Applying digital twins in the aircraft manufacturing industry

Digital twins can have a positive impact on already partially automated production processes as a virtual derivative. At NLR (Royal Netherlands Aerospace Centre) a digital twin is being developed for the Resin Transfer Moulding (resin injection) process as part of the production process of composite parts. During the Machine building event, this year as an online knowledge week, Erik Baalbergen from NLR will provide explanations.

By: Dimitri Reijerman

Baalbergen outlines his role in the development of this assistive technology: “At NLR, within the AVCE department (Aerospace Vehicles, Collaborative Engineering & Systems), I work on supporting technologies for aircraft development and construction. My specialty is making people and systems work together. If you add that up, you are dealing with modern automation and with more and more sensors that provide access to a great deal of data. In the production of composite parts, we innovate in our pilot plant in the Noordoostpolder. We set up this test environment together with Fokker Landing Gear a few years ago.”

He continues: “This pilot plant includes an RTM (Resin Transfer Moulding) machine for resin injections. Once you have made a semi-finished product, you have to inject it with resin. The RTM is in fact a conglomerate of machines, including the resin injector but also a number of water heaters to keep the resin warm on its way to the mould. That is a fairly complex setup and an operator has to be there continuously to keep an eye on everything. And we want to help the operator with that.”

With this starting point, Baalbergen got to work, looking at the latest developments in digital support for production processes. He explains: “The challenge was to connect the OT and IT techniques, in short, a real industrial automation job for the RTM setup. I immediately included the concept of “digital twin”. You have to see that as a digital counterpart of a physical thing or process, in this case a digital copy of the RTM process.”

Operator assistance

The use of a digital twin had a clear predetermined goal: “Ultimately, this digital twin should help the operator,” says Baalbergen, “so that he or she does not have to respond to all kinds of alarm bells as often. The digital twin should keep an eye on all the details. In some phases of the resin injection process, the operator needs to have a feel for responding to certain situations. For that, you need to run simulations and perform data analyses. Ultimately, we are pursuing a higher goal: we want to have the entire pilot plant controlled by one operator. In doing so, you not only need to automate many more things, but also respond more intelligently to incidents. You need to prevent too many false alarms, so you only want to trigger pinpointed alarms for an operator.”

NLR must overcome various challenges, partly because strict regulations apply to the aircraft industry. Baalbergen: “All processes are certified, so we cannot simply “leave too much to a computer”. A good example is: the temperature of a mold must remain 80 degrees and the alarm bell must go off at 82 degrees. The standard action is that the operator lowers the temperature setting slightly when an alarm bell goes off. You could of course automate that, but that is not allowed. The process must be assessed by an operator. So we have many preconditions, but within those conditions we still try to automate as much as possible and support the operator.”

Further development

As a result of the development of a digital twin, NLR is working with an aircraft manufacturer, a university and an equipment supplier to develop a digital twin for an innovative production process in a regional project. “This requires many more sensors in machines,” says Baalbergen, “because you want to use as much data as possible for a good digital twin. Ultimately, you want to work as green as possible and use as little energy as possible and produce as little waste as possible. That is the ultimate goal of this project.”

The operator's profession will also not be lost due to these technical developments, he says: "You are really not going to phase out the operator, but deploy him in an area where he is much better at; giving more space to his own creativity. We have interviewed operators and when you explain the advantages of digital twin technology, they also become enthusiastic. Because you help them to reduce boring administrative aspects of the work. So you have to explain the potential of digital twin technology well. We also want to achieve that when digitizing complex production processes and systems, people do not have to adapt to the "computer". Let the computer adapt to the person! That way you can work much more efficiently. DT technology simply makes it easier for the end user, so that the operator can use his or her creativity better."

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