Evaluation of the Fatigue Characteristics of Laser-processed Hot Work Tool Steel Based on Reliability

It is reported that laser-processing is effective to repair the heat checks, which are fine shallow cracks on a surfaceof die-casting dies.     

Damage Analysis of Hanshin Expressway Viaducts during 1995 Kobe Earthquake. III: Three-Span Continuous Girder Bridges

Almost all the single reinforced concrete (RC) piers from P35 to P350 received consistently severe damage, considering the large residual inclination of piers included in earthquake-induced severe damage. However, some of the piers in the section from P35 to P350 remained lightly damaged, and this phenomenon is observed especially in many piers under fixed bearings in continuous girder bridges. In this study, using experimentally based models for metal bearings and installing them to an existing FEM code, a nonlinear dynamic response analysis of a continuous girder bridge system is conducted. It is shown that the results depend on the ground motion, but the fuse effect of the breaking of the bearings could have been a reason for the phenomenon.     

Analysis of γ′/γ equilibrium in Ni−Al−X alloys by the

Various characteristics of γ′/γ phase equilibrium in ternary Ni−Al-X alloys are analyzed by the cluster variation method (CVM) with the phenomenological Lennard-Jones pair potential. Among the eleven alloy elements studied, three types of substitution behavior in γ′,i.e., the preferential substitution for Ni sites (Co and Cu), the almost entire substitution for Al sites (Ti, Nb, Mo, Hf, Ta, and W), and the substitution for both (Cr, Mn, and Fe), are recognized depending upon the relative magnitude of the Ni−X and Al−X interactions. In the last type, the substitution site appears to depend remarkably upon the Al and/or X concentrations in γ′: while X atoms enter preferentially, the Al sublattice in the case that the sum of the two concentations is less than the stoichiometry composition (0.25), they begin to enter the Ni sublattice as the sum exceeds it. The predicted substitution behavior is in good agreement with direct and indirect experimental evidences thus far reported. The direction of γ′/γ equilibrium phase boundaries, the equilibrium partition coefficient of X, and the effects of alloying upon the order-disorder transformation temperature from metastable γ′ to γ all appear to be closely related to substitution behavior. Also, the variation of lattice constants of γ′ and γ with the alloy element concentration may be better understood by collation with the substitution sites or the short range order in each phase.     

Conducting polypyrrole composite thin films chemically prepared by spreading on surface of aqueous solution containing oxidizing agent

Polypyrrole–PMMA composite films have been prepared with the chemical oxidative polymerization by spreading the water-insoluble solvent solution of pyrrole and PMMA mixture on the surface of the aqueous solution containing K₂S₂O₈, the oxidizing agent. The conductivity of the films increases rapidly, passes through a plateau, and then decreases gradually as the reaction time increases. The conductivity of the oxidized side of the film is higher by over 1 order of magnitude than that of the evaporated side. It is due to the fact that the former is rich in polypyrrole while the latter is rich in PMMA. The thickness of the films can be controlled by adjusting the PMMA concentration. However, the lower limit of the film thickness is practically in submicron order. The relationship between the transmittance and the logarithm of the conductivity of the films gives a straight line with a gradient, ca. −8. The conductivity of the films is stable on silicagels in a desiccator over 2000 h at 25°C. The conductivity of the film is, however, very sensitive to the moisture in atmosphere and gives rise to decrease with humidity.     

Automatic welding of pipeline in Japan: Part 2—The development of a method for the branch pipe joint in ship pipeline

The pipelines used in a ship amount to tens of thousands of metres per ship, and so automatic welding of the pipelines has been widely applied from the viewpoint of saving labour. In most cases the automatic welding process has been used for the welding of butt-joints which can be applied to the pipes in rotary motion, and it has also been used for fillet-welding of the connection between flange and piping. In the butt-welding of fixed pipings, automatic welding processes are now being partly used for position welding but up to the present time automatic welding has seldom been applied to the various types of branch pipe joints in which the welded lines form three-dimensional curves.In recent years, great progress has been made in the technique of constructing steel pipe structures and in the development of practical gas cutting processes to prepare the curves needed for the various welded joints used in piping. This paper deals with various conditions and performance requirements needed for automatic welding, such as the selection of shapes of prepared edges of pipings to be welded, the control of welding positions, the control of welding torches in operation, and the solution and control of other production variables.     

3-Dimensional graphic image representation of holographic microscopical displacement pattern by using cubic spline function

For quantitative measurement of microscopical displacement of an object surface due to thermal stress, the holographic pattern measuring system (HPMS) has been developed by the authors, which is combined both the techniques of holographic interferometry and graphic image processing.

In this measuring sytem, a cubic spline function was applied to get the 3-dimensional graphic image patterns of the distribution of the displacement. The displacement is calculated from the interferometry fringe pattern, and the system was applied to deformation analysis of printed circuit board (PCB) due to thermal stress. The PCB deformation was expresed by 3-dimensional graphic image. A smooth curve could be obtained from rather less number of sampled data of interferometry fringe.     

Finite difference implementation of distributed parameter filters

The numerical problems associated with the full three-dimensional (spatial) distributed parameter filters demand a novel technique that maintains accuracy and efficiency for the complex partial differential Riccati equation governing the filter variance. The filters can be successfully implemented by using numerical operators that can, in various ways, be factored. Use of the finite difference method having this property increases the accuracy and efficiency of the implementation.

This paper outlines a time-splitting technique for the numerical implementation of distributed parameter filters. The paper provides rationales to the square root and U-D factorizations of the distributed parameter filter by means of the time-splitting finite difference method.     

Effect of Heat Treatment on Plasma-Sprayed Zircon (ZrSiO ZrSiO4)

The effect of heat treatment on the structure and properties of a plasma-sprayed zircon coating was evaluated. The as-sprayed coating, with open porosity of 10%, is composed of t-ZrO₂ and amorphous SiO₂ After heat treatment at 1473 K, ZrO₂ grows in columnar shape perpendicular to the coating surface, while SiO₂ crystallizes to cristobalite. The open porosity decreases to about 5% after the heat treatment. This can be attributed to the sintering of SiO₂ and the phase transformation of zirconia. When heat-treated at 1673 K, the coating is composed of ZrSiO₄ with dispersed fine m-ZrO₂ The open porosity increases again up to 10%. The thermal conductivity of the zircon coating increases with increasing heat treatment temperature.