figures but rotated by 901 and deemed genuine; whereas the
white area labelled artefact was only visible in one image. This
provides confidence that the features are real and not artefacts.
This procedure of rotating the probe was adopted for validating
true features from artefacts in the advanced trials.
3.4. Floor assembly
For real applications, it is not practical to mill the indentation;
therefore a 20 mm abrasive disc attachment in a conventional
rechargeable hand tool was trialled to provide a flat surface
necessary for the ultrasonic scanner. In addition, A-scan techniques
rely heavily on operator’s skills therefore it is desirable to
make the technique less dependent on the operator. In these
trials, two researchers were used to make independent measurements
in order to assess the consistency of the technique. Fig. 16
shows a typical section of the floor evaluated.
3.4.1. Independent measurement
Thirty six of the fifty two welds on the floor structure were
found to be accessible for the C-scanner by the two operators.
Fig. 17 shows two examples of the C-scan images obtained from
two different welds (numbers 2 and 8 respectively); joining
1.5 mm sheet to sheet and joining 1.5 mm sheet to extrusion, in
the floor assembly. Though all images contain some artefacts the
general shape and size of the weld features are comparable and
demonstrate that similar C-scan images can be obtained independently.
The colour range and details presented in the images
are dependent on the settings used including; gain, gate size and
lookup table. These parameters were optimised to allow for the
shallow form that was present in the floor assembly flanges,
compared to the flat lab strips. The same parameter settings were
used by both operators for the analysis carried out. Each of the
C-scan images was measured to determine the average weld size,
as described in 3.3.2. The results from all the welds measured,
across the range of joints with different weld nugget diameters
and alloy forms, are compared numerically with each other in
Fig. 18. As can be seen, a good agreement between the two
independent operators was achieved and the technique works
irrespective of the aluminium forms joined together.
figures but rotated by 901 and deemed genuine; whereas the
white area labelled artefact was only visible in one image. This
provides confidence that the features are real and not artefacts.
This procedure of rotating the probe was adopted for validating
true features from artefacts in the advanced trials.
3.4. Floor assembly
For real applications, it is not practical to mill the indentation;
therefore a 20 mm abrasive disc attachment in a conventional
rechargeable hand tool was trialled to provide a flat surface
necessary for the ultrasonic scanner. In addition, A-scan techniques
rely heavily on operator’s skills therefore it is desirable to
make the technique less dependent on the operator. In these
trials, two researchers were used to make independent measurements
in order to assess the consistency of the technique. Fig. 16
shows a typical section of the floor evaluated.
3.4.1. Independent measurement
Thirty six of the fifty two welds on the floor structure were
found to be accessible for the C-scanner by the two operators.
Fig. 17 shows two examples of the C-scan images obtained from
two different welds (numbers 2 and 8 respectively); joining
1.5 mm sheet to sheet and joining 1.5 mm sheet to extrusion, in
the floor assembly. Though all images contain some artefacts the
general shape and size of the weld features are comparable and
demonstrate that similar C-scan images can be obtained independently.
The colour range and details presented in the images
are dependent on the settings used including; gain, gate size and
lookup table. These parameters were optimised to allow for the
shallow form that was present in the floor assembly flanges,
compared to the flat lab strips. The same parameter settings were
used by both operators for the analysis carried out. Each of the
C-scan images was measured to determine the average weld size,
as described in 3.3.2. The results from all the welds measured,
across the range of joints with different weld nugget diameters
and alloy forms, are compared numerically with each other in
Fig. 18. As can be seen, a good agreement between the two
independent operators was achieved and the technique works
irrespective of the aluminium forms joined together.
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