Easing the wheels of development

The demand to lower product development cycle times is found in many areas of manufacturing, but especially in aerospace where so many complex components and systems have to be brought together to produce an end result such as an airliner.

One element that undergoes extensive testing is the landing gear. This critical subsystem is one of the hardest worked parts of an aircraft subjected to heavy impact loads on landing, braking forces and wear and tear during take-off and taxiing. Landing gear assemblies have to pass stringent regulatory and safety requirements whilst also delivering lighter and more energy efficient designs.

SPHEREA Test & Services specialises in providing electronic testing for many areas in aerospace and defence. The group can trace its roots back to the development of Concorde when it produced the first automatic test benches for testing avionics in the programme. Since then the group has undergone a number of incarnations; firstly as part of EADS, then Cassidian and finally as SPHEREA after the restructuring of the Airbus Group. As well as design and production sites in France, Germany and the UK, the 500 strong company also has offices in the US, Singapore and China. In 2013 it had total revenues of €102 million. <Real and virtual>

The group's U-Test system was used more recently to develop elements of the landing gear of the A350. U-Test combines both simulated virtual systems and physical hardware to carry out test procedures when developing landing gear.

Dr Yann Fusero, innovations manager at SPHEREA comments: “U-Test is a real-time, adaptable, modular test environment, for design, integration and qualification of complex systems. It drives efficiency through more thorough testing by combining simulation and real components at the design phase. This ability to include instruments and elements of the platform under development saves time, reducing the overall cost of the system. It provides a framework to system engineers with a core capability to carry out testing on real or virtual systems (models) that are either the system under test or the tooling that is necessary to perform the test.

“In terms of developing landing gear the benefit is that you can start integrating and testing the capabilities and the performance of a system even before you have the real components available. It allows incremental validation of the design. The key is to get models through the development process that are consistent with what will be ultimately delivered and that represent the expected performance.

“Another advantage is that it significantly reduces the overall cost of development of the landing gear. Indeed, Model Based System Engineering combined with U-Test enables far earlier detection of design flaws or errors than if you had to work with real prototypes.”

U-Test can be utilised right from the early development phase when models of landing gear structures are being developed through to actual hardware testing on test rigs.

Fusero continues: “If we start with the final physical integration on the test rig, there are targeted actuators that make up part of the final system under test. Before that there are active hydraulic actuators that provide representative stress and forces. These are what we might call a [real life] environment simulation. These real life simulations are based on data from former aircraft programmes from in-the-field recording systems. This information provides huge added value for the landing gear manufacturer engineers that develop these simulations.

“Earlier in the development phase the virtual models have the same interfaces as the real equipment so they also have to develop models that are complete simulations of the real life environment. This modelling capability is also a key added value for the manufacturer's system engineers.”

Fusero says that the biggest trend currently affecting landing gear and avionics integration rigs in general is the development of buses with greater bandwidth and increased reliability. He also points to the increase in electrical systems in aircraft generally, although he says there is little current evidence of electrical systems replacing the hydraulic element in landing gear any time soon.

<Global integration>

He also explains that as the industry becomes more global with engineers spread geographically further apart, better transfer of design and test data is required.

“We have to make test systems that can be connected with one another globally to several sites. System engineers who work with models want to exchange components, data and information without having to be physically in the same place. There are ordinary conflicts between what engineers want to do in terms of communication and what general IT systems can provide taking in account security constraints.”

So what are the main benefits of using U-Test for landing gear development?

“U-Test addresses the need for a consistent framework to carry out testing in the different phases of development which at the beginning may just be the modelling of the design and pure virtual testing; through to progressive integration of the real components once they are ready. U-Test means you can have a consistent testing framework for system engineers that enable them to focus on the real competitive added value of a new design.

“There are two main benefits U-Test provides; one is speeding up the development process to make validation happen more quickly. The second is the system is also flexible so it can factor in the latest standards demanded by legislation or new specifications required by an OEM.”

As well as aerospace, U-Test has also been used in applications in the rail, energy and automotive sectors.
Fusero concludes: “Virtual and Hybrid testing systems like U-Test allow aircraft manufacturers to be more competitive and perform the complete integration of systems in advance. Being able to deliver this kind of virtual equipment or systems is a key benefit for their competitiveness and an indicator of how mature and efficient development teams are in a company.”

www.spherea.com