Fatigue crack growth tests were conducted on whisker-reinforced metal SiC/2025Al over a wide range of fatigue crack growth rates covering the threshold stress intensity factor range AK**. The effects of the whisker volume fraction, orientation and stress ratio on the fatigue crack growth characteristics were investigated on the basis of fracture mechanics and fractography. The whisker reinforcements of the high strength Al alloy were found to be effective in improving the fatigue crack growth resistance, especially the near-threshold stress intensity factor range.

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The effect of cathodic protection on corrosion-fatigue strength in synthetic seawater was investigated for notched specimens of high-tension steels (HT50 and HT80). For slight notches (stress concentration factor, a_k≤2), fatigue strengths with cathodic protection were almost the same as those in laboratory air, because the cathodic protection retarded the formation of corrosion pits. When a_k was further increased, corrosion-fatigue strengths reached a value which is probably the fatigue strength of the circular cracked specimen. The value is higher than that in laboratory air due to the initiation of nonpropagating cracks. The fatigue strengths of welded specimens were compared with those obtained for the notched specimen.

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Rotating bending fatigue tests were carried out on plain specimens of an annealed 0.50% carbon steel in 3% NaC1 water. The behavior of corrosion pits and fatigue cracks was made clear by the successive surface observations using the plastic replica mehod.

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Push-pull low-cycle fatigue tests were conducted on ferrite-base spheroidal graphite cast iron using thin plate specimens with as-cast surface. Both stress-controlled and strain-controlled fatigue testing conditions were employed. The fatigue crack initiation and propagation processes were observed microsopically as well as macroscopically. The material tested showed intensified cyclic hardening behaviour at an early stage of the fatigue life. The fatigue lives under both testing conditions indicated no noticeable difference and satisfied the Manson-Coffin type of relationship. The microcrack initiation originated at the surface defect, a cluster of inclusions or spheroidal graphite. Macroscopic crack initiation sites examined through fractographic observation were also different according to the specimen and were classified into four patterns. The microcrack propagation law satisfied a linear type of relation, (dl/dN)/Δε_p^α=Cl. The microcrack propagation rate was also characterized in terms of a cyclic J integral, ΔJ Finally, the effect of amount of silicon content on fatigue life and its scatter was discussed.

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Low cycle fatigue tests and small crack propagation tests were conducted on two kinds of annealed low carbon steel having fine and coarse grained microstructures with a special interest in the influence of grain refinement and mean strain on the low cycle fatigue life and on the fracture mode transition. Results show that (i) a difference in the fatigue lives for the fine and coarse grained steels under mean strain e=0 is caused by a difference in a crack initiation life for both materials, (ii) a surface to internal fracture mode transition occurs easily with an increase in mean strain and grain size and, (iii) the fatigue life of the specimen failed in the surface fracture mode at a small plastic strain is not primarily controlled by the exhaustion of ductility. In such a regime, the characteristics of fatigue life under mean strain for both materials can be predicted by the calculation of a low cycle fatigue life on the basis of the law of small crack growth.

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In butt-welded joints with a backing strip, the fatigue strength is controlled by a notch (a gap between the base metal and the backing strip) at the root of the joint. The effect of the notch on the fatigue strength of welded joints depends on material properties, especially the value of the notch root radius ρ₀ at the branch point (the critical point where a nonpropagating crack appears) . In this paper, the experimental results obtained from the bending fatigue tests of simulated welded joints made by two kinds of steel are analyzed based on the characteristic fatigue behavior of standard notched specimens. The effect of reinforcement on the fatigue strength is also discussed from the same physical background.

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Rotating bending fatigue tests of graphite steels were carried out on plain specimens and specimens with a small blind hole in order to investigate the effect of microstructurens on crack growth. The crack growth rate increases with increasing the volume fraction of graphite. This is explained from the results that graphites cause voids and intergranular facets. The crack growth resistance in graphite steels was evaluated based on the small-crack growth law, dl/dN= Cσⁿ_al(σ_a : stress amplitude, l : crack length, C and n : constants), consequently, their excellent properties against fatigue were confirmed in comparison with those of a spheroidal graphite cast iron and annealed carbon steels.

