Phased Array Probe Research Articles

Profile reconstruction and quantitative detection of planar defects with composite-mode total focusing method (CTFM)

The profile reconstruction of planar defects by ultrasonic imaging is helpful for obtaining the flaw type, size, orientation and other characteristics. In this paper, composite-mode total focusing method (CTFM) is proposed by selecting the strongest response from 21 views at every reconstructed point, realizing the profile reconstruction and quantitative detection of priori unknown planar defects except for the near-horizontal defects with a set of phased array (PA) probe and wedge. Subsequently, eight effective views corresponding to 45° longitudinal-wave wedge are determined considering Snell's law and beam directivity. The 64-element linear array probe with 5 MHz central frequency and 45° wedge were used to reconstruct a series of 5 mm length cracks with different orientations (0°, ±15°, ±30°, ±45°, ±60° and ±75°) by CTFM in simulation. The measurement errors of crack lengths, orientation angles and central depths with the 6 dB drop rule were within 0.42 mm, 1.87° and 0.58 mm, respectively. The experimental results showed that the characteristics of 5 mm length slots were presented with high accuracy, verifying the feasibility of CTFM. Meanwhile, the planar and volumetric defects can be distinguished qualitatively by CTFM. Finally, the reconstructed image by naive sum is compared with the CTFM image, and the effects of wedge angle and number of elements on profile reconstruction are discussed.

Optimizing Probe Active Aperture for Phased Array Weld Inspections

Phased array ultrasonic testing (PAUT) has become a popular nondestructive technique for weld inspections in piping, pressure vessels, and other components such as turbines. This technique can be used both in manual and automated modes. PAUT is more attractive than conventional angle-beam ultrasonic testing (UT), as it sweeps the beam through a range of angles and presents a cross-sectional image of the area of interest. Other displays are also available depending on the software. Unlike traditional A-scan instruments, which require the reconstruction of B- and C-scan images from raster scanning, a phased array image is much simpler to produce from line scans and easier to interpret. Engineering codes have incorporated phased array technology and provide steps for standardization, scanning, and alternate acceptance criteria based on fracture mechanics. The basis of fracture mechanics is accurate defect sizing. There is, however, no guidance in codes and standards on the selection and setup of phased array probes for accurate sizing. Just like conventional probes, phased array probes have a beam spread that depends on the probe’s active aperture and frequency. Smaller phased array probes, when used for thicker sections, result in poor focusing, large beam spread, and poor discontinuity definition. This means low resolution and oversizing. Accurate sizing for fracture mechanics acceptance criteria requires probes with high resolution. In this paper, guidance is provided for the selection of phased array probes and setup parameters to improve resolution, definition, and sizing of discontinuities.

Online nonlinear ultrasound imaging of crack closure during thermal fatigue loading

A thermal fatigue surface crack (6 mm deep × 23 mm wide) in a thick austenitic stainless steel plate is opened and closed with thermal heating and cooling cycles. This closing and opening of the crack is recorded with using fundamental wave amplitude difference (FAD) technique with 5 MHz 64 element phased array probe. In addition, the contact pressure and crack opening state at different time intervals were estimated using finite element (FE) simulation. In combination with the nonlinear output from the FAD and FE simulation gave insight at which level the contact pressure or the distance between crack faces prevents the contact acoustic nonlinearity (CAN) from happening. Predictably, no clear nonlinear response was recorded at crack face locations experiencing high contact pressure and on the locations where the crack could be considered fully open, as predicted by the FE simulation. Therefore, the FAD technique can be utilized within the constraints quantified in the paper.

