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Predecessor
Volume 26, Issue 1
Displaying 1-6 of 6 articles from this issue
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Takao YOSHIKAWA, Shinobu YAMAOKA, Minoru AKAISHI, Hisao KANDA, Osamu M ...1988 Volume 26 Issue 1 Pages 3-10
Published: January 25, 1988
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSFor the artificial growth of diamond crystals using the belt type high pressure apparatus, it is very important to control precisely the temperature distribution in specimen.
To clarify the temperature distribution in specimen, the measurement using thermocouples gives rise to much difficulty, since the wires of the thermocouples are easily cut off due to the thermal deformation of specimen.
In this paper, numerical analysis using the finite element method (FEM) is adopted to calculate the temperature distribution in specimen.
Main conclusions are as follows:
(1) The usefulness and accuracy of the FEM analysis are comfirmed by comparison between the calculated results and measured ones.
(2) It is confirmed that the temperature distribution in the specimen is adequate for diamond growth.
(3) The maximum diameter of carbon heater in specimen can be decided, referring to the temperature of the cylinder wall of belt type high pressure apparatus and the strength of wall material.View full abstractDownload PDF (2618K) -
Takashi TANIGUCHI, Ken-ichi KONDO, Akira SAWAOKA1988 Volume 26 Issue 1 Pages 11-19
Published: January 25, 1988
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSThe plane shock wave profiles obtained in the two kind of α-Al2O3 powder compacts with different grain size (100-350μm and 0.5μm) have been observed up to stress level of 45GPa by using multiple in-material gauge systems for particle velocity and stress measurements. The porosity is 42% for the coarse compact and 45% for the fine compact. The influence of the grain size on the shock wave profile was not detected. In the both compacts, elastic precursor wave depending initial interparticle bonding was not observed. The particle velocity profiles and stress wave profiles are almost the same. The wave profiles show relaxation behind the shock front and attenuation of the shock front, depending on a propagation distance of the shock wave. These results suggest that spatial-and time-depending heterogeneities of the shock state exist in the powder compact. Analized attenuating shock wave by using the path line system suggest that the shock wave front seems to change with time so as to form the suitable structure to effectively shrink the powder compacts. The mechanism of shock compression of powder matrix was discussed on the results of present study.View full abstractDownload PDF (7196K) -
Yasuhiro IWASAKI, Tetuo ICHIKIZAKI, Keiichi HORI, Kazuhiko OSHIUMI1988 Volume 26 Issue 1 Pages 20-27
Published: January 25, 1988
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSIgnition temperatures and flammability of organic materials and low alloy and stainless steels for high pressure and high temperature apparatus were studied at various pressures and concentrarions of O2 gas.
The results of this study are summarized as follows.
(1) Ignition temperatures of the organic materials and the low alloy steels decrease with an increase in partial pressure of O2 gas. On the other hand, the stainless steels do not ignite at temperatures below the melting point.
(2) The practical uses of the organic materials are limited by the decomposition temperatures of their components, which are lower than the ignition temperature.
(3) The organic materials and the low alloy steels have the posibility of ignition in the O2 gas flow if they have an initial temperature above the room temperature.View full abstractDownload PDF (759K) -
Kazuyoshi SEKINE, Kazuhiko NITTA, Kazushige TSUKUI1988 Volume 26 Issue 1 Pages 28-34
Published: January 25, 1988
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSThe Fourier descriptors method has been used in eddy current signal processing to sort defects in the wall of zircaloy cladding. The Fourier descriptor coefficient of the eddy current Lissajous pattern from defects contains information which describes the shape and character of signals, and therefore its algebraic properties can be used for classifying defect signals. This paper describes a simple procedure for defect characterization using some complex sorting-parameters derived from Fourier coefficients of the Lissajous pattern. The signal classification algorism devoloped is based on the geometrical representation of the complex numbers of sorting-parameter in the two-dimensional complex plane.
The proposed procedure has been applied to defect sorting of zircaloy cladding tubes having several kinds of artificial defect and the experimental results were successful with the exception of those concerning very small size of defects.View full abstractDownload PDF (616K) -
Tadao IWADATE, Hiroyuki TAKEMATA, Shin-ichi ONO1988 Volume 26 Issue 1 Pages 35-43
Published: January 25, 1988
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSFor high pressure reactor vessels such as for polyethylene production, autofrettage is used extensively to have the fatigue life elongated. In this study, to evaluate the material degradation based on the autofrettaged strain, the repeated internal pressure fatigue tests were conducted using the actual reactors, where the effect of autofrettage on the fatigue crack growth rate was investigated.
(1) Fatigue crack growth rate of the autofrettaged cylinder is smaller than that of the non-autofrettaged one, especially near the bore surface.
(2) Autofrettaged stain near the bore surface does not affect the material degradation, which means that the delay of fatigue crack growth rate is mainly caused by the highly compressive residual stress at the bore surface.
(3) The stress intensity factor expression of an autofrettaged thick cylinder was developed successfully which is based on the use of the effective stress intensity factor, Keff, considering the highly compressive residual stress.View full abstractDownload PDF (2252K) -
Analysis of Electrical Equivalence of Corroding Iron in Sulfuric Acid SolutionsIsao NAKATSUGAWA, Yoichi UEHARA, