The element free Galerkin method (EFGM) is a meshless method presented by Belytschko, Lu and Gu in 1994. A feature of the method is that only nodes are required in modeling of objects. Another feature is that distributions of stresses become continuous because the interpolation function used in EFGM is based on the moving least-squares method (MLSM). In this paper a formulation for geometrically nonlinear EFGM is presented, and it is applied to the analysis of membrane structures that are generally supported by the geometrical stiffness. As an illustrative example, a membrane structure whose shape is represented by bi-quadratic function is analyzed. It is also analyzed by finite element method, and results are compared.

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In this paper, an effective boundary element method was developed for predicting galvanic corrosion rate for complicated structures. A direct application of conventional numerical procedures to this practical problem causes an increasing of boundary elements. Firstly, a rational criterion for an application of axis-symmetrical elements was proposed. Secondly, a method which analyzes only focused region of a structure was developed. By using these proposed methods, the number of boundary elements is decreased. A example for practical sea water pump is presented to demonstrate the practical applicability of the proposed methods.

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This paper describes the multiple fracture phenomena of brittle material plate using the discrete element method (DEM). As an analytical model, triangular plaster of Paris plate is selected and explosively loaded at the center of the base. The obtained analytical results using DEM are compared with the corresponding experimental results. The fracture patterns are almost identical each other. Moreover, we observed how different explosive loads influence the fracture pattern. From the numerical simulation, it is obvious that reflecting tensile stress is sole reason causing the fracture of brittle material plate, and multiple fracture phenomena can be forecasted by analyzing whole stress distribution of sample varing with time.

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A boundary integral method is newly applied to a plate structure, where the structure is divided to some plates and each plate is dealed with a thin plate under in-plane loading and bending loading. Although each plate is like a plate-bending element of FEM, it should not be divided into small elements any more by using BFM and the calculation is more effective than that by FEM. This method is a approximate method, (because it is based on Kirchhoff's hypothesis). Therefore the stress state of the bonded part of the plates is not exactly satisfied. However adequate solution can be obtained with very little input data.

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An X-ray diffraction technique for measurement of stress of materials having a nonlinear sin² ψ diagram was proposed. A specimen was prepared from a cold-rolled austenitic stainless steel JIS type SUS304. Various stresses σ_a were applied to the specimen and peak positions of diffraction lines were measured at seven ψ angles. Peak positions oscillated with sin² ψ. A straight line was fitted to oscillatory peak positions in the sin² ψ diagram for each applied stress σ_a. The straight lines for various applied stresses intersect at a point in the sin² ψ diagram. The slope M and the intercept N of the straight lines vary in proportion to an applied stress σ_a. The stress constants K and L can be determined experimentally as the reciprocals of the slope of the strtaight lines of M and N versus σ_a, respectively. The stress and the stress constants can also be determined from a straight line connecting two end points in the sin² ψ diagram.

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A formulation is proposed for identification of spatially distributed Young's modulus based on strain input. The strain and its sensitivity with respect to isotropic Young's modulus are analysed by the finite element method with the initial guess of Young's modulus in order to obtain the firstorder approximation of strain change. The numerical strain, obtained by the finite element analysis, is compared with such strain input as measured strain, and the current guess of Young's modulus is renewed iteratively so as to eliminate the deviation between the numerical strain and strain input until the Young's modulus is settled by the renewal converged. The fluctuation of the identified Young's modulus that arises from uncertain error involved in the strain input is estimated in the form of interval by means of the convex modeling of the error and Lagrange multiplier method. The validity of the present formulation is shown by the numerical example of axial distribution of Young's modulus identified by the skin strain of beam bending.

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A three-dimensional distinct element method using ellipsoidal elements is developed to take account of non-spherical geometry of particles in forming of granular materials. Three-dimensional equations of motion solved for individual elements in a small time step are expressed in vector forms to make the three-dimensional formulation easy. For the detection of the contact between the elements, a polynomial equation derived from the two curved surfaces of the ellipsoids is not solved but a common normal to surfaces of the two elements is iteratively calculated. This leads to a simple treatment and stable solution for the detection. Elastic repulsive and frictional forces for the contact and force for a viscous material among the particles are applied to the elements. As an example of application, three-dimensional alignment of grains in upsetting of a mushy-state cylindrical magnet is simulated. The calculated degree of grain alignment is in good agreement with that obtained by a model experiment using acrylic grains, a plasticine capsule and Vaseline.

