This study describes the design of braiding construction using computer simulation. Braiding construction is one of the reinforcement configuration in three dimensional fiber reinforced plastics. A simulation program for the braiding mechanism is prepared in this study. Simulation programs which predict the braiding construction through the thread movements are developed for the flat braiding and the cord braiding. Two kinds of simulation programs by micro-computer can realize the graphic animation of yarn and also estimate the braiding angle and the fiber content of the composite cylinder with braiding construction.

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We previously showed mechanism simulation techniques for basic flat braiding and basic cord braiding. In this paper, the simulation program of cord braiding has been developed as follows ; (1) the drawing-up speed of the mandrel is estimated to obtain the required braiding angle in the case of a circular cylinder composite. (2) in the tublar composites, with changing the cross section to the longitudinal direction, the drawing-up speed of the mandrel must be varied to obtain the same braiding angle according to the shapes of cross section. (3) the maximum braiding angle is predicted taking the width of the yarn into consideration.

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A new estimating method of Weibull parameters has been examined, using the strength data of individual fiber fractures, what we call "singlet", in unidirectional composites by a Monte-Calro simulation, on the assumption that the fiber fractures can be acoustically counted by a non-destructive inspection. This method is based on the realization that the i-th weak fiber fracture i-thly in the composites, and the strength scatters upon trying the tensile-test several times. That is to say, the strength is a random variable based on the order statistics, and the Weibull parameters can be estimated by joint distribution of the first several order statistics. The results showed that the accuracy of the estimation became good with an increase in the number of the singlets, and the sample number of 30 and 50 gave good accuracy. Additionally, the recursion analysis technique proposed by Harlow and Phoenix was employed to investigate the effects of the stress concentration caused by the adjcent fiber fractures. The limit of the number identified as singlets was found for some composite sizes.

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The dependence of duct shape on the Barus effect of ABS resin has been studied. It has been established that the swelling ratios of the extrudates through the capillery and the slit that include the throttle consist of the following two components : one is caused by the change of the shape of the duct, and the other is caused by the shear strain in the flowing resin. Then the swelling ratio of the extrudates was correlated with the frozen strain recovery of infection molded specimens.

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Completely reversed strain controlled low cycle fatigue properties at room temperature are investigated for SUS304 austenitic stainless steel and weld metals. The metal specimens deposited by shield metal arc welding (SMAW) and gas metal arc welding (GMAW) were taken from multi-pass weld metal such that gage length consisted entirely of the weld metal. The results indicate that there is a trend toward reductions in the low cycle fatigue life of weld metals as compared with the base metals in the range of 3×10²<N_f<6×10⁴. They are explained in terms of lack of ductility by the deformation-induced martensitic transformation in SUS304. The martensite transformation is hardly induced in weld metals with 311% delta ferrite and the fatigue properties of weld metals are clearly different from the base metal (SUS304). This study leads to the conclusion that fairly accurate estimates of the low cycle fatigue life of weld metal can be obtained and the life estimation of SUS304 is impossible using Manson's universal slope method.

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This paper treats an inverse problem for transient thermoelasticity in a long circular cylinder taking into account the coupling term so as to determine the temperature of the outer medium under prescribed mechanical boundary conditions. In the outer medium and thermal stresses are obtained. The numerical results for the temperature and thermal stresses are shown in figures.

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This paper describes the applicability of the indirect fictitious boundary integral method to the thermo-elastic contact problem. As an example, a notched bar constrained by two hot rigid surfaces in contact with both its end surface is treated. As a results, the isothermal line, the stress distribution etc., are shown.

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Elastic thermal stresses in a column of wall, such as a boier wall, with concave or convex surfaces are analyzed by the indirect fictitious boundary integral method. As a example, we treat a wall, which has a cncavity (notch) or convexity (protrusion) on the one side of the wall and is heated on either side. As the results the temperature distributions and the thermal stresses were obtained and the influenced of shape parameters such as a depth of notch where observed. Also the availability of this method to this problem we shwon.

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This paper treats the bending problem of an axi-symmetrically loaded circular plate which is simply supported on two equal and diametrically opposite portions of its edge, the remaining edge portions being free. The deflection and the bending moments at the center of the plate are calculated by an iterative method, which was proposed in our previous paper for bending problems of circular plates with the mixed boundary conditions of other kinds. The calculated results are compared with those obtained by other researchers. It is also shown in this study that the problems of axisymmetrically loaded circular plates can be easily solved by using the results obtained for cases of uniformly distributed load.

