AE sensing is commonly used in mechanical testing on coupons, components or structures to give extra information about the type of damage (including location and severity) occurring within the material. There is great interest in developing Structural Health Monitoring systems using AE sensors.
When certain dynamic processes occur rapidly in or on the surface of a material some of the energy which is released generates elastic stress waves; we might say vibrations within the material. These stress waves propagate from the source and eventually reach the surface, so producing small temporary surface displacements. Sensitive transducers, commonly piezoelectric sensors, convert the accelerations at the surface into an electrical waveform signal. By studying the characteristics of the waveform it is possible to determine important information regarding the material condition.
Risø has close links to the large wind turbine manufacturing industry in Denmark, and the AFM provides them with support through a broad range of materials related technology including non-destructive evaluation and instrumented testing of coupons, components and structures. The manufacture of wind turbines is experiencing tremendous world-wide growth and the trend is towards larger and larger platforms and blades in increasingly remote locations, including offshore construction. This has increased the attraction of remote structural health monitoring solutions to managers of large windfarms. By improving data regarding the health of the towers and the blades, expensive and hazardous maintenance operations (which are currently schedule based) involving the transport of personnel by helicopter and/or ship is minimised without compromising structure reliability. |