A nonlinear ultrasonic modulation approach for the detection and localisation of contact defects

Critical metallic and composite structures are periodically inspected for contact defects such as kissing bonds and delamination, using phased array techniques based on linear ultrasound. The detection of contact flaws at multiple depths in the material can be challenging due to high signal attenuation and noise level. In this study an alternative ultrasonic phased array approach relying on the nonlinear modulation of dual-frequency excitation was introduced to improve the sensitivity and accuracy in the detection of contact defects. A phased array probe was used for the generation of single-frequency and dual-frequency waves, and the capturing of echoes. The flaws were detected using a new nonlinear modulated parameter characterising the response of the material arising only from the modulation sidebands at the sum and difference frequencies f2+f1 and f2-f1. Ultrasonic tests were conducted on materials with multiple contact interfaces. The novel parameter was plotted against the linear response, and the peaks indicating the contact interfaces were compared based on their signal-to-noise ratio (SNR), their width at half-height (6 dB drop) and their positioning error. The peaks of the nonlinear modulated parameter offered up to 103 times higher SNR, up to 10 times smaller width at half-height and around 45% smaller localisation error than the peaks in the classical linear ultrasonic response. The results showed that the proposed approach could lead to more effective detection and more accurate localisation of contact defects in structural materials such as kissing bonds and closed delamination.

Automated Defect Detection From Ultrasonic Images Using Deep Learning.

Nondestructive evaluation (NDE) is a set of techniques used for material inspection and defect detection without causing damage to the inspected component. One of the commonly used nondestructive techniques is called ultrasonic inspection. The acquisition of ultrasonic data was mostly automated in recent years, but the analysis of the collected data is still performed manually. This process is thus very expensive, inconsistent, and prone to human errors. An automated system would significantly increase the efficiency of analysis, but the methods presented so far fail to generalize well on new cases and are not used in real-life inspection. Many of the similar data analysis problems were recently tackled by deep learning methods. This approach outperforms classical methods but requires lots of training data, which is difficult to obtain in the NDE domain. In this work, we train a deep learning architecture EfficientDet to automatically detect defects from ultrasonic images. We showed how some of the hyperparameters can be tweaked in order to improve the detection of defects with extreme aspect ratios that are common in ultrasonic images. The proposed object detector was trained on the largest dataset of ultrasonic images that was so far seen in the literature. In order to collect the dataset, six steel blocks containing 68 defects were scanned with a phased-array probe. More than 4000 VC-B-scans were acquired and used for training and evaluation of EfficientDet. The proposed model achieved 89.6% of mean average precision (mAP) during fivefold cross validation, which is a significant improvement compared to some similar methods that were previously used for this task. A detailed performance overview for each of the folds revealed that EfficientDet-D0 successfully detects all of the defects present in the inspected material.

Phased Array Ultrasonic Testing of Inconel 625 Produced by Selective Laser Melting

Abstract We investigate the use of phased array ultrasonic testing (PAUT) as an offsite non-destructive quality assurance technique for parts made by selective laser melting (SLM). SLM is a popular additive manufacturing (AM) approach for fabricating high-value metallic components with complex geometries. Slight variations in the laser power during fabrication might lead to internal defect development within the part, which could compromise its mechanical strength and fatigue life. PAUT is employed to detect typical internal porosity generated in Inconel 625 samples due to laser power fluctuation during SLM. The typical defect size, shape, and distribution are first identified using metallography and X-ray computed tomography (XCT). B-Scan images of the defect region is then generated experimentally using a 5-MHz linear UT phased array probe. Finite elements simulate wave propagation using geometries obtained from XCT images. The simulation results are compared to the experimental imaging of large defect regions and then used to generate total focusing method images of isolated clusters of 50–200 μm defects. The testing technique illustrates a successful application of PAUT for quality inspection of SLM parts.

