An elastic bending deformation analysis of fracture line generation for anisotropic side plates [width L=60-120mm, height h= (0.8-2) L and longitudinal elastic coefficients E_x=2.94×10³N/mm² and E_y=1.24×10³N/mm² in width and height directions and Poisson's ratio ν_xy=0.10 for width direction strain effect to height direction strain] in the case (square tube panel) of the corrugated fiberboard box shape (CFCBS) under uniform compression loading p_y0 was considered. Deflection W of side plates distributes symmetrically to center lines of width and height directions and becomes the distribution pattern of the convex-concave shape on outer surfaces of side plates. And rate h'*/L (h'* : maximum distance between upper or lower surface and fracture line) becomes nearly constant in range h/L>0.8 and fracture lines for side plates become curves of sine square root in similar figures, and independently of the change of h. Their fracture lines are denoted by the position which loading stress is equal to compression strength per unit area. And the shape of side plates made by fracture lines is similar to the barrack shape. Total load for fracture line generation is nearly constant.

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Residual stresses and the resulting dimensional changes due to thermal spraying can be a major factor in affecting the performance of fabricated parts and components. In this study, the residual stress and deformation behaviors of square plate due to blasting treatment and thermal spraying was clarified by based on an inherent strain method... It was found that the inherent strain of blasted surface, that was calculated by the deflection measurement of substrate (JIS SS400, 150×150×1 ^tmm), was +0.026% in x-direction of square substrate and +0.082% in y-direction of square substrate. Also, it was found that the inherent strain of titanium plasma sprayed layer on the blasted substrate that was calculated by the deflection measurement of the blasted plate was -0.061% in x-direction of substrate and -0.16% in y-direction of substrate. It was also confirmed that the inherent strain method due to deflection measurement was applicable to estimate the residual stress distribution in case of the titanium plasma sprayed steel plate with blasting treatment. As a result, it was found that the residual stress at the surface of plasma sprayed steel plate was 7.60 MPa in x-direction of substrate and 20.4 MPa in y-direction of substrate.

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The concept of the parameter U* has been introduced by the authors to express load transfer in structures. In this paper, an extended definition of U* is introduced for structures under multiple loadings. The new expression of U* with the matrix formulation of internal stiffness can effectively be applied to an efficient calculation of U* distribution. Examples of U* calculation for an actual truck cab structure under multiple loading are demonstrated. Calculation results of U* for cases under multiple loading condition and single loading condition are compared, and the applicability of St. Venant's principle concerning U* distribution is discussed.

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In this report, adhesive strength criteria are investigated experimentally and analytically. Both the cylindrical butt joint specimen subjected to various combined tensile and torsional loadings and the round bar butt joint specimen with various angles of interface edge are used for the experiments. Temperature dependency is also investigated. Principal stress, principal strain and von Mises stress distributions at the adhesive interface of these specimens under the critical load are obtained by the elasto-plastic finite element analysis using MARC. As a result, the mean value of von Mises stress distribution at the singularity area is found to be the most dominant factor of adhesive strength for the case with stress singularity area. This fact is confirmed also for the strength evaluation of the double lap joint subjected to tension through the additional examination and the corresponding three dimensional elasto-plastic FEM analysis. The critical von Mises stress can be obtained directly by a usual experimental method using a cylindrical butt joint specimen under torsion without any numerical analysis.

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Numerical simulations are performed to investigate the austenite-to-ferrite transformation in Fe-C alloy by employing a phase-field method, which can simultaneously simulate both interface migration and carbon diffusion without complex tracking of the interface position. The effects of transformation temperature and initial carbon concentration in austenite on the transformation behavior are investigated in detail as a one-dimensional problem. Simulation results show that the transformation kinetics varies between diffusion-controlled mode and interface-controlled mode depending on the temperature and carbon concentration. Therefore, the local equilibrium condition is not satisfied at the interface during the interface migration, while carbon concentration at the interface in austenite increases as the ferrite phase grows. Furthermore, we have evaluated the critical composition in which interface-controlled transformation occurs in the temperature range from 873 K to 673 K. It is clarified that the interface-controlled transformation cannot occur in the two phase region below 723 K.

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Inelastic deformation of a defect-free lattice emerges when the elastic stiffness coefficients for the whole system, or the global (system) stability, loses the positive definiteness. Disordered crystals, however, show inhomogeneous deformation from the very begining and the coefficients never becomes negative even at the onset of inelastic deformation. The present study is the first report on the relationships between the global and local (atomistic) stabilities in such disordered systems. First, many static calculations are performed for the global stability of nickel nano-polycrystals by changing cell size, ratio of grain boundaries and grain orientations in a cubic periodic cell. The global stability increases by grain subdivision of 2×2×2, then decreases with the number of grains. This is because of hardening by random crystal orientation and softening by increase of grain boundaries. Then the polycrystals with the cell size of 30a×30a×30a (a is the lattice parameter of nickel) are relaxed by means of molecular dynamics simulation to evaluate the local stability before loading. Contrary to the global stability, the average of local stability monotonically decreases with the number of grains, from that of a perfect lattice to amorphous. Finally, we have performed tensile simulations and investigated the change in yield stress, global and local stabilities.

