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By the year 2025, Lilium plans to launch a “flying car”, an electric five-seater air taxi, into the air-mobility scene. With such innovative aircraft models, we are dealing with new architectures, with no previous knowledge, with unknown dynamics, and with many configurations that need to be designed, redesigned and tested—and these companies want to fly very quickly!
In the past, aircraft bodies used to be made almost entirely out of metal, and the performance and dynamics of the materials used were well-understood.
However, today, many aircraft companies are already developing the airplanes of the future; experimenting and testing innovative designs, and with innovative materials. The layouts and structures of these new models are also different from those in the past. But with innovation, comes uncertainty.
More composite materials are being used to achieve lighter bodies. But that means that you can no longer rely only on historical knowledge or classical experience. Even a small change, like changing some hinges, will affect the structural dynamics of any model.
For a successful new aircraft, many steps need to be taken before actually flying it. First, you must design the aircraft model. This step is crucial, as it needs to be as accurate and prepared as possible before manufacturing an expensive prototype.
Here is where the use of a structural finite element (FE) model allows you to play with the model to design the highest structural performance for as little weight as possible—all in simulation.
After the design is finished, the validation process takes over. These are all tests that occur later in the program, when the design is completed and the model built. At this stage, the pressure and stakes are very high.
A major milestone in the aircraft program is the verification of the structural dynamics performance of the fully integrated aircraft. The ground vibration test (GVT) provides profound insight into structural dynamics behavior of the aircraft and helps calibrate simulation models used later on for critical flutter predictions. The last step of the validation process is a real-life flutter test which confirms that there is no aeroelastic instability within the flight envelope, in accordance with Part 23 or Part 25 of the certification requirements.
This validation process, of course, comes with its own challenges. During the design phase of an aircraft, the challenge is to validate and optimize everything as quickly as possible—the quicker you do it, the more designs you can validate. You want to make sure there is smooth flow of data from the simulation team to the testing team, and vice-versa. The verification of the structural dynamic performance must be efficient, as you want to get as much as a possible in a limited amount of time. You also want to make sure not to miss any critical phenomena, and yet, accelerate the process.
Typically, there are delays already before reaching the validation stage, which not only cost time, but an incredible amount of money too. This means that the validation phase needs to be well-prepared and performed properly.
The goal, then, is to balance accuracy and risk, performance and time, as well as efficiency and traceability.
With our Simcenter Testing Solutions, we seek to alleviate these concerns and meet the goals mentioned above. Through the Simcenter simulation and testing software and hardware, we can accurately capture all relevant phenomena related to aircraft structural dynamics, minimizing the risk of missing any important detail. With these solutions, tasks are performed in the fastest time possible, ensuring efficiency during the entire process from detailed FE model creation to validation of these models with experimental data and accurate prediction of aeroelastic response. With a focus on data traceability, the pairing and feedback between test and simulation streamline both the aircraft’s design and the validation process and allows to accelerate and secure the aircraft certification process.
To learn more about aircraft validation processes, flutter testing, and more, sign up for this Live Webinar on December 12.
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