Abstract: In accordance with an aspect of the present application, a system is provided for crack monitoring in a structure of interest, comprising means for extracting wave modes existing in a frequency interval of interest, means for finding a source of emission on the structure of interest, means for correcting for dispersion to reconstruct an original ratio of wave modes at the source of emission, and means for correlating the original ratio of wave modes to a crack depth. One advantage of this solution in contrast to prior art techniques is that no a priori knowledge on propagation speed is necessary since actual wave modes can be detected from dispersion relations of wave modes, e.g. Lamb waves at a fixed frequency band in accordance with their calculated speeds. Decentralized acquisition and processing, i.e. monitoring a structure from a localized area, is an important feature of this solution, consequent to which, the data transfer and storage are reduced substantially.

Abstract: A method and device are discussed for determining quantitative parameters of a bond between two elements, for example an adhesive bond between two aluminium plates of an aircraft. A pulsed wave is provided to a first element. The elements, including the bonded region, act as a waveguide. Any discontinuities, an end of the bonded region or imperfections, result in a change of parameters of the waveguide. This results in reflections. By analysing characteristics of the reflections, along with the actual bond length and a signal expected from a good quality bond, an equivalent bond length may be determined.

Abstract: A defect monitoring system has ultrasound transmitters and receivers on a wall of a structure under test such as a pipeline. The receivers are arranged in an array of locations that substantially encloses an area under test on a wall of a structure under test. The array may comprise two circumferential rings along a pipeline at different axial positions. The array of ultrasound receivers is used to measure signals that result ultrasound that leave the area through the wall for other parts of the wall. From the measured signals backward propagated signals are computed for a location within the enclosed area, compensated for a modelled effect of propagation from the location within the area to the locations of the receivers at the perimeter. The backward propagated signals for the location in the enclosed area are summed over the locations of the receivers to obtain an approximate integral over the perimeter of the area.

Abstract: In accordance with an aspect of the present application, a system is provided for crack monitoring in a structure of interest, comprising means for extracting wave modes existing in a frequency interval of interest, means for finding a source of emission on the structure of interest, means for correcting for dispersion to reconstruct an original ratio of wave modes at the source of emission, and means for correlating the original ratio of wave modes to a crack depth. One advantage of this solution in contrast to prior art techniques is that no a priori knowledge on propagation speed is necessary since actual wave modes can be detected from dispersion relations of wave modes, e.g. Lamb waves at a fixed frequency band in accordance with their calculated speeds. Decentralized acquisition and processing, i.e. monitoring a structure from a localized area, is an important feature of this solution, consequent to which, the data transfer and storage are reduced substantially.

Abstract: A defect monitoring system has ultrasound transmitters and receivers on a wall of a structure under test such as a pipeline. The receivers are arranged in an array of locations that substantially encloses an area under test on a wall of a structure under test. The array may comprise two circumferential rings along a pipeline at different axial positions. The array of ultrasound receivers is used to measure signals that result ultrasound that leave the area through the wall for other parts of the wall. From the measured signals backward propagated signals are computed for a location within the enclosed area, compensated for a modelled effect of propagation from the location within the area to the locations of the receivers at the perimeter. The backward propagated signals for the location in the enclosed area are summed over the locations of the receivers to obtain an approximate integral over the perimeter of the area.