|
|
||||||||
|
|
||||||||
Experimental Mechanics @
|
||||||||
|
|
||||||||
|
|
Abstracts on Photoelasticity |
|
||||||
|
|
|
|
|
|||||
|
|
|
|
|
|||||
SIMULTANOUS
OBSERVATIONS OF PHASE-STEPPED IMAGES FOR AUTOMATED PHOTOELASTICITY
E A Patterson and Z F Wang Journal of Strain Analysis (1998) Vol 33, No 1, pp. 1-15 Abstract: A novel instrument is
described for the simultaneous observation and capture of four phase-stepped
photoelastic images. A theoretical description of the optics of the
instrument is presented for the first time. Three examples are given of the
use of the instrument in reflection photoelasticity to generate full-field
maps of isochromatic and isoclinic parameters. The results from these
experiments show close correlation to results from both theoretical analyses
and manual measurements. The instrument can be used in either reflection or
transmission mode and it is concluded that the new instrument significantly
enhances the potential for real-time studies using reflection
photoelasticity. |
||||||||
|
|
||||||||
THE APPLICATION OF EVOLUTIONARY AND MAXIMUM
ENTROPY ALGORITHMS TO PHOTOELASTIC SPECTRAL ANALYSIS
M. N. Pacey, X. Z.
Wang, S. J. Haake and E. A. Patterson Experimental Mechanics (1999) Vol
39, No. 4, pp 265 – 273 Abstract: Over the past 10
years, spectral analysis has been shown to have the potential to be a
reliable means of automating photoelasticity. However, the four methods of
analyzing the spectra that have previously been proposed are slow and, in
some cases, inaccurate. This paper describes three new methods for spectral
analysis based on the maximum entropy method, a genetic algorithm and a memetic algorithm. Thirty-five spectra for known fringe
orders were recorded and used in testing the four existing methods and the
three new ones. It was found that the new methods were all considerably
faster than the existing methods, although less accurate than the best
existing method. By combining the maximum entropy method with either the
genetic algorithm or the memetic algorithm, spectra
could be analyzed up to 30 times as fast as they could with any of the
existing methods and with comparable accuracy. |
||||||||
|
|
||||||||
A NOVEL INSTRUMENT FOR AUTOMATED PRINCIPAL STRAIN
SEPARATION IN REFLECTION PHOTOELASTICITY
Mark N. Pacey, Steve J.
Haake, and Eann A.
Patterson ASTM J. Non-destructive Testing & Evaluation,
2000, pp. 229-235 Abstract: A novel instrument is
presented capable of measuring the principal strains at a point on a
photoelastic coating. The oblique incidence method of principal strain
separation is employed. using three fringe order
measurements which are made by the automated method known as spectral
contents analysis. The oblique incidence measurements are made after rotation
of the polariscope about any two orthogonal axes. Three polariscopes are
built into the instrument as is a CCD camera to facilitate accurate
positioning of the instrument. The instrument was used to analyse
the principal strain distributions in a disk under diametrical compression. a plate with a central hole under tension. and a stepped plate in tension. The strains in the disk
and the plate with a hole were compared with theoretical results. and the strains in the stepped plate were compared with a
finite element analysis of the problem. The correlation between the
experimental and theoretical or numerical strains was better than 0.95 in
most cases. |
||||||||
|
|
||||||||
|
|
|
|||||||
|
|
|
|
|
|||||
|
|
|
|
||||||
|
|
|
|
||||||
|
|
|
|||||||
|
|
|
|||||||
|
|
|
|||||||
|
|
||||||||
