Pulse compression based phased array ultrasonic inspection: Optimization of the system and the code selection (original) (raw)

Large steel forgings are used in numerous industries. This paper investigates the possibility of adapting ultrasonic phased array testing to the inspection of forged steel blocks with dimensions of up to 1000 mm in every direction. The paper looks at two objectives in order to provide the best inspection performance: (1) the ultrasonic phased array probe optimisation and (2) the ultrasonic wave transmission sequence in a total focusing method imaging scenario. The CIVA software suite was used to optimise the phased array probe element count and width in a full matrix capture configuration. Based on the simulation results, a 32-element transducer was then built and tested in a 777 mm forged steel block using full matrix capture, plane wave and Hadamard transmission sequences. It was observed that plane wave and Hadamard sequences transmit significantly more energy inside the test sample because the elements are emitting simultaneously, therefore leading to an improved signal-to-noise...

In this paper, we present challenges and achievements in development and use of a compact ultrasonic Phased Array (PA) module with signal processing and imaging technology for autonomous non-destructive evaluation of composite aerospace structures. We analyse two different sets of ultrasonic scan data, acquired from 5 MHz and 10 MHz PA transducers. Although higher frequency transducers promise higher axial (depth) resolution in PA imaging, we face several signal processing challenges to detect defects in composite specimens at 10 MHz. One of the challenges is the presence of multiple echoes at the boundary of the composite layers called structural noise. Here, we propose a wavelet transform-based algorithm that is able to detect and characterize defects (depth, size, and shape in 3D plots). This algorithm uses a smart thresholding technique based on the extracted statistical mean and standard deviation of the structural noise. Finally, we use the proposed algorithm to detect and cha...

Most frequently applied ultrasonic inspection techniques measure the reflectivity of geometric scatterers that are caused by impurities, flaws and defects in the material. Based on the echo sounder principles, the reflector has to be insonified by directed sound pulses. This requires a large number of transducers with different incident angles and sound field patterns, which are more and more replaced by phased array sensors. Phased array inspection systems can control the insonification direction and the focus of the applied sound field, but they do not alter the principles of multi-angle and multifocus inspection; the resulting scanning speed limitation is obvious. In addition, flaw imaging only displays the position and amplitude height of the reflection and does not provide an image of the actual shape of the reflector. Thus, the evaluation of state-ofthe-art ultrasonic imaging is based on the extension and maximum amplitude of the identified reflector applied to specified refer...

Novel ultrasonic phased arrays were developed and the feasibility was tested for the condition assessment of concrete structures. These sensors are based on low frequency ultrasound technology, which is the preferred method for concrete testing to date. By combining multiple transducer elements in a linear configuration, dynamic phase fo-cusing and/or steering of the ultrasound beam is possible. Using electronic scanning instead of mechanical scanning, these sensors eliminate the labor intensive physical relocation of a single element transducer. They realize high-resolution nondestruc-tive evaluation (NDE) of concrete by enabling real-time two-dimensional imaging of the internal flaws and damage of concrete structures, a key improvement to current ultrasonic instruments utilized in Civil Infrastructure Systems (CIS). A systematic approach using an automated testing assembly was used to assess the steering and focusing performance of the array in a cementitious medium. Exper-imental...