All kinds of engineering infrastructures undergo aging, and damage appears as a consequence of the loads applied to them, so inspection and maintenance actions are required to predict and lengthen their lifetime thus avoiding catastrophic failures. Due to the harsh conditions suffered by aircraft structures, periodic and scheduled inspection and maintenance tasks are essential for safe and efficient operation. The cost for the personnel needed to carry out these procedures is high, but the cost due to aircraft downtime during these time-consuming inspections is significantly greater.
Aircraft components and the composites they’re built from need to be as light as possible (while still able to carry out their role). Composite materials are defined as non-metallic non-homogeneous combinations of fibers and resins. It is mixture of two or more than two materials (reinforcement, fillers and binder) which considerably differ in physical and chemical properties, that when combined, make a material with appearances different from the individual components.
The virtues of composite structure typically include reduced weight, increased performance, and fuel economy.These components often carry high loads, and their lightweight nature mean that even small flaws can lead to failure. Failure of the structural component can have catastrophic consequences with the resultant loss of life and the aircraft. Cost and risk, especially when human life is involved, have impeded the use of advanced composites in commercial and military aircraft; however, these barriers are being overcome as both positive outcomes and user experiences increase. In general, failures occur when a component or structure is no longer able to withstand the stresses imposed on it during operation.
Michael Hoke, president of Abaris Training, a Reno, Nev.-based school for advanced composites fabrication, says delamination is a common problem in composites–like cracking is in metal–and isn’t necessarily serious. The Federal Aviation Administration (FAA) has ordered the visual inspection of all Airbus A-300-600 and A-310 aircraft–both among the first planes to incorporate composite tails. FAA says possible warning signs include edge delamination, cracked paint, surface distortions, and other surface damage. Hoke points out that more sophisticated techniques including ultrasonic, X-ray, and thermal-imaging methods do a better job of detecting delamination than visual inspection does.
Testing for flaws is essential, but needs to be carried out in a non-destructive way, which limits the testing options. As a result, the military actively seeks new ways to carry out non-destructive testing (NDT). Researchers from the National University of Science and Technology MISiS (NUST MISiS) have recently come up with a revolutionary non-contact method for stress monitoring in polymer composites, which provides a way to not only identify but to predict the emergence of defects.
One of the most promising new methods uses smart materials. A three-ply “skin” that can sense damage and report it to operators in real time before the damage causes a problem has been developed. Conversely, it can also report when it’s still in operational condition and doesn’t need to be replaced.
University of Queensland alumnus Dr Nigel Greenwood from Evolving Machine Intelligence (EMI) developed the technology and worked with others from UQ to build real-world applications. Dr Greenwood called upon the expertise of UQ mechanical engineer Dr Ingo Jahn and his research team to apply the same artificial intelligence to aviation turbine engines and their related systems. “We’re able to use EMI’s breakthrough AI technology to predict aviation engine component degradation and plan services to improve performance,” Dr Jahn said. “It allows us to evolve computational models of aviation engines as if they were organisms and the AI can explain explicitly what it thinks is happening inside the engine.”
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