019). Then, the pandemic intervened and we did not finish testing until May 2021 by which time, we had also evaluated it for monitoring damage in composite A350 fuselage panels (see ‘Noisy progressive failure of a composite panel‘ on June 30th, 2021). In parallel, we have installed our ‘DIMES system’ in ground tests on an aircraft wing at Airbus in Filton (see image) and, using a remote installation, in a cockpit at Airbus in Toulouse (see ‘Most valued player performs remote installation‘ on December 2nd, 2020), as well as an aircraft at NRC Aerospace in Ottawa (see ‘An upside to lockdown‘ on April 14th 2021). Our innovative technology allows condition-led monitoring based on automated damage detection and enables ground tests on aircraft structures to be run 24/7 saving about 3 months on each year-long test.
Composite materials have revolutionized many fields of engineering by providing lightweight strong components whose internal structure can be tailored to optimise their load-bearing capabilities. Engineering composites consist of high-strength fibres embedded in a lightweight matrix that keeps the fibres in position and provides the shape of the component. While many composite materials have an impressive structural performance, some also exhibit spectacular failure modes with noises like guitar strings snapping when fibres start to fail and with jagged eruptions of material appearing on the surface, as shown in the image. A year ago, I reported on our work in the DIMES project, to test the capabilities of our integrated measurement system to detect and track damage in real-time in a metallic section from an aircraft wing [see ‘Condition monitoring using infrared imaging‘ on June 17th, 2020]. Last month, we completed a further round of tests at Empa to demonstrate the system’s capabilities on composite structures which have been tested almost to destruction. One of the advantages of composite structures is their capability to function and bear load despite quite high levels of damage, which meant we were able to record the progressive rupture of one of our test panels during cyclic fatigue loading. Watch and listen to this short video to see and hear the material being torn apart – ignore the loud creaking and groaning from the test rig, it’s the quieter sound like dead leaves being swept up.
While pandemic lockdowns and travel bans are having a severe impact on spontaneity and creativity in research [see ‘Lacking creativity‘ on October 28th, 2020], they have induced a high level of ingenuity to achieve the final objective of the DIMES project, which is to conduct prototype demonstrations and evaluation tests of the DIMES integrated measurement system. We have gone beyond the project brief by developing a remote installation system that allows local engineers at a test site to successfully set-up and run our measurement system. This has saved thousands of airmiles and several tonnes of CO2 emissions as well as hours waiting in airport terminals and sitting in planes. These savings were made by members of our project team working remotely from their bases in Chesterfield, Liverpool, Ulm and Zurich instead of flying to the test site in Toulouse to perform the installation in a section of a fuselage, and then visiting a second time to conduct the evaluation tests. For this first remote installation, we were fortunate to have our collaborator from Airbus available to support us [see ‘Most valued player on performs remote installation‘ on December 2nd, 2020]. We are about to stretch our capabilities further by conducting a remote installation and evaluation test during a full-scale aircraft test at the Aerospace Research Centre of the National Research Council Canada in Ottawa, Canada with a team who have never seen the DIMES system and knew nothing about it until about a month ago. I could claim that this remote installation and test will save another couple of tonnes of CO2; but, in practice, we would probably not be performing a demonstration in Canada if we had not developed the remote installation capability.
The DIMES project has received funding from the Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 820951. The opinions expressed in this blog post reflect only the author’s view and the Clean Sky 2 Joint Undertaking is not responsible for any use that may be made of the information it contains.