In this paper, a new method is developed that can be applied efficiently in reliability analysis and design verification of structures under random vibration. This method is based on singular value decomposition of modal coordinates cross covariance matrix. Computational algorithm and relative flow chart for this method is developed and compatible reliability criterion with this algorithm has been extracted. In order to results verification, we use Miles relation and Monte Carlo simulation -that are two well known methods in reliability analysis- and all of these methods are applied to a simple finite element model. Results show that new algorithm is more efficient for reliability analysis of structures under random vibration.

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The effect of glass cullet on physical and mechanical properties of glass-ceramics developed from zinc hydrometallurgy waste and glass cullet was investigated. The glass-ceramics were prepared by mixing zinc hydrometallurgy waste with glass cullet through vitrification process. Two difference types of glass cullet (clear and amber cullet) were used. The parent glasses were ground and pressed into bars and sintered at low temperature (850°C) for 2 hours. The obtained glass-ceramics had low porosity. The glass-ceramics with clear cullet exhibited higher density and strength, comparing with the glass-ceramics with amber cullet. The type and the amount of the glass cullet present in the glass-ceramics have strong effect on their properties.

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Carbon nanotubes (CNTs) have been attracting attention because of their prominent mechanical and electronic properties. In this study, we investigate the deformation of single-walled carbon nanotubes (SWCNTs) with a bend junction using molecular dynamics in order to analyze strain concentration due to the tube shape (macroscopic effect) and the membered ring shape (microscopic effect). At first, we propose a method for evaluating the local strain at each memberded ring. Then, we analyze the strain concentration at the bend junction due to the both of macroscopic and microscopic effects. The strain concentration caused by the microscopic effect is separated by a rough analysis; and it is about 1.5 times higher than that caused by the macroscopic effect.

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The parameter U^* has been introduced by the authors to indicate the load paths in a structure. The most serious problem encountered when calculating U^* for actual structures is the high computation time required. In the present study, we propose two methods for reducing the time of FEM calculations required to obtain U^* distributions. In the first method, essential terms are extracted from the inverse structural stiffness matrix, and these terms are used to calculate the internal stiffness. In the second method, three independent inspection loadings are applied to each point. In this operation, multiple geometry conditions are converted to multiple mechanical boundary conditions. An actual structure is calculated using this second method, and the rate of decrease in the calculation time is over 90 percent.

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Recently, development of medical devices such as catheter and stent are advanced in the low invasion medical field. Considering the functions of human body are affected severely by the medical devices, the high strength reliability of devices must be secured. In these circumstances, the thin metal film, which has high reliability of strength, is useful structural material for further development of low invasion medical device. As the strength characteristics of a thin film depend on thickness and formation process of itself, there is little strength database concerning a thin metal film. In this study, a tensile fatigue testing apparatus with cyclic loading frequency up to 30Hz and maximum loading 8 N for the thin metal film has been developed, and thin rolled films Ti and SUS304 were evaluated on tensile and load-controlled fatigue strength. The static tensile tests give that both are also over the twice of the bulk material on the tensile strength, and the proof stress is high-strength with over 90% of tensile strength respectively. The fatigue test shows that Ti thin film has long life in comparison with the bulk material, however, the fatigue characteristic itself is similar like that of bulk material.

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This paper deals with experiments for detecting two-dimensional microscopic deformations by laser speckle pattern interferometry system. The optical setup uses a laser diode for the source together with a lens to expand the laser beam, and an inspection area can be chosen with the optical setup between 5×7.5 mm² (microscopic range) up to 200×300 mm² (macroscopic range). The measurements by the macroscopic and microscopic ranges are performed without marking to get overall and detailed deformations of porous ceramic materials respectively. In the macroscopic measurement, it was shown that pore of the ceramics is recognized as a kind of the marker in generating interference fringe. On the other hand, displacement behavior related to the microscopic structure of material can be observed when spatial decomposition of measuring distance is smaller than the pore size is achieved by limiting the inspection area to micro region. In this condition, displacement data with continuous distribution has not been obtained, because displacement measured at pore inside and that at material surface are detected in the one under way without distinguishing at all in the measurement for this microscopic region. However, through the measurement of displacement behavior in crack tip vicinity, it was confirmed that measured displacement distribution agrees with the analytic solution if the data is detected in the position where pore and surface concavity are avoided along the crack edge. By arranging measured data based on above-mentioned processing, valuable information such as strain distributions between adjacent pore was obtained from the measurement for microscopic region.

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This paper presents the development of a new structural optimization technique and its application to flat-face cathode ray tubes (CRTs). A hybrid genetic algorithm (GA) using four optimization parameters is proposed for application to the design of lightweight and flat-face CRTs. In this unique design procedure, a penalty function method is introduced in order to improve the efficiency of optimization. The optimization was carried out by taking into consideration various limiting conditions associated with the strength of materials, product functions and their manufacturing. It was found that the proposed hybrid GA effectively improves the efficiency and stability of optimum design. Moreover, a prototype of the flat-face CRT was manufactured on this basis. It was proved that the measured stress of the prototype corresponds with the analysis and the weight reduction of the prototype was 11% of a conventional CRT.

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An analytical method is derived for obtaining the in-plane static closed-form general solutions of shear deformable curved beams with variable curvatures. The shear deformation effect based on the Timoshenko beam theory is included to develop the general theories of thin and thick curved beams. In these theories, the governing equations are formulated as functions of the tangent angle by introducing the coordinate system defined by the radius of centroidal axis and the angle of tangent. To solve the governing equations, one can define the fundamental geometric properties, such as the first and second moments of the arc length with respect to horizontal and vertical axes. As the radius of centroidal axis is given, the fundamental geometric quantities can be calculated to obtain the static closed-form solutions of the axial force, shear force, bending moment, rotation angle, and displacement fields at any cross-sections of curved beams. The closed-form solutions of the ellipse, parabola, and exponential spiral beams under various loading cases are presented. The results show the consistency in comparison with existed results.

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Bolt-nut fasteners are widely used in mechanical structures due to the systems' ease of disassembly for maintenance and their relatively low cost. However, vibration-induced loosening has remained problematic. In this paper, we investigated the mechanisms of the loosening process due to micro bearing-surface slip within the framework of the three-dimensional finite element method (FEM). The results show close agreement with Kasei's experimental results. It is found that the early-stage nut rotation observed experimentally originates from simultaneous bolt-nut rotation induced by the tightening torsion of the bolt and does not correspond to loosening rotation. Therefore, loosening rotation should be defined by the relative rotation angle of the nut with respect to the bolt. It is also found that small loosening is initiated when the vibration force reaches about 50 to 60% of the critical loading necessary for bearing-surface slip. Attention should be paid to the contact state of both bearing and thread surfaces when considering the loosening of bolt-nut tightening systems. Contact states can be classified into three types: complete slip involving no sticking region, micro slip involving no constant-sticking region over a vibration cycle, and localized slip involving a constant-sticking region over a vibration cycle. It is also found that loosening rotation can proceed when either micro slip or complete slip occurs at both the thread and bearing contact surfaces.

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