In this repot, we obtained the useful results of the stress and deformation of an underground pipe fixed at both ends and subjected to the soil pressure due to a vertical concentrated load acting on the surface of the ground by the method proposed in the previous paper. Numerical computations were carried out for the more various cases and the results were shown graphically to be practical use.

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Procedure to analyze the crack initiation under strain path changed during multiaxial low cycle fatigue is developed based on a damage mechanics approach. The fatigue tests of pure copper are conducted to investigate the crack initiation behavior for changing biaxial strain ratio during low-cycle fatigue. The parameter referred as the intensity of slip band is used to describe the oriented distribution of slip band and the crack initiation life depending on the strain biaxiality. A model for the crack initiation under multiaxial stress states is proposed assuming the non-linear accumulation of the intensity of slip band. The estimation based on the proposed model showed a good agreement with the experimental results when compared with the result by Miner's law.

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Fatigue damage accumulation induced by rotating bending (RB) and cyclic torsion (CT) is examined on a low carbon steel. The effect to the load sequence on fatigue damage accumulation was investigated microscopically as well as macroscopically. The loading type of RB-to-CT switching strengthened the fatigue life of the second stress cycle, while the fatigue damage accumulated linearly in the case of CT-to-RB loading. This trend of load sequence effect on the fatigue damage accumulation is clarified through microscopic observation of the fatigue process. The fracture mechanics-aided interpretation of the microcrack growth behavior from the slip band cracking to visual crack also supports this tendency.

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Several studies have been performed concerning the effect of pre-strain on fatigue strength. According to their general trends, the fatigue strength decreases due to small pre-strain and it increases with further pre-strain. In this paper, the physical background of pre-strain is investigated based on the successive observations of fatigue damage on the specimen surface. As a factor in pre-strain, the change in mechanical properties is observed, for example the increase in yield stress and the decrease in reduction of area. A close relation between the change in mechanical properties and the crack initiation life is hardly observed, and the effect of pre-strain on initiation life is very small. On the other hand, the effect of pre-strain is observed in propagation behavior, that is, the crack propagation life decreases due to small pre-strain and it increases with further pre-strain. The change in propagation life due to pre-strain can be evaluated approximately by its mechanical properties.

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A method based on crack closure was proposed to predict the growth rate of short fatigue cracks in either smooth specimens or notched specimens. The material properties used in this prediction were the growth behavior of long cracks and the fatigue limit of smooth specimens. The predicted results for notched specimens showed that the growth rate of short fatigue cracks first decreased with crack length, and then increased when the applied stress range was high or kept decreasing to zero when the range was low. Good agreement was obtained between the predicted results and the experimental results of a low-carbon steel. In the case of smooth specimens, the predicted results showed that the crack growth rate increased continuously with crack length. The difference in the growth behavior between notched specimens and smooth specimens was attributed to the difference in the increasing rate of the maximum stress intensity factor, K_max, with crack length ; for a crack at a notch root, the increasing rate of K_max may be smaller than the increasing rate of crack opening stress intensity facto, K_op.

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The propagation behavior of short fatigue cracks formed at a notch root was studied by using low-carbon steel plates with center notches of various tip radii. The development of crack closure with crack growth was measured through the compliance method. Although the growth rate of short cracks was higher than that predicted from the rate-ΔK relation for long cracks, it was uniquely related to the effective stress intensity range and the relation was identical for long cracks. The increase in K_op with increasing crack length was independent of the notch root radius. The length of a non-propagating crack was affected by the notch root radius when it was a short, part-through crack. As the length of a non-propagating crack became longer, the threshold stress intensity range increased and the effective opening fraction decreased. The threshold value of the effective stress intensity range took a constant value irrespective of the crack length.

