The impact that the aerospace industry has had on our lives and the world economy over the last fifty years is difficult to exaggerate. Aside from the obvious advantages relating to quick, affordable travel to far-off locations there are many more ways in which this revolution has changed our lives. The effect the aerospace industry has on the world’s
economic position is even more pronounced. The current global market is unimaginable without the existence of aircraft. Also, research and development for aerospace applications
is at the forefront on engineering achievements and many new technologies have been transferred to other fields in recent years. However, current economic, technical and social demands have resulted in challenges for aircraft designers and operators. New large capacity aircraft are being developed and will be used widely in the future. Many
of these structures will make greater use of composite materials. At the same time the current aircraft fleet is ageing continually. All these developments are a major challenge
to inspection and maintenance.
Aerospace structures are currently inspected using traditional nondestructive techniques
such as visual inspection, radiography and eddy current. Recent years have shown a
range of different technologies and sensing techniques developed for damage detection
in metallic and composite materials. This includes Acousto-Ultrasonics and guided Ultrasonic waves. Both technologies utilise optical fibre and piezoceramic sensors for damage detection. New techniques are capable of achieving continuous monitoring, integrated nd on-line damage detection systems for aircraft maintenance. Recent developments in advanced signal processing, such as neural networks or wavelets, also offer the potential for more reliable and robust damage detection and prediction. This is a great opportunity for aircraft designers, manufacturers and operators. It is now clear, that sooner or later, new damage detection techniques, combined with advanced signal processing, are destined to become one of the core monitoring elements of aircraft structures. The integration of sensors, actuators, signal processors and controllers is associated with a new design philosophy leading to multifunctional and adaptable structures. The attractive potential of such technologies arise from a number of elements such as: reduced life cycle costs, reduced inspection/maintenance effort, improved performance, improved high rate operator availability, extended life of structures and improved safety. This leads to more efficient and economically attractive aircraft. All these elements are important to both manufacturers and operators of civil and military aircraft.