The feasibility of graphical stress analyzing methods in photoelasticity based on the equation of equilibrium in polar coordinates: “the wedge method” and “the arc method” is examined by the experiment of a circular ring subjected to a diametral compression. The results obtained show that the former enables us to determine the stress components separately along a straight line more accurately than the usual methods, while the latter to analyze stresses along a circular arc satisfactorily.

抄録全体を表示

In this paper, an effective hybrid method to obtain the principal stresses throughout the whole interior region of a two-dimensionally stressed photoelastic model is reported. The main feature of this method consists in the brief and accurate technique to separate the principal stresses, and the contents of this report are briefly stated as follows. (1) By using the isochromatic figure which has the high experimental accuracy together with the boundary element method which only needs the discretization along the boundary, the degree of error is considerably decreased. (2) For the photoelastic model which has numerous interior points and the long boundary, we can greatly save the C.P.U. time in computation by using the blocked boundary element method instead of the ordinary boundary element method. (3) The boundary element method gives a high degree of freedom in choosing the interior points at which the principal stresses must be separated because we can arbitrarily specify the interior points according to demand. (4) Once the isochromatic figure is obtained, the separation of the principal stresses will be performed at any time in need.

抄録全体を表示

Photoelastic stress analysis has been used to determine stress intensity factors for two types of models (C-R and L-R) with two cracks at outer surface of cylindrical pressure vessel. The crack geometry is a portion of a circular arc. Analysis method used in this paper involves a Taylor series correction for the maximum in-plane shear stress and does not involve stress separation, which is proposed by C.W. Smith, et al. Results were qualitatively compared with the theoretical results derived for the one outer crack and the two inner cracks in internally pressurized cylinder by A.S. Kobayashi, et al. and by R.J. Clifton, et al. respectively. It is shown that the obtained data are consistent with the theoretical results and the Smith's method can be reasonably applied to three-dimensional crack problem in photoelasticity method.

抄録全体を表示

The shearing force ratios of earthquake resisting shear wall with square opening to boundary columns in elasticity have never been precisely examined. The main purpose of the present paper is to examine the shearing force ratio of the wall and column by using photoelastic experiments. As a result of this experiment, it is proved that the shearing force ratio is affected not only by the periphery ratio of the wall opening but by the shapes of the rectangular column sections.

抄録全体を表示

This paper is concerned with the mechanical and optical characterization of epoxy resin for practical photoviscoelastic analysis. The birefringence and stress are measured under various constant strain-rates at various constant temperatures. The results obtained are summarized as follows: (1) The epoxy resin used has a strong time and temperature dependence upon mechanical and optical properties. Using thermo-rheologically simple properties, the master curves of relaxation modulus Er and relaxation birefringence-strain coefficient C_∈·rcan be obtained. (2) The time-temperature shift factor of Er coincides well with that of C_∈·r and they are approximated with two Arrhenius'equations having different activations energies. (3) The temperature correction according to the theory of rubbery elasticity can be omitted when the master curve of Er is obtained. (4) The inverse relaxation stress-birefringence coefficient and the inverse creep strain-birefringence coefficient, which are necessary for practical photoviscoelastic analysis, are calculated using the master curves of Er and C_∈·r· Based on this calculation, the convenient approximation by Knauss can be applied with estimating the error of approximation from the slope of curves of Er and C_∈·r·

抄録全体を表示

The variational quantity of principal refractive index and the birefringence of polymers during the creep under a constant stress and at a constant temperature were investigated in the temperature range from -100°C to 120°C using the Mach-Zehnder interferometer and photoelectric method. In the present study, it can be found that the birefringence N of polymers consists of two components with the sign of positive or negative. Namely, two components are the instantaneous birefringence NE which appears in the moment after loading and the delayed birefringence NR which appears as loading time goes by. It is understood that NE is due to the perfect elasticity in the moment after loading and NR originated with the retarded elasticity. Thus, birefringence behaviors of polymers are classified into four types of properties by combinations of signs. These classified properties are as follows. Types 1: NE +, NR +, N=NE+NR +, Types 2: NE +, NR -, N=NE+NR +→0→- (as loading time goes by), Types 3: NE -, NR +, N=NE+NR -→0→+ (as loading time goes by), Types 4: NE -, NR -, N=NE+NR -, (+: positive, -: negative). Moreover, visco-elasto-plastic stresses and strains in polymers and aluminum metal plates were analyzed with relations among loading time, birefringence, stress and strain which were obtained from tensile creep testings for birefringences and strains of these materials.

抄録全体を表示