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Advanced calculation due to progress in computing power and the development of mesh-generating capabilities for analyzing structures have led to the need for a pre-processor that can generate an optimal mesh quickly and accurately. Tetrahedron and hexahedron meshes are generally used in structural analysis ; the former is very adaptable to various structural configurations, and the latter calculates accurate results. Using these features, we have developed an automatic mesh pre-processor that can generate a hexahedron mesh for the part requiring precise results and tetrahedron mesh for the remaining part. To conserve displacement compatibility, a pyramidal mesh is used for the interface between these two meshes. Simulation showed that this method works well for finite-element-method modeling of holed-plate extensions and gearings.

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A stress raiser such as notches, holes and structural discontinuity is commonly contained in machine components, which reduces the fatigue life time. The extension of the fatigue life time is quite significant problem in notched components from the viewpoint of engineering. The pre-tensile loading has been extensively known as one of useful means for improving fatigue strength. The fatigue tests, however, showed that pre-tensile loading hardly influenced the fatigue crack growth rate in the notched cylindrical specimen. The stress/strain analysis was conducted for the notched cylindrical component using the elastic-plastic finite element method, where cyclic softening and variation of mean strain were taken into account. The stress/strain analysis showed that compressive residual stress attenuated around the notch root in the fatigue process. Almost no influence of pre-tensile loading on fatigue crack growth seems to be induced by such a redistribution of residual stress occurring during cyclic loading.

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Near-threshold fatigue crack propagation tests were performed on circumferentially precracked round bars of a medium carbon steel under torsional loading or tensile-torsional loading. The applied stress ranges expressed in terms of the stress intensity ranges of mode I, ΔK_I, and mode III, ΔK_III. were divided into three levels : no-crack growth, crack arrest, and fracture. The threshold condition of crack extension from a pre-crack is expressed by the following elliptic function : (ΔK_I/ΔK_{I th})²+(ΔK_III/ΔK_{III th})²=1 where ΔK_{I th} and ΔK_{III th} are the threshold stress intensity ranges of crack propagation for mode I and III, respectively. The threshold condition for fracture is also expressed by another elliptic function. At the intermediate stress ranges, the propagation rate of initiated cracks decreased with crack extension because of the contact of the crack faces. Scanning electron microscopic observation showed the flat fatigue fracture facet made coplanar to the precrack plane at stress level just above the crack extension threshold value for any mode ratio. When the stress level was higher than threshold value and when ΔK_III component was predominant, the fatigue fracture surface turned to be factory-roof type after a small flat extension of a crack.

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Uniaxial tensile fatigue tests were carried out on high strength steel to investigate the relation between fatigue characteristics and fracture origins. The examination compared two surface finishing conditions, one grinding polished by the emery paper and the other electro-chemically polished. The emery paper finished specimens showed a stepwise S-N diagram while the electro-chemically polished specimens had a straight S-N diagram. The sites of fracture origins changed from surface to interior of test pieces as the stress level was reduced on both kinds of test piece. An examination of the initial stress intensity factor range ΔK_ini of fracture origins was interpreted to show that large surface defects in the grinding condition lowers the fatigue strength of surfaceoriginating fractures, resulting in the stepwise S-N diagram. Interior-originating fractures showed that cracks originate and propagate from inclusions with much smaller ΔK_ini than the surfaceoriginating cracks.

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A simple method to evaluate cyclic fatigue strength in ceramics was proposed using load range, ΔP-increasing procedure and applied for silicon nitride. The proposed method enabled to obtain statistical property of cyclic fatigue strength by much less number of specimens compared to that required in the conventional procedure of statistical fatigue tests. The ΔP-increasing condition was expressed by initial value of maximum stress, σ_{max, 1,} and increasing rate of maximum stress, dσ_max/dN. These parameters influenced the maximum stress at failure, σ_{max, f}, which could be approximated by two-parameter Weibull distribution. P-S-N curve was estimated by two Weibull distributions under different ΔP-increasing conditions based on the assumption of crack growth law and of linear cumulative damage law. The estimated P-S-N curves were independent of the assumptions and agreed with the experimental data obtained under ΔP-constant condition at the higher stress level, while it was conservative under lower stress level.