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This paper discusses the characteristics of the small crack prpagation behaviour near the stress level of the endurance limit in association with a role of a pearlite structure on the above propagation of small crcaks subjected to rotating bending. The results obtained are as follows : (1) According to the coalescence of cracks, the feature of small crack propagation on the surface of the smooth specimen shows the apparent manner of microstructural sensitive propagation up to a range of a relatively large size of the above crack (2) The transition of the crack propagation mode from a microstructurally sensitive to an insensitive manner in the growth of a single crack without the accompanying coalescence occurs at a relatively short crack length. (3) The length of the critical nonpropagating crack at the stress level of endurance limit corresponds to the transitional crack length from the microstructurally sensitive crack to the insensitive crack.

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Bending low cycle fatigue tests were carried out on the specimens with a blind hole of an annealed 0.45%C steel in SEM. COD was measured by SEM photographs. The small-crack growth law was discussed based on COD. The main results obtained are as follows : (1) When strain level is constant, the shapes of the rims of cracks are geometrically similar to each other and the crack opening ratio, U, is nearly constant. (2) When dl/dN in several specimens are equal, COD near the crack tip are also nearly equal. (3) The phenomena mentioned above support the small-crack growth law dl/dN∝l.

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A resistance-curve method was proposed for predicting the growth threshold of short fatigue cracks emanating from the notch root under arbitrary stress ratio. The resistance curve was determined from the experimental result obtained from the fatigue tests of single-edge-notched plate of low-carbon steel under several stress ratios. The relation between the crack opening stress intensity factor at threshold, K_{op th}, and the nonpropagating crack length, c_np, was approximated by K_{op th}= K_{op th∞}[(c_np-c₁)/(c₂-c₁)]^l/2, (c₁&ltlarr;c_np&ltlarr;c₂), K_{op th}= K_{op th∞}, (c₂<c_np), where K_{op th∞} was the value for long cracks, c₂ was proportional to K_{op th∞}, and c₁ was constant. Under compressive mean stresses, the effect of notch plasticity on crack closure was superposed on the above-mentioned closure. Good agreement between prediction and experiment was obtained for the fatigue limit for fracture and the nonpropagating crack length. The fatigue limit for crack initiation of a stage II crack was almost constant, and equal to the value predicted for the case of R=-1.

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Tension-compression and torsional low-cycle fatigue tests were conducted on specimens containing an artificial small hole. Even in the range of low-cycle fatigue, the plastic strain range which can be detected from hysteresis is extremely small. The relationship between total strain range (Δε_t, Δγ_t) and fatigue life (N_f) is expressed byΔε^4.18_tN_f=2.06×l0^-5(N_f≤3000) for tension-compression andΔγ^2.90_tN_f=5.48×10^-2 (N_f≤2000) for torsion. Fatigue life is mostly spent by the propagation of small cracks except for the case of N_f>10⁴ in tension-compression fatigue. The prior fatigue history hardly influences crack growth rate in later cyclic loading and this assures Miner's rule to hold under variable amplitude loading. In torsional fatigue, cracks initiated not only at the edge of an artificial small hole but also in the vicinity of the hole, and therefore not only cracks with ±45 degrees angle against specimen axis but also axial and circumferential cracks were observed. This crack initiation mechanism can be explained by the elastic-plastic analysis based on the combination of the finite element method and the body force method.