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Theoretical analyses are presented for postbuckling behavior of compressed columns reinforced with a beam, considering the effect of non-linearity due to a stretching of the beam, under three sets of boundary conditions. Introducing the coordinate function which is expressed with the product of the power series truncated with fourth order and the trigonometrical function to the Galerkin procedure, basic equations are reduced to coupled non-linear equations for unknown coefficients. The deflections of the column with the reinforcing beam are determined in each boundary conditions. Stabilities for the deformation of the columns are also examined. It is found that the reinforcing beam with immovable clamped ends and an appropriate supporting point gives high rigidity in the postbuckling state of the columns.

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The elementary beam theory is based on the Bernoulli-Euler hypothesis, in which no shear deformation is allowed to occur excluding the case of torsional deformation. This theory involves some theory to be improved. We consider here a refined beam theory taking into account the effect of shear deformation. This theory may be applied to any cross section of beam using the finite element method. Next, we asked for the stiffness matrix of an element of space framework taking into account the effect of the shear deformation. Some numerical examples of the present theory are shown and compared with values obtained by other methods.

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The ductile fracture mechanism of a round bar of S 15 CK with a hole is investigated in order to obtain an understanding of the extension behavior of a ductile surface crack from a hole. A ductile crack starting from a hole grew stably with mixed mode fracture which combined tensile mode and shear mode fracture, and the nondimensionalized growth rate of crack for strain increment was proportional to nondimensionalized crack size l/D independent of the hole shape, which can be written as d(l/D)/dε∝l/D where l is crack length, D is the diameter of a specimen and ε is the true strain. Hence, the extension behavior of a ductile crack depends on crack size in this investigation. The ductile fracture originated in a surface is different from the cup-and-core type in macro-scopic features.

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The preceding paper has reported on the numerical evaluation of quench crack susceptibility. The disadvantage of the experimental method has been the assumption of a great number of samples i.e., high cost. This paper deals with a modified method for evaluating quench crack susceptibility. Quenching was repeated n-th times until a crack was generated, using 45 test pieces. The results obtained are discussed and compared with the data presented in the preceding paper. In quench cracking of a high carbon and chromium steel bar, vertical crack value in 1/n crack generation is closely related to the crack percentage, while fin crack value slightly deviates. The residual stresses caused by repeated quench were measured by the X-ray diffraction method. The residual stresses caused by repeated quench were measured by the X-ray diffraction method. The residual stress (tensile stress) on the surface increased with repeat time. It was clarified on the basis of observations using a metallurgical microscope that the repeat of quenching should be less than 34 times.

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The quantitative evaluation of the subcritical crack growth behavior of nuclear pressure vessels and piping steels in pressurized high temperature water has been receiving extensive attention to ensure the structual integrity of nuclear pressure vessels and piping. Recent research progress in this field suggests the significance of the sulfur content of steels in assessing susceptibility to environmentally assisted cracking of these steels in high temperature water from the view point of solution chemistry at a crack tip, where dissolution of MnS, non-metallic inclusion, results in an enrichment of S anion, such as SO₄^2-. Hence, it is neccesary to simulate the solution which has been commonly used as a useful tool to see stress corrosion cracking characteristics in a short time. In this material/environments systems are examined quantitatively as a function of temperature, sulfur content in steels and also SO₄^2- contents in solution, simulating crack tip solution chemistry. Cracking potential showed a lower value of about 250°C, rather than 288°C. Sulfur content of steel and SO₄^2- concentration in solution can drastically influence the cracking potential and some amount of sulfur in steels or SO₄^2- anion at a crack tip make it possible to crack at a BWR or PWR condition.

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An application of the finite element method to the elastic-plastic analysis is presented using the quadratic programing technique with bounded variables. A yield function in the theory of plasticity is given in terms of not only the second invariant of the deviatoric stress tensor J'₂ but also of the third J'₃. Two numerical examples are shown for the stress concentration problem under the plane stress state. The result obtained by the yield function with J'₃ is compared with that obtained by the conventional J₂ theory. The difference of the distribution of stresses and strains between two theories depends on the stress ratio. The magnitude of the stresses and strains obtained by the theory with J'₃ is larger than that by the conventional one. The distribution of the larger effective plastic strain in a cross-section is calculated by the present theory compared with that obtained by using J₂ theory especially in the range of the large plastic deformation.