Towards using convolutional neural network to locate, identify and size defects in phased array ultrasonic testing

Machine learning algorithms are widely used in image recognition. In Phased Array Ultrasonic Testing (PAUT), images are typically formed through constructive and destructive superpositions of signals backscattered from flaws or geometric features. However, all PAUT data acquisition schemes require several emissions and the duration of the acquisition may be too slow in high-speed manufacturing. In this study, the Faster R-CNN was used to identify, locate and size flat bottom holes (FBH) and side-drilled holes (SDH) in an immersed test specimen using a single plane wave insonification. The training was performed on segmented and classified data generated using GPU-accelerated finite element simulations. SDH and FBH of different diameters, depths and lateral positions were included in the training set. The thickness of the test specimen was also variable. An ultrasonic phased array probe of 64 elements was simulated. All elements of the phased array probe were fired at the same time and the time traces from each element were recorded. The individual time traces were concatenated to form a matrix, which was then used in the training. This inspection scenario enables fast acquisition of data at the expense of poor lateral resolution in the resulting image. The trained neural network was initially tested using finite element simulations. Results were assessed in terms of the intersection of the union (IoU) between the ground truth geometry and the predicted geometry. With the simulated cases, the thickness of the test specimen was detected in all cases. When using a 40% IoU threshold, the detection rate of the FBH was 87% while only 20% for the SDH. The smallest detected FBH had a 0.56 wavelength depth and a lateral extent of 1.04 wavelength. Drawing a box using the −6dB drop method around the FBH always led to an IoU under 15%. On average, the lateral extent of the FBH using the −6dB method was three times larger than the diameter predicted by the proposed method. Then, the training was continued with a small augmented dataset of experiments (equivalent to 3% of the simulated dataset). In experiments, the results show that the test specimen was always correctly identified. When using a 40% IoU threshold the experimental detection rate of the FBH was 70%. The smallest detected defect in experiments had a depth of 2 wavelengths.

Ultrasonic Testing of Rough Surfaces Using Phased Array Probe

Ultrasonic Testing of Rough Surfaces Using Phased Array Probe

GPU-Based Simulation of Echocardiography Volumes Using Quantitative Fiber-Angle-to-Backscatter Measurements.

The intensity of backscattered ultrasound signal from heart muscle is known to be related to the angle between cardiac fibers and the insonification direction. In this work, a GPU-based method of simulating three-dimensional (3D) echocardiographic images from an empirically derived angle-to-backscatter relationship is developed and validated. Images of a rotating fiber phantom are simulated, and it is validated that the angle-to-backscatter relationship is accurately reflected by the simulated envelope data. In a second experiment, echocardiography images are simulated from a diffusion tensor magnetic resonance imaging (DT-MRI) volume of a canine heart to demonstrate that the method produces view-dependent speckle. 3D volumes of a parametrically generated ideal left ventricle phantom are also simulated and processed into fiber orientation maps using the underlying quantitative parameters. Images are simulated based on the characteristics of a 35-by-32 two-dimensional (2D) matrix array probe and a clinical one-dimensional (1D) phased array probe. The processed fiber volumes exhibit good agreement with the virtual phantom's ground truth, having an average acute angle error (AAE) of less than 10 degrees for both probes. The simulation method is fast and opens a new approach for ultrasound fiber imaging.

Measurement of coronary sinus blood flow using transesophageal echocardiography to estimate the adequacy of revascularization in patients undergoing off-pump coronary artery bypass grafting

Introduction Revascularization of coronary artery increases the blood flow in the coronary sinus (CS) too. The study aimed to measure the CS blood flow using transesophageal echocardiography (TEE) to estimate the adequacy of revascularization in patients undergoing off-pump coronary artery bypass grafting. Patients and methods After ethical committee approval, 100 patients scheduled for elective coronary artery bypass grafting were included in this study. After induction of balanced anesthesia according to institutional protocol, a 5-Hz multiplane phased-array TEE probe was inserted into patients’ esophagus, and the following parameters were calculated at pre-revascularization and post-revascularization periods: velocity time integral of CS, coronary sinus diameter, coronary sinus cross-section area, and coronary sinus blood flow (CSBF) per beat and per minute. Results Our study showed a statistically significant increase in velocity time integral in the post-revascularization period as compared with the pre-revascularization period (P Conclusion TEE is a superior modality to evaluate CSBF before and after coronary artery bypass revascularization to determine the adequacy of surgical revascularization in real time during off-pump coronary artery bypass revascularization.