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In order to clarify the fatigue damage of plain specimens under complex loadings, it is important to investigate the effect of stress change through the behavior of a small crack because the fatigue life of the specimens is occupied mainly by the propagation life of a small crack. However, these kinds of studies made in heat-treated carbon steels are few. In this study, the fatigue tests of heat-treated carbon steel plain specimens under two-step loading were carried out and the effect of stress change on the behavior of a small crack is investigated. Results show that the value of cumulative cycle ratio Σ(n/N) is smaller than unity when the first stress level σ₁ is higher than the second oneσ₂, however Σ(n/N) is about unity whenσ₁ is lower than σ₂. This difference in the value of cumulative cycle ratio is explained by the behavior of a small crack after the stress change.

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Using the three-parameter Weibull distribution function, we analyzed two kinds of fatigue life data. Three parameters estimated by the Maximum Likelihood Method are dependent on the stress, and have strong relationships between each other. Using these relationships, we proposed a new formula of Weibull distribution, which has only one parameter, shape parameter m. and three material constants. We clarified the meaning of each material constants included in the formula of the distribution function by numerical simulation. We applied this new distribution to the actual data, namely, the rotating bending test data of S 45 C and repeated internal pressure test data of A 7075-T 73 cylinders, which proved the validity of the new equation.

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Repeated impact bending tests were carried out on isotropic nuclear graphites for HTTR. Each specimen whose length differed was centrally impacted by an instrumented pendulum. The simple one-dimensional model taking the Hertzian contact theory into consideration has been applied to evaluate the relationship between the maximum stress of the specimen generated by impact, the impact force and the impact energy. It has been confirmed that the endurance curves in terms of impact energy is dependent on the length of specimen but the one in terms of the evaluated maximum stress is independent of that, and the strength of graphite is lower in impact fatigue than in non-impact fatigue.

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Steel prismatical specimens were struck by a falling weight of 5.19 kg under a constant drop height of I m in order to determine the effects of heat-treatment and length of specimens on the appearance of the plastic zone and plastic strain in a specimen of finite length by an impact compression. Length of specimens used were 20, 40 and 60 mm. All specimens were quenched after heating at 850°C for 0.5 hr and tempered at 400, 500, 600 and 700°C, or annealed at 650°C for 1.5 hr. The theoretical relation between the plastic zone length and plastic strain in a specimen were estimated based on the plastic wave propagation in a specimen, and the influences of specimen length and of strain hardening on plastic strain were discussed. The plastic strain values measured experimentally coincide well with the values calculated by the equation with the plastic zone length measured for a large strain hardening specimen. Swelling over the plastic zone and microhardness distribution along the centre line of the specimen surface were studied. According to the morophorogic observation on the plastic zone which appeared on a specimen surface using a SEM, it was determined that there existed not only a slip in a ferrite grain but also a gap along the grain boundary between two pearlite grains near the top end of the annealed specimen.

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An estimation of the impact force applied to the arbitrary shaped body is described. The estimation method is based on the principle that the impact force applied to the elastic body can be expressed by the convolution integral of the produced strain and the transfer function for the each position of the body. Approximating the transfer function with a progression of impulses, the convolution integral and its reverse calculation are carried out directly. In order to ascertain the present method some londitudinal impact tests were done for the straight round bar and the stepped one and the impact forces applied to the top ends of the bars were estimated. As a results it was found that the estimated values by the present method are more closely agreed with the measured values than that by FFT. And using the present method, the impact forces of some Charpy impact tests were also estimated.

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A handy closed-form expression for the transient response is obtained. It becomes feasible to calculate easily the response dominated by low wave number components. The analysis of an elastic layer to the transverse impact is based on the classical plate theory. Therefore, the use of the expression should be restricted, but very useful. When the spatial and temporal distribution of the impact load is prescribed by the Gaussian distribution function, the restriction may be given by the combination of characteristic spatial width δ and time duration τ of the applied impact load. To show a validity of the expression, a calculated waveform is shown and compared with the real one recorded in the experiment.

