- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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An automated shearography system for cylindrical surface inspection
摘要： A shearography system has been developed to inspect the external heat proof coating bonded to a cylinder. The system consists of a shearography device integrated with thermal excitation, a mechanical translation and rotation device, and a central control unit. The translation and the rotation are driven with 2 servo motors. The combination of these two movements enables full inspection of the entire surface of the cylinder. The inspection sequence is automatically scheduled by inputting the geometry of the sample. Artificial intelligence (AI) has been first introduced to aid defect recognition from the resulted phase shifting fringe patterns. A recognition algorithm based on deep learning has been developed using Faster R-CNN model for recognition of bonding defects. By training the system using typical butterfly fringe patterns which are captured from bonding samples, the system can accurately identify the bonding defects on the cylindrical surface at a high success rate.
关键词： Defect recognition,Automatic inspection,Shearography,NDT
更新于2025-09-23 15:23:52
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The application of SLM in shearography detecting system
摘要： The paper presents a new shearography system which applies a spatial light modulator (SLM). The system can control the shearing amount and direction as well as introduce the phase shift accurately and automatically, making shearographic testing easier and more practical. Shearography has the known advantages for nondestructive test and strain measurements of being fast, full-field, and having high sensitivity. Traditionally, the shearing amount is controlled by adjusting a reflector mechanically. Mechanical adjustment of the reflector is slow, inconvenient and not well suited for in-field NDT practice. For application of phase shift techniques, a piezoelectric transducer (PZT), which is usually used for application of phase shift techniques, introduces random error due to its tendency to be nonlinear. This paper introduces a new shearographic detection system with a spatial light modulator. The spatial light modulator controls the liquid crystal by using a birefringence effect and twisted nematic effect. The spatial light modulator can change the phase of the light and shearing amount accurately and automatically, thus eliminating the nonlinear random error in the phase shift method. Furthermore, this system also improves testing efficiency. In this paper, the fundamental of SLM shearography is presented. The capability of this optical configuration is demonstrated theoretically as well as through experiments.
关键词： Nondestructive detecting,Spatial light modulator,Shearography,Phase series
更新于2025-09-23 15:22:29
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Shearography for non-destructive testing of specular reflecting objects using scattered light illumination
摘要： Shearography has been widely used in non-destructive testing due to its advantages of fast, full-field, and high sensitivity for nondestructive test and strain measurement. Shearography has been applied successfully to various industry applications. However, traditional shearography requires the surface under test to be sufficiently rough. This study presents a modified shearography setup that can be applied to workpieces with specular surface which is illuminated by light scattered from a rough plane to generate speckle patten. In the optical setup, the specular surface is conjugated to the phase map to simplify the positional correspondence between the interferogram and the internal defects. The sensitivity factor is analyzed through ray tracing method based on geometric optics which is influenced by the surface normal. The experimental results are described and presented as well.
关键词： Non-destructive testing,Shearography,Specular surface
更新于2025-09-23 15:19:57
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[IEEE 2018 International Joint Conference on Neural Networks (IJCNN) - Rio de Janeiro (2018.7.8-2018.7.13)] 2018 International Joint Conference on Neural Networks (IJCNN) - Defect classification in shearography images using convolutional neural networks
摘要： High subjectivity, lack of attention and fatigue are factors inherent to human analysis in inspection activities such as shearography, a non-destructive optical method. In order to minimize the probability of human error, a study was conducted in which a binary classification from 256 shearography test samples obtained from pipes repaired with glass fiber patches was performed. The dataset was split into major and minor defects and used to train two convolutional neural networks architectures, - a specific artificial neural network well known for its application on image classification. Architecture A achieved a maximum accuracy of 73% on major defect detection, while architecture B, slightly more complex, led to better results. Posterior studies on architecture B led to the conclusion that a combination of double layer filters and dropout layers are the best setup for this type of classification problem. It is possible that other architectures might lead to better results, but no grid search was performed to confirm this assumption. An accuracy of 79% was achieved with Architecture B, therefore is reasonable to say that convolutional neural networks are able to learn from parameters which are difficult to correctly process, such as the fringe patterns obtained from shearography test samples.
关键词： non-destructive testing,convolutional neural networks,composite material,shearography,binary classification
更新于2025-09-19 17:15:36
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Double Imaging Mach–Zehnder Spatial Carrier Digital Shearography
摘要： This paper presents a Double Imaging Mach–Zehnder Spatial Carrier Digital Shearography (DIM-SCDS) system. Compared to traditional Spatial Carrier Mach–Zehnder shearography, DIM-SCDS has two advantages: one is that it can adjust shearing amount and spatial carrier frequency independently; the other one is that it can measure a larger area with a shorter working distance. Two pairs of imaging lenses and apertures are placed in the two arms of Mach–Zehnder interferometry, respectively. Shearing amount is adjusted by the mirrors in the two arms, and spatial carrier frequency is determined by the angle between the two apertures when they are mapped to the same optical axis. Shearograms of the object under test are recorded using a CCD. Shearogram phases are calculated as the measurement results. Finally, the performance of DIM-SCDS is proved by experiments.
关键词： Mach–Zehnder interferometer,spatial carrier,dynamic measurement,Digital shearography
更新于2025-09-09 09:28:46