Application of Image Processing and Computer Cluster in the Development of Full-Field Measurement for Electronic Speckle Pattern Interferometry and Digital Image Correlation
Date Issued
2012
Date
2012
Author(s)
Chang, Ching-Yuan
Abstract
This dissertation applies parallel computation technique into experimental mechanics, and mainly contributes to a) enhancing the signal-to-noise ratio of experimental signal and image, and b) improving computational speed of the denoising algorithms. This study measures an object deformation or profile using three non-contact inspection methods: electronic speckle pattern interferometry (ESPI), digital image correlation (DIC), and lens inspection system. The three methods are full-field measurement and use high-resolution image to record interference fringe, characteristic region, or intensity pattern. An embedded program controls frequency step and loading steps, and a digital camera takes sequential images at each controlled condition, storing the experimental data into a solid disk drive. Analytical programs load thousands of image and billions of pixels, and take several hours to retrieve a denoising result with excellent quality. Computer cluster of central processing unit (CPU) and graphic processing unit (GPU) are used in the computation, and we discuss the performance of denoising algorithm based on CPU and GPU architectures. This article also proposes a vectorizing process which converts for and while loops to equivalent matrix operations, and presents the speedup for different cases. The vectorizing method provides significant gain in analyzing experimental data, in which the displacement filed and strain distribution obtained using DIC method gauge a deformed object on sub-micron scale, while provides high accurate result. The frequency-sweeping curve obtained using ESPI not only indicates the resonate frequency of a vibrating piezoelectric thin plate, but also provides mode shape while approaching and leaving eigenmode, and gives a consistent result compared with those obtained using finite element method, impedance analyzer, and laser Doppler vibrometery.
Subjects
electronic speckle pattern interferometry
digital image correlation
vectorization
piezoelectric plate
resonant frequency
resonant vibration
mode shape
non-contact inspection
parallel computing
Type
thesis
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