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The influence of the grain shape on the microscopic deformation of polycrystalline metals was studied analytically by the finite element method in the uniaxial elastic deformation. In the present analysis, a plane model of polycrystals was used and the elastic constants of the polycrystals and the X-ray elastic constants were also calculated. The stress in individual grains became uniform when the grain was oblate in the direction of the applied stress, while the strain became uniform when it was prolate. The stress at the region across the grain boundary changed with the crystal orientation and the shape of the grains, and it was closely related to the deformation of the grain. The elastic constant was affected by the shape of the grains, indicating that the anisotropic properties in the polycrystals arose from the elongated grains. The influence of the grain shape on the X-ray elastic constants S₁, S₂/2 was dependent on the diffraction plane. In the case of α-iron, the influence on S₁ was small for the refection from the (211)planes.

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Thin-walled tubes of a carbon steel were subjected to nonproportional cyclic loading. A new expression for describing the cyclic deformation under multiaxial stresses was demonstrated for examining the propriety of the constitutive equation in cyclic plasticity presented in a previous paper, based on the random barriers theory. With this expression, the cyclic deformation, both under the proportional loading and under the nonproportional loading, could be discussed inclusively in the same category. The experimental results proved that the plastic potential function used in the equation and its change characteristics depending on the cyclic history, induced from the experiments on the uniaxial stress cycling, were applicable to the case of the multiaxial stress cycling. Moreover, it was suggested that an effect of anisotropy produced by cyclic deformation might be reflected in the internal structure variable which was one of the fundamental components in the constitutive equation.

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Impact tensile experiments were carried out at 77K for welded steel plate specimens. Four types of specimen, with a crack at different distance from the weld line, were used The dynamic strain behavior was measured on each specimen. Reduction in dynamic fracture toughness K_dc was discussed in comparison with static K_sc. The main reason was attributed to the negligible blunting of the crack tip in the case of impact loading, and the effect of dislocation emission on the blunting was discussed. The scattering of K_dc increased considerably with the increase of impact velocity when a crack was on the weld line.

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This paper deals with the thermal shock problem of an infinitely long circular cylinder with an edge crack initially at uniform temperature being suddenly immersed into medium at lower temperatures. It is assumed that the thermal disturbance near the crack tip may be neglected in the analysis of the temperature field of the elastic solid with a crack, because thermal shock occurs rapidly. We analyze the transient thermal stress problem of the elastic solid with acrack and determine the stress intensity factor at the crack tip. The nondimensional maximum transient stress intensity factor is expressed as a function of Biot's number and the nondimensional crack length. Then, we propose simplified formulation of the nondimensional maximum transient stress intensity factor as a function of Biot's number and the nondimensional crack length.

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The stress intensity factors of rectangular plates with a single-edge crack or double-edge cracks under transverse bending are evaluated by the body-force doublet method. The stress field due to a pair of point moments (doublet) in a semi-infinite plate is used to solve these problems. According to the results, the effect of plate length on K₁ is less under transverse bending than under uniform tension, in rectangular plates of the same form.

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A method of solution is developed for the stress concentration problem of an elastic strip with an elliptic elastic inclusion under tension. It is assumed that the contact surface between the inclusion and the surface of hole in the strip are perfectly bonded to each other. The fundamental principle of the method of solution is to distribute body forces in the interior of a strip and an infinite plate so as to satisfy the boundary conditions of the contact surface. For this purpose, we apply Green's functions for body force problems of a strip for the solutions of a strip with a hole, and fundamental solutions for an infinite plate for the solutions of an inclusion. Stress distributions around the inclusion in a strip are shown by numerical calculations and the influences of the moduli of elasticity and the sizes of inclusion to stress distribution are investigated.

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This report proposes a new iterative method for the elastic-plastic stress analysis by the finite element method (FEM), of which scheme simultaneously satisfies the normality condition of plastic strain increments and two other conditions : the conditions that the stress point must move on the yield surface during plastic deformation and that the plastic strain increments relate to the hardening parameters. The combined hardening rule is used in this FEM program. In order to evaluate the accuracy and the computational time for the proposed new iterative method, we analyze an axisymmetric problem that is a round bar with a U groove loaded in the uni-axial direction. Good accuracy is obtained by using the incremental displacement (load) which produces the equivalent plastic strain increment within 0.01 in each step.