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Corrosion fatigue test of Type 403 stainless steel was performed under constant frequency of 5 Hz in pure water at room temperature in order to evaluate the effect of loading and MnS inclusion on the initiation of corrosion pits. Corrosion pits initiation which is the initial phenomenon of corrosion fatigue damage occurs on the MnS inclusion which appears on the specimen, and crack initiation depends on the shape, size and distribution of MnS inclusion in the matrix. Therefore it was clarified that fatigue strength can be improved by suppressing the formation of MnS inclusion which reduces the fatigue strength. And applied loading will act on the dissolution of MnS inclusion. Therefore, it was considered that corrosion pits initiated even in the pure water due to the change of water chemistry near the MnS inclusions for their dissolution.

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In this paper, we investigate crack extension behaviors for a linear elastic body with a parallel interacting crack at the neighborhood of the main crack tip. We compute the energy release rate for all the crack tips at the onset of a main crack kinking : E integral is path independent even for a path containing a kinking crack tip and/or the interacting crack tips ; however, for such cases, the well-known J-integral is not path independent. As a result, assuming the isotropy of fracture toughness of the body and judging from the criterion based on the energy release rate, we find that there exist the relative positions of the interacting crack which promote or interrupt the straight extension of the main crack and which make the main crack jump to an extension of an interacting crack.

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In order to clarify the dynamic response of a fluid-filled crack in the earth's crust, dynamic elastic response of a penny-shaped fluid-filled crack is studied, emphasizing the effect of fluid viscosity, permeability of rock and the stiffness due to contact between the asperities on the upper and lower surfaces of the crack. It is revealed that the eigen angular frequencies normalized by C_r/a (C_r : S wave phase velocity, a : crack radius) are governed primarily by the crack interfacial stiffness. The aspect ratio, i.e., the ratio of the crack radius to the initial aperture of the crack, has only weak effects on the normalized eigen angular frequencies except for the case of a crack that is completely open initially. It is also revealed that, for larger crack interfacial stiffness, the normalized eigen angular frequencies become smaller with permeability and attenuation becomes stroger with permeability. When crack interfacial stiffness is absent, permeability has weak effect on the normalized eigen angular frequencies and intensity of attenuation.

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This paper treats the three-dimensional elastic problem for a nonhomogeneous medium whose shear modulus G increases with coordinate variable z according to relation G (z)=G_o (1+z/a)^m (G_o, a and m are constants). The fundamental equations system for such nonhomogeneous medium is given by using three kinds of displacement functions. As an analytical model, a nonhomogeneous semi-infinite body subject to an arbitrary shaped distributed load on its boundary surface is considered. Numerical calculations are carried out for several cases taking into account the variation of nonhomogeneous elastic properties, and the numerical results are shown graphically.

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In this study, the theoretical analysis of a three-dimensional thermal stress problem is developed for a multilayered anisotropic laminated plate due to partially heat supply in a transient state. As an analytical model, we consider a laminated rectangular plate consisting of an orthogonal pile of layers having orthotropic material properties, i.e. a cross-ply laminate. We obtain the exact solutions for the three-dimensional temperature change in a transient state and three-dimensional transient thermal stresses of a simple supported plate. As an example, numerical calculations are carried out for a 3-layered cross-ply laminate, and some numerical results for the temperature change, the displacement and the stress distributions are shown in figures.