Phased array probe for the inspection of large steel forgings

Reliable inspection of large steel forgings is a significant problem across multiple industries. When the dimensions of forgings are at least 1000 mm in each direction, ultrasonic phased array inspection becomes difficult because conventional probes are not designed to transmit and focus acoustic energy over such large distances. Using simulations and experiments, this article aims to discuss the possibilities and limitations of phased array imaging of large forged steel ingots. Simulations were used to design a transducer based on the reflected amplitude, as well as the lateral and axial resolutions of defects in a 1000 mm thick block. It was shown that when limiting the aperture to allow easy handling in an industrial inspection setting, the lateral resolution and the reflected amplitude were the main limitations. Increasing the element width maximizes the energy transmitted into the material, but it also moves elements away from each other, thus reducing the lateral resolution. Based on the simulations, an experimental phased array transducer was manufactured with eight elements of 9.25 × 22.5 mm. The probe was used to perform measurements and generate total focusing method images of three different at a depth of 370 mm in a 776 mm forged steel block.

Effect of the Acoustic Impedance Mismatch at the Bone-Soft Tissue Interface as a Function of Frequency in Transcranial Ultrasound: A Simulation and In Vitro Experimental Study.

The transcranial Doppler (TCD) ultrasound is a method that uses a handheld low-frequency (2-2.5 MHz), pulsed Doppler phased array probe to measure blood velocity within the arteries located inside the brain. The problem with TCD lies in the low ultrasonic energy penetrating inside the brain through the skull, which leads to a low signal-to-noise ratio. This is due to several effects, including phase aberration, variations in the speed of sound in the skull, scattering, the acoustic impedance mismatch, and absorption of the three-layer medium constituted by soft tissues, the skull, and the brain. The goal of this article is to study the effect of transmission losses due to the acoustic impedance mismatch on the transmitted energies as a function of frequency. To do so, wave propagation was modeled from the ultrasonic transducer into the brain. This model calculates transmission coefficients inside the brain, leading to a frequency-dependent transmission coefficient for a given skin and bone thickness. This approach was validated experimentally by comparing the analytical results with measurements obtained from a bone phantom plate mimicking the skull. The average position error of the occurrence of the maximum amplitude between the experiment and analytical result was equivalent to a 0.06-mm error on the skin thickness given a fixed bone thickness. The similarity between the experimental and analytical results was also demonstrated by calculating correlation coefficients. The average correlation between the experimental and analytical results came out to be 0.50 for a high-frequency probe and 0.78 for a low-frequency probe. Further analysis of the simulation showed that an optimized excitation frequency can be chosen based on skin and bone thicknesses, thereby offering an opportunity to improve the image quality of TCD.

Effect of Machine Settings on Ultrasound Assessment of B-lines.

ObjectivesB‐lines are a lung ultrasound (LUS) artifact that often indicate pathology. Little is known about the optimal ultrasound machine settings to assess B‐lines. We compared settings typically used to evaluate B‐lines at our institution with adjusted settings based on recent studies.MethodsIn order to determine typical settings for B‐line assessment, we retrospectively reviewed LUS images obtained at our institution. We then prospectively performed LUS with both typical and adjusted settings, using curvilinear and phased array probes, in 20 patients presenting to the emergency department with shortness of breath. The prospectively obtained clips were rated for quality and quantity of B‐lines by 14 clinicians with experience in LUS, with 1 assigned for typical settings “much greater,” 2 for typical settings “slightly greater,” 3 for both settings “similar,” 4 for adjusted settings “slightly greater,” and 5 for adjusted settings “much greater.”ResultsMean ratings and 95% confidence intervals significantly exceeded the null value of 3 for both B line quality (curvilinear probe: 4.68, 4.50–4.85; phased array probe: 4.02, 3.70–4.35) and B line quantity (curvilinear probe: 4.16, 3.84–4.49; phased array probe: 3.68, 3.41–3.96).ConclusionsB‐line quality and quantity were rated higher using adjusted settings based on recently published evidence than when using settings that are typically employed in our institution. Our findings suggest that B‐line assessment should be performed with focal zone at the level of the pleura, harmonics off, and gain increased in the far field.

