METHOD FOR THE NONDESTRUCTIVE EXAMINATION OF A TEST SPECIMEN BY USE OF ULTRASOUND

Abstract

The invention is a method for the nondestructive examination of a test specimen by use of ultrasound, in which ultrasonic waves are coupled into the test specimen with ultrasonic transducers and ultrasonic waves reflected within the test specimen are received by the ultrasonic transducers and converted into ultrasonic signals. The ultrasonic signals are stored and subsequently divided into discrete signal information by use of a propagation time-based, phase-corrected superposition in a course of ultrasonic signal data processing. Discrete signal information is assigned to a volume element within the test specimen. The method determines an average noise level, to which all discrete signal information is subjected, determines voxels, assigned to discrete signal information having a signal level with a signal-to-noise ratio R which is referred to as an average noise level, with 6 dBR, determines voxels, between respective pairs when the spatial distance A is smaller than or equal to a wavelength of the ultrasonic waves coupled into the test specimen, respectively combines the determined voxels into a voxel group, and evaluates the discrete signal information, based on at least one of polarization, frequency, wave type and wave mode.

Claims

1.-15. (canceled)

16. A method for the nondestructive examination of a test specimen by use of ultrasound, in which ultrasonic waves are coupled into the test specimen with ultrasonic transducers and ultrasonic waves which are reflected within the test specimen are received by ultrasonic transducers and converted into ultrasonic signals, wherein the ultrasonic signals are stored and subsequently divided into discrete signal information by use of a propagation time-based, phase-corrected superposition in the course of ultrasonic signal data processing, and wherein each discrete signal information is respectively assigned to a volume element within the test specimen, comprising the steps: determining an average noise level, to which are discrete signal information is subjected; determining voxels to which are respectively assigned discrete signal information of having an average signal level with a signal-to-noise ratio R, with 6 dBR; determining voxels which between respective pairs of voxels have a spatial distance A smaller than or equal a wavelength of ultrasonic waves coupled into the test specimen; combining the determined voxels into a voxel group; and evaluating the discrete signal information, of voxels of combined into a voxel group based on at least one of signal information contents of polarization, frequency, wave type and wave mode.

17. The method according to claim 16, wherein: the signal information assigned to each voxel by use of propagation time-based, phase-corrected superposition, including ultrasonic signal components of ultrasonic signals of all ultrasonic transducer combinations of coupling and receiving ultrasonic transducers.

18. The method according to claim 17, wherein: the ultrasonic signal components respectively include information regarding amplitude, polarization, frequency and wave type.

19. The method according to claim 16, wherein: A/2 of the coupled ultrasonic wavelength is chosen as distance.

20. The method according to claim 17, wherein: A/2 of the coupled ultrasonic wavelength is chosen as distance.

21. The method according to claim 18, wherein: A/2 of the coupled ultrasonic wavelength is chosen as distance.

22. The method according to claim 16, wherein: the evaluation of signal information within a voxel group is carried out as statistical evaluation having a degree of similarity between respectively identical signal information contents of the signal information which is determined, wherein the examination of the test specimen is based on the degree of similarity.

23. The method according to claim 17, wherein: the evaluation of signal information within a voxel group is carried out as statistical evaluation having a degree of similarity between respectively identical signal information contents of the signal information which is determined, wherein the examination of the test specimen is based on the degree of similarity.

24. The method according to claim 18, wherein: the evaluation of signal information within a voxel group is carried out as statistical evaluation having a degree of similarity between respectively identical signal information contents of the signal information which is determined, wherein the examination of the test specimen is based on the degree of similarity.

25. The method according to claim 19, wherein: the evaluation of the discrete signal information within a voxel group is carried by a statistical evaluation so that a degree of similarity between respectively identical signal information contents of the signal information is determined, and the examination of the test specimen is based on the degree of similarity.

26. The method according to claim 16 for determining the acoustic density of a test specimen with a heterogeneous material composition, wherein at least a degree of similarity of polarizations included in the signal information is determined during the evaluation of discrete signal information within a voxel group, wherein the degree of similarity is proportionally related to acoustic density of the test specimen within the voxel group.

27. The method according to claim 17 for determining the acoustic density of a test specimen with a heterogeneous material composition, wherein at least a degree of similarity of polarizations included in the signal information is determined during evaluation of discrete signal information within a voxel group, wherein the degree of similarity is proportionally related to acoustic density of the test specimen within the voxel group.

