The mechanics of a safer, greener flight
With more and more people taking to the skies, global air traffic continues to increase by an average of 5 % per year. With the sector responsible for an estimated 2 % of all human produced CO2, any annual increase adds up fast. In fact, for every 100 kilometres that just one passenger flies, up to four litres of fuel is burned. These numbers make it increasingly difficult to attain any targeted reduction in greenhouse gas emissions – especially considering the high expectations set by Europe. According to the 2020 Vision targets set by the Advisory Council for Aeronautics Research and Innovation in Europe (ACARE), the entire European air transportation sector is aiming to attain a 50 % reduction in CO2 and fuel consumption relative to the year 2000. But with more people choosing to fly and the ongoing pressure to keep air travel safe and affordable, some may see such targets as simply unrealistic. But not ALAMSA. The EU-funded project is going to the mechanics of an aircraft to ensure Europe not only reaches its ambitious targets, but exceeds them. Maintaining efficiency To reduce emissions, ALAMSA set its sight on aircraft maintenance. Specifically, the project worked to achieve ACARE targets by increasing the efficiency of aircraft maintenance operations, extending the damage tolerance of aircraft materials, reducing the usage of materials and extending the overall lifespan of an aircraft’s operating structures. Project researchers started by developing an innovative class of non-destructive techniques known as Nonlinear Elastic Wave Spectroscopy (NEWS). NEWS uses simulated stress waves to detect the presence and degree of flaws or damage to an aircraft’s structural materials. Cracks and delaminations, for example, exhibit elastic non-linearity, thus producing additional frequencies that are not present in the original stress waves. These ‘new’ frequencies are associated with the harmonic and/or intermodulation distortion that arises when elastic waves encounter a flawed or damaged region. ‘With NEWS imaging and self-monitoring solutions, we can diagnose such manufacturing defects as porosity, component assembly contact conditions, micro cracks, clapping areas, adhesive bond weakening and thermal or chemical damage,’ says Project Lead Prof Michele Meo. ‘This process offers higher sensitivity and enables imaging of internal areas of aeronautic components not accessible by conventional methods.’ Self-healing wounds Another innovative outcome of the project is a range of self-healing composite materials for aircraft structures. Upon thermal activation, these materials have a built-in capability to repeatedly restore mechanical properties through multiple cycles of healing, allowing damage reoccurring at the same location to be automatically repaired. ‘Linking automatic self-monitoring systems to these smart in-situ self-repair mechanisms allows for the continuous monitoring and restoration of an aircraft’s material integrity,’ explains Prof Meo. The system acts as a trigger mechanism, allowing it to compute the degree of malfunction and autonomously assess whether specific aircraft structures need intervention. More efficient aircraft for a safer, greener flight For European air passengers, the concepts developed by the ALAMSA project mean a significant increase in an aircraft’s lifespan, passenger safety and operating time. ‘At the same time, our work also contributes to substantial cost savings through optimised quality control and maintenance systems, thus paving the way towards the recycling of composite materials,’ adds Prof Meo. ‘Add these benefits together and you quickly see how by just focusing on aircraft maintenance we can help Europe achieve its ACARE goals.’
Keywords
ALAMSA, ACARE, Nonlinear Elastic Wave Spectroscopy, NEWS, aircraft maintenance, self-healing composite materials