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To examine the effects of the surface finish and defects on fatigue limit, specimens differently finished, i. e., sand paper (Grade #600, #80) finish and electrolytic polish, were prepared. Moreover, to simulate surface defects, a small artificial hole of which diameter is varied from 40 to 200 μm is introduced on the specimen surface. Both as-received and annealed specimens were applied so as to extract the effect of the work-hardened surface layer on the fatigue limit. Through examination of the fatigue limit and ten non-propagating crack the following results are obtained: (1) the surface roughness slightly influences the fatigue limit, while the work-hardened surface layer has a primary effect on the fatigue limit. (2) An increase in the diameter of the small hole decreases the fatigue limit and results in the prolongation of the non-propagating crack. (3) For the non-propagating crack, the threshold stress intensity factor range ΔK_th decreases with a decrease in the crack length.

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It has become clear that the damage on the contact surface is much affected by the tangential force. However, it seems that its influence over the wide range of contact conditions still remains quantitatively indefinite. In this study, some experiments were performed under various unlubricated contact conditions of a hard metal sphere against a hard metal surface subjected to the oscillating tangential force with several static normal loads. The occurence of damage (especially cracking) on the surface in the contact field without any macro slip has been observed. The effects of the normal load and the range of the oscillating tangential force on the occurence of surface cracking and its advance have been investigated. It was also found that these effects can be explained using stress field.

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Fatigue tests were carried out under a Gaussian type block- and random loading, using a newly developed computer- controlled high-speed fatigue testing system equipped with a random wave generator based on the matrix method. It was found that the fatigue life under random loading is shorter by half than that under block loading even for the same frequency distributions of the loads. A simple life-prediction procedure was developed by considering the local stress-strain behavior and fatigue damage parameter concept. The predicted fatigue life agreed well with the test results under block loading in different mean load level conditions. In the case of random loading also, the life prediction gave satisfactory results, but it was necessary to assume a value of critical fatigue damage accumulation of 0.5 instead of unity.

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Fretting fatigue tests on leaf springs and small axial-loading specimens were carried out under constant loading and random loading simulating field load spectra. The results of leaf springs were compared with the literature data for similar springs. The behavior of fretting fatigue crack initiation and propagation in the leaf springs was found to be almost the same as those in the small laboratory specimen. No significant differences between their fretted surfaces or between their fatigue fractured surfaces were observed. Random loading reduced the fretting fatigue lives by a factor of 1.5. The effects of shot peening on fretting fatigue were also investigated. Shot peening improved the fretting fatigue strength in both specimens by a factor of two. The residual compressive stress induced by the shot peening process was attributed as being the controlling factor to the improvement. It was suggested that the fretting fatigue life of leaf springs can be estimated from that of laboratory specimens, if the clamping pressures and the relative slip amplitudes of both the specimens have the same magnitudes.

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The effects of loading history on threshold stress intensity range (ΔK_th) were investigated in a low alloy steel SFVQ1A (A508-3) and a low carbon steel S10C. A single overload and multiple overloads were chosen as loading history. Crack growth and crack closure following the loading histories were measured at load ratios of 0.05 and 0.07. Threshold values were determined as a fatigue limit of preloaded specimens. The ΔK_th values increased with increasing overload stress intensity factor (K_h). For a given K_h value, multiple overloads produced much larger increase in ΔK_th than a single overload and threshold values expressed by maximum stress intensity factor (K_{max, th}) were almost constant, independent of stress ratio. The results obtained were discussed in terms of crack closure behavior, and a method was proposed to evaluate the threshold value based on plasticity-induced crack closure.

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Investigations have been made on the fatigue crack propagation behavior of surface pre-cracks in tensile residual stress fields induced by water-cooling from the temperatures of 873 K and 673 K, as well as in no residual stress fields. The analysis for a three-dimensional crack in an infinite body, proposed by R.C. Shah and A. S. Kobayashi, has been used for determining the stress intensity factor of a surface crack, in consideration of the correction factor for a finite plate. The fatigue crack growth law of surface cracks, depending on the maximum K_max as well as the range ΔK of the stress intensity factor, has been obtained from fatigue tests under various mean stresses. The effect of tensile residual stress distribution on the fatigue crack propagation rate of surface pre-cracks has been found to be quantitatively evaluated by the use of the proposed fatigue crack growth law, in which K_max was calculated from the maximum stress distribution including residual and applied stresses. Also, the shape of surface fatigue cracks has been found to be dependent on the residual stress distribution.

