The bolts and nuts are widely used in various fields as important joining elements with long history. However, screw loosening is easily induced by vibration and external loads, and sometimes causes very serious accident without notice. In this paper, a special stud bolt named “Super Stud Bolt (SSB)” is studied, which can prevent loosening effectively. Between the upper threads and the lower threads, there is a thin walled tube which can be deformed along the axial direction so that the phase difference is designed and SSB is developed. During fastening, this phase difference induces the contrary forces on the surfaces of the upper threads and the lower threads, which bring out the anti-loosening performance. In this study, both courses of processing and fastening are simulated, and the relationship between axial force and displacement is illustrated with the finite element method. In this analysis, the large plastic strains and elastic-plastic large deformation theory are applied to 4 nodes axial symmetric FEM models. Through the comparison among the results, the desirable range of the phase difference of lower and upper threads is decided. Since the thin walled tube is the heart of anti-loosening mechanism, optimum original dimensions are discussed in this study.

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This paper deals with the singular stress field at the adhesive dissimilar joint, and discusses the effect of material combination and adhesive thickness on the intensity of the singular stress when bonded strip is subjected to tension. A useful method to calculate the intensity of singular stress at the adhesive dissimilar joint is presented with focusing on the stresses at the edge calculated by finite element method. The intensities of singular stress are indicated in charts with varying adhesive thickness t under arbitrary material combinations for adhesive and adherents, and it is found that the intensity of singular stress increases with increasing the adhesive thickness t until t =W , when W is the width of adhesive. The intensity of singular stresses are also charted under arbitrary material combinations which are presented by Dunders’ parametersα ,β when t /W = 0.001 and t /W = 0.1 , and it is found that for a fixed value β the intensity of singular stress increases with increasing α when α is small while it decreases with increasing α when α is large.

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In this study, acceleration responses of layered cylindrical structures are obtained using finite element analysis (FEA) and wave tracing technique. The wave tracing technique implies a direct application of the wave propagation equation which includes propagating wave and its reflections at the interfaces due to effect of impedance differences in layered structure. Wave tracing clearly supported FEA results which had showed that interference between applied impact and reflected waves affects wave propagation both negatively and positively depending on material combinations of the structure. The study showed that structures made in order of high-low-high impedance materials reduce magnitude of acceleration responses compared to homogeneous structures made of only high impedance material when there is no interference. While structures made in the order of low-high-low impedance materials reduce magnitude of acceleration responses compared to homogeneous structures made of only low impedance material with and without the interference. Furthermore, FEA results showed that structures made of high-low-high impedance materials reduce high frequency accelerations compared to homogeneous high impedance material structures. These results were experimentally verified with the previously reported results.

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From a traffic safety point of view, there is an urgent need for intelligent tires which can optimize braking control by estimating the slip ratio and friction coefficient between road surface and tire. In previous studies, we have proposed an application of strain data for estimating a friction coefficient. However, it only investigated the condition when the vertical or frictional loads changed but the other load remained constant. Since both of the frictional and vertical loads alter the measured strain data, an independent applied load estimation method is needed. This study develops a concurrent method for estimating the frictional and vertical loads applied to the tires from the measured strain data when both loads change. The method decomposes the measured circumferential strain to the frictional and vertical strain components using their symmetrical and anti-symmetrical characteristics. FEM analysis is used for simulating tire deformation under various wheel loads and braking torques and the relationship between the strain distribution at the sensing point and the applied loads are calculated. When the estimated and true applied loads were compared, it was confirmed that the vertical and frictional loads can be estimated independently from the circumferential strain with sufficient accuracy. Using this method, one can represent the slip slope curve during driving, which enables the optimization of vehicle control and implementation of a road condition warning system.

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Uniaxial tensile tests of glass specimens were carried out at a range of strain rate and temperatures. The strain rate and temperature dependencies on the tensile strength (breaking stress) of the glass were investigated in detail. The relationship between tensile strength, strain rate and temperature can be expressed using exponential functions given by Norton's law and an Arrhenius type equation. An empirical equation expressing the temperature and strain rate dependencies of tensile strength was obtained from the experimental results. The strength of the glass was discussed from the standpoint of the thermo-viscoelastic properties of the material.

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Components and structures like pressure vessels and high temperature exchangers undergo multiaxial low cycle fatigue (LCF) damage. It has been reported that fatigue lives are reduced accompanying an additional hardening under strain controlled non-proportional loading in which directions of principal stress and strain are changed in a cycle. Developing an appropriate design parameter for multiaxial LCF is required for the reliable design and maintenance of structure components. This study examines the relationship between additional hardening and reduction in fatigue life due to non-proportional loading and its material dependence. By performing the multiaxial LCF tests using different materials, a material constant, α, used in a strain parameter for life evaluation under non-proportional multiaxial LCF is discussed.

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Hollow eutectic tin-lead solder spheres with diameters from 3.5 to 4.5 mm have been produced directly from the melt. Raw solder placed in a crucible was melted at a temperature of typically about 50 °C above its melting point. The molten solder was then extruded vertically downward into air at room temperature through the outer nozzle of a coaxial nozzle mounted at the crucible bottom. Capillary instability of the extruded hollow molten solder jet led to the formation of hollow solder spheres. This formation was assisted by a transverse nozzle placed close to the coaxial nozzle, which directed an inert gas past the hollow jet at position where sphere detached. The spheres were then quickly cooled and solidified by water mist prior to collection in a container filled with water. Most of these spheres were completely hermetic and had a relatively smooth surface. Hollow water spheres were also formed as a test of production of hollow solder spheres through the nozzle.

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