Evaluation of material degradation using phased array ultrasonic technique with full matrix capture

This paper presents a new approach based on phased array ultrasonic technique (PAUT) with full matrix capture (FMC) to effectively measure acoustic properties such as ultrasonic wave velocity and attenuation coefficient and to evaluate material degradation. This paper also proposes the use of PAUT with FMC, to simultaneously generate and detect ultrasonic waves such as longitudinal, shear, and Rayleigh waves in the material. A theoretical model is developed to derive the analytical solution of ultrasonic waves induced in the material by an ultrasonic phased array probe. Based on the theoretical prediction, experiments are carried out on AISI 316L stainless steel specimen of 3 mm thickness, and a 2D finite element model is built to verify the generation and detection of these waves. Furthermore, measurements of acoustic properties are carried out on the specimen using the proposed approach as well as the conventional ultrasonic testing (CUT) technique and their sensitivities are compared. The measurements of time-of-flight and back-wall echo amplitude are more accurate with the proposed approach than the CUT technique, which makes the former technique better than the latter for the evaluation of material degradation. Finally, experiments are performed on AISI 316L specimen degraded with different levels of tensile stress to verify the capability of PAUT with FMC. The results show that the velocities and attenuation coefficient increase with an increase in tensile stress until material fracture. This phenomenon is interpreted as resulting from microstructural changes such as dislocations during material degradation. From the experimental results, it is proposed that PAUT with FMC can potentially be used to evaluate early-stage materials degradation.

Safety, feasibility and performance of Valvosoft non-invasive ultrasound therapy in patients with severe symptomatic calcific aortic valve stenosis. First-in-Man

Abstract Objectives We recently developed a unique transthoracic non-invasive ultrasound therapy device called Valvosoft to treat aortic stenosis. The therapy consists in delivering trans-thoracically precisely focused and controlled short ultrasound pulses (<20μsec) at a high acoustic intensity to produce non-thermal mechanical tissue softening of the calcified aortic valve with the ultimate aim of improving the valve opening. Ultrasound imaging enables to follow valve movements in real-time and thus targets the ultrasound waves on the valve with great precision. After having validated this concept in pre-clinical studies, we aimed at applying this technique in human. The primary objectives were to assess the safety and feasibility of this novel technique along with its performance by evaluation of the valve leaflets mobility and valve opening area. Methods This is a multi-center, prospective, controlled first-in-man study. Ten patients with severe symptomatic calcific aortic stenosis and not eligible for SAVR/TAVR underwent a Valvosoft ultrasound therapy. The therapy consists of 6 sessions of ultrasound therapy. The Valvosoft transducer is applied on the patient's chest and coupled at its center with an echocardiography phased array probe to allow real-time control of the therapy (cavitation bubble detection). Preselection of the region of interest is performed by echo still frame before each session. Ultrasonic evaluation was performed by an independent core lab at baseline, discharge, 30-day and 3 month follow-up along with clinical follow up. Results Enrolled patients were advanced in age (84.1±6.5 yrs) with severe comorbidities (8 with heart failure, 5 with coronary heart disease and 5 with kidney failure). All had extensive aortic valve calcification (mean calcification volume of 687.28 mm3) with mean AVA of 0.61±0.17 cm2 and mean pressure gradient of 37.5±10.5 mmHg (6 patients had SV<35ml/m2). No adverse events were recorded during the procedures other than some benign ventricular extrasystoles. The mean treatment time was 52 minutes. At 3 months follow-up, one patient had died due to end stage heart failure not linked to the procedure (9 weeks post procedure) and another got finally TAVI (45 days post procedure). Of the other 8 patients, 6 experienced an improvement of their NYHA status. No device or procedure related major adverse events nor deterioration of neurological status were observed at 3 months follow-up. Of the 7 patients that had echo follow-up at 3 months (one patient refused to get echo evaluation), 5 increased the AVA (between 14% and 46%) and 4 patients decreased the mean pressure gradient (from 6% to 44%). No AI or EF deterioration occurred during follow up. Conclusion Non-invasive ultrasound therapy is feasible and safe in patients with severe aortic valve stenosis and is able to improve AVA and pressure gradient in some patient. Larger studies with longer follow up will need to be conducted. Funding Acknowledgement Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Cardiawave SA, Paris, France

