共查询到18条相似文献,搜索用时 82 毫秒
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电子散斑剪切干涉术作为一种高精度全场测量技术,已被广泛应用于无损检测(NDT)、应变分析、振动检测和流场分析等领域.主要分析了电子散斑剪切干涉术在振动检测领域的应用,分析了它利用时间平均法检测振动的原理,并为实现物面振动的大面积检测进行了电子散斑剪切干涉仪光学结构的参数设计,一次可以检测大小为669 mm×502mm的矩形物面.利用计算机模拟产生随机高斯相关表面的高度分布函数及振动散斑剪切条纹图.结果表明电子散斑剪切干涉术用于振动检测. 相似文献
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散斑检测技术及其应用 总被引:4,自引:0,他引:4
李喜德 《理化检验(物理分册)》2004,40(5):245-251
综述了散斑计量中的主要检测技术。主题包括散斑照相技术、散斑干涉技术、电子散斑干涉技术、数字散斑相关技术和时间序列散斑检测技术。介绍了散斑计量在科学和工程研究中的一些重要应用。 相似文献
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玻璃幕墙是现代建筑的重要组成部分,检测其内部缺陷对建筑安全评估具有重要的意义。该文提出一种数字剪切散斑干涉玻璃幕墙缺陷无损检测方法,探索一种适用于玻璃幕墙检测的实验方法,通过对玻璃进行热加载,在温降阶段一定时间间隔前后利用四步相移法分别获取散斑相位图,接着提取温降前后相减的相位差图的相位差并计算全场形变的空间位移梯度,从而检测出玻璃幕墙的缺陷位置。实验结果表明,剪切散斑干涉技术能够检测出玻璃幕墙缺陷处形变的空间位移梯度及其缺陷位置,因此使用剪切散斑干涉技术对玻璃幕墙缺陷进行无损检测是一种有效的方法,对评估幕墙玻璃安全隐患具有重要意义。 相似文献
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本建立了一套相移激光数字散斑干涉自动测量系统,运用一系列的图象处理方法,实现了高精度的自动测量,显地提高了数字散斑干涉计量技术的可靠性、实用性及自动化程度。该计量系统被应用于变形、振动等参数的测量中,取得了较为理想的结果。 相似文献
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白光频闪散斑干涉术的研究 总被引:1,自引:1,他引:0
在利用白光对振动物体进行测量时,由于白光的相干性较差,难以得到质量较好的图像,为了克服这一缺点,本文提出了一种用白光光源照明进行振动测量的新方法-白光频闪散斑干涉术.阐述了白光频闪散斑干涉术的基本原理,分析了提高图象质量的主要原因,采用了相干性较好的白光光源和合理的光路,使系统的时间相干性和空间相干性得到提高,从而提高了图像的质量.实验结果表明,该方法用于振动的测量,能给出物体在任一瞬时的振动信息,得到清晰的、高对比度的全场干涉条纹图,图像的质量得到大大提高. 相似文献
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Characterisation of Thermal Expansion Coefficient of Anisotropic Materials by Electronic Speckle Pattern Interferometry 总被引:2,自引:0,他引:2
Abstract: Carbon fibre composites find wide applications in aerospace, sporting goods industry and biomedicine. Mechanical and thermal properties of such materials are highly anisotropic; therefore, adequate experimental measuring methods are requested to determine them. This paper describes the application of electronic speckle pattern interferometry to full-field, real-time characterisation of the coefficient of thermal expansion (CTE) of anisotropic materials. The topics such as correlation fringes tilt and influence of small rigid body rotation were theoretically described and experimentally verified. A series of measurements was carried out to determine the CTE tensor for unidirectional and bi-directional carbon fibre laminates and to prove the feasibility of the method. The measuring set-up developed includes a temperature control unit for cooling and heating and a one-dimensional in-plane speckle interferometer. 相似文献
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Abstract: This paper deals with the application of a speckle interferometer, which works on the new operating principle of double‐focusing presented by the authors in recent studies, to the field of non‐destructive testing (NDT). Using this interferometer, the components of displacement given by holographic interferometry can be measured, but with no need for an external reference beam. The implementation of this interferometry can be indifferently carried out by adopting a Michelson or a Mach–Zender configuration. In the paper a double‐focus interferometer based on the Michelson design and sensitive to out‐of‐plane displacements was implemented and applied to a metallic specimen which simulates the deformations of a typical debonding. 相似文献
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Pavel Fomitchov Liu-Sheng Wang Sridhar Krishnaswamy 《Journal of Nondestructive Evaluation》1997,16(4):215-227
