| Research Abstract |
The main purposes of this study are how to overcome difficulties in accurate and precise measurement of three parameters in the polarimetry technique eliminating the rotation of polarization axis along the path of incident light, and to establish a useful method for 2D and 3D photoelastic stress and strain analysis not only in symmetrical but in unsymmetrical stress fields. The results are summarized as follows ;
(1) Jone's Matrix Fourier Image Polarimetry Technique : Till the end of last fiscal year, the hardware system for the polarimetry technique has been established utilizing the grant-in-aid in 1998. Then, the technique for 2D fields is successfully applied to the accurate measurement and determination of retardation, azimuth and ellipticity angles both in thin and thick disks under diametrical compression. In order to determine the secondary principal stress field in a 3D sphere model, double beam incident technique is now developed. Although some further improvements are needed,
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the fundamental algorithms and techniques are completed.
(2) Scattered Light Photoelasticity Technique with Tricolor Laser : Another approach to 3D analysis with high expectation is the improvement of the scattered light technique using a tricolor laser for light source sloughing off the current technique with a monochromatic light. In this study, secondary principal stress difference and azimuth angle in a sphere under diametrical compression is successfully analyzed not only in symmetrical but unsymmetrical planes of stress distribution. Further improvement in accuracy of azimuth measurement is still exist, but the technique is proven to be very useful.
(3) Photoelastic and Photoviscoelastic Techniques with Elliptically Polarized White Light : In the current photo (visco) elastic technique, more than two different optical information have to be obtained. The fact means that it has been impossible to trace the time variation of stress field, particularly in cases of crack tip and/or contact regions under moving condition. The technique proposed enables simultaneous measurement both of isochromatics and isoclinics with a single exposure, using elliptically polarized white light. Several applications of the technique to the evaluation of crack tip stress field is successfully demonstrated. Less
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