By Mianmian Fei, Junior Project Manager - Academic Relations

The digital world has changed how we design, test, and operate systems. A modern aircraft is an example of a complex system with different materials, propulsion, actuators, energy distribution, electronics and sensors. In the 6th edition of our Connected Series on October 21, 2020, Prof. Dr. Michel Guillaume from the Zurich University of Applied Sciences (ZHAW) and Dr. Xu Han from Beihang University introduced to us how intelligent design as well as virtual testing and operation in aviation are taking advantage of recent computer and simulation technology. While Prof. Dr. Guillaume’s presentation centered around the optimization of the aircraft’s life cycle, Dr. Han focused on actuation equipment, which is the elementary constituent of an aircraft.

Libing Gu (middle), Head of Academic Relations at swissnex China, hosted the webinar with Prof. Dr. Guillaume (left) and Dr. Han (right).

First, Prof. Dr. Guillaume, Head of the Centre of Aviation (ZAV) at ZHAW, gave us a presentation titled “Virtual Design and Operation for the Optimization of the Life Cycle.” He kicked off his presentation by giving an example of how complex a system a modern aircraft is – the Airbus A380 includes over 250,000 sensors. Today, the system interface of an aircraft is not only physical as it was the case of early days. Rather, it has become a digital database with increasing data sharing.

As systems grow in performance and complexity, more and more design requirements are added for aircrafts. In the end, three factors are the core of design considerations: affordability, operability, and effectiveness. Beside these, we cannot ignore human factors – even if we talk about virtual design, there are still humans working on the algorithm of artificial intelligence. Instead, we should think more about the roles of humans in virtual design and operation. Who makes the key decisions? Can we trust autonomous systems in making key decisions? Where are the limits?

Prof. Dr. Guillaume then introduced the life cycle of an aircraft. Today, it takes between 6 to 10 years to develop a certified aircraft from scratch. Then the aircraft will serve around 20 to 25 years. As aircrafts have become more and more digital today, the challenge is to accommodate changes of the data scene, supplier industry and domestic market during the two decades. He gave an example of the Airbus A320, which had a great market 20 years ago but went out of business now because there is no more demand in the market.

One solution that all aerospace companies take now is CEASIOM, a framework developed 20 years ago that integrates discipline-specific tools like 3D Mesh Generator and flight control system to bring optimization to aircraft conceptual design. The key here, again, is the human. Even though we can optimize everything by computers, sometimes the solutions we get are not physically practical at all. As a result, we have to integrate in certain steps human experts to make the right decisions.

Prof. Dr. Guillaume then showed us how the virtual airframe design works through each of the five levels of the design process. Today, the goal is to utilize more virtual testing and simulation to obtain fatigue certification and reduce development time. However, Prof. Dr. Guillaume emphasized that currently this strategy is good only for WindCube-designed aircraft. He believes we should go back to basic physics and get more familiar with the concepts for blend wind body design. Then we will be able to adjust our current tools and methodologies and eventually go into more simulation.

Today when we design an aircraft, we talk about its digital twin – a digital mockup of the aircraft. With the help of artificial intelligence and virtual reality, this technology enables us to take into account the operation of the aircraft in its design process. Indeed, the database of the digital twin is the base of digital design, which can help optimize operation and maintenance of the aircraft and achieve maintainability, reliability, and safety in the end.

Data not only helps with virtual design, but also has great potential in virtual operation for the optimization of the life cycle. The Aircraft Communications Addressing and Reporting System (ACARS) developed in the 70s is an example of how data is used for virtual operation. In ACARS, sensor data is communicated between an aircraft in the air and a technology department on the ground so that maintenance can be prepared in advance before the aircraft lands. What we try to achieve nowadays is full virtual operation on the ground, in which future problems can be simulated through operational data from sensors of all airlines. With full simulation of operation, the whole life cycle of the aircraft can be optimized in an economical way.

Prof. Dr. Guillaume concluded his presentation by going through some of the key challenges of virtual design operation. One is data availability from operators like airlines and maintenance organizations, since some of these operators may not want to share their data with manufacturers. Another is the high cost to maintain and update the digital database during an aircraft’s operation time. Regardless of these challenges, later in the Q&A session, Prof. Dr. Guillaume predicted that virtual design and testing will be state-of-the-art in the next 20 years, and it will shorten the life cycle of an aircraft to 12 to 15 years to achieve more sustainability.

Next, Dr. Xu Han presented to us the intelligent design and virtual testing for actuation equipment, the elementary part for machinery and vehicles including aircrafts. He started by showing us how actuators have evolved over the past 60 years, from mechanically controlled actuator in the 50s to analogically and digitally controlled ones in the late 60s, then to independent modules (EHA) nowadays. Beside advancing performance of the actuator itself, its developing method is also being improved over the past decades.

While the traditional actuator development process is iterative and costly, the model-based design with the help of simulation and intelligent algorithms nowadays can elaborately evaluate the solution and thereby optimize the design, mitigate the risks and omit physical tests. The model-based design can be divided into several phrases, from conceptual design, to preliminary design, and then to detailed design. After the design is completed, virtual testing is introduced to help designers gain confidence to manufacture their design solutions.

V-model of the development process extended through simulation and intelligent techniques.

Dr. Han’s group is currently working to involve control and thermal attributes in preliminary design in order to reduce the calculation cost. They are also developing virtual testing for electro-hydraulic actuators by combining the 1-D lumped parameter model with 3-D CFD model. Doing so will help achieve relatively high accuracy of temperature prediction and relatively low calculation cost at the same time.

Dr. Han concluded his presentation by giving some perspectives of future design methods. He believes machine learning will especially be helpful for the preliminary design phrase. Not only can it estimate model parameters and simulate actuators’ performance, a machine learning based model may also be able to design actuators directly in the future when it is fed with requirements of actuators. Although this is challenging, he believes it is also worth trying, starting by using machine learning to design components of actuators. With this regard, he emphasizes that experts working on actuators should always keep an eye on other communities, such as artificial intelligence and big data, because these new technologies have the potential to revolutionize actuators in the near future.

In the Q&A session, when he was asked about the possible development and breakthroughs in intelligent design and virtual testing for actuation equipment in the next 20 years, Dr. Han predicted that actuators worth 70% of the market value will be developed totally by computers. With intelligent design based on machine learning and virtual testing, the cost and development time of actuators will be reduced, and their performance will be improved.

We want to express our thanks and appreciation for Prof. Dr. Michel Guillaume and Dr. Xu Han for their interesting and in-depth presentations and thoughtful answers during the Q&A session. We are glad to hear that a collaboration agreement was established between ZHAW and Beihang University in terms of academic exchanges last year. We are looking forward to more specific projects between the two schools in the following years.

Please find a link to the slides and webinar recording below:

· Recording: view and download here.

· Slides: download here.