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This paper is concerned with the theoretical treatment of a two-dimensional coupled thermal stress problem of an orthotropic material. In order to separate the coupled thermal and thermoelastic fundamental differential equations for the orthotropic body, we introduce a perturbation technigue for temperature and thermoelastic fields. Taking advantage of this technique, we can obtain the coupled thermoelastic solutions for the orthotropic body. As an example, we have analyzed the two-dimensional problem of an orthotropic thick plate due to symmetrical heating. And we have carried out numerical calculations for several values of thermal and thermoelastic orthotropic parameters. These effects on temperature and associated stress distributions are examined precisely.

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Three methods for detecting cracks embedded in the structural members by an infrared thermal video system have been proposed. The device used in the present study is TVS (Thermal Video System)-3300, by which the distribution of temperature on the surface of the specimen can be measured and processed to express its real time pictures. The methods proposed are (1) internal heating method where increase of temperature due to plastic deformation at the crack tip is detected, (2) external heating method by high frequency electric current, and (3) laser heating method. The above three methods have been compared each other. Finally the authors have discussed the applicability of the proposed method to the practical problems.

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An alternating current (ac) potential technique was developed for the measurement of short surface cracks in smooth specimens of a ferromagnetic material. For a constant crack length, the potential difference (E₀) between two probes located across the crack was found to be directly proportional to the operating ac frequency. The relation between E₀ and crack length (α) changed specimen by specimen, because the value of E₀ was very sensitive to placement of lead wires for potential measurement. The relation of ΔE₀(=E₀-E_0I) vs. a, however, was uniquely determined, independent of specimen, where E_0i Was the potential difference for a reference crack length, e. g., initial crack length. Therefore, surface crack lengths were able to be determined through the equation for ΔE₀ vs. a. Best accuracy was obtained for the operating ac frequency of 2 kHz in this study. In fatigue crack growth tests, the potential difference (E) was found to be a function of loading conditions. In this case, the crack length was calculated with good accuracy through the equation for ΔE₀ vs. a by substituting ΔE (=E-E_i) for ΔE₀, where E was the potential difference under loading, and E_i was the value at reference crack length.

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Nonmagnetic austenitic stainless steel is the candidate alloy for structural material in superconductive magnets which can control the plasma in a fusion reactor because this steel has widely used cryogenic applications. Therefore, strength and toughness are required to guarantee the structural integrity during operation. However, it is often hard to evaluate correct fracture toughness at 4K since serration occurs due to martensitic transformation. This phenomenon can cause not only a temperature rise at the crack tip but also extra deformation. This paper presents the effect of the strain rate on fracture toughness at 4K relating to martensitic transformation. It is found that the fracture toughness decreases with the increase of strain rate although the material ductility is apparently promoted by martensitic transformation. The difference in fracture mechanisms corresponding to each strain rate is also discussed based on SEM examination.

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In order to study the static fatigue behavior of soda-lime glass, disk specimens with an indented-induced flaw at the center were fractured under a constant load applied by a diametral compression of the disk, where a transverse tensile stress across the loaded diameter was present, with the compressive stress acting in the direction of loading. Equibiaxial tension static fatigue tests were also conducted by loading a disk with concentric rings to examine the effect of the stress applied parallel to the crack. Although the scatter in these fatigue data was large, the time-to-failure increased with decreasing applied stress, and the degree of the increase was significantly lower in the diametral compression loading. This suggests that the nominal compressive stress applied parallel to the initial crack plane causes intensified tensile stress at the crack tip blunted by the annealing process, and promotes the occurrence of a sharp crack.