Lung ultrasound in early SARS-CoV-2 pneumonia and the LUS-CoV criteria

There is a scarcity of data on lung ultrasound (LUS) in SARS-CoV-2 pneumonia. As with many other pulmonary conditions, ultrasound may be a better diagnostic tool than routine chest radiography. In an era where computed tomography scanning is deferred because of the potential for cross-contamination, we evaluated the ability of LUS to detect a pattern of lung injury in SARS-CoV-2 pneumonia. A limited anterolateral LUS was performed to limit time spent in isolation rooms by ultrasound operators. We chose to use a hand-held ultrasound device due to portability and superior confidence in infection control. Both linear and phased array probes were used to obtain images of the pleura and lung. Of 69 patients who had lung ultrasound images saved and were included in the analysis, 36 were positive for SARS-CoV-2. Multifocal confluent B-lines, pleural irregularities, and the absence of moderate or large pleural effusions were the predominant pattern observed in most (86%) of SARS-CoV-2–positive patients. We evaluated the accuracy of the above criteria (LUS-CoV) and report a high sensitivity (91%) and specificity (86%) for SARS-CoV-2 pneumonia. In conclusion, a characteristic sonographic pattern of multifocal confluent B-lines with irregular pleural markings was seen on LUS in patients with SARS-CoV-2 pneumonia.

Image-Guided Treatment of Primary Liver Cancer in Mice Leads to Vascular Disruption and Increased Drug Penetration.

Despite advances in interventional procedures and chemotherapeutic drug development, hepatocellular carcinoma (HCC) is still the fourth leading cause of cancer-related deaths worldwide with a <30% 5-year survival rate. This poor prognosis can be attributed to the fact that HCC most commonly occurs in patients with pre-existing liver conditions, rendering many treatment options too aggressive. Patient survival rates could be improved by a more targeted approach. Ultrasound-induced cavitation can provide a means for overcoming traditional barriers defining drug uptake. The goal of this work was to evaluate preclinical efficacy of image-guided, cavitation-enabled drug delivery with a clinical ultrasound scanner. To this end, ultrasound conditions (unique from those used in imaging) were designed and implemented on a Philips EPIQ and S5-1 phased array probe to produced focused ultrasound for cavitation treatment. Sonovue® microbubbles which are clinically approved as an ultrasound contrast agent were used for both imaging and cavitation treatment. A genetically engineered mouse model was bred and used as a physiologically relevant preclinical analog to human HCC. It was observed that image-guided and targeted microbubble cavitation resulted in selective disruption of the tumor blood flow and enhanced doxorubicin uptake and penetration. Histology results indicate that no gross morphological damage occurred as a result of this process. The combination of these effects may be exploited to treat HCC and other challenging malignancies and could be implemented with currently available ultrasound scanners and reagents.

