Pulsed arrays : a new method of flaw detection by generating a frequency dependent angle of propagation

A new method of using an array of generation sources, pulsed simultaneously to generate a wavefront with a frequency dependant angle of propagation, has been developed. If pulsed arrays are used to generate a wave with a frequency dependent angle of propagation, the angle at which the wave was launched can be identified by measuring the frequency of the detected wave. In an isotropic material this means that it is possible use a second transducer to locate the position of the scatterer, whereas with a conventional single element generator method, it can only be located onto an ellipse. In addition to an increased scan speed, the resolution of detection should also be improved. A theoretical framework is put forward to explain how the wavefront is created from the superposition of the waves from the individual elements, and how the frequency varies along the wavefront. Finite element models and experimental measurements were also carried out, and both agreed with the analytic model. This method will have applications within NDE, but could also extend to sonar and radar techniques