Phased Array Ultrasonic Technique Parametric Evaluation for Composite Materials

Present state of the art sizing measurements of defects by ultrasonic techniques has been inadequate, especially in support of a quantitative fracture mechanical analysis of the strength of a material. Present capabilities of defect sizing in some cases do not allow an accept/reject decision to be made. Currently, ultrasonic imaging systems including phased array, synthetic aperture, and wavefront reconstruction systems are being developed to quantitatively measure defect sizes. Also, in the medical field phased array systems have been developed for imaging purposes. Ibis work describes an annular phased array system which is being developed for general NDE applications on metal and ceramic materials. The main usefulness of phased array techniques is the ability of electronically changing the focus of the acoustic beam radiating from a phased array transducer or reflecting from a defect in a solid material.

Two dimensional echographic imaging of the left ventricle: Comparison of mechanical and phased array systems in vitro

New non-destructive examination methods have been available for many years. These include time of flight diffraction and phased array methods. These are routinely used for inspection of welds. Work is ongoing at ISO and CEN for standardization of these methods. First the time of flight diffraction was drafted and now ISO and CEN are working on a standard for phased arrays. These drafts are used for welding inspections. The acceptance criteria is in draft form for time of flight diffraction which will be followed by that for phased array. Standards are already available for base material phased array inspection such as the ASTM document “Standard Guide for Evaluating Performance Characteristics of Phased Array Ultrasonic Examination Instruments and Systems”. Several ASME code-cases have been issued in recent years on weld inspection. Qualification for the ASME code is also planned for this novel technique.

New non-destructive examination methods have been available for many years. These include time of flight diffraction and phased array methods. These are routinely used for inspection of welds. Work is ongoing at ISO and CEN for standardization of these methods. First the time of flight diffraction was drafted and now ISO and CEN are working on a standard for phased arrays. These drafts are used for welding inspections. The acceptance criteria is in draft form for time of flight diffraction which will be followed by that for phased array. Standards are already available for base material phased array inspection such as the ASTM document “Standard Guide for Evaluating Performance Characteristics of Phased Array Ultrasonic Examination Instruments and Systems”. Several ASME code-cases have been issued in recent years on weld inspection. Qualification for the ASME code is also planned for this novel technique.

The work explores the possibilities of application of ultrasonic testing in the assessment of fibre metal laminates. Basic problems concerning the use of ultrasonic methods in the research of laminates are explained, and methods for solving these problems are suggested. Tests were conducted using two phased array methods: ultrasonic pulse-echo and through transmission. The efficiency of both selected ultrasonic methods are compared with respect to detecting and dimensioning defects in laminate structures. Based on the analyses and proposed solutions, it has been proven that the developed through transmission phased array (TTPA) method ensures a much more effective, in terms of quality and quantity, assessment of the condition of hybrid laminates than conventional ultrasonic methods, irrespective of the degree of surface deformation and the type of laminate structure.

Development of a 20-MHz wide-bandwidth PMN-PT single crystal phased-array ultrasound transducer

Phased array approach to generate guided waves and extract phase velocities using the V(z) method.

Phased array inspection was conducted on a V-butt welded steel sample with multiple shallow flaws of varying depths. The inspection measurements were processed using Wiener filtering and Autoregressive Spectral Extrapolation (AS) to enhance the signals. Phased array inspections were conducted using multiple phased array probes of varying nominal central frequencies (2.25, 4, 5 and 10 MHz). This paper describes the measured results, which show high accuracy, typically in the range of 0.1-0.2 mm. The results concluded that: 1. There was no statistical difference between the calculated flaw depths from phased array inspections at different flaw tip angles. 2. There was no statistical difference in flaw depths calculated using phased array data collected from either side of the weld. 3. Flaws with depths less than the estimated probe signal shear wavelength could not be sized. 4. Finally, there was no statistical difference in the calculated flaw depths using phased array probes with different sampling frequencies and destructive measurements of the flaws.

We investigate Hotelling observer performance (i.e., signal detectability) of a phased array system for tasks of detecting small inhomogeneities and distinguishing adjacent abnormalities in uniform diffusive media. Unlike conventional phased array systems where a single detector is located on the interface between two sources, we consider a detector array, such as a CCD, on a phantom exit surface for calculating the Hotelling observer detectability. The signal detectability for adjacent small abnormalities (2 mm displacement) for the CCD-based phased array is related to the resolution of reconstructed images. Simulations show that acquiring high-dimensional data from a detector array in a phased array system dramatically improves the detectability for both tasks when compared to conventional single detector measurements, especially at low modulation frequencies. It is also observed in all studied cases that there exists the modulation frequency optimizing CCD-based phased array systems, where detectability for both tasks is consistently high. These results imply that the CCD-based phased array has the potential to achieve high resolution and signal detectability in tomographic diffusive imaging while operating at a very low modulation frequency. The effect of other configuration parameters, such as a detector pixel size, on the observer performance is also discussed.

