It is known that the photoelastic coating method is a powerful technique for the determination of stress or strain of metal surface, but there are some errors due to the thickness of the coat, because the whole coat does not always follow the metal surface. To investigate the following of the coat, using the theory of elasticity we calculate the stress distributions in a beam which is fixed on a uniformly elongated floor by its bottom edge. From the results it is shown that observed fringe order becomes smaller with increase of the thickness than that expected from the true strain of the metal surface and the increase beyond a quarter of its length is of no use to obtain higher fringe order. Considering the above, experimental results must be corrected for the estimation of strain of the metal and the optimum thickness may be taken as about 15% to the length of the coating sticked on the metal surface.

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A study was conducted to determine stress distributions in a ringed cylindrical pressure vessel subjected to internal pressure. The stresses were determined by using stress-freezing method for three-dimensional photoelasticity. Circumferential and meridional stresses on inside surface are presented and these are compared with the stresses in the case of a non-ringed cylindrical pressure vessel. And also, the effect of Poisson's ratio (ν) on the stress values of the cylindrical pressure vessel which determined by stress-freezing method have been investigated using finite element analysis. The results show that the ring reinforcement was not fully effective, however, the circumferential stress value of the cylindrical part decreased compared with that of the non-ringed pressure vessel. On the other hand, the ring (s) of the pressure vessel did not affect the stress values at the bottom of the vessel. The results of the finite element analysis indicate that when compared with ν=0.3 and 0.45, the influence of Poisson's ratio on the stress values of the pressure vessel was dependent upon wall thickness of the pressure vessel.

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Many theoretical studies have been already published on the three dimensional analysis of box beams, but there are not quite the studies on the three dimensional analysis by the photoelastic experiment. Therefore, the present writers made the three box beam models by the epoxy resin plates of the Riken Keiki Company and the bonding material of epoxy resin in the first place, and they performed tentatively the three dimensional analysis by the photoelastic experiment. Next, the present writers made the six box beam models by pouring Alaldite (B) to the mold and scooping out by the mechanical work and performed exactly the three dimensional analysis of the photoelastic experiments. By the above-mentioned experimental analysis, they clarified and discussed the absorbing stress characteristic of box beam models, and compared considerately the influence of two different manufacturing method of models.

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The principal refractive index, birefringence and its sign of the photoviscous flow were investigated by using Mach-Zehnder interferometer and photoviscous method. The present photoviscous fluids were prepared from viscous liquid which were suspended milling yellow dye 1.0, 1.2 and 1.4% by weight in water. And the effect of each density and temperature for the principal refractive index, birefringence and its sign of the photoviscous flow were investigated, too. It is understood that the principal refractive index in the photoviscous flow decrease, that is, Δn₁ and Δn₂ are negative, |Δn₂|>|Δn₁| and the sign of birefringence Δn_1-2 is positive, in the present study.

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A series of systematic experiment on the optical and mechanical properties of Araldite B were carried out in detail to determine the “figure of merit Q=αE” as a function of freezing temperature TM and to find out the most desirable TM at which the highest value of Q is obtained. Four-point bend beam specimens made of Araldite B in various curing conditions are heat-treated under loading in an oven with glass windows through which α and E of the material are measured every moment. The results obtained show that the most desirable stress freezing heat treatment from the view point of minimizing model deformation cannot be attained at the usual transition point T0, but at a certain point TM about 35°C lower than that. It has been found that the Q at TM is about 3 to 5 times as high as that at T₀. The effects of optical and mechanical creep on the Q are also thoroughly investigated.

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