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Typical Applications of Single-Manipulator NDT Technique
Published in Chunguang Xu, Robotic Nondestructive Testing Technology, 2022
The ultrasonic thickness measurement system based on the principle of the pulse reflection method needs to accurately measure the sound interval difference between two echoes of the ultrasonic wave propagating in the material, in order to calculate the specimen thickness [2]. The calculation method most commonly used in this system is to take the maximum value of surface/bottom echo signals as an eigenvalue and analyze and calculate the sound interval difference between the two echoes by using the eigenvalue. However, waveform is seriously limited in this method. The complexity of detection process will lead to the position deviation of the maximum or minimum value of ultrasonic echo signals, so the eigenvalue of ultrasonic echo signals can’t be accurately extracted and the workpiece thickness can’t be accurately measured. Therefore, this method cannot be widely used in the automatic online thickness measurement system where the waveform distortion is easily found [3]. However, the following two methods can effectively solve the above problem.
Full thickness material tests for impact analysis verification
Published in C. Guedes Soares, Y. Garbatov, Progress in the Analysis and Design of Marine Structures, 2017
To measure the acceleration of the punch, two 200 g accelerometers are attached to the impactor. The drop distance is measured using a wire. The thickness of the steel plate has been gauged by ultrasonic thickness measurement. The specimens have a speckle pattern applied on both sides. The final 3-D deformation of the specimen relative to the initial configuration is measured using Digital Image Correlation (DIC) in 3D with an accuracy of 100 μm/m. Results are used to determine the major and minor strains of the test specimen. This technique was used to compare the pre- and post-impact pictures of the specimen. Dots are applied on the top and bottom surfaces of the specimen and pictures are taken before and after the testing. With special data processing software, the strains in major and minor directions are determined.
Inspection Methods
Published in Mohamed Abdallah El-Reedy, Assessment, Evaluation, and Repair of Concrete, Steel, and Offshore Structures, 2018
UT is a very short ultrasonic pulse-wave with center frequencies ranging from 0.1 to 15 MHz and occasionally up to 50 MHz penetrating into materials to detect internal flaws or to characterize materials. A common example is ultrasonic thickness measurement for measuring the webs and flanges thickness for the existing steel structure.
A novel permeability perturbation testing method for delaminations in steel plates
Published in Nondestructive Testing and Evaluation, 2022
Gongzhe Qiu, Yihua Kang, Shenghan Wang, Si Cheng, Bo Feng
Delaminations can seriously influence the mechanical properties of steel plates, shorten their service life and even result in production accidents [1]. It is one of the most dangerous defects in steel plates. Thermal imaging method [2], acoustic emission method [3–5], eddy current method [6–9] and ultrasonic method [10–13] are often used for the detection of delaminations of carbon fibre-reinforced polymer. The ultrasonic method is also widely used in delaminations detection of metal plate, which mainly include Lamb wave method [14–17] and ultrasonic thickness measurement method [18]. Lamb wave has multi-modality and disperse properties, and its interaction mechanism with defects is very complicated. Interpreting the received signals quickly is a huge challenge in the application of Lamb wave method. Ultrasonic thickness measurement method is sensitive to delaminations, but there are blind zones in the near surface of the tested material due to the interference of initial wave and interface wave. As a consequence, it is difficult to find defects such as outer folding and double skin by ultrasonic thickness measurement method. In addition, the repetition frequency of acoustic excitation limits the detection speed.
Implementation and evaluation of an autonomous airborne ultrasound inspection system
Published in Nondestructive Testing and Evaluation, 2022
Dayi Zhang, Robert Watson, Charles MacLeod, Gordon Dobie, Walter Galbraith, Gareth Pierce
Ultrasonic thickness measurement is attained by deploying a 5 MHz, 10 mm diameter, split-crystal transducer, accompanied with customised ultrasonic transceiver circuitry. The transducer is manufactured by GB Inspection with plastic housing that reduces its mass to 17 g [22]. Like most hard-face transducers, it requires appropriate angular alignment and utilises acoustic couplant gel, placed between the asset and transducer surfaces, to eliminate any air gap and propagate acoustic energy.