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Recently, the authors have shown that the combined method of the path-independent J' integral (dynamic J integral) and a moving isoparametric element procedure is an effective tool for the calculation of dynamic stress intensity factors. In the moving element procedure, the nodal pattern of the elements near a crack tip moves according to the motion of the crack-tip. An iterative numerical technique was used in the previous procedure to find the natural coordinates (ξ, η) at the newly created nodes. This technique requires additional computing time because of the nature of iteration. In the present paper, algebraic expressions for the transformation of the global coordinates (χ, y) to the natural coordinates (ξ, η) were obtained by using a computerized symbolic manipulation system (REDUCE 3.2). These algebraic expressions are also very useful for remeshing or zooming techniques often used in finite element analysis. The present moving finite element method demonstrates its effectiveness for the simulation of a fast fracture.

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The maximum point of stress is found in a beam of the circular cross-section with a radial hole which is perpendicular to the neutral axis. Both the yielding and the rupture of beams are analyzed by taking a strip parallel to the neutral axis at that point and by considering the effect of the surface layer which is inherent for the material. The analytical results conform very closely with the experiments of the mild steel, the plaster and the graphite shown in the 1st report. The thickness of the surface layer taken in this case is 0.20 mm for the mile steel, 0.26 mm for the plaster and 0.36 mm for the graphite. And the conclusion derived from the analytical results is that there are limits of the upper and lower stresses in the strength of beams.

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The reflection and interference of stress-waves play an important role in dynamic cases. It is very desirable to study the time variation of the stress distribution and especially the dynamic stress concentration factor in three-dimensional solid bodies. Hence, we have already reported the dynamic stress concentration factor around a spherical cavity in a smoothed cylindrical bar. Further, we have analyzed the stress propagation and the dynamic stress concentration phenomena around a spherical cavity in the various grooved cylindrical bars by utillizing the strain gage method and also the finite element method. Emphasis was laid on the dynamic stress concentration analysis of bodies with inner cavities, such as those often found in welded parts or castings. We found that the three-dimensional dynamic stress concentration factors obtained by the present two methods are in general agreement. In the small radius grooved cylindical bars, the dynamic stress concentration factor inside the inner spherical cavity does not give a larger variation, and at the circular notch the root becomes larger, with increasing diameter of the cavity. On the other hand, when the circular notch radius of the grooved cylindrical bar becomes larger, it's value becomes opposite.

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The grid illuminating moire method is known as a simple means for measuring the surface contour of an object. But, when this method is evaluated from the viewpoint of practical use, there remain some problems to be solved. That is, the concave and convex regions of an object with a complicated shape cannot be discriminated from the fringe pattern formed, and when the experiment is carried out under the condition that the measuring surface is out of contact with the grid plane, the firnge index cannot be determined. In this paper, it is shown that these problems can be solved easily by using the fringe patterns formed before and after the measuring object is shifted in the direction normal to the grid plane.

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Two-dimensional stress waves in an elastic circular tube are analyzed numerically when axisymmetric impacts are applied to the end face of the tubes. For the numerical analysis, a finite difference method along the bicharacteristic is bicharacteristic is employed. By obtaining the numerical results for various tube sizes, and for the impact loading condition, it is clearly demonstrated that, when the rise time of the applied impact velocity is sufficiently short, a large tensile stress arises on the boundary of the internal surface of the tube. It is also found that the maximum value of the caused tensile stress on the boundary of the internal surface becomes larger when the rise time becomes shorter, and when the ratio of the thickness of the tube to the outside diameter becomes larger than about 0.3.

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This paper describes the experimental results of mechanical ratchetting under biaxially varied stress conditions. The experiments were conducted by subjecting thin walled tubular specimens of a carbon steel to combined cyclic axial load and internal pressure at room temperature. The effect of simultaneous variation of maximum effective stress, stress ratio and 'superposed stress', with an increasing number of cycles, on the behavior of biaxial strain accumulation is discussed. The 'delay' of the orientation of strain accumulation was observed in the ratchetting under varied 'superposed stress' conditions. The numerical simulations, by use of the costitutive equation for the mechanical ratchetting previously proposed by the authors, agree comparatively well with the experimental results, except for the case of the rapid variation of 'superposed stress'.

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