Damage localization in aluminum plate with compact rectangular phased piezoelectric transducer array

The increasing use of high-speed trains, resulting in higher stress to the material and serious accidents with human injuries in the past, lead to a demand for shorter inspection intervals, extended scope of inspection and more stringent test requirements to be applied to the critical components. One component, which is inspected in regular intervals, is the axle of the railway wheel set. Critical areas for cracks are mainly the wheel and brake disc seats and the cross section transition areas. The manual ultrasonic inspection of used axles by experienced personal is time-consuming (since several sound beam angles have to be used to cover the complete test area), expensive and, of course, subjective. It represents a bottleneck in the inspection line. One way to overcome this bottleneck is the automation of the test process and the use of phased array probes. GE Inspection Technologies, in co-operation with the German railways (DB) and the 'Bundesanstalt fur Materialprufung'(BAM), developed a system to automate this inspection. This system applies the phased array technique to detect transversal cracks in the most critical areas of the axle. The different angles of several conventional probes are replaced by steering the beam angle of one phased array probe accordingly. Mechanical movement is substituted by software control. Two of these automated systems have been delivered to the German Railways. When taking these systems into operation, several problems arose, caused by the variety of the axles, coupling surface conditions and differences in the sound attenuation even within the axle. This paper describes the technical concept and reports some practical experience, problems and solutions in the commissioning phase of the automatic inspection lines.

The welding quality of the GIS shell is critical to preventing SF6 gas leakage in the Gas Insulated Switchgear（GIS） equipment of the substation, and phased array ultrasonic testing（PAUT） technology can intuitively and efficiently inspect the butt welds of the GIS shell. Since the GIS shell is mostly non-magnetic aluminum alloy material, the scanning process can not use the magnetic wheel to allow the scanning device to adsorb on the detection surface.in order to solve the problem of coupling between the phased array probe and the surface of the GIS shell during the inspection process, automatic scanning device for PAUT of butt welds of GIS shell was developed. The scanning device uses the main frame, straps, probe lifting assembly and waterway tap assembly to effectively fix the phased array probe and the curvature wedge on the GIS shell, on the one hand, to ensure the close fit between the probe and the detection surface in the inspection, on the other hand, to ensure that the data can be automatically collected along the established trajectory during the inspection process.The scanning device ensures the quality of the collected data while improving the detection efficiency, and the feasibility of the scanning device is verified by experiments.

A phased array ultrasound system with a robotic arm for neuromodulation.

Ultrasonic testing of metal welds has been in use for many years. Scanning methods using both contact and immersion methods are often used at the time of manufacture and also during periodic in-service inspection programs. But because of a variety of component configurations and potential flaw geometries it is often necessary to perform several inspections, each with a different probe configuration to assure adequate defect delegability. It is possible that a properly designed phased array probe can perform several different inspections without changing hardware thereby reducing inspection times. This presentation reviews the design and operation of ultrasonic phased array transducers and the necessary features to achieve the desired performance. Situations in which these probes have already been implemented effectively are also discussed.

The digitalization of testing procedures is one of the challenges in the development of modern non-destructive testing systems. In order to guarantee a high level of inspection reliability, the assignment of measurement data to the measurement position plays an important role as well as the optimal inspection hardware. In a cooperative research and development project, an optical tracking system has been developed with which it is possible to determine the positions of different ultrasonic probes in space without contact. Thus, the position of the measurement is linked to the measurement results directly. Infrared LED markers attached to the ultrasonic probes are used for this purpose. The position of the markers are tracked in space with a camera. By linking several cameras and trackers, a positional accuracy of a few millimeters can be achieved for a camera specimen distance of 2 m. The more cameras are used the bigger the investigated part can be. For the tracking system, an existing optical camera system is coupled with a conventional of the shelve ultrasonic phased array device by means of a newly developed universal encoder. Different single transducer probes or phased array probes can be used. The costly and time consuming use of mechanical encoders is thus eliminated. This combination enables the further digitalization of hand-guided ultrasonic testing precisely in those areas where robot-based testing is not feasible. Additionally, a much easier way of documentation is possible. Due to the exact position determination a better evaluation of the measurement data can be carried out via a subsequent 3D display of the ultrasound data.