The state of the art of non-destructive acoustic tests provides information on the type of transducers and on the number of tests to be conducted in order to obtain satisfactory mappings on the surfaces of the elements under test, to trace shape and size of defects, both in Test Method for Transparency (with emitter and received transducer arranged in corresponding points on two opposite surfaces) either by using Tomographic Methods. The main problem in this type of analysis is related to the strong attenuation of the signals in reception, which often have amplitudes of the same order of magnitude of noise. For this reason, in this work we use cross-correlation between emitted chirp signal and the relative received signal, that allows to assess significant amplitudes. For this paper one refers to tests using Test Method for Transparency applied on a grid of points. The aim of this work is to assess how the relative position between the transducers and the defects affect the accuracy of the results obtained. To implement this study, we use orthogonal chirp signals. The study is performed using a specimen of steel of dimensions (34×135×8) mm3 with three defects consisting of holes of 1 mm diameter with different depth. To do the simulations we used the commercial finite element software COMSOL in the frequency domain. In a second phase experimental verifications will be made to verify the obtained results and to tune the model. The instrumentation is as follows: function generator NI PXIe-6251 (NI PXI- 1042 chassis), TiePie Arbitrary Wave Form Generator, Handyscope HS5 and Krautkramer SEB 10 KF-3 @10MHz double probes.
Sensitivity analysis of test signal with respect to the transducers position in ultrasonic NDT testing
USAI, MARIANGELA;MEDDA, ANDREA
2013-01-01
Abstract
The state of the art of non-destructive acoustic tests provides information on the type of transducers and on the number of tests to be conducted in order to obtain satisfactory mappings on the surfaces of the elements under test, to trace shape and size of defects, both in Test Method for Transparency (with emitter and received transducer arranged in corresponding points on two opposite surfaces) either by using Tomographic Methods. The main problem in this type of analysis is related to the strong attenuation of the signals in reception, which often have amplitudes of the same order of magnitude of noise. For this reason, in this work we use cross-correlation between emitted chirp signal and the relative received signal, that allows to assess significant amplitudes. For this paper one refers to tests using Test Method for Transparency applied on a grid of points. The aim of this work is to assess how the relative position between the transducers and the defects affect the accuracy of the results obtained. To implement this study, we use orthogonal chirp signals. The study is performed using a specimen of steel of dimensions (34×135×8) mm3 with three defects consisting of holes of 1 mm diameter with different depth. To do the simulations we used the commercial finite element software COMSOL in the frequency domain. In a second phase experimental verifications will be made to verify the obtained results and to tune the model. The instrumentation is as follows: function generator NI PXIe-6251 (NI PXI- 1042 chassis), TiePie Arbitrary Wave Form Generator, Handyscope HS5 and Krautkramer SEB 10 KF-3 @10MHz double probes.
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