Papers by Author: T. Kihara

Abstract: The stress analysis for a model with initial stresses, which we term a residual stress model, is performed by digital photoelasticity. The stresses applied on the residual stress model are obtained by analyzing both the initial stresses and the resultant stresses. The method used for analyzing the stresses applies the principle of superposition of the stress to photoelasticity, which is a well-known technique in the field of elasticity. In the digital photoelasticity technique used, the principal stress direction and the relative phase retardation  are analyzed by photoelastic techniques using linearly polarized light. This technique overcomes the phase difference error associated with a quarter-wave plate by employing incident light at three different wavelengths, and using an unwrapping technique that allows and  to be determined using the arctangent function. A residual stress model produced by a disk containing frozen stresses that was subjected to a diametral compressive load at an angle of 31 was used to experimentally test this method. The values of the stresses of the loaded disk model analyzed were in good agreement with corre- sponding theoretical values at all locations far from the loading points of the residual stress model.

Abstract: Formulations of the theory of automated photoelasticity are expressed simply by use of the Stokes parameters. In the automated photoelasticity, the measurement of the total relative phase retardation must often be performed over a wide wavelength range. The Stokes parameters (S0, S1, S2 and S3) need to be measured over a wide wavelength range. The Stokes parameters of monochromatic light can be measured by the adjustable azimuth settings of a retarder and analyzer (ARA) method. When undertaking the measurement of the Stokes parameters of light of an arbitrary wavelength over a wide wavelength range, the measurement of S3 by the conventional ARA method is dependent on the phase difference error
ρ i of a quarter-wave plate mismatch as well as Stokes parameter S2. The measurement of S3 by a judicious choice of azimuth settings of a quarter-wave plate and a polarizer (JCAQP) as in the method proposed can be obtained by considering
ρ I . The JCAQP method is clarified by employing the Poincaré sphere. It is shown that application of the JCAQP method yields the principal axis and the relative phase retardation of the birefringent plate free from the
ρ i of the quarter-wave plate for incident elliptically polarized light of an arbitrary wavelength.