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Most structures have a region where stresses concentrate, and the probability of fatigue crack initiation may be higher than in other parts therefore, to improve the reliability of an LBB design, it is necessary to evaluate the growth and through thickness behavior of fatigue cracks in the stress concentration part. In this paper, a fatigue crack growth test at a stress concentration region has been made on 3% NiCrMo and HT 80 steel. Stress concentration is caused by a fillet on the plate. The main results obtained are as follows : (1) Before cracking through the plate thickness, stress concentration has a remarkable effect on the fatigue crack growth behavior and it flatens the shape of a surface crack. The crack growth behavior can be explained quantatively by using the Newman-Raju equation and the stress resolving method proposed by ASME B&P Code SecXI. (2) The da/dN-ΔK relation obtained in a stress concentration specimen shows good agreement with that obtained in a surface cracked smooth specimen. (3) It is shown that stress concentration caused by a fillet has little effect on the crack growth rate after cracking through the plate thickness. (4) By using the K value based on eq. (1), (2), particular crack growth behavior and the change in crack shape after cracking through thickness can be explained quantatively.

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Micro-crack initiation and growth behavior were observed on the surface of nondegraded and degraded CrMoV cast steels under various strain wave shape loadings at a high temperature. The degraded steel was taken from the inside of a main steam valve casing after 140 000 h of service. No significant difference in crack growth behavior was observed in low cycle fatigue in both steels ; however, the crack growth rate in the degraded steel was higher than that in the nondegraded one in creep fatigue under S-F straining. This was caused mainly by coarsened grain boundary carbides. A residual life assessment method, based on micro-crack growth and the statistical properties of micro-crack length distribution, gives an estimation close to the experimental results.

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Near-threshold fatigue crack propagation properties were investigated for Cr-Mo-V steel at elevated temperature of 200, 300 and 400°C under testing frequencies f=0.5, 5 and 50Hz. The results were compared with those for SB42 and SUS304 steels in the previous work. The main conclusion obtained are as follows : (1) At f=50Hz, Aunique ΔK-value of about 2.8MPa·m^1/2 was obtained, independently of material and temperature, at high stress ratios where the closure did not occur, while ΔK increased at low stress ratios due to oxide-induced closure. (2) The crack propagation rate exceeded the value at room temperature and generally with a more pronounced degree with increasing temperature and decreasing frequency. (3) Intergranular cracking, which might be related to creep damage, was not found even at the highest temperature of 400°C and the lowest frequency of 0.5Hz in this work.

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The fracture behavior of three-layered stainless plates was investigated, related to each layer thickness. The layered plates were prepared by explosive bonding. The central layer consisted of a SUS 304 plate and both surface layers consisted of SUS 316 LN plates. The fracture toughness test for the plates was conducted at 77 K. Every crack was extended in the edgewise direction of each plate. The experimental procedure conformed to ASTM E 813-81 standards. The crack extension of the plates were calculated as the average of the ones in the flatwise direction. It is understood that the elastic-plastic fracture toughness, J_IC, and the tearing modulus, Tmat, increase with an increase in the total thickness of SUS 316 LN of both surface sides, and these values correspond with the law of mixtures. The J_IC and Tmat, which were evaluated by the crack extension of the central SUS 304 layer only, are higher than those of the SUS 304 base material.

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Quench cracking and distortion are generally considered to occur under united thermal and transformational stresses. In this paper quench residual stresses were examined by using a S 55 C steel bar. Various polyalkylene glycol (PAG) solutions and oil were prepared for the quench cooling solutions. The micro structure of the test piece was observed with a metallurgical microscope. The residual stresses caused by quenching were measured by Sachs' method. Considerable tensile and compressive stresses existed on the surface and in the center of the steel. The distribution of stresses and the hardness were related to the PAG content and could be explained clearly by the quench cooling rate.

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A discussion was made on the initiation of grain-boundary fracture during creep and the toughening mechanism in heat-resisting alloys, using two kinds of continuum mechanics models which incorporated the recovery effect by diffusion of atoms. The result of the calculation based on these models was compared with that of the creep rupture tests on austenitic 21Cr-4Ni-9Mn steel. These models were than applied to the prediction of the rupture life in creep. A good correlation was found between the result of the calculation based on the models and that of the experiment. Further, a simple heat treatment was proposed for the improvement of the creep-rupture properties.

