An analysis for the bending of a transversely isotropic, rectangular thick plate with free edges, subjected to a partially distributed uniform load is presented. A tenth-order theory of moderately thick plates is used for the analysis. A particular solution deduced from the generalized Elliott solution and a homogeneous solution consisting of plane stress, generalized plane stress, and antisymmetric stress solutions is used. Numerical results for displacements and stresses in graphite epoxy and E glass epoxy, as well as in an isotropic material, are presented. The effect of anisotropy and thickness-width ratios on the displacements and the stresses is examined.

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Thermal stress distribution in a butt adhesive joint composed of two finite thin plates, of which both end surfaces are kept at a constant temperature and the other surfaces at a different temperature, is analyzed using the two-dimensional theory of elasticity. In the case where the joint is made of similar adherends and kept at the same high temperature at both free end surfaces of the joint, it is seen that the maximum tensile stress occurs at the end of the interface between the adherend and the adhesive, and compressive stress around the center of the interface. The effects of the ratios of the coefficient of thermal expansion, Young's modulus and the thickness of the adherend to those of the adhesive on the thermal stress distributions are obtained by numerical calculations. Moreover, in the case where the adherbnds are kept at different temperatures at each free end surface of the joint, the thermal stress distributions at each interface are obtained numerically. For verification, the thermal strain distribution near the interface was measured using strain gauges, and also, the photoelastic experiment was carried out on the joint where an epoxy resin plate was used as an adhesive. The analytical results were satisfactorily consistent with the experimental ones.

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The residual stress of epoxy resin for IC plastic packages generated in the curing process as well as in the cooling process is studied both analytically and experimentally. The property of thermal expansion in the temperature history and the viscoelastic properties at various temperature conditions are measured by the thermal test method and the creep test, respectively. The adhesive strength of the resin is determined by subjecting tubular adhesive-bonded butt joints to axial and torsional load. With these mechanical properties, the residual stress development is investigated using a 4-parameter viscoelastic model with a thermal shrinkage element. The residual stress is analyzed by the finite element method (FEM) for consistency with a model of resin block which contains a metal plate, and the strength of the model is evaluated for residual stress. The analytical results show a tendency similar to experimental results and the critical position indicated by the residual stress is found to occur at the corner of the buried metal plate.

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The impulsive responses of carbon fiber reinforced plastics(CFRP)-laminated plates are analyzed by using higher-order shear deformation theory and homogeneous anisotropic laminated plate theory. The plate of unidirectional prepregs is simply supported on all four sides and is hit by a spherical steel impactor at its center. The impact load histories are calculated numerically by using the nonlinear integral equation derived from Hertzian contact law. The strain histories of the plate are evaluated using higher-order theory and the numerical impact load histories obtained above. The theoretical results are in good agreement with the experimental results obtained by strain gauges and a piezoelectric transducer.

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Stresses in a slab with three orthotropic laminated layers are analyzed by the three-dimensional theory of transversely isotropic elasticity. The slab is subjected to transverse concentrated or distributed load at the center part on the top face. To obtain qualitative knowledge for delamination of carbon fiber reinforced plastic (CFRP) laminates, numerical results of interlaminar stresses are given for [0°_n/90°_n]_sym graphite/epoxy square laminates. It is shown that shear stresses on the upper interlaminar boundary are larger than those on the lower one. At each interlaminar boundary, shear stresses are maximal just below the concentrated load point or the edge of the distributed load area, although these stresses are zero at the center point.

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Gas flow in the airway and lung deformation due to tissue elasticity and surface tension are the main characteristics of respiratory dynamics. In this study, a simulation with the discretized model as a distributed parameter system is used extensively to identify some of the model parameters which could not be measured directly, and to estimate the real situation of lung respiration. With the use of 5 excised lungs from Japanese white rabbits, the pleural pressure vs lung volume change (P_pl-ΔV) relations are observed in situ under oscillating pleural pressure. The elastic properties of the lung tissue are measured under biaxial tension. The unknown parameters, such as that for the surface tension in the alveoli, are identified so that the P_pl-ΔV relations calculated by the simulation coincide with the experimental ones for an individual lung. The simulation studies with identified parameters demonstrate potential for estimation of the actual phenomena inside of an excised lung.

