When every gram counts

In addition to emergency braking on all 20 wheels of the A380, the local electro hydraulic generation system (LEHGS) with its electronic control unit (ECU) also provides backup hydraulic power for the nose wheel steering system.To save weight on the A380 superjumbo aircraft, Messier-Bugatti used LMS Imagine.Lab AMESim and the Ground Loads solution to design an innovative decentralized hydraulic generation system with lightweight micro-pumps delivering power locally to emergency braking and landing gear steering systems.

Size definitely matters, especially when you are developing the world’s largest passenger jet, having an overall length of 73m and a wingspan of nearly 80m. Airbus A380 provides seating for 525 passengers and a range of more than 9,400 miles. To gain maximum fuel efficiency and payload capacity, weight savings was necessary when developing this plane. Composites and other lightweight materials account for more than 25% of its structure.

Of particular interest were the hydraulic lines running the length of the aircraft from the large centralized pumps to the brakes, landing gears, and the nose wheel steering system. Ordinarily, large commercial jets have three sets of redundant hydraulics: two primary circuits and a third back-up for safety, all adding up to a big load of heavy piping.

To reduce this bulk, the all-hydraulic backup circuit was replaced with a decentralized fluid-power generation system. Signals from electronic control units (ECU) activate multiple small, electrically-driven micro-pumps, each located close to the systems to be controlled. The micro-pumps provide 5,000psi (350 bar) of local hydraulic pressure over short runs of small-diameter lightweight piping.


A Tall Order
In optimizing system performance, the engineering team on this project faced major challenges in integrating and sizing the large number of different physical parts, assemblies, and subsystems for the mechanical, electrical, and hydraulic systems. Moreover, they needed to assess any risk factors such as electrical overheating.


The Solution:
Messier-Bugatti met these challenges with the LMS Imagine.Lab Ground Loads solution based on the AMESim simulation platform, which the company had implemented on previous projects for predicting the behavior of complex, multi-domain intelligent systems. Unlike conventional system modeling languages that require computer programmers to write software, the overall system model is graphically created in LMS Imagine.Lab AMESim, where engineers are prompted to enter parameters where necessary. In this way, the software creates a multi-domain system model from the overall conceptual information of interconnected parts and subsystems without requiring a full 3D geometry representation. Then, engineers can simulate and predict the behavior of intelligent systems long before detailed CAD geometry becomes available.


Simulating Behavior
The analysis capabilities allowed Messier-Bugatti to analyze the system’s hydraulic behavior in terms of performance, stability, and robustness. Engineers also used the model to study the thermal characteristics of the hydraulic circuit. These results were used to establish the sizing, output, and other product specifications for the entire hydraulic power generation system including the tank, pump, and accumulator.

By using the LMS Imagine.Lab Ground Loads solution, engineers were also able to explore a large set of parameters and scenarios.


Reducing Guesswork
“Simulation enabled us to anticipate and reduce the inherent development risks of a new technology by incorporating an upstream validation regarding the technical choices,” says Michael Benmoussa, senior design engineer.

In this manner, the Ground Loads solution enabled the engineering team to significantly reduce guesswork and freed them to focus on innovation and R&D. “Messier-Bugatti was able to predict systems and equipment performances – including critical new technologies – on the entire flight domain,” Benmoussa comments. “The A380 enters into service with its nose wheel steering system control loop only tuned with LMS Imagine.Lab AMESim. Tests were just performed to confirm the good system performance.”


LMS,
Troy, MI
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