ESPY measurements of submerged composite plate vibrations
An Electronic Speckle pattern interferometer (ESPI) was constructed which performs full-field surface displacement measurements. This measurement technique when combined with a single-point measurement known as laser vibrometry, can completely determine the vibrational characteristics of complex structures. This information can, in turn, be used for nondestructive testing as well as for modal analysis. One NDT&E technique is to vibrationally excite the object and evaluate the time averaged interferograms from the ESPI and the vibration spectra from the vibrometer. Anomalies in the interferograms can be related to subsurface defects such as defective weld joints, internal cracks, voids, etc. All of this can be accomplished in a noncontacting and nonintrusive manor. In many instances, a finite element analysis in concert with this approach can be useful in interpreting the results. Since ESPI is analogous to optical holography, other methods equivalent to real-time and double-pulse holography may also be easily applied. As in holography, EXSPI is sensitive to out-of-plane surface displacements. Other optical arrangements can be implemented with the same equipment to give in-plane displacements which would give results similar to Moire interferometry without the need to apply gratings to the object under test. The advantage of this method over holographic interferometry is that the feedback from the measurements is for all practical purposes instantaneous. This has important positive ramifications with regard to the ease of performing measurements, relaxed stability requirements, and reliability.
- Research Organization:
- Westinghouse Savannah River Co., Aiken, SC (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC09-89SR18035
- OSTI ID:
- 10136244
- Report Number(s):
- WSRC-MS-90-303; CONF-9011174-5; ON: DE92010997
- Resource Relation:
- Conference: 32. meeting of the Weapons Agencies Nondestructive Testing Organization (WANTO),Aiken, SC (United States),27-29 Nov 1990; Other Information: PBD: [1990]
- Country of Publication:
- United States
- Language:
- English
Similar Records
Non-destructive evaluation of impact damage on carbon fiber laminates: Comparison between ESPI and Shearography
Image Correlation Applied to Single Crystal Plasticity Experiments and Comparison to Strain Gage Data