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In this study, a neural network is applied to optimization problems of material compositions for a nonhomogeneous plate with arbitrarily distributed and continuously varied material properties such as Functionally Graded Material. Unsteady temperature distribution for such nonhomogeneous plate is evaluated by taking into account the bounds of the number of the layers. Furthermore, the thermal stress components for an infinitely long nonhomogeneous plate are formulated under the mechanical condition of being traction free. As a numerical example, the plate composed of zirconium oxide and titanium alloy is considered. And, as the optimization problem of minimizing the thermal stress distribution, the numerical calculations are carried out making use of neural network, and the optimum material composition is determined taking into account the effect of temperaturedependency of material properties. Furthermore, the results obtained by neural network and ordinary nonlinear programming method are compared.

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To learn and understand the mechanics of materials in the curriculum of mechanical engineering the students are expected to be experienced to solve the exercises, however it is difficult at the present situation to expect the almost students to exercise spontaneously and positively. Therefore the authors have developed CAI program to assist the students to be interested in the study of the mechanics of materials through the exercise via CAI. In order to evaluate the progress of the students in understanding of the mechanics of materials through the CAI exercise the authors introduced a neural computer whose neural network was programmed to correlate the results between the CAI exercises and the past examinations of the mechanics of materials, therefore the students can estimate a test score at the next examination according their results of the CAI exercise using the neural computer. Comparison of the average test scores between the students with and without the experience of the CAI exercise, i.e. the students experienced the CAI exercise obtained 10's points in average better than the another students, verified that the CAI program proposed in the present paper is available to improve the education of the mechanics of materials.

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Characteristics of the stress intensity factor of a circumferential crack in a cylinder under radial temperature distribution, which can be regarded as linear, were investigated systematically ; by applying the simplified method previously developed by the authors. The investigation was conducted to comprehend the previously reported fact on the stress intensity factor : the stress intensity factor under a given temperature distribution tends to decrease after it reaches the maximum, as the crack becomes long. It was shown that this tendency was a fundamental characteristic of the stress intensity factor for the problem, and was concluded that the cause of this was the moment redistribution due to the increase in crack length. In addition, it was pointed out that the stress intensity factor of a specific cylinder length was larger than that of an infinite length.

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Devices of thin film in the high-Tc superconductor are subjected to thermoelastic loads because they are processed in high temperature and operated in cryogenic temperature. Serious problems exist in the reliability of the devices due to thermal stresses. In this study, the stress distribution and singularity near the edge of the interface between a thin film and its substrate are discussed by thermoelastic analysis. A boundary element method using fundamental solution of dissimilar materials is extended to the thermoelastic problem. The stress distribution near the edge of the interface can be calculated with high accuracy, because there is no boundary integral terms at the interface. The singular stress field near the edge of the interface is also obtained.

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This paper presents the theoretical solutions of a two-dimensional isotropic elastic medium (matrix) containing many different isotropic circular elastic inclusions under uniform out-of-plane shear stresses at infinity as well as a point force or screw dislocaton at a finite point. This analysis is based on the complex variable method using the Mobius transformation. Using these solutions, several numerical examples are shown by graphical representation.

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The present paper discusses a plane strain problem of transient thermoelasticity in a circular cylinder which is in asymmetric contact with rigid bodies. Employing Airy's thermal stress function, this problem can be formulated in terms of a dual-series equation which is reduced to a simultaneous algebraic equation by means of Neumann's series. The radial, hoop and axial stresses have singularities at the end of the contact surface of the cylinder. The stress singularity coefficients are introduced and the relations among three coefficients are derived. Finally numerical results for the temperature, radial displacement, stresses and stress singularity coefficients are illustrated graphically.

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An elastic-plastic-viscoplastic constitutive equation has been proposed in which the understress is introduced to the plastic strain and the overstress is employed for the viscoplastic strain. The constitutive equation has a form in which the inelastic strain component is consists of steady and unsteady component. Using the equation, an analysis on the one-dimensional wave propagation in the uniaxial stress state at the spacial coordinate is done by the characteristic method. As the results, equations describing the wave propagation speed and the relation of the every physical quantities in Eulerian coordinate. Also, it is shown that the theories are derived of an elastic-plastic, elastic-viscoplastic and longitudinal elastic wave propagation in Eulerian coordinate from that of the developped elastic-plastic-viscoplastic wave propagation.