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In order to investigate the basic mechanical properties of a bias-type two-way shape memory component, thermal cyclic experiments were carried out on a TiNi shape memory alloy wire under a constant spring constant of a bias spring. The cyclic characteristics of recovery stress and recovery strain and the conditions for application of cyclic recovery stress and recovery strain were discussed. The main results can be summarized as follows. (1) The recovery stress and recovery strain induced in the two-way component take the maximum values at the initial strain near the completing point of the stress-induced martensitic transformation. (2) The recovery stress and the recovery strain decrease significantly in the early cycles, but take almost constant values after these cycles. (3) In order to obtain large recovery stress, it is necessary to make the spring constant of the bias spring high and to make the initial strain small. In order to get large recovery strain, it is necessary to make the spring constant low and the initial strain large. (4) The transformation temperatures of the stress-induced martensitic transformation and the reverse transformation rise with the number of thermal cycles. (5) In progress of thermal cycles, the stress-induced martensitic transformation and the reverse transformation occur gradually with variation in temperature, and the starting and completion temperatures of each transformation become unclear.

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The literature shows that nonlinear stress-strain curves have been obtained in tensile tests of an epoxy-coated hourglass-shaped rock specimen under confining pressures and concludes that this nonlinearity is caused in part by plasticity and mainly by nonlinear elastic behavior. However, in addition to these causes, some contribution of pore-fluid diffusion in a specimen is expected to occur. The hourglass-shaped specimen was examined in a previous paper. For a noncoated cylindrical specimen (core sample), the present paper analyzes the contribution of radial pore-fluid diffusion to nonlinearity and yields the same conclusion as that in the previous paper; that is, this apparent nonlinearity is small but not negligible. A formula is also given to estimate the bend of the stress-strain curve due to diffusion. Furthermore, stress-strain hysteresis curves are given for the same purpose.

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In a frontal collision of an automobile, side members are the most important factor in occupant protection. When the side members collapse axially, they absorb a sufficient amount of crash energy to avoid deformation of compartments. To promote axial collapse without bending, beads are generally provided on the side member. However, it is very difficult to determine the effective position for beading on the members because the relation between the buckling wave and the beads cannot be clearly seen in a bending crash mode. In this study, we show an analytical method of beading on the side members along the buckling mode calculated by a finite-element analysis.

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The finite element method (FEM) plays an important role in computer-aided engineering (CAE). The FEM and CAE require the use of a large-capacity machine such as a mainframe computer. Requirement for the utilization of microcomputer-aided FEM (MiFEM) and/or engineering (MiCAE) arises in small- and medium-size companies which are not equipped with a large machine. This paper deals with a MiFEM to analyze three-dimensional large-scale Problems, with the utilization of an external storage unit such as the floppy disk. First, we describe an efficient composition method for small-size submatrices divided from a large-size total stiffness matrix. Next, we present a new LDU decomposition method for submatrices. A new MiFEM is developed using both the efficient composition and the LDU decomposition methods. This MiFEM is equivalent to a generalized version of the ordinary FEM, which is dependent on a large machine, because the MiFEM can be executed on every computer. Furthermore, the MiFEM makes it possible to develop a MiCAE.

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A constitutive model for determining the flow stress of SUS 304 austenitic stainless steel has been formulated for cold forming conditions by using an energetic criterion which defines the energy consumed to deform the phases in the system as being equivalent to energy consumed to deform the aggregate. A general constitutive relationship is explicitly established by using the volume fraction of the strain-induced martensitic phase and the flow stress and strain ratio of both the austenitic and martensitic phases. The volume fraction of martensite is determined through a series of uniform compression tests under isothermal conditions. Flow stress of austenitic phase at several constant temperatures is determined by conducting differential compression tests. On the other hand, martensitic flow stress is determined by differential compression experiments aided by numerical simulations of aggregate deformation. Through several finite-element analyses, the strain ratio between each phase has been determined numerically. It has been demonstrated that the developed constitutive expression, successfully predicts the flow stress behavior.

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The melting process of a solid contained in a rectangular enclosure is investigated by an unsteady two-dimensional analysis of induced natural-convection heat transfer in the liquid region via the Boussinesq model. The mathematical model represented by the system of governing partial differential equations, as well as the initial and boundary conditions for the field variables, is transformed into an equivalent variational form by using the adjoint variational formulations. The weighted function finite element method was used to descretize the resulting variational principles into a system of algebraic equations suitable for numerical calculations. Numerical results obtained by a computer program designed for this purpose, i. e., values of the Rayleigh numbers in the range of 1O⁷-1O⁸, showed good agreement with experimental and other numerical data available for such problems.

