The purpose of this paper is to demonstrate a new procedure for conducting membrane analogy experiment to analyze Saint-Venant torsional stresses. Using the procedure, two torsional bar section, square and twist drill section have been investigate and the results were compared with the ones obtained by numerical finite difference method.

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Nevertheless recent development in hardware devices has been remarkable, it is still difficult to get noise-free data of photoelastic fringes with a wide use polariscope. It must be reasonable, moreover, to consider that photoelastic data include both dense and sparse portions of fringe. Thus, unavoidable noises affect the accuracy of analysis for the location of fringes, particularly in highly dense portions. In order to improve the accuracy of analysis, an atempt of linearly proportional enlargement of the dense area seems to be available. This method, however, could not be useful, because of several kinds of aberration of lens and discrepancy in a scale-down of image into the original size. This paper describes the method of conversion of a fringe pattern obtained in a rectangular array (Cartesian coordinate) into a polar coordinate. After analyzing locally enlarged portions, fringes are transformed inversely back into the original coordinate system. Several examples of application of this method show its availability in extraction of photoelastic isochromatic fringes.

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Some technical problems involved in the iterative numerical solution of Laplace's equation with respect to sum of principal stresses are investigated in this paper, in order to obtain individual principal stress σ₁ and σ₂ separately. Two points: determination of assignment of distributed load (including a concentrated load), and the relationship between the accuracy of the results and number of repetition, number of nodal point, and so on, are emphasized and examined in detail.

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Photoelastic stress analysis of a disc with an elliptical ho1e subjected to internal or externa1 pressure load is carried out. The mode1s of discs are made of soft epoxy resin plates and the hole is systematical1y varied from very s1ender elliptic to circular. The tangentia1 stresses produced on the inner boundary of the model are analyzed from the photoelastic isochromatic fringe patterns under internal or external pressure for the discs having various elliptical holes. The diagrams of stress concentration factors are presented in respect to the maximum tangential stresses. Furthermore, the stress intensity factors are evaluated for the discs with a central crack subjected to the pressure on the edges of crack or on the outer boundary of disc and are compared with numerical values calculated with finite element method.

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Behavior of bending stress waves propagation, stress distribution and stress concentration, for cantilever beams under transverse impact, was analysed by means of high speed photoelasticity. An empirical formula with two parameters, that is, specimen size and energy of impactor, was derived from the experimental results for stress concentration.

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Anew analytical method was developed and reported here, which accepting the thickness change along the boundary of model and the coordinate values of photoelastic isochromatic fringe as the only parameters inputted to the personal computer, the Laplace's equation ∇∇2 (σ1+σ2) =0, and Poisson's equation ∇∇²σ_y=∂∂² (σ₁+σ₂) /∂xx², ∇∇²τ_xy=∂∂² (σ₁+σ₂) /∂_x∂_y, are changed into the finite difference equations, and σ_x, σ_v, τ_xy, σ₁, σ₂, and the direction of the principal stress θ₁, θ₂, are systematically solved by the iteration method. As an analytical example, the stress allalysis of a semi-infinite plate compressed by a square aluminum plate was carried out. Furthermore, a high precision comparator was used to measure the thickness change of the model. The boundary condition to determine the distribution of σ_y is approXimated equal to the principal stress σ₂, for the τ_xy the boundary condition is assumed to be 0.

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The shear walls have been commonly used in reinforced concrete structures. As compared with other aseismic elements, the horizontal rigidity of the shear walls are large. For this reason, the shear walls in reinforced concrete structures are important aseismic elements against the horizontal shear force such as earthquake. Up to now, the shearing force ratios and the shearing stresses in the wall and boundary frame with rectangular opening in elasticity have never been precisely examined. The main purpose of this paper is to examine the shearing force ratios of the wall and column, and the shearing stresses in the wall by using photoelastic experiments. As a result of this experiment, the shearing force ratios of the wall and column, and the shearing stresses in the wall are quantitatively presented.

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