The theories of Drucker-Mindlin and Mindlin-Goodman point out that the ratio R plays an important role in 3D photoelasticity. R is a ratio whose numerator is the rate of rotation of the secondary principal axes and whose denominator is the rate of relative phase retardation that would obtain in the absence of rotation. In this paper a set of tranformed equations having explicitly the ratio R is derived from the 3D photoelastic equations, which are Aben's equations and Mindlin-Goodman's equations applied to a monochromatic field. Properties of the resulting equations are clarified by using the Poincare sphere. The equations obtained here are available for 3D photoelasticity.

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Based on the two dimensional theory of elasticity for an orthotropic plate, similarity law of stress fields between two different orthotropic plates is considered. Accoding to the similarity law, a convenient photoelastic method to analyze the stress field of orthotropic material by using an isotropic plate is presented. The difference of the stress fields between isotropic and orthotropic plates under the same boundary conditions is shown by the present method.

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The mixed-mode stress intensity factors for the crack in the corner of keyway of the rotating disc are evaluated by means of photoelastic stress freezing method. The epoxy resin disc models with the systematically varied crack depth and crack angle are prepared and installed in the rotating instrument incorporated into the furnace.
The data collected from the isochromatic fringe patterns around the crack tip by utilizing the image processing analyzer are estimated by means of the over-deterministic method. The results obtained for stress intensity factors are shown in diagrams.

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Domes carry vertical loads onto their base by mainly compressive membrane-stresses. In a membrane inflated by air, only tension stresses occur. When a dome is formed in a shape the same as that of the inflated membrane, and is subjected to external pressure, only compressive membrane-stresses will occur, prompting the label of “membrane-dome” for such structures.
In this paper, the determination of shape of membrane-dome with regular polygonal boundaries is introduced; thin rubber sheets are fixed on the required boundary, inflated by air, and the resulting shapes are measured by using a moire technique.

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This paper deals with the propagation of partially polarized light through media with birefringence and dichroism on the basis of vector equations and the resulting scalar equation. The vector equations are derived from general coupled-mode equations by the Stokes parameters transformation. The evolution of the polarization sate of partially polarized light is compared with that of polarization state of completely polarized light by using the unit Poincare sphere and the shrinking sphere. This propagation theory of absorption is applied to photoelastic media when they are absorbing.

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A composite quarter wave plate has been made from two sheets of transparent polymers. The condition in which two phase plates satisfy as a quarter wave plate is discussed using the Poincare sphere. The relation between azimuth angle and retardation of each plate is calculated and shown on the Tables. Retardations of two plates must be measured for each wavelenght. The composite quarter plate is used as a circular polarizer for all visible region of light by changing azimuth angles of phase plates. A trial composite quarter plate is tested for several wave lengths. It is confirmed that the composite quarter plate can be used as a quarter plate even if the wavelength of light changes.

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