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An ultrasonic axial bolting force inspection system is developed for the control of bolts used on turbine outercasings in a thermal power plant. The ultrasonic time of flight through the bolt under stress is analysed using acoustoelastic law. The proportional constant, conventionally called the material constant, is determined by an acoustoelastic constant k and Young's modulus E as (1- kE). Measurements of k for some kinds of steel bolts revealed that k is approximately the same value (-1.1x1O^-11 m²/N) independent of heat treatment. Based on these results, the ultrasonic axial bolting force inspection system is developed. Applying this system to turbine bolts, it is found that the bolts could be controlled more precisely than ever.

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The resonance method of three-dimensional free vibrations with the cylindrical specimen, which has been developed by the authors, was applied to determine the elastic constants of polycrystals in a temperature range of 4-300 K. It was found that the temperature dependence of elastic constants of pure aluminum agreed well with published data measured by the ultrasonic pulse-echo technique over the temperature range of measurements. A sluggish change induced could also be detected in niobium. In addition, the temperature dependence of elastic constants for superconducting Al-Si and Al-Ge supersaturated solid solutions was examined, and the Debye temperature was determined by extrapolating the elastic constants to the values at 0 K.

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Temper embrittlement in low-alloy steels, one type of typical material degradation, occurs during service, and it is important to detect this embrittlement by means of a nondestructive technique. In order to develop a nondestructive method of evaluating embrittlement for Cr-Mo-V rotors, a study was conducted using lab-charged P-doped and Sn-doped steels. P-doped steels showed evident embrittlement by segregation of P at grain boundaries. On the other hand, Sn-doped steels showed little embrittlement when compared with P-doped steels. Various testing methods were investigated and compared in terms of their sensitivity and factors were detected, using these steels. The chemical etching test was found to be a very good measure of embrittlement. That is, it was found that there is good correlation between the width W of the etched grain boundary measured by the penetration of replicas and FATT. The correlation between W and FATT was also recognized for samples taken from long-term-serviced rotors. The relation had the same slope as that found for lab-charged steels. From this, multiple regression analysis was conducted in order to express FATT using W and variables which are known or are nondestructively measurable. As a result, a regression equation which gives an estimate of the actual FATT with the scatter of ±20°C was obtained.

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In the present study, the influence of the microstructure of materials on the characteristics of small-crack growth was investigated, and the minimum crack length to which the small-crack growth law (dl/dN∝l) is applicable was evaluated in the cases of ferrite-pearlite steel, ferrite-martensite steel and quenched and tempered carbon steel. Initial crack growth is influenced markedly by the grain boundary, pearlite structure and martensite structure, and these influences decrease with increase in crack length. However, even in the process in which crack growth is influenced by the microstructure, the mean crack growth rate is estimated by extrapolating the crack growth rate in the region where it is mainly controlled by the mechanical parameter alone.

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In relation to the evaluation of remaining life of high-temperature components based on statistics of extremes, this paper is concerned with application of image processing to measurement of small crack lengths. Creep-fatigue tests were carried out on SUS 316 L. Smooth specimens were subjected to slow-fast cyclic strain of a total strain range of 1% at 65O°C in air with ε^^.=2x1O^-5/s in tension and ε^^.=2x1O^-3/s in compression. Taking replicas of the specimen surface, the images of the replicas were put into the image processing unit. Using some new algorithms and conventional algorithms, individual crack lengths were measured. The crack length measured by means of image processing was compared with that determined by manual measurement with a microscope. The distribution of the small crack length was also studied. Furthermore, propagation and coalescence behavior of cracks was investigated by means of image processing.

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The evolution of surface roughness of aluminum foil caused by fatigue slip deformation is dependent on cyclic stress and the number of cycles. In order to use aluminum foil as a fatigue gauge by utilizing its surface roughness, isoroughness curves are obtained and an empirical formula for them is proposed. The effect of material factors, i.e., grain size and thickness of the foil, on the evolution of roughness is also investigated. It is found that an increase in roughness is well represented by R_a=(σ^α/2/k_O)N^1/2+m, where α, k_O and m are material constants. Accordingly, if the number of cycles N and the center line average height R_a are measured, the applied stress σ is evaluated by this formula. It is also found that the effect of the thickness on the roughness is remarkable, while the effect of the grain size is very small. This is beneficial to control the strain sensibility of the gauge without changing the gauge length.

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