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A modeling of wrinkled membranes based on projection operator is presented within the classical membrane theory. The total strains in wrinkled membranes are decomposed into elastic and zero-strain energy parts. A projection matrix that extracts the elastic parts from the total strains is derived from the view point of linear algebra. The resulting modified elasticity matrix that represents the stress-strain relations in wrinkled membranes is thus obtained as product of the classical elasticity matrix and projection matrix. A qualitative comparison is conducted between the presented modified elasticity matrix and the existing modified elasticity matrices.

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An experimental study of tear strength of styrene-butadiene rubber (SBR) filled with various concentrations of HAF carbon black has been carried out. A trouser-leg tear test was used to determine tear strength. We focus attention with tearing initiation strength and the associated elongation ratio. The effects of temperature and tearing speed on the initiation of the tear properties were investigated. The values of tearing initiation strength obtained at every temperature and every tearing speeds for a kind of samples were found to be approximately proportional to the associated elongation ratios. As results of trying superposition for tear strength at initiation of rubber, time-temperature superposition principle of tearing initiation properties was found to be effective.

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An electrodeposited copper foil that possesses conical projections regularly is applied to measure the pressure between two rollers in contact. Before measuring the pressure, the effects of number of cycles and frequency of the pressure on the ratio of real contact surface area to bottom area of the projections are investigated using servohydraulic testing machine. The cyclic softening of the copper foil is gradually recognized after 10³ cycles and its frequency dependence is also recognized in the pulsating compression test. Namely, if the number of cycles is the same, the increase of the frequency delays the progress of cyclic softening. However, if the number of cycles is 10² cycles in which the cyclic softening hardly proceeds, the ratio of real contact surface area to bottom area of the projections doesn't depend on the frequency, and the ratio is almost same value in the static test. The pressure between two rollers is measured at 10² cycles. The mean pressure over the width direction of the roller obtained by this method is in good agreement with theoretical values obtained by load cell.

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The allowable defect size for a helicopter rotor hub made of high strength glass fiber reinforced plastic (GFRP) was evaluated based on the damage tolerant design method. The threshold values of the energy release rate range, ΔG_th, for fatigue crack propagation were established under the pure and mixed modes of I, II and III for GFRP. An initial delamination crack was located at various positions in rotor hub. The energy release rate range, ΔG, was calculated for each position using the finite element method. The allowable defect size was determined from the threshold values and the energy release rate range, ΔG. The maximum energy release rate ranges of mode II and III, ΔGII and ΔGIII, for an internal elliptic crack were generated at the crack front edge in the centrifugal direction, and in the perpendicular direction. The maximum value of ΔGII is large than that of ΔGIII, but the threshold value of mode III, ΔGIII_th, is smaller than that of mode II. This suggests that, for an internal elliptic crack, the energy release range at the crack front edge in the centrifugal direction is critical for damage tolerant design. The region where the allowable defect size was determined to be the smallest corresponded to the position that showed the peak shear stress in the absence of cracking, which, for the hub in this study, was the center of the plate thickness at the thickness change division.

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This paper describes the fatigue behaviour of Mg₂Si-particulate reinforced magnesium alloy composites. Rotating bending fatigue tests have been performed using smooth specimens of two materials, Mg₂Si/AZ 31-H and Mg₂Si/AZ 31-L, extruded at high and low billet temperatures, respectively. Fatigue strength was evaluated and compared with a conventional extruded AZ 31 alloy, and fracture mechanisms were discussed. Fatigue strength was strongly affected by billet temperature during the extrusion process, where Mg₂Si/AZ 31-L exhibited significantly higher fatigue strength than Mg₂Si/AZ 23-H. When compared with the extruded AZ 31 alloy, Mg₂Si/AZ 31-L also showed slightly higher fatigue strength. In Mg₂Si/AZ 31-L, fatigue cracks initiated in the matrix microstructure near particles, while in Mg₂Si/AZ 31-H, generated at the interface between the matrix and particles, and subsequent small cracks grew faster in Mg₂Si/AZ 31-H than in Mg₂Si/AZ 31-L, which were responsible for the observed billet temperature dependence of fatigue strength.

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Surface degradations are induced in components of industrial machineries during long period of operation. The integrity assessment for aging component requires the consideration of actual operating conditions. Among those, surface degradation and low strain rate are the major factors to be considered for fatigue assessment in high temperature water. Fatigue tests using notched specimen in oxygenated high temperature water 300°C were performed to establish the assessment criterion for degraded material. It showed that deeper notch caused more reduction of the fatigue strength at long life region and the lower strain rate resulted in shorter fatigue life. The formation of corrosion groove was also investigated using temperature changing test. The formation of corrosion groove was caused by the rupture of oxidation film at the bottom of groove with the aid of mechanical strain cycling. The oxygen concentration cell assisted the corrosion process. This process was accelerated at relatively low temperature, i.e. 150°C. Fatigue life assessment method was proposed for aging component, which incorporated both effects of surface degradation and strain rate.

