Knowledge of the size and location of a defect together with the load history of the appropriate part of a structure can provide valuable data from which the lifetime of that structure can be predicted. In this paper, a sensor that can be configured to fulfil both of these functions is described. The use of fibre Bragg gratings (FBG) to measure static strain and the very small, high-frequency in-plane strains that are associated with the propagation of an ultrasound wave are described. Investigation of their directional characteristics is also carried out and it is demonstrated that by configuring three or more of these sensors into a rosette, static strain mapping and the calculation of the direction of an incident acoustic wave can be achieved. Extending this technique by using two or more rosettes allows the source of an acoustic wave to be determined and thereby the location of a hole, which can be considered to be a passive source.
|Number of pages||13|
|Journal||Fatigue and Fracture of Engineering Materials and Structures|
|Publication status||Published - Oct 2008|
- fatigue crack
- fibre bragg grating
- lamb wave
- structural health monitoring