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The fracture strength was varied by changing an inter-grip distance (which we call a gage length here) of a sharply center-notched tensile sheet specimen of unsaturated polyester resin, where the specimen width, thickness, crack length and loading method were kept constant. The loading method is such that the main load works on a central-line parallel to the axis of loading which crosses perpendicularly the central crack length. We call this an inside loading in contrast to an outside loading (1). The number, density, area ratio of fracture surface marks vary with the fracture strength of the material. The total number of marks increases with the fracture strength. The density and area ratio marks increase at each different rate with respect to fracture strength. These results are discussed with the analytical relations of the fracture strength, the dynamic stress-intensity factor and the dynamic strain-energy-release rate by employing the reported relations. The fracture surface marks are examined by the two-dimensional equation of fracture surface marks, and the analytical area ratio of the marks is also calculated.

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The strength evaluation of adhesively bonded scarf joints having adherends of similar materials was investigated both analytically and experimentally, in order to establish the strength design of adhesive bonding. The strain and stress distributions in the joints of carbon steel (S45C) bonded with epoxy resin were analyzed by applying the elastic finite element method. The strength of the joints was predicted by applying the strength laws to the adherend, adhesive layer and their interfaces. The validity of the predicted joint strength was confirmed by the experimental results. The effects of the joint dimensions on the strength were examined by varying the overlap length (or scarf angle) and the adherend thickness. The analytical strain distributions were in good agreement with the experimental ones. The results of strength prediction coincided approximately with the experimental ones, so the joint strength was successfully predicted by applying the strength laws to those analytical results.

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The strength evaluation of adhesively bonded scarf joints having adherends of dissimilar materials was investigated both analytically and experimentally, in order to establish the strength design of adhesive bonding. The strain and stress distributions in the joints of dissimilar materials bonded with epoxy resin were analyzed by applying the elastic finite element method. The strength of the joints was predicted by applying the strength laws to the adherend, adhesive layer and their interfaces. The validity of the predicted joint strength was confirmed by the experimental results. The effects of the mechanical properties on the joint strength were examined by varying the materials of the adherends. The analytical strain distributions were in good agreement with the experimental ones. The results of strength prediction coincided approximately with the experimental ones. The deformation state and fracture process of the joints having adherends of dissimilar materials were remarkably different from those of the joints having adherends of similar materials.

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For the study of fracture criteria, adhesive tensile strengths (σ_Y) of scarf joints with a scarf angle of 30^o and butt joints bonded by a brittle epoxy adhesive A and a ductile epoxy adhesive B have been measured at adhesive layer thickness (h) from 0.05 to 5.0 mm, and three-dimensional elastic finite element analyses have been performed. σ_Y of each joint decreased with an increasing value of h. A brittle fracture occured on the scarf and butt joints bonded by adhesive A and the butt joints bonded by adhesive B. The fracture of scarf joints A and B satisfied a maximum principal stress criterion and the von Mises criterion, respectively. Gradients of σ_Y-h curves for butt joints A and B were greater than those predicted from the results of stress analyses. The location of fracture initiation and fracture modes of adhesive layers observed with an optical microscope agreed with those expected from the results of experiments and stress analyses.

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This paper deals with a two-dimensional stress analysis of adhesive butt joints subjected to tear loads. The purpose of the present paper is to contribute to an establishment of the fracture criteria of joints. Similar adherends and an adhesive bond are replaced with finite strips in the analysis. Stress distributions in adhesive joints are analyzed by using the two-dimensional theory of elasticity. The effects of the ratio of Young's modulus of adherends to that of the adhesive and the thickness of adhesive bonds on the stress distributions are shown by numerical computations. For verification, experiments are performed with respect to the strain of adherends. The analytical results are in fairly good agreement with the experimental ones.