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The ductile fracture of a surface crack is studied experimentally and numerically using A 533 B steel. At first, a new method by which one can obtain a surface crack with a different aspect ratio with good reproducibility is propose. Then the ductile fracture test is carried out using four kinds of specimens with different aspect ratio. The distributions of SZW. a. and CTOD are neasured along the crack front, and the effect of the spect ratio on their distribution patterns are discussed. Three-dimensional finite element analyses are also carried out and the distributions of J are evaluated. By comparison with the experimental results, the availability of fracture criterion used in two-dimesnional fracture mecahnics is discussed.

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In the previous paper, a theory of caustics was developed for elastodynamically propagating cracks under an inplane mixed-mode condition. A new procedure was also proposed for the evaluation of the dynamic stress intensity factors. In this paper, the theory of caustics was also extended for dynamically propagating cracks under general mixed-mode conditions including modes I, II and III. Complex potentials for the general solutions of the near-tip field which have been previously derived by the authors were used in this theoretical development. The effects of crack velocity and the mixed-mode condition on the caustic pattern and the initial curve were investigated. It was found that even a small magnitude of the mode III loading influences the shape of the caustic pattern. The deformed surface around a crack tip under the above condition was also clarified.

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This paper investigates the methodology of the large deflection analysis of the axisymmetric problem using the nonlinear programming theory. In the strain-displacement relationship, the out-of-plane displacement is assumed to be the nonlinear term. The total potential energy is expressed by the regular quadratic, cubic, and quartic terms. The cubic energy element indicates the coupling term between the out-of-plane and in-plane displacements. The exact total potential energy is directly minimized by the Davidon-Fletcher-Powell method. The numerical examples of a rigidly clamped annular plate subjected to the compressive load are shown. The maximum deflection and the stress distribution of the annular plates are given in the case of the coupling and noncoupling theories. The results obtained by this method are compared with the previous solutions. It is concluded that the large deflection in the plate bending can be analyzed by this method in a single loading without using load increments.

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In order to investigate the effects of the specimen size and the shape on the transverse-rupture strength of a cemented carbide, bending tests were carried out using two kinds of specimens (a square specimen and a round specimen). In the square specimen, the transverse-rupture strength was nearly constant regardless of the specimen width. On the other hand, in the round specimen, the transverse-rupture strength increased with increasing specimen diameter. And the transverse-rupture strength of the round specimen was larger than that of the square specimen. It was clarified that the above-mentioned effects of the specimen size and shape on the transverse-rupture strength of a cemented carbide were caused by the following three factors : 1) the distribution of the defects in the specimen, 2) the 3-dimensional stress distribution in the specimen, and 3) the critical condition of the specimen rupture.

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In X-ray stress measurement, to obtain accurate results, it is necessary to determine experimentally the X-ray stress constant. However, values measured by X-ray diffraction have variability arising from inherent X-ray counting statistics. Therefore, it is important to investigate the reproducibility of the measured values by using the standard deviation representing the size of the variability caused by counting statistics. The equations are derived analytically for calculating the standard deviations of the stress, X-ray stress constant, and elastic constants. These equations give the standard deviations from a single measurement. The variances in these values are expressed in terms of a linear combination of the variances in peak positions of the diffraction line. The standard deviations of these values decrease in a manner inversely proportional to the X-ray counts. The X-ray stress constant and the elastic constants, along with their standard deviations, were deter-mined by the Gaussian curve method using a quenched and tempered steel.

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This paper describes a generalization method and the ability to determine the isochromatic fringe order more accurately over the entire region of a 2-dimensional photoelastic model. The isocromatic fringes measured under various conditions were automatically extracted as the extreme points of "smoothing spline functions" using a microcomputer. By utilizing the well-known formula for the light intensity of a beam, the accurate fringe order, which varies continuously between the adjacent fringes, was automatically determined. Then by applying the concept of multidimensional unfolding, the specific fringe order distribution obtained was successfully adjusted and generalized, taking the variation of test conditions into consideration. The values of the principal stress difference computed numerically by this method were compared with theoretical values and a close similarity was observed.

