Proposed inelastic constitutive equations relevant to describing the effect of plasticity-creep interactions is classified and reviewed. Emphasis is focused on the unified constitutive models which are expected to provide the applicability to high temperature material behavior. Two series of simulations of material response by use of the models for the uniaxial and multiaxial stress states are presented for evaluation ; one is the results of a cooperative benchmark project carried out by the Subcommittee on Inelastic Analysis and Life Prediction of High Temperature Materials, JSMS, and the other is by the author.

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Supersaturated solid-solution alloys of Al-Cu systems of up to 8 at%Cu were prepared by means of heat treatments under a pressure of 5.4 GPa and a temperature of 720°C for 10 hours. The elastic constants of the prepared specimens were measured by a three-dimensional resonance method. The Young's modulus E and the shear modulus G of the solid solutions increased with increased concentrations of the Cu atoms in the alloys, and features related to the mean numbers of valence electrons per atom (e/a) were discussed by the free-electron theory. The specimens of the solid solutions were measured step-by-step. The maximum shear modulus was observed during the precipitation of the θ'-phase at 300°C-aging. Temperature coefficients of the moduli of the Al-6 at%Cu specimens were also measured throughout various stages of the treatments.

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A new model one-dimensional wave equation is constructed, which is adapted for the study of longitudinal waves in rods having some inhomogeneities in physical properties and/or in geometry. This equation is then applied to scattering of longitudinal waves in circular rods, where the elastic constants such as Young's modulus and Poisson's ratio become locally inhomogeneous along their axes due to local heating. In the experiments, strain waves are produced by impacting cylindrical bullets at one end of a stainless steel rod which is heated locally at its intermediate portion. The main interests are devoted to the dispersion effect on waves scattered by the inhomogeneities and also the validity of the present equation.

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An investigation concerning the effects of sheet thickness on the in-plane stretch forming limit in 1 100 aluminum sheets with thicknesses of 0.5 to 1.0 mm, prepared by electropolishing, has been carried out experimentally and analytically. Development of surface roughness is represented by a linear relation between surface roughness are observed. However, the forming limit which depends on the thickness is observed, and less thickness results in a decreased forming limit. Good agreement between measured and theoretical strains from modified M-K theory is obtained. The thickness dependence of a half angle of pointed vertex, θ₀, is introduced in Gotoh theory, assuming that the onset of localized necking in a sheet is the result of a bifurcation from a state of uniform deformation. The values of θ₀ are in the range between 70 and 90 degrees in all the materials examined and satisfy the relation θ₀=π/2-q₁ε^^-q0, in which the coefficients q₀ and q₁ are material constants.

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The infinitesimal free longitudinal or torsional vibrations of a thin straight rod, and the infinitesimal free transverse vibrations of a taut string are all governed by a Sturm-Liouville differential equation, and their discrete approximations by a second order difference scheme. The inverse procedure is presented for constructing the mass and stiffness parameters of the discrete model from a knowledge of the natural frequencies and the static displacement of the system.

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The shape of a structure must be determined optimally from the viewpoint of safety and economy. Especially if we have uncertainty concerning the loads or strengths, the conventional treatment which is represented by the safety factor cannot satisfy the requirement. This report proposes a method for the determination of a structural shape for the case where the structure is subjected to static loads whose magnitudes vary according to the normal probability density function and is excited by random loads which cause dynamical responses, and where the local sizes, material properties and strengths are also assumed to be random variables which are governed by normal distributions. The object of the design is to minimize the volume of the structure ; as design constraints, the probabilities of the first excursion failure and fatigue failure are taken into consideration so that they don't exceed a certain value. In the numerical treatment, an effective procedure is used in order to obtain pseudo-optimum shapes.

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This paper is concerned with the theoretical aspect of proof testing of ceramics. In the case when slow clack growth occurs during the unloading process of proof testing of ceramics, the minimum strength after proof testing, S_{f min}, becomes lower then the proof stress σ_p. The equations for S_{f min} in such cases were derived by Evans and Ritter. However, existence of he three distinct regions I, II and III in da/dt-K diagram was not fully taken into account in their equations. Thus, in this paper, a detailed analysis was carried out taking into account the actual crack growth characteristics, and the equation for S_{f min} was derived. A convenient diagram for determining the proof testing condition was also proposed.

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This paper is concerned with the problem of the sound transmission loss through a three-layered cylindrical shell subjected to inner plane acoustic waves. Each layer of the shell is modeled as a single shell, and the whole shell equations are connected together through the assumption that the displacements and the tractions are continuous at the shell interfaces. Sound transmission loss TL is calculated for various combinations of the facings and the core with different physical properties, Further, the acoustic design method of the layered shell with high transmission loss is presented and illustrated with some examples.