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A method of solution of the bucking load and the bucking mode of the general axisymmetric shell due to some axisymmetric load considering the non-linear prebuckling deformation is proposed is this study. This problem has been already treated by many general purpose programs using the finite element method or the finite difference method. But it is said that these programs often give somewhat different results from each other for non-linear problems. In this study, a method is proposed to achieve results as accurate as possible. Our method is based on Flugge's shell theory and makes use of the finite difference method. As examples, the partial spherical shell, the tori-spherical head of a pressure vessel and the U-shaped bellows are treated, and some calculated results are compared with those of other researchers.

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An efficient alternating method is developed for the analysis of a group of interacting elliptical cracks in an infinite solid. In this alternating method an analytical solution for an elliptical crack in an infinite solid is used. To save computation time, the geometrical symmetries of crack shapes and locations are effectively utilized in conjunction with the symmetry of the analytical solution with respect to the Cartesian coordinate system. Parametric studies on the interaction behavior of multiple coplanar elliptical cracks are made for several example problems. The stress intensity factors for those problems are determined efficiently and accurately by the present alternating method.

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This paper deals with the dynamic interaction among Penny-Shaped cracks under a normal impact load. Laplace and Hankel transforms are used to reduce the mixed boundary value problems to a set of dual integral equations. The solution is expressed in terms of a Fredholm integral equation of the second kind having a kernel with fast rate convergence. A numerical Laplace inversion technique is used to recover the time dependence of the solution. The dynamic stress intensity factor is determined and its dependence on time and the geometry parameter is discussed.

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The elastic analysis of a crack in a finite height plate is presented. The crack opening displacement is calculated for the cases of roller-fixed type and rigid-fixed type clamps, with changing the position and length of the crack. The continuously distributed dislocations model is employed for the analysis. The results show that the profile of the crack opening displacement has peaks which exceed the applied displacement in the case of long cracks.

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The thermal and mechanical properties of materials vary with temperature, so the temperature dependence of materials must be taken into consideration in the thermal stress analysis of modern structural elements. This paper is concerned with a transient thermoelastic problem in a long circular cylinder exhibiting temperature-dependent thermal and mechanical properties. This problem is solved by the perturbation method. The fundamantal problem for the perturbation method may be treated by the thermoelastic potential function and Love's function, and the n-th problem can be solved by displacement functions.

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This paper deals with a transient thermal stress problem in an infinite circular cylinder whose the heat-transfer coefficient depends on a position. The finite difference method is used with respect to a time variable, because of difficulty in obtaining the analytical expression. Thus, the analytical expression with respect to the spatial variables may be obtained. The temperature solution is reduced to solution of a dual-integral equation. The numerical results of the effect of variation of the heat-transfer coefficient as to a position on thermal stresses are shown in figures.

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Crack energy density is the parameter which is defined clearly, without any restriction on constitutive equation, throughout the life of a crack and is expected to successfully describe all kinds of behaviors of a crack. So it may well be thought that the parameter is defined reasonably for a 3-dimensional crack. The purpose of this study is to indicate the property of crack energy density on 3-dimensional cracks for evaluation of this parameter. The contents of this report are as follows. (1) Define crack energy density on a 3-dimensional crack by using two crack models, and make it clear that the value of crack energy density is determined independently of coordinate system and plane on which the integral path is set. (2) Define crack energy density as a path-independent integral, and compare it with the J-integral of a 3-dimensional crack. (3) Propose a method to estimate the value of crack energy density from load-displacement curves.

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A simple equation of the J-integral proposed by Rice et al does not take consideration of the notch length of the test specimen, although is does into consideration the non-linearity of the materials. So, the J-integral equation which modified the effect of notch length is confirmed for brittle and porous polymeric materials, i. e. RIM Polyurethane at low temperature, in which the skin layers are removed. It is found that the equation can be applied to ductile and porous polymeric materials at a temperature of 20°C. The equation is examined by changing the specimen thickness at that temperature. It is found that the J-integral resistant curve determined by this method is independent of specimen thickness.