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The stress concentration factors in unidirectional fiber reinforced metal matrix composites with random distances between the fibers were simulated based on shear-lag analysis, on the assumption that the shear deformation of the matrix metal adjacent to a broken fiber could be approximately identified as a deformation of the elastic linear hardening plasticity. The results showed that the average value of the stress concentration factor gradually decreased as the applied stress at infinity increased, and gave almost the similar value as that obtained analytically in the case of the constant distances between the fibers. Further, it was shown that the increment in the stress concentration factor was expressed approximately by 2-parameter Weibull distribution, similar to the situation in which the matrix behaved elastically in the vicinity of broken fiber. However, the degree of the variation was extremely small in the former as compared with the latter.

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The effects of frequencyb and waveform of cyclic stress on the slip initiation are investigated using several kinds of metal foils. On a directional copper foil, the critical stresses of the slip initiation expressed in terms of the loading time agree with one another regardless of the frequency, and they're independent of waveform. On the other hand, an iron foil shows obvious dependence of the slip initiation on both the frequency and waveform of cyclic stress. With an appropriate prestraining, however, these characteristics of the iron foil develop a similar tendency to those of the copper foil. Consequently, a directional copper foil or an appropriately prestrained iron foil is remarkably effective for the practical stress measurements in case that the frequency and waveform of repeated loads acting on a machine element vary in operation.

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The stress dependency of magnetically induced velocity change (MIVC) is studied on a welded joint of carbon steel with particular reference to the influence of the structure anisotropy on MIVC. The advantage of the present method using MIVC is cleared in comparison with the conventional method. The results obtained are as follows: (1)The magnetic field dependency of MIVC is insensitive to the structure anisotropy of base and weld metals. (2)The effect of stress on MIVC is equivalent to the effect of magnetic field. The stress dependency of MIVC is insensitive to the structure anisotropy of base and weld metals. (3)The present method using MIVC is more effective than the conventional method because of its insensitivity to the structure anisotropy. The present method is available to nondestructive measurements of residual stresses.

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Experiments on TiNi shape memory alloy wire under uniaxial tension with cyclic loading and unloading were carried out. The influence of shape memory processing temperature, test temperature and maximum strain upon cyclic characteristics of pseudoelasticity was examined. The results obtained are summarized as follows. (1)Yield stresses of stress-induced martensitic transformation and of inverse transformation and stress corresponding to maximum strain decrease with number of cycle. (2)Strain ranges of martensitic transformation and of inverse transformation roughly coincide. The strain ranges decrease with number of cycle. The amount of decrease is small. (3)Residual strain in each cycle increases with number of cycle. Residual strain is proportional to maximum strain* shape memory processing temperature and test temperature. (4)Recoverable strain energy and dissipated strain energy per unit volume decrease with number of cycle. (5)Every characteristic value (1)-(4) varies significantly in early cycles, but becomes stable after a certain cycles.

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Diagnostic expert system for an ultrasonic testing was built upon based on Method of Ultrasonic Angle Beam Testing and Classification of Test Results for Butt Welds in Steel Plates, WES2021-1987. In the present expert system, it may be advantage to use a production role and a backward inference when knowledge presentation was done. The diagnostic time could be reduced because the inference process become evident. Non-destructive inspection engineers can use this expert system on a general microcomputer. In order to confirm the expert system, the ultrasonic testing, which was diagnosed by the present expert system, and the radiographic testing were performed on butt welded joints in steel plate. Results of ultrasonic testing were almost coincident with those of radiographic testing. Therefore, it has been confirmed that the expert system was available on inferring method of ultrasonic testing.