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A fracture problem in unidirectionally fiber-reinforced composites containing a T-shaped crack at the interface is considered. The T-shaped crack consists of an interface crack and a crack perpendicular to the interface. A system of integral equations is formulated based on the two-dimensional elasticity and Fourier transforms. The integral equations are evaluated by a numerical method using only the Gauss-Chebyshev integral formula, which was developed by the present authors in the last paper. First, the numerical results are compared with the previous results for a T-shaped crack in a homogeneous material, verifying the present method to be highly satisfactory. Next, three kinds of stress intensity factors ( SIFs), such as Model SIF of a perpendicular crack and Mode I and II SIFs of an interface crack, are presented for glass/epoxy, carbon/epoxy and tungsten /epoxy and tungsten/copper composite systems with various geometrical parameters.

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Since the stress and displacement fields near a bonding edge show singularity behaviors, the adhesive strength evaluation method, using maximum stresses calculated by numerical stress analysis such as the finite element method, is generally not valid. In this paper, a new method, which uses two stress singularity parameters, is presented for evaluating adhesive strength. This method is applied to several kinds of molded models, composed of epoxy base resin and Fe-Ni alloy sheets. Predictions about the initiation and extension of delamination are compared with the results of observations made by scanning acoustic tomography on molded models.

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J_IC tests were carried out on SUS 316 steel by means of the JSME R-curve method as well as the JSME streched-zone width (SZW) method. The effects of side-grooves on the J_in value at the onset of stable crack growth were investigated using CCT specimens of two thicknesses (B=1 mm and 2 mm). The ratio of the net thickness to the gross thickness was maintained at 0.5. The J_in value of the side-grooved specimen of 2 mm thickness was smaller than that of the standard CCT specimen. Further, as the thickness of the specimen became thinner, the J_in value decreased. In the case of 1 mm-thick CCT specimens with or without a side-groove, the contraction percentage of thickness was very large so that it was not appropriate to use these specimens for the fracture toughness test. In the case of the thin or side-grooved CCT specimens, the J-value, which is evaluated from the load versus displacement curve using Rice's formula, cannot estimate the J-integral at the central part of the specimen. Therefore, a J-integral estimation method would have to be established using 3-D elastic-plastic analysis.

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The present paper proposes a new algorithm of the integrity evaluation of the pressure vessel of nuclear reactors under pressurized thermal shock, PTS. This method enables us to perform an effective evaluation by superimposing proposed stress intensity factor transient curves and fracture toughness transient curves, and is superior to conventional methods in the following points : (1) It is easy to obtain an overall view of the result of the PTS event for the variations of several parameters. (2) It is possible to evaluate a safety margin for irradiation embrittlement. (3) It enable the construction of a expert-interactive evaluation system. In addition, the results shows that we can execute a safety assurance test using a flat plate model with the same thickness as that of the real plant.

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Ernst et al proposed a method to calculate the deformation theory J, J_D which takes into account the influence of crack growth on J. Furthermore, Ernst introduced a modified version of the J-integral, J_M, to allow a large relaxation of restrictions on the amount of crack extension and specimen configuration. In this work, simple formulas for the deformation theory J-integral and the modified J-integral are developed. The methods are applied to the static J_IC test and the instrumented Charpy test. The accuracy of the methods in the determination of the J-R curves is discussed, emphasizing the difference between J-R curves for J_D and J_M.

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In this study, stress concentration factors and fatigue strength reduction factors are obtained for the case of a round bar of mild steel with a V-groove under ultrasonically vibration stress. The stress concentration factors are determined by FEM analysis on the eigenmodes. The fatigue strength reduction factors are obtained by combining the above analysis and the results of the ultrasonic fatigue tests. These factors are determined under ultrasonically vibrating stress. These results could make the ultrasonic fatigue test more popular than the ordinary fatigue test.

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In order to examine the threshold condition for the propagation of a through crack under the mixed mode, plane bending tests, cyclic torsion tests, and their various combinations are carried out under the condition of the stress ratio R=-1 using annealed center-cracked specimens made of carbon steel. Taking account of the frictional stress acting on the crack surface under cyclic torsion, and adopting the strain-energy density criterion, the threshold stress of crack propagation under the combination of plane bending and cyclic torsion can be deduced from the individual test results of plane bending and cyclic torsion.

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In order to examine the threshold condition for the propagation of a through crack under the mixed mode, plane bending tests, cyclic torsion tests, and their various combinations are carried out under the condition of the stress ratio R=-1 using annealed center-cracked specimens made of carbon steel. Taking account of the frictional stress acting on the crack surface under cyclic torsion, and adopting the strain-energy density criterion, the threshold stress of crack propagation under the combination of plane bending and cyclic torsion can be deduced from the individual test results of plane bending and cyclic torsion.

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Plane bending and cyclic torsion tests, and their combination are first carried out at a stress ratio R=0 using annealed cracked specimens made of carbon steel. The threshold stress of small fatigue crack propagation under a mixed mode is determined using the maximum principal stress criterion since there is not crack closure effect in this case. Next, plane bending test are performed for various values of the stress ratio R. Assuming that the crack opening displacement on the threshold level is constant regardless of R, and empirical relation between R and the threshold stress is developed. The suggested expression is found to be in good agreeement with the test results and can be applied to both the positive and the negative ranges of the stress ratio.

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