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Rice has shown a simplified method for estimating the J-integral of a deeply cracked bend bar, that is J==2U/Bb where U is the area under the load versus the load point displacement curve, B is the specimen thickness and b is the remaining ligament. It has not been made clear, however, how deep is a deep enough crack for finite size specimens. In this study, an applicable range of the Rice formula for the three-point bend specimen used in the elastic-plastic fracture toughness J_IC test is studied analytically. The Rice formula is compared directly with the definition of J as a change in potential energy. Results show that an assumption of a deep crack is required only for a linear elastic material and is not required necessarily for a rigid perfectly-plastic material. In order to obtain the quantitative data, the conditional equation is calculated numerically by varying the crack length for three materials; linear elastic, rigid perfectly-plastic and elastic perfectly-plastic. Results show that the Rice formula is valid when a/W≳0.4 for a linear elastic material. Based on the results, a recommended precrack length of the three-point bend specimen in the J_IC test is newly proposed.

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The buckling deformation behavior of centrally of centrally cracked rectangular plates subjected to a uniaxial tension is analyzed by the finite element method, taking both geometrical and material nonlinearities into consideration. The finite element formulation is based on the total Lagrange coordinate system and the flow theory of plasticity. The effects of an initial imperfection on the crack buckling deformation are studied in some detail. The post-buckling behavior is discussed in relation to the undesired effects on the fracture of cracked plates. The results of elastic analyses show that the magnitude of the stress intensity factor increases after buckling. The results of elastic-plastic analyses and experiments show that the residual strength of cracked plates is reduced due to interactions of the buckling deformation and the plastic deformation at the crack tips.

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A constitutive equation in rate-independent cyclic plasticity was presented with a new plastic potential function depending on the field of resisting force against the movement of dislocations. By extending the model proposed in the previous paper for a uniaxial case, it was assumed in this study that each process of the cyclic deformation under multiaxial loading should be attached to either the to-motion process or the fro-motion process, and a simple rule of conversion from one process to the other was postulated by considering the stress history. Moreover, an effect of anisotropy produced by cyclic deformation was reflected in the internal structure variable which was one of three internal state variables describing the force field. The propriety of this equation without any yield surface has been examined with some experiments obtained from the axial-and torsional-load cycling tests with tubular specimens of a carbon steel.

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The fringe order obtained by the photoplastic test gives important information on the mechanical properties of transparent polymers. However, the effect of viscosity on the fringe order has not been investigated sufficiently. In this paper, the time-dependent photoplastic properties of Cellulose Acetate was examined by means of the recovery test under uniaxial tension. The optical and the mechanical characteristics after unloading were measured as a function of elapsed time. As a result, it was observed that the recovery of both strain and fringe order increase rapidly at first, and then gradually approach constant values. Moreover, the relation between the residual strain and fringe order during recovery is represented in a linear relation independent not only of room temperature but of recovery time. In addition, strain and fringe order obtained by loading below the yield stress vanish completely by unloading and recovering.

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An analytical approach plays an important role in evaluation of fracture toughness of materials and strength of flawed components under the condition of dynamic loading. The present work is an attempt to apply BIEM, in which the derived constraint equations are functions of the Laplace transform parameter, to dynamic SIF analysis. Some remarks are obtained for the series expansions of the kernels and the relationship between time-space solutions and the discretization interval of the Laplace transform parameter. Utilizing the extrapolation method, a calculation is carried out for the dynamic SIF of a crack located on an inner surface of piping.

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In this paper a method is proposed for calculating the large deflection of beams on elastic foundation by the boundary integral equation method. The elastic foundation is assumed to be of the Winkler type. In the analysis we transform the governing equation into a more convenient from in such a way that we can apply the iterative scheme to the present problems. A fundamental solution needed in the formulation is the deflection of a beam on elastic foundation that is subjected to constant tensile axial force and transverse unit load at its mid-span. Therefore, we derive the fundamental solution by solving the singular differential equation. Some numerical results based on the formulation are given for various types of boundary conditions. Moreover, to show the availability of the proposed method, large deflection problems of beams on the Winkler foundation that has a partly different modulus of the foundation are computed.