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A nonaffine molecular chain network model of glassy polymers in which the number of entangled points of molecular chains may change according to the local distortion caused by the deformation and the temperature increase has been developed. A simple evolution equation which correlates the number of entangled points to the distortion and the change of the temperature has been proposed. Subsequently, the corresponding three-dimensional thermo-elasto-viscoplastic constitutive equation is developed. The finite element simulations with the proposed constitutive equation has been carried out for the glassy polymer blocks under plane strain tension and simple shearing. It is clarified that the neck and shear band propagate under low deformation rate, whereas they stay at their initial location due to the excessive softening caused by the temperature increase as compared with the orientation hardening. In simple shearing, the high temperature area corresponds to the significantly distorted area, while, in tension, they are different. Thus, the contributions of temperature and distortion on the reduction of the number of entangled points are different depending on the deformation modes.

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Full gear rolling, that is one of plastic working methods, has a lot of merits of cost. But it has some problems for practical employment. One of the most principle problem is lap defect. It is initiated on follow side addendum after rolling process. Therefore the aim of this study was simulating full gear rolling process and solving the lap defect problem with use of FEM analysis by MARC. It was high performance analysis because of the simplification of FEM analysis modeling and made the reduction of total calculating time. The main results were as follows. (1) High performance FEM analysis on full gear rolling process could be carried out in order to examine the locus of rolling dies movement. (2) Lap defect was caused by the difference of material flow between follow and driven side on pinion tooth. (3) Initiation and growth of lap defect could be shown on computer simulation and the result of FEM analysis was roughly the same as the results of proof test. (4) It was suggested that control factor of lap defect was work-hardening exponent (n value). Therefore, blank, which has low n value, makes large lap defect.

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The effect of the mesostructure of Si₃N₄ particulates and PAI resin film on the wear of the film surface due to sliding motion of paper were experimentally examined in respect to the self-lubrication. And wear process of this hybrid resin film was simulated visually on the computer. We tried to examine wear mechanism by means of the visual simulation. The results were as follows. (1) Wear amount of mesostructural resin film due to the sliding of paper has been reduced approximately to one tenth as compared with conventional epoxy plastic film. (2) Rolling and sliding trace of Si₃N₄ has been observed over the film surface in the sliding direction of paper after sliding the paper. The trace that was found in this instance can be called as Meteoric Track. (3) We closely looked at the particle movement, made a simple model, and simulated visually. By this simulation, we could observed the particle behavior and meteoric track behavior of wear process which is not possible at actual experiment. (4) The change of wear volume in the simulation almost agreed with that of experiment. So, this simulation was suitable, and can analyze the Meteoric Wear. And, we propose the new evaluation expression of Meteoric Wear by modifying Rabinowicz's abrasive wear model.

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Crack healing behaviour of monolithic Si₃N₄ and Si₃N₄/SiC composite have been investigated, systematically. In these ceramics, 8 wt.% Y₂O₃ was used as a sintering additive. The semicircular crack (average diameter was 110 μm) was made in the center of specimen using Vickers hardness indenter. Some of the cracked specimens were heat-treated at 1 300°C for 1 hour in air or in argon gas atmosphere. Bending strength was measured at room and elevated temperature up to 1 300°C in air by 4-point bending test system. Bending strength was measured at room and elevated temperature up to 1 300°C in air by 4-point bending test system. Bending strength of cracked specimen reduced to about 50% of that of smooth specimen. However, bending strength of pre-cracked and heat treated specimen recovered completely up to that of smooth specimem. And in most specimens tested, failure occured from the outside of pre-cracked area even at 1 300°C. By the systematical investigation, it is concluded that crack healing due to oxidation results the recovery in bending strength since precrack was filled in oxides, such as Y₂Si₂O₇ and SiO₂, which were produced by heat treatment in air. Crack healing behaviours in the both ceramics were also investigated, as a function of heat treatment temperature and times, initial crack size and bending test temperature. Based on the these results, it was concluded that crack healed part in Si₃N₄/SiC composite ceramics has enough strength up to 1 300°C.