Multi Display Scan in Detecting Weld Discontinuity of Thick Carbon Steel Plate using Ultrasonic Testing Phased Array (UTPA) with Comparison to Conventional Ultrasonic Testing (UT)

Non-destructive testing (NDT) is a method of testing and analysis that relies on the application of physical principles to determine the integrity of materials without causing damage. The existence of weld discontinuity can affect the service ability of the structures. Ultrasonic testing Phases Array (UTPA) is advanced ultrasonic testing technology widely practiced in many industries. The multiple ultrasonic elements and electronic time delay will create constructive and destructive interference and steering capability, which could improve detectability compared to a single element of conventional UT. The multi displays presented in A-Scan, S-scan, B-Scan, and C-Scan of UTPA equipment capable of locating, inspecting, and characterise defects within the welded component. Two carbon steel plates with thickness 18 mm and 24 mm were prepared and cut to V-shape configuration and welded using shielded metal arc welding (SMAW) process, labelled as NDE-8826 and NDE-8827 respectively. Both samples were induced with artificial defects of the weld. 16 elements of phased array probe with 0.5 mm pitch and 4 MHz were carried out for this study with encoded scanning to identify weld discontinuity plotted in different types of UT displays. Additional testing was performed using conventional ultrasonic testing (UT) using a 4 MHz probe to compare with the UTPA results and the acceptability of each defect detections. The length and datum of toe crack, slag, and lack of inter run fusion detected by UTPA in NDE-8826 give the same value as the actual value. However, the localisation of the defect is slightly different at 1.0 mm for UT detection. While the detection value for slag gives the same values for UT and UTPA, which also the same as the actual values. The detection of lack of penetration and lack of fusion in sample NDE-8827 was precisely can be detected by UT and UTPA; hence their datum value has slightly different in the centerline crack and porosity at 2.0 mm for UT measurement, and as for UTPA, it was found that the porosity at 3.0 mm which higher value compared to the actual value, 250 mm. From the result, a relevant indication from the UTPA and conventional UT collected it was found that the UTPA technique is capable of improving the Probability of Detection (POD) of defects compared to the conventional UT.

Optimizing linear phased array transducers for non-destructive evaluation of thin layers

AbstractIn this work, a numerical method is proposed in order to achieve design optimisation of phased array (PA) probes for the special application of defects detection in thin films. This approach relies on an extended Fourier-based model that was adapted to predict the two-dimensional ultrasonic displacement field taking place in a thin plate under individual excitation of PA probe elements which have arbitrary orientation with respect to the examined part surface. Excitation is applied through a fluid couplant and is operated at scheduled delays that are managed to enable emission of constructive pulses. This gives the possibility to steer sound waves towards a direction and to focalize the beam in a selected point. An optimisation algorithm based on the concept of pattern search that does not require evaluation of a gradient was used to find the best match in the multidimensional analysis space of possibilities including the elements orientation angles, the elements lengths, the inter-elements distances and work frequency. Optimisation was performed with the objective to maximize the displacement amplitude at the focal point while minimizing simultaneously the effect of beam side lobes. The results obtained by this approach reveal that focalisation can be achieved with enhanced features in comparison with previous algorithms assuming linear elements that are parallel to the surface of the plate.

Experimental validation of a phased array probe model in ultrasonic inspection

New manufacturing technologies such as additive manufacturing facilitate flexible and complex designs and production of components. However, these new techniques should not compromise the safety aspect, which imposes higher demands on the integrity insurance and inspection methods. Phased array ultrasonic testing (PAUT) provides advanced inspection and evaluation processes, whereas qualification is still needed when applied together with new manufacturing techniques. Numerical modeling, as one of the potential qualification methods, has been developed for decades and should be validated before practical applications. This paper presents an experimental validation work of the phased array probe model implemented in a software, simSUNDT, by comparing the maximum echo amplitudes between the physical experiments and simulations. Two test specimens with side-drilled holes (SDHs) and different materials are considered for validation and practical purposes. An experimental platform with a mechanized gantry system, which enables stabilized inspection procedure, is built and applied during the validation work. Good correlations can be seen from the comparisons and this model is concluded as an acceptable alternative to the corresponding experimental work. The relation between depth and beam angle is also noticed and investigated, which is essential to guarantee an accurate inspection.