The stress-birefringence relaxation-behavior at the constant strain under the elasto-prastic stress conditions produced by the simple tension of constant strain rate on flat specimens of mixed polyester resin and aluminum metal were investigated with the photo-visco-elastic method. By using the method, the relaxation-behaviors of stress distributions in tensile strips with circular holes of those materials under the elasto-plastic stress conditions were analyzed.

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In this present study, photoviscosity of three dimensional viscous flow were investigated, and open, closed rectangular channels and the deionized photoviscous solution which were suspended milling yellow dye 1.2 percent by weight in water were prepared for the experiment. From the results of present study, it is understood that the equation of isochromatics in three dimensional photoviscous flow is equal to that of two dimensional. More over the effect of photoviscosity in a closed channel is similar to that of an open channel.

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The structural change in the necking part of polymer monofilament has been investigated by means of the micro-photoelasticity. Its change depends on the humidity during storage of samples. Two samples were used in the present study, one of them was kept in moist atmosphere for a month and the other sample which was a part of the former was subsequently kept in a desiccator with P2O5 for a week. The wet sample is elongated by low load without yielding, and the dried sample makes yielding and necking under loading. In an unelongate portion of the necking part, the surface of monofilament is elongated more than its inner part. In the dried sample, it seems that the surface is harder than the inner and monofilament is easily elongated by concentrated force. After full elongation, the strains are same both in the surface and inner parts. And the behavior of elongation is different between under loading and stress relaxation.

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A fully automatic system of two-dimensional photoelastic stress analysis with aid of a microcomputer is developed. The main elements of the system are composed of 1) a two-dimensional photoelastic model under a linearly increasing load with time or under a constant load with a light source of varying wavelength for obtaining isochromatic fringe order automatically at each pixel, 2) discretized A/D storage of light intensity of isochromatics at each pixel (512×512) using a TV camera, 3) computation of sum of principal stresses in Laplace's field by the iteration harmonization procedure and separation of principal stresses and stress components, 4) automatic tracing of stress trajectories by the use of Lamé-Maxwell's equations of equili- brium.

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A fully automatic system of two-dimensional photoelastic stress analysis using a TV camera and a microcomputer developed by the authors (Proc. Jpn. Soc. Photoelasticity, Vol. 8, No. 2, pp. 1) is applied to solving a two-dimensional elasticity problem-a circular ring under diametral concentrated loads. The distributions of σ₁-σ₂, σ₁+σ₂, σ₁, σ₂, directions of principal stresses φ, θ and stress components σ_x, σ_y, τxy were automatically obtained satisfactorily as quickly as approximately 3.5h without any need of researcher's interactive control.

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The stress distribution in a bolted joint and the pressure distribution on the bearing surface of a hexagon nuts with flange have been examined by the three-dimensional photoelastic experiment. The experiment shows that the stress distribution in a bolted joint is axially asymmetrical, because the screw part has an axi-asymmetrical shape. The pressure distribution on the bearing surface of hexagon nuts with flange has the asymmetry corresponding to that stated above. The radial distribution of the bearing surface pressure concentrates at the inner part of the flange, while the pressure on the bearing surface at the outer part of the flange is reduced to almost zero. Namely, the pressure on the bearing surface of the hexagon nuts with flange is not uniformly distributed. Accordingly, the improvement of the fastening function of a hexagon nuts with flange is necessary.

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