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There are various kinds of rotary machines such as the turbine rotor, compressor rotor, flywheels, etc. Fracture of blades or disks due to centrifugal force in rotary machines has often caused serious accidents. Therefore, great emphasis should be placed on studies of the intensity versus the type of fracture, as the findings obtained from such studies are applicable to safety design. Stress intensity factors K₁ are calculated by the method of photoelastic and caustic experiments, as a function of the inclination cracks of length a (a=1, 2, 3, 4, 5, 6, 7, 8 mm) at a velocity of 2 000 rpm, and are measured in models of rotating disks using the photoelastic stress freezing method. The stress intensity factor has been determined by using isochromatic fringe loops and by using a caustics pattern on the screen. The results of this experiment coincided favorably with the theoretical analysis results of Ishida and Terada.

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Because the theories of rebound hardness suggested until now are based on Meyer's Law which expresses the fully plastic deformation of a specimen under a spherical indenter, the experimental results of impact carried out over a wide range conditions of specimens and indenters can't be explained by it fully and quantitatively. To solve the above points, first the simple theory of rebound hardness is obtained on the basis of three points ; (1) The relative equations of a specimen and a spherical indenter in the elastic-plastic transient indenting process (at the 1st report) are used. (2) To correspond to the various profile of indenters (D type Shore hammer, etc.), the relative equations of rebound energy including the elastic effect of the holding shaft on an indenting sphere (at the 3rd report) are used. (3) The dynamic work necessary to produce a unit volume of the permanent indentation is different quantitatively from the dynamic mean contact pressure. Secondly, the impact experiments are given by the two tip ball type indenters for several specimens, and the necessary expressions are formulated to calculate the concrete values of rebound hardness number. Finally, the experimental results by IIZUKA regarding the influence of the wide conditions of D type Shore hammer on rebound hardness number are quoted and compared with the calculated values using this theory and a good coincidence is obtained between them quantitatively in all points.

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Using electrodeposited copper foils, the relation between the magnitude of cyclic stress and the number of cycles for the initiation of grain growth and the threshold stresses for grain nucleation and grain growth were examined. Based on the test results, the possibility of the stress measurement using grain growth process was investigated. The threshold stress of grain growth is remarkably lower than that of grain nucleation and the former is controlled by the amplitude of shearing stress as well as the latter. So, taking notice of the phenomenon of grain growth threshold, stress measurement can be done under lower strain amplitude compared with the electroplating method used until now.

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A generalized reaction force at a fixed point of a structure consists of six components which include information on the loads with their eccentricity, the initial imperfection and the deflection of structures. These factors seriously affect the load-deflection relations and the buckling load of structures. But it is usually difficult to measure these in the case of fixed ends structures, spatial structures such as coiled springs and structures deflecting to indefinite direction. In this study, multi-component loadcells consisting of strain trusses have been developed for the testing of the structures listed above. An inline data processing system has also been developed to calculate the six components of the reaction force from the strains of the truss members. Loading tests of the loadcells showed good accuracy and linearity in their structure testing use.

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The temperature variations of strain gages, caused by the power dissipated in the gage are calculated by the three-dimensional finite element method. When gages are bonded to materials with lower thermal diffusivities, such as plastic, the rise in the temperature of the gages depends not only upon the area of the grid of the gage, which is often used to characterize the heat-dissipation characteristics of a strain gage, but upon the length and the width of the filament, and the number of filaments. When gages are bonded to materials with higher thermal diffusivities such as steel or alumimum alloy, most of the temperature rise is produced in the base of the gage, so as to depend upon the heat flux per unit area of filament and the thickness of the base. Temperature variations of strain gages caused by ambient-temperature variations with time are also calculated using an axis-symmetrical model. In various conditions of a gage installation, the effective factors which govern temperature variation were clarified.

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This paper proposes the use of the boundary element method in the optimal structural design based on the inverse variational principle. The optimal conditions of the inverse variational shape determination method can be expressed in terms of the boundary data alone. Firstly, using the displacements obtained by BEM, the shape of a body is reformed so that the strain energy density might become uniform everywhere on the designed surface. Volume changes in the iterative process are calculated by the movements of the extreme points of the BEM. In the boundary element approach, the initial division into elements and redivision for reanalysis can be more easily performed than in finite element method.

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