Abstract/Details

The development of photo-stimulated luminescence spectroscopy for three-dimensional stress measurements

Raghavan, Seetha.  Purdue University. ProQuest Dissertations Publishing, 2007. 3334068.

Abstract (summary)

The development of photo-stimulated luminescence spectroscopy (PSLS) for stress measurement in chromium-doped alumina has been motivated by the need for a nondestructive technique to establish the integrity of the thermally grown oxide (TGO) layer on turbine blades of jet engines. Applications of PSLS have been based on the R-line peak positions and their stress dependence has been fully exploited for planar measurements. However, factors associated with the oxide layer, such as its undulated nature and growth stresses, emphasize the need to measure other stress components unavailable with the planar model in use today. Our new findings on the piezospectroscopic nature of vibronic bands in the optical spectrum of chromium-doped alumina pave the way for a 3-D model of stress measurement never before established. The focus of this research is on developing the PSLS technique to measure 3-D stresses in chromium-doped alumina by studying the behavior of these less explored parameters and the experimental factors that affect their measurement. The development of a spectral analysis methodology based on genetic algorithms for optimization of the curve fitting was instrumental in detecting and monitoring the shifts of the peaks within the vibronic bands with stress. The stress measurement model was applied to polycrystalline alumina and thermal barrier coating specimens and data for future validation was obtained using synchrotron x-ray diffraction. This work leads to an improved stress-prediction method in non-destructive testing of the TGO and eventual life prediction of the thermal barrier coatings of aircraft engine turbine blades.

Indexing (details)


Subject
Aerospace engineering
Classification
0538: Aerospace engineering
Identifier / keyword
Applied sciences; Piezospectroscopy; Synchrotron radiation; Thermal barrier coatings; Vibronic bands
Title
The development of photo-stimulated luminescence spectroscopy for three-dimensional stress measurements
Author
Raghavan, Seetha
Number of pages
118
Degree date
2007
School code
0183
Source
DAI-B 69/10, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
978-0-549-85749-5
Advisor
Imbrie, P.K.
Committee member
Crossley, William A.; Farris, Thomas N.; Sun, Chin-Teh
University/institution
Purdue University
Department
Aeronautics and Astronautics
University location
United States -- Indiana
Degree
Ph.D.
Source type
Dissertation or Thesis
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3334068
ProQuest document ID
304840345
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
https://www.proquest.com/docview/304840345