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Nondestructive Testing of Polymer Matrix Composites
Published in Manoj Kumar Buragohain, Composite Structures, 2017
The most common NDT methods in PMCs are ultrasonic testing and radiographic testing. These methods complement each other and are effective in the detection of a wide variety of defects. Acoustic emission (AE) testing and infrared thermography provide their own unique advantages and they are popular in many applications. Eddy current testing is based on the principle of electromagnetic induction; it is applicable to only conducting materials and its use is primarily limited to CFRPs. Shearography is an optical method that is routinely used in the rubber industry and has wide acceptance in the aerospace composites applications as well. Table 12.1 gives a summary of these methods.
laser shearography NDE of masonry and concrete structures
Published in Claudio Modena, F. da Porto, M.R. Valluzzi, Brick and Block Masonry, 2016
A.M. Amde, R. livingston, J.W. Newman
ABSTRACT: laser Shearography is a full field, non-contact, non-contaminating NDE method and offers near real time inspection of surface and subsurface anomalies in materials or structures by imaging submicroscopic deformation derivatives of a test part surface when an appropriate stress is applied. Shearography is capable of inspecting structures for defects such as impact damage, delamination, and micro cracks. Our research has shown that laser shearography has an outstanding ability to detect and measure near surface and surface breaking cracks in cementation systems.
A review of NDE techniques for hydrogels
Published in Nondestructive Testing and Evaluation, 2023
Sasidhar Potukuchi, Viswanath Chinthapenta, Gangadharan Raju
Shearography, also called speckle pattern shearing interferometry, is a full-field detection method that can estimate the mechanical deformation of a sample. It has the capability to inspect relatively large areas at a given time. As shown in Figure 11, this technique uses highly coherent laser light to illuminate a sample that scatters and reflects the light beam. This creates an interference pattern called a speckle which passes through a shearing device (example, Michelson interferometer) and splits the beam into two images. The polariser nullifies one of these images, and the camera captures the other one as a fringe pattern. This process is repeated twice to detect defects or flaws, once without loading the sample and once on loading the sample. The difference in the two fringe patterns highlights the defect.
The Nyquist criterion and its relevance in phase-stepping digital shearography: a quantitative study
Published in Journal of Modern Optics, 2022
Awatef Rashid Al Jabri, Kazi Monowar Abedin, S. M. Mujibur Rahman
Digital shearography has become a well-established tool for the measurement of strain on an extended object, and also in the non-destructive testing (NDT) of industrial objects [1–8]. In digital shearography, the object surface, which is optically rough, is illuminated by a laser, and the laser speckles generated by the rough surface, through the process of interference, are imaged through a modified Michelson interferometer system. One of the mirrors in the Michelson interferometer is tilted slightly to produce the necessary image shear. One form of digital shearography has become particularly useful, namely, phase-stepping digital shearography, where the phase map of the physical object deformation is directly generated by the shearographic system. This results in improved contrast, higher resolution, and higher sensitivity of detection in NDT and strain measurements [1,2].
Multi-directional shearography based on multiplexed Mach–Zehnder interference system
Published in Journal of Modern Optics, 2020
Shimin Zhong, Fangyuan Sun, Shuangle Wu, Fengqing Bao, Yonghong Wang
With the development of various technologies for use in aerospace, marine, and military industries, a series of new composite materials has also been developed. Internal defects, such as bubbles, impurities, layers, and debonding, are inevitably generated during production and utilization of materials. Such defects affect material performance and lead to accidents. The non-destructive testing of the internal defects of composite materials is necessary. Traditional non-destructive testing methods mainly include ultrasonic, X-ray, thermal detection, eddy current methods, and so on. At present, shearography has become a commonly used non-destructive testing method owing to its several advantages, including fast testing speed, full-field, non-contact, high precision, high sensitivity, and real-time measurement.