New Materials for Next-Generation Commercial Transports (1996) / Chapter Skim
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8 Nondestructive Evaluation
8 Nondestructive Evaluation
Pages 67-70
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From page 67... ...
Inspection issues continue to create problems for the airlines during maintenance of aging aircraft. The most critical issues inhibiting a successful maintenance program include inadequate inspection standards, lack of quantitative defect interpretation, and lack of definitive rejection criteria.
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From page 68... ...
However, this technique is still an emerging, technology and requires additional work to verify that the implications based on laboratory calibration standards are consistent with the effects of corrosion on actual aircraft structures. ACOUSTIC EMISSION Acoustic emissions are transient elastic waves emitted when there is a sudden change of stress in materials.
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From page 69... ...
The capability to distinguish the defect noise from other airframe noise continues to be a major issue that will require additional research. LASER NDE METHODS There are several types of laser NDE methods: acoustic holography, shearography, laser ultrasonics, optical holography, and acoustic microscopy.
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From page 70... ...
The measurement model must also consider characteristics of the energy interaction with the material, noise sources, energy losses due to material anisotropy, and any other variations caused by the entire system. Several NDE measurement models have been developed over the past several years, including models for ultrasonics, eddy current, and radiography (Thompson, 1992~.
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