Materials to signal structural defects automatically Materials capable of responding to deformations by producing magnetic or electric fields are of particular interest for monitoring the integrity of engineering structures. EU-funded scientists developed thin films of such materials for this purpose. Industrial Technologies © Thinkstock The discovery of multifunctional materials, those whose multiple functions together surpass the performance expected by the sum of individual functions, has led to amazing technological advances in recent years. Multifunctional materials often go hand-in-hand with smart materials, those that respond to their environment much as a living organism does. Some change shape or size when an electric field is applied, some generate a magnetic field in response to pressure or stress, and yet others can change from a liquid to a solid when near a magnet. Shape memory alloys (SMAs) are metallic materials that, as the name suggests, remember their shapes. In other words, they return to their original shape after being heated or cooled and deformed into another shape. As metals, they also present the opportunity to exploit electrical and magnetic properties. The EU-funded ‘Multifunctional ceramic layers with high electromagnetoelastic coupling in complex geometries’ (Multiceral) project aimed to strengthen cross-coupling effects through the development of novel single-layer films and composites. Building on cross-coupling between materials with electrical and/or magnetic properties and those like SMAs, scientists produced novel multifunctional thin films. Employing a variety of advanced deposition techniques and advanced characterisation tools, scientists produced and analysed numerous films produced with respect to electromagnetoelastic coupling. High quality electrically conductive nanotubes (miniature molecular tubes) were also produced and evaluated for their response to stress and deformation. Finally, the Multiceral consortium designed, manufactured and tested several prototype devices for structural health monitoring (SHM) based on the developed films of various complex geometries. SHM is the process of fault or damage detection in engineering structures such as aeroplane turbines or rail components. Non-destructive testing (NDT) based on materials that themselves send signals in response to elastic changes are of obvious interest. Multiceral thin film technology based on multifunctional materials combined electrical and magnetic properties with elastic or stress-related ones to produce smart SHM devices. The technology will no doubt be welcomed by a variety of manufacturing and maintenance sectors.