28. The method according to claim 18 for determining the acoustic density of a test specimen with a heterogeneous material composition, wherein at least a degree of similarity of polarizations included in the signal information is determined during evaluation of discrete signal information within a voxel group, wherein the degree of similarity is proportionally related to acoustic density of the test specimen within the voxel group.

29. The method according to claim 19 for determining the acoustic density of a test specimen with a heterogeneous material composition, wherein at least a degree of similarity of polarizations included in the signal information is determined during evaluation of discrete signal information within a voxel group, wherein the degree of similarity is proportionally related to acoustic density of the test specimen within the voxel group.

30. The method according to claim 22 for determining the acoustic density of a test specimen with a heterogeneous material composition, wherein at least a degree of similarity of polarizations included in the signal information is determined during evaluation of discrete signal information within a voxel group, wherein the degree of similarity is proportionally related to acoustic density of the test specimen within the voxel group.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Exemplary embodiments of the invention are described below with reference to the drawings and without limitation of the general inventive idea. In these drawings:

[0035] FIG. 1 shows a schematic representation of a test specimen with jacket tubes that have different filling levels; and

[0036] FIG. 2 shows a schematic representation for determining the acoustic density of a half filled jacket tube within a test specimen with the use of an ultrasonic transducer assembly.

DETAILED DESCRIPTION OF THE INVENTION

[0037] FIG. 1 shows a test specimen 1, having a surface 2 of which an array-like assembly of n=18 DPC ultrasonic transducers 3 is arranged. In the example shown, three jacket tubes 4a, 4b are 4c are arranged within the test specimen 1, which preferably is concrete or a similarly inhomogeneous construction material. The jacket tubes have a jacket tube wall 5 that is preferably made of steel and are respectively encompassed by the concrete matrix of the test specimen 1. The measuring task is measuring the filling level of the individual jacket tubes 4a, 4b and 4c, which respectively differs from the example according to FIG. 1. In this case, the jacket tube 4a is empty, the jacket tube 4b is half filled and the jacket tube 4c is completely filled, for example with a liquid such as water or with solid sediments.

[0038] In FIG. 2, the upper illustration shows a measuring situation and the lower illustration shows a measurement evaluation. The ultrasonic transducers 3 are arranged on the surface 2 of the test specimen 1 relative to the half filled jacket tube 4b. The ultrasonic transducers 3 respectively emit ultrasonic waves simultaneously into the test specimen 1 and detect the ultrasonic wave components reflected on or in the jacket tube. The reflected ultrasonic wave components, which arrive at the location of the ultrasonic transducers after respectively traveling propagation paths of different lengths, are converted into ultrasonic signals US1, US2, US3 and US4, stored and evaluated offline based on a reconstruction algorithm.

[0039] In the course of the evaluation, at least part of the test specimen volume is divided into uniformly dimensioned volume elements or voxels 6. Signal information is respectively assigned to The voxels. The signal information results from the superposition of all ultrasonic signals, which are respectively received from a voxel 6 from the n ultrasonic transducers. Only voxels 6 has the signal information which has a metrologically relevant signal-to-noise ratio That is the signal level deviates from the average noise level by at least 6 dB, which is used for the evaluation. Voxels 6, having a spatial distance from one another which preferably is equal to or less than half the ultrasonic wavelength of the ultrasonic waves emitted into the test specimen 1, are furthermore combined into a voxel group 7 for the evaluation. In the example according to FIG. 2, these are all voxels that at least partially contain the jacket tube 4b. Tn this context, see the voxels 6 located within the voxel group 7 defined by bold lines.

[0040] The polarization information per voxel 6, which is included in each information signal, preferably is used for the signal evaluation from which a degree of similarity between the individual polarization information of the voxels combined into a voxel group 7 is determined. The higher the determined degree of similarity, the lower the acoustic density within the examined volume area of the test specimen 1. In this way, the filling level within the jacket tube 4b can be deduced based on the determined degrees of similarity between the individual voxels 6 regarding the polarization information.

[0041] The frequency information or the information on the wave type or wave mode naturally also can be used for correspondingly determining a degree of similarity.

LIST OF REFERENCE SYMBOLS

[0042] 1 Test specimen [0043] 2 Test specimen surface [0044] 3 Ultrasonic transducer [0045] 4a, 4b, 4c Jacket tube [0046] 5 Jacket tube wall [0047] 6 Voxel [0048] 7 Voxel group [0049] US1, US2, US3 and US4 Ultrasonic signals