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云纹/光栅测试技术的几点讨论 总被引:2,自引:0,他引:2
本文用信号处理的方法系统地阐述了云纹/光栅测试技术。以面内云纹/光栅测试为例,首先说明了光栅是位移和变形信息的空间载体;位移和应变分别是对载体的相位和频率调制;而云纹现象则是试件栅频谱向零频处平移的结果或说云纹是对光栅载体信号解调的过程;进而讨论了云纹技术与光栅技术的本质区别。其次分析了云纹/光栅测试系统的性能,讨论了条纹分析方法及数字图象处理手段对云纹/光栅系统的测试精度、灵敏度、空间分辨率的影响。 相似文献
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云纹法是一种新的位移场或应变场测试技术,本文采用云纹法论述的遥测自动云纹引伸仪系统包括云纹引伸仪、位移信息转换和传输装置以及显示接收监测台。由于采用了轮形光栅从而使引伸仪突破了传统的测量限制,从理论上讲,量程可达无穷大。 相似文献
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高灵敏度,高温全息云纹光栅及其应用 总被引:3,自引:0,他引:3
本文简要介绍了高灵敏度,高温全息云纹光栅技术,主要包括旋转点光源激光全息干涉制栅系统,折射率介质超高频光栅制作技术,双镀层抗高温氧化制栅技术,耐高温光刻胶模板及转移技术,现场变形栅转移技术。在此基础上还给出了高灵敏度,高温全息云纹光栅的几个典型应用实例 相似文献
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文中就云纹干涉法,电子束云纹法,原子力云纹法,扫描电镜云纹法,聚焦离子束云纹测量微区变形的原理和适用性进行了讨论.应用1200线/毫米的云纹光栅并结合云纹干涉法,电子束云纹法,原子力云纹法,扫描电镜云纹法测量QFP和BGA型电子封装组件的热变形.提出一种新型聚焦离子束云纹法,在MEMS结构上制栅形成FIB扫描云纹,成功的实验结果表明这种方法的可行性. 相似文献
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为了提高云纹法的准确度,文中提出了使倍增后的云纹宽度变细并进行显微测量的技术,以及由密集云纹场测算应变的条纹间距插值和小间距均匀法。给出了估计由此法算得的应变的误差及其修正方法。所做的曲杆实验其数据与理论值符合得很好。文中还将云纹法中闪耀光栅与振幅栅相匹配的光学空间滤波系统改进为实时系统,导出其条纹倍增率及云纹图的最佳对比度条件。 相似文献
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硅橡胶光栅在高温力学性能测试中的作用 总被引:1,自引:0,他引:1
在光栅制作中,硅橡胶是一种很好的光栅传递材料,而且普通的硅橡胶又具有耐高温性。我们利用硅橡胶的这些特性,通过大量的实验工作,制作了耐热试件光栅,用于材料高温力学性能测试,解决了350℃以下制作耐高温光栅的困难。本文详细地介绍了硅橡胶光栅复制技术,在铝基碳化硅材料的高温力学性能测试中得到了很好地应用。硅橡胶试件光栅的应用,对推广云纹干涉法,特别是高温云纹测试技术都具有重要意义。 相似文献
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应用相位移法的二维光栅测量 总被引:4,自引:0,他引:4
本文介绍了二种二维位移测量的光栅方法。测试系统采用CCD摄象系统记录正交光栅图象,通过调整摄象机变焦镜头的放大倍数来控制采样的空间频率。采样后用数字信号处理的方法,通过软件手段实现水平向和垂直向光栅信号的分离,然后运用了相位移技术及载波—相位移技术得到二维位移。所开发的测试系统除具有高精度、高灵敏度的特点外,还具有较高的空间分辨率。 相似文献
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基于锁相循环投影的物体形貌检测 总被引:2,自引:1,他引:1
本文提出将相位锁定循环技术应用于栅线投影方法,将规则栅线投影到物体表面得到变形栅线,用相位锁定循环法解调含有物体表面高度信息的位相。用该法不需传统的相位去包裹,即可完成对二维栅线图扫描,从而确定其相位。通过对典型试件的检测,得到了比较满意的结果。 相似文献
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薄壁柱壳的圆度及三维变形测量技术 总被引:2,自引:0,他引:2
本文采用一种新的形状位置(Profilimetry)自动测量计算机处理方法,对钢质圆柱壳的椭圆度进行了测试。具体使用投影光栅,于壳体表现形成栅线影象,自动形成栅线光频率线性编码,用CCD摄象机采集到频率编码壳体光栅影象,构成形西半球工波图。将载波的图象经过计算机图象系统获得数值图象。计算机经过快速富立叶变换法解码,输出频率位相值,经数据处理可得到精确的壳面尺度。 相似文献
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Calculation of strain from an object grating on a reseau film 总被引:1,自引:0,他引:1
A correlation technique for the automatic calculation of grating coordinates in digital images is presented yielding displacements and strain on plane surfaces with an accuracy of 100 to 300 microstrain. It is shown that a large grating area can be investigated when the object grating is filmed by a reseau camera. Each segment of the negative can be digitized with a high-resolution CCD-camera resulting in a global resolution of about 6000*6000 pixels in the whole image. To improve the accuracy of the grating coordinates and to avoid segmentation errors at the overlapping edges, the distortion of the CCD-camera and of the digitizing setup is corrected by a two-dimensional polynomial function. This is derived from the distortion of a digitized image of a high-precision reference grating. The strain calculation considers large deformations as well as rigid-body rotation. 相似文献
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Andrew K. Mitchell 《Experimental Mechanics》2005,45(3):250-258
This paper describes a non-contacting optical technique for vibration measurement, which can be used to determine the magnitude
and phase of every point of a continuous surface under steady-state conditions. In this method, the vibrating surface to be
studied is illuminated by a white-light, sinusoidal grating projected from an oblique angle. A series of precisely timed digital
images of the vibrating object is recorded as the grid is moved across the surface. An automated analysis then extracts magnitude
and phase data at each pixel in the recorded images. The use of white light makes it possible to study the motion of larger
