INSTRUMENTATION & CONTROL | ULTRASONIC DEFECT DETECTION
Above, figure 1: Diagram of the Soak-test Sample. In the left-hand pane, a perspective projection of the sample is shown with the PUMA monitoring array in green and the synthetic defect in red. The right-hand pane shows a closer view of the array and defect. Selected array elements are numbered
thick and 28 elements were fitted to the sample. They were arranged in a 4 x 7 (XY) array. The array was symmetrically located over the defect such that the fourth Y element in the array column was located directly over the synthetic defect. In the trial case the array spacing was ~10mm. Strong signals from the defect were discernible across the entire monitoring array leading to the conclusion that the array density could be decreased. Electrical connections were made onto the sensors and then to monitoring equipment. On fitting the sensors, an installation tool broke which limited fitting quality for one of the sensors. The result was reduced sensitivity and increased noise on that channel (marked by a pink circle in Figure 3, right). The variation in sensitivity could be measured by
examining the backwall echo in pulse echo operation across the array and was better than 4dB across the set (excluding the damaged element). During the soak-test, the sensitivity of each element either stayed the same or slightly improved. System noise also remained constant. Throughout the test, signals due to the defect were clearly discernible in the data. These signals were constant and
processing returned the same defect size and location at setup, during trials at elevated temperature and post- trial.
The PUMA monitoring system comprises inexpensive
components which means that the cost of equipment tied- up during monitoring is not excessive. The current system accumulates response data at a rate of about 10 elements per second including repeat firing for averaging purposes. Data collection rates could be increased, but there is no particular merit in high data rates as the time to acquire data is virtually unlimited during plant operation. Scans can be repeated as often as desired and repeat data are automatically compared by the monitoring software over the collection period to check for sensor deterioration or initiation or growth of defects. Differencing of historic and current data means small changes associated with sensor deterioration, or defect growth can be recognised and that a data storage regime can be selected to keep stored, important data without excessive data storage. Data are regularly uploaded to the Cloud for remote analysis and storage. Note too that this facility makes the process available to update system digital twins.
Above, figure 2: 2D model for the full field presentation in the left-hand pane showing displacement colour coded In the right hand pane and a-scans for an array column straddling the defect. The a-scans show the sequence when one is fired and all including the firing element receive the fired pulse scattered by the defect and backwall. The plot shows (A) the defect echo, (B) the backwall echo and (C) the transmitter element’s response in red
22 | July 2024 |
www.neimagazine.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53