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The behavior of a pure copper subject to pure creep and cyclic creep under an imposed load is examined at room temperature, and at 250, 300, 350, 400 and 450°C to show the relation between these two kinds of phenomena. Formulating the cyclic creep behavior using not the cycle number but the real time during deformation, cyclic creep strain as well as creep strain are represented well by the function of stress, stress ratio and the ambient temperature both in the primary and the secondary stages. The examination of temperature dependency on cyclic creep shows the existence of the critical temperature, at which cyclic creep and pure creep with same amount of the maximum stress produce same amount of strain. Then over the critical temperature pure creep governs the material behavior, and under the temperature cyclic creep become prominent.

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Large deformation elastic creep analyses were perforemed on externally pressurized long cylinders Three computer codes, MARC (FEM), C-BUCKL (FDM) and BOSOR-5(FDM), were used to calculate creep buckling time, deformation-time relations, stress-time relations and other creep behaviours. In FEM analysis three-dimensional and axisymmetric shell elements were employed. The results of MARC and C-BUCKL showed a good agreement with experimental data, but those of BOSOR-5 did not. It was found that a follower force term in a large deformation formulation is effective to get accurate results. From the comparison of results of the axisymmetric model with those of the three-dimensional shell model it seems that a cylinder can be assumed as a tourus with a large radius.

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This paper presents an efficient calculation method using the LDU decomposition process of the stiffness matrix of a tandem-type substructure composed of various substructures in numerical solutions of the finite element method (FEM). This method is applicable to an analysis of the two-dimensional elastic strips with and/or without semicircular notches. The FEM using this method decreases CPU time and memory capacity in comparison with the conventional FEM applied to the whole structures. The use of the method also gives good accurate results. Therefore, this method is effective for microcomputer-aided FEM.

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This paper deals with the shape determination problem of the cantilever column, i. e. Beck's column, subjected to the follower force. The objective is to maximize the critical load under constraints of volume constancy and lower limit of design variables, under the influence of internal and external damping. The governing equation of motion is transformed into a matrix system by the finite element method with the adjoint variational principle based on the Lagrange multiplier method. The shape improvement process is formulated by the gradient projection method based on the sensitivity of critical load to the design. Numerical results show that improved shape has a higher critical load than the initial shape (uniform) and makes three eigenvalues achieve a critical point simultaneously.

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Optimum Design of Structures Subjected to Random Loads : 2nd report : In the Case of Uncertain Load Position Governed by Given Probability Law yukio TADA, Ryuichi MATsuMOTO and Kaaru KUSAKA In this paper, we consider a shape determination problem of a beam, which is subjected to a given random load such that its load position is uncertain but thought to be governed by a given probability law. In the case of an actual structure, the load position of the random load isn't strictly fixed. But if the load position is assumed to be governed by a certain probability law, we can obtain its influence term without additional eigenv8lue analysis. By using it in the design stage, in which we use "Energy-Ratio-Method", the optimum structural design can be accomplished with the sale iterations as in the case of a determinate load position. The optimum shape gives a considerable reduction of the expected value of the strain energy under the condition that the volume of the beam is constant. It means that we can obtain the shape with higher stiff-ness without increase in the computing time of analysis.

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Turbine rotors and compressor rotors are subject to centrifugal and thermal loads. These loads increase proportionally with tip speed and gas temperature respectively. Additionally, rotor weight must be decreased to improve rotor dynamics and to restrict bearing load. Thus, an optimum design technique is required which offers the lightest possible wheel shape under the stress limit restriction. This paper introduces an optimum design system developed for turbo-machinery rotors, and discusses several applications. The sequential linear programming method is used in the optimizing process, and unsteady state thermal analyses of variable thickness wheels are performed using the numerical analysis method of multi-ring model. Centrifugal and thermal stress analyses of these wheels are performed using Donath's method with same multi-ring model. This optimum design program is applied to the design of axial flow compressor wheels. Finally, the validity of these applied results are confirmed by the transient thermal and stress analyses using the Finite Element Method.

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