Instantaneous velocity displacement and contour measurement by use of shadow moiré and temporal wavelet analysis
A temporal wavelet analysis method is proposed for velocity, displacement, and three-dimensional surface-profile measurement of a continuously deforming object by use of the shadow moire´ technique. A grating is placed close to a deformin...
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| Main Authors: | , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
2010
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| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/92039 http://hdl.handle.net/10220/6472 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | A temporal wavelet analysis method is proposed for velocity, displacement, and three-dimensional
surface-profile measurement of a continuously deforming object by use of the shadow moire´ technique.
A grating is placed close to a deforming object, and its shadow is observed through the grating. The
moire´ fringe patterns, generated by the interference of the grating lines and their shadows, are captured
by a high-speed CCD camera with a telecentric gauging lens. Instantaneous frequency of gray-value
variation is evaluated point by point with the continuous wavelet transform. From the instantaneous
frequency of each point on the object, the velocity, displacement, and high-quality surface profile at
different instants can be retrieved. In this application, two specimens are tested to demonstrate the
validity of the proposed method: One is a small coin with a rigid body motion, and the other is a simply
supported beam subjected to a central point load. The results are compared with those obtained from
temporal Fourier-transform and mechanical stylus methods. |
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