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The Weibull distribution of the bending strength of silicon nitride specimens ground parallel to the longitudinal direction was measured before and after proof testing. The effect of grinding residual stresses on crack growth and strength degradation during proof testing was investigated. The results were obtained as follows : (1) The stress intensity factor K_res due to grinding residual stresses was negative for a dominant surface crack in bending specimens. Grinding residual stresses serve to inhibit crack growth during proof testing. (2) As the length of a dominant surface crack grown stably by proof testing got large, the stress shielding effect due to K_res became small. (3) Apparent strength degradation during proof testing occurs when the proof stress for ground specimens is set to higher values than that for lapped specimens with the increment of the bending strength due to grinding residual stresses taken into account.

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The strength of Al-Al₃Ni functionally graded material (FGM) has been studied through 3-point bending experiments for two different manufacturing conditions. Specimens with rectangular cross-section of 8 mm thickness×9 mm width are machined from thick-walled tube, which are manufactured in laboratory and vacuum atmosphere. They have graded compositions of Al₃Ni phase in aluminum matrix in the radial direction. The nominal volume fractions of Al₃Ni phase at the crack initiation site are V_f=41 and 15 vol.% under air, and V_f=35 and 0 vol.% under vacuum casting. Fracture of specimens occur more abruptly in the case of specimens manufactured in air than those made under vacuum condition. The fracture strengths are calculated from maximum bending load considering the graded Young's modulus and are plotted on the Weibull probability sheet. Each data set obeys a good linear relationship and the reliability of strength data is better in case of vacuum specimens. The average value of fracture stress improved with increase of volume fraction of Al₃Ni for both the manufacturing conditions. However, in the case of vacuum manufactured specimens, coefficient of variation is small. The bending strength of Al-Al₃Ni FGM is controlled by size, shape and distribution profile of Al₃Ni particles, because the cleavage fracture of Al₃Ni phase dominates the fracture process.

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The effect of microstructure, especially DAS II (Secondary Dendrite Arm Spacing) and chill layer in ADC10 aluminum alloy die castings on the tensile properties, the fracture toughness and the crack propergation is examined by preparing the die castings which have different DAS II and different thickness of chill layer cast under several casting conditions by cold chamber die casting machine. The results are as follows. (1) The tensile strength increases with the decrease in DAS II and there is the Hall-Petch relation between DAS II and 0.2% proof stress. While DAS II doesn't affect the fracture strain. (2) As a crack propagates through the boundary between α-phase and eutectic Si crystal, the increase in DAS II makes the fracture surface be rougher and it causes the increase in the fracture toughness. (3) The tensile strength and the surface hardness of chill layer are higher than substrate. It is possible for the reason to be not only relaxation of stress concentration due to small DAS II but also strengthening by solid solution due to the larger amount of occluded copper and magnesium.

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A series of stress corrosion cracking (SCC) tests was carried out on the peak-aged Al-Li-Cu 2090 alloy plates to examine the effect of zinc addition on static- and dynamic-SCC properties. The alloy with 0.7% Zn addition showed an improved static-SCC resistance in the S-L direction. The reference 2090 alloy exposed to aqueous sodium chloride solution exhibited an accelerated dynamic-SCC growth in the T-L direction, relative to exposure to laboratory air, while the alloy with Zn addition revealed a reduced environment-sensitive crack growth. The dynamic-SCC was transgranular, the crack path appearing tortuous, which is assumed resulting from localized planar slip associated with {110} <211> texture and inhomogeneous distribution of T₁ precipitates. It was found that Zn addition is effective in reducing the slip planarity and preferential dissolution along slip bands.

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This paper shows the optimal placement method of distributed actuators for static deformation control in composite structures where the deformation of laminated plates is controlled using piezoelectric actuators bonded symmetrically to the laminate surfaces. The actuator locations are determined sequentially one by one so as to minimize the objective function which consists of the norms of the deformation and the actuator voltage. The optimal voltage for the specified actuator locations is obtained by the least squares method. The present method is verified by several numerical examples for laminated plates under various loading conditions.