surfaces than might be conveniently possible with more conventional Moiré or holographic techniques, and the optical arrangement
used seems relatively insensitive to external disturbances. The method seems particularly well suited to the study of structures
undergoing relatively low-frequency, large-amplitude vibrations. 相似文献
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This paper investigates an advanced grating-transferring technique combined with geometric phase analysis (GPA) for residual strain evaluation of curved surface. A standard holographic grating is first transferred to a pre-produced epoxy resin film and then consolidated to a test region of curved surface. With a rubber mold and silicone rubber the deformed grating is replicated to a sheet metal after hole-drilling for release of residual stress. After that the grating is transferred from the sheet metal to the glass plate, which would be served as an analyzer grating (specimen grating). By GPA the local strain distributions related to the phase difference between the reference grating and analyzer grating for the released stress can be evaluated. A validation test has been conducted on the weld joint of a stainless steel tube and the obtained results demonstrate the ability of the method in measuring the residual strain of curved surface. 相似文献
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Projection moiré is frequently used to examine the out-of-plane displacement of thin-walled shells during buckling. One way
of implementing this technique is to use double exposure photography to superimpose the initial and deformed images of a grating
projected onto the surface of the specimen. This generates a pattern of fringes representative of points of equal displacement,
thus presenting a snapshot of the full-field buckling behavior.
This paper outlines a technique to extend this method to provide a computer generated real-time fringe pattern throughout
the whole buckling and post-buckling process. This is achieved by using a CCD camera and specially developed processing software
to continuously superimpose the initial image of the grating (i.e., the first frame of the captured video) onto subsequent
frames in which this grating is deformed due to the displacement. This method produces series of fringes in digital format,
which are ideal for further processing. 相似文献
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本文应用数字图象处理技术,对光栅应变法图象进行处理,提出了一种简捷的重心算法,使整个图象处理过程快速简单,自动化程度高,并能保证测量精度,使光栅应变法便于实际测试应用。 相似文献
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Measuring accurate displacement distributions for large-scale structures is an important issue and a very challenging task.
Recently, a simple and accurate phase measurement technique called sampling moiré method [Exp Mech 50–4:501–508, (2010)] has been developed for small-displacement distribution measurements. In this method, the phase distribution of moiré fringes
can be analyzed from a single grating image by simultaneously performing down-sampling image processing and intensity-interpolation
to generate multiple phase-shifted moiré fringe images. In addition, the phase of the original grating can also be obtained
from the phase of the moiré fringe by adding the phase of the sampling grating. In this study, the measurement accuracy of
the sampling moiré method was analyzed through computer simulations and a displacement measurement experiment. Four factors
of the sampling moiré method were investigated, including the sampling pitch, the order of the intensity-interpolation, random
noise, and the form of grating. The results show that determining the optimal sampling pitch is an important factor for obtaining
better results but it is not critical. In addition, a practical application of the sampling moiré method is presented that
involves a deflection measurement on a 10-meter-long crane. The experimental results demonstrate that submillimeter deflections
of the crane can be successfully detected. 相似文献