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Since alloy 690 and its welds are superior materials for PWSCC susceptibility, application for many components of PWR has been increased instead of alloy 600. It has recently been reported that the materials show intergranular cracking and reduction of fracture toughness in low temperature water with high hydrogen. In this study, fracture toughness tests at slow loading rate were conducted to clarify the possibility of low temperature cracking (LTC) in simulated PWR primary environment. While LTC occured in water with DH=30 cc/kgH₂O and 150 cc/kgH₂O at 54°C, no LTC was observed without hydrogen even in low temperature water. Also, fracture resistance of the specimens, in which LTC was observed, decreased significantly compared with that in air. The results indicate that LTC is an issue only in hydrogenated water. In addition, the effect of pre-immersion in high temperature hydrogenated water on susceptibility of LTC was investigated and showed not to accelerate LTC. As hydrogen content in tested specimen was almost same independent of dissolved hydrogen of test water, the possibility that hydrogen was charged into specimen during laboratory test would be low. One of mechanism of LTC was considered that constant hydrogen supply to crack tip resulted in the ductility loss of material.

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In this study, the photoelastic experiment hybrid method was introduced and applied to the fracture problems of the isotropic polycarbonate plate, used as structural components, with a central crack under the uniaxial or various biaxial tensile loads. And then, the influences of biaxial tensile load ratio on the stress fields and stress intensity factors near the mode-I crack tip were investigated. As the results, the vertical tensile loads added to mode-I load (changing the biaxial tensile load ratio) had no influence on the magnitude and distribution shape of σ_y/σ₀ and τ_xy/σ₀, but changed the shape and slope of isochromatic fringes and the region of compressive area of σ_x/σ₀. As the biaxial load ratio (P_x/P_y) increases, the value of stress intensity factor, K1 decreases. P_x/P_y and K1 are negatively related. However, the changes in K1 are smaller than the changes in P_x/P_y.

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In order to investigate the flow of molten metal in a cavity of a die, experimental simulation was carried out by using water flow model. The experimental cavity was constructed of a backward step configuration for test zone, in which flow behavior and air exhaust process from the cavity were investigated. With rib material installed down the step, its effect on air exhaust promotion was examined for various flow velocities. The main results obtained are as follows : Air exhaust from the cavity is remarkably promoted by installation of rib because the strong turbulence around the rejoining potion of two different flows, which are separated by the rib at the upstream, broke rapidly the trapped air into small bubbles. The time taken to complete air exhaust process is in inverse proportion to the flow velocity in the high velocity region, while it is proportion to the flow velocity to the -2.27th power in the low velocity region.

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It has been well known that mechanical properties of steels are improved by gain refinement, smaller cementite particle and finely dispersing cementite particle, It is enabled by super rapid induction tempering the the smaller cementite particle and the finely dispersing cementite particle. In this study, mechanical properties of induction quenching and tempering carbon steel using super rapid induction heating system were investigated. Dtail, the effect of quenching time on tensile properties is examined. The quenching time was changed in four steps of 0.44 s (1163 K), 10 s (1233 K) +10 s (1153 K), 20 s (1273 K) and 20 s (1433 K). As a result, it was found that the tensile strength of QT steel indicated an increase tendency with hardness. The yield strength was in proportion to a square root of grain size. However, the ductility improvement effected by super rapid induction quenching was not found, reduction of area did not depend on grain size.

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This paper deals with the temperature-dependent elasto-viscoplasticity behaviour of a highly ductile acrylic adhesive and its effect on plastic bending of adhesively bonded sheet metals. Tensile lap shear tests of aluminium single-lap joints were performed at various temperature of 10-40°C at several tensile speeds. Based on the experimental results, a new constitutive model of temperature-dependent elasto-viscoplasticity of the adhesive is presented. From V-bending experiments and the corresponding numerical simulation, it was found that the gull-wing type geometrical imperfection of the V-bent sheet is suppressed by high-speed forming at a lower temperature.

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A cavitation erosion vibratory apparatus was developed for low-temperature melting alloys. The temperature can be changed from room temperature to 150°C. The erosion tests of SUS 304 were carried out in liquid lead-bismuth metal and in deionized water. The erosion rate was parameterized in terms of a relative temperature defined as the percentage between freezing and boiling points. At 14°C relative temperature, the erosion rate was 10 times in lead-bismuth, and 2 to 5 times in sodium, compared with that in deionized water. The erosion rate can be evaluated as a function of material density and sound velocity. Finally, the temperature dependence was discussed in terms of liquid vapor pressure.

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Mussels living in the ocean adhere to shore reef and each other with byssus formed by insolubilization of a bonding protein, whose application to the new bio-adhesion material has been expected. Their adhesive strength has not been accurately measured because peeling test method is not established since the contact areas between a plaque and the substrate are less than 1 mm². Present paper attempts to measure adhesive strength of the plaque using original simple peeling test method and investigates the influence of environmental change on the adhesive strength and the change of the adhesive strength in the lapse of time. The results show that the-adhesive strength of the plaque decreases with the change in the environment by moving mussels from the beach to an experimental environment and the adhesive strength changes along with the elapsed time after the plaque is formed.

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