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Long fiber effects on static and fatigue strengths of discontinuous glass fiber reinforced thermoplastics with polypropylene matrix (FRPP) were examined. The FRPP were fabricated using the long fiber pellets (the longest type : 25.0 mm) in the new press-injection molding method [called Casting and Compression Molding (CCM)], which can reduce the fiber breakage. Microscopic observation was combined with mechanical testing and acoustic emission monitoring to study details of the damage accumulation process. Maximum stress and fatigue life all increased with increasing fiber length on each condition. Mechanical response, acoustic emission signatures and micrographs of the fracture surfaces all showed a fiber length dependent transition in failure mechanism. Especially, it was induced that long fiber was effective in increasing the fatigue strength as the fatigue life became short. Results show the practical way of the material design to make the most effective use of the long fiber composites.

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Ductile-brittle transition of the material fracture is studied in terms of the fractal dimension measured on the fractured surface. The tensile fracture tests are conducted for notched round bar specimens made of carbon steels. The notch radius and the carbon content of materials are changed to produce the ductile-brittle transition in the fracture. The fractal dimension is correlated with the absorbed energy. Two distinct regions appear in the plots of fractal dimension vs. absorbed energy : the fractal dimension for brittle fracture surface varies with observing scale, while that for ductile fracture remains almost constant. The variation in fractal dimension for brittle fracture surfaces can be interpreted by the size effect of brittle fracture.

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Fracture condition of brittle materials under unloading process was analytically discussed by using the fundamental equations and the constitutive equation between a and K_I (a ; the crack velocity, K₁ ; the stress intensity) used by Fuller et al, who formulated the truncated strength as the function of unloading rate in proof test. Whether or not the fracture criterion K₁=K_IC used in their analysis and their analytical results is physically acceptable has been rechecked out from a standpoint of survival condition without using any fracture criterion. By the present analysis, it has been cleared not only that the fracture criterion K_t=K_IC used by them has been not sufficient to represent fracture and survival condition in proof test but that the truncated strength in proof test of brittle materials does not exist as far as the materials are rate sensitive.

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Changes in electrochemical properties of directionally solidified Ni-base superalloy CM 247 LC due to creep have been investigated. The electrochemical polarization technique has been applied to creep-ruptured and creep-interrupted specimens under various creep condition in order to examine a detectability of creep damage. Experimental results on electrochemical polarization measurements revealed that the peak current density "I_p" and "I_pr" which appeared at a specific potential during potentiodynamic polarization reactivation measurements in dilute glyceregia solution increased with increased thermal history and showed a good correlation with Larson-Miller Parameter value. I_p and I_pr value reflected both a thermal aging effect and a stress effect, and increased with a creep life fraction. The increases in I_p and I_pr were mainly corresponded to increases in preferential dissolution rate of γ' phase at γ/γ' interface. This preferential dissolution was considered as a result from degradation of corrosion resistance of γ'phase at γ/γ'interface which may be attributable to creep damage accumulation. As a consequence, the creep damage in CM 247 LC can be quantitatively evaluated by the electrochemical technique.

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In this paper, corrosion damage in the modular femoral hip prosthesis which is retrieved from the physiological environment for 58 months after insertion, has been analyzed with the parameter of the square root of projected area of corrosion pit from the view point of fracture mechanics. The effects of the pitting damage on fatigue properties of Ti-6Al-4V alloy was discussed based on the previous experimental result. Accelerated laboratory corrosion testing method which simulates the physiological corrosion environment has been developed on the basis of the results of corrosion test in simulated environment with Ti-6Al-4V alloy. The empirical formula which represents the relationship of applied current, corrosion time and maximum size of corrosion pit (√(area)_max) has been proposed.

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We need very high magnetic field and hence large Superconducting Magnet to meet a demand of ITER (International Thermonuclear Experimental Reactor). So we need high rigidity SC magnet, which contribute the accuracy of the generate magnetic field. To design the high rigidity magnet we need firstly to estimate the rigidity of SC magnet from its form, dimension and the number of turns and layer. At a glance the basic unit of the rigidity seem to be each conduit. But we found that is false in experiment and FEM. So we defined proper basic unit of the conductors, and made it connected with full model of SC magnet conductors. This method of evaluating can be applied any other new developing form conductors and magnet.

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