Iterative time reversal based flaw identification

In the field of ultrasonic non destructive testing ultrasonic impulses are used to detect cracks in components without causing damage. When performing only experiments it is possible to infer the state of the component but usually no additional details about the interior damage like position, dimension or orientation are available. Furthermore, the amount of sensors that can be used to record the signals is limited to only a few because of the shape and dimension of typical specimen. The information about these details is hidden in the recorded experimental signals. The idea of the proposed method is to use this experimental data together with a wave speed model of the healthy component and to try to adapt the model to generate these experimental measurements. Formally, the problem is posed as nonlinear optimization and the wave speed model is adapted such that the discrepancy between experimental measurements and the model output is minimized. Moreover, to overcome the problem of only few available sensor measurements, a combination of multiple experiments is used to improve accuracy. Following this approach, the position, dimension and orientation of a crack is detected for an emulated cracked aluminum plate. When only few sensors are available, it is shown how a combination of similar experiments can be used to improve the inversion results.     «

In the field of ultrasonic non destructive testing ultrasonic impulses are used to detect cracks in components without causing damage. When performing only experiments it is possible to infer the state of the component but usually no additional details about the interior damage like position, dimension or orientation are available. Furthermore, the amount of sensors that can be used to record the signals is limited to only a few because of the shape and dimension of typical specimen. The informa...     »