In conventional optical nondestructive evaluation (NDE) of structures using shearography or electronic speckle pattern interferometry (ESPI), results are typically provided in the form of fringe patterns or deformation contour plots. However, in order to fully automate the process of defect detection, it is desirable to obtain simpler results which are easier to interpret. We present here one such optical system based on additive–subtractive shearography/ESPI. This system processes additive–subtractive fringe patterns and provides the sizes and locations of defects such as disbonds in adhesively-bonded composite structures. This is achieved by exciting the structure under inspection using an acoustic stressing mechanism which sweeps a range of vibration frequencies of the structure. Since the defective areas of the structure have different mechanical properties from their neighboring regions, varying and complex fringe patterns are obtained at different stressing frequencies. We propose an algorithm which enables the automatic identification and selection of relevant additive–subtractive fringe patterns that pertain only to localized deformations associated with defects, and which excludes images that pertain to any overall modes of the entire structure. The algorithm also includes a pixel-by-pixel adjustable thresholding scheme which compensates for intensity variations due to nonuniform reflectivity from unpainted and dirty test objects. Morphological processing is then performed to extract the shapes of the defect from the processed fringe clusters. Various structures, from simple aluminum specimens with simulated defects to a complex honeycomb-based aviation repair patch specimen, have been successfully evaluated using this system. 相似文献
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M. J. Pechersky 《Strain》2002,38(4):141-149
ABSTRACT: A new technique for the measurement of residual stresses is presented. The technique is based on strain measurements following thermal stress relaxation. The heat input is supplied by a low power infrared laser and the strain is measured with speckle pattern correlation interferometry. This paper presents a comprehensive overview of the technique and an example of how it has been applied in a practical situation. 相似文献
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Abstract: In this paper, the displacement field induced by the split‐sleeve cold expansion of holes was measured using both digital image correlation (DIC) and digital speckle pattern interferometry (DSPI) techniques. Thus, the experimental results, which were evaluated on the inlet surface of a 6082‐T6 aluminium plate, were compared with those from theoretical prediction. DIC provided accurate measurements up to the elastic–plastic boundary, whereas the DSPI technique highlighted the changes of displacement in the elastic domain. Prediction of the displacement based on the existing analytical model agreed with the experimental results achieved with both techniques. Possible explanations for the differences are discussed. 相似文献
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流场光学诊断的光偏振相移数字剪切散斑干涉 总被引:2,自引:0,他引:2
本文提出了应用于流场光学诊断的使用光偏振相移的数字剪切散斑干涉技术,它具有如下两个显著的优点,首先,产生干涉效应的两相干光束均是物光束。它们通过几乎相同的光学元件与几何空间。这样可以降低测量过程中对环境的防震需求,便于工程中的实际应用。其二,采用光偏振相移方法来获取了干涉图上的位相信息,与通常使用的压电陶瓷相移方法相比,不需要复杂的标定,使用更为方便。 相似文献
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Abstract: Several tensile specimens with a central hole were subjected to a cyclic loading for which the Von Mises stress was beyond the initial yield stress in the vicinity of the hole. The tensile machine was fixed together with a phase‐shifting electronic speckle‐pattern interferometry measurement bench that makes it possible to perform strain measurement along the tensile axis. The plastic strain map corresponding to the 30th cycle was obtained. For the considered measurement field, the resolution of the strain measurement is close to 10?5. By varying the loading, it was possible to detect and observe the deformation corresponding to an early stage of the ratcheting phenomenon. The non‐ratcheting cyclic plasticity behaviour was not observed during the 30th cycle. In the Discussion section, the experimental results were interpreted using Melans’s theorem, which allowed us to determine an upper bound for the yield stress. Eventually, it is shown that the procedure followed in this work could be a way to obtain some interesting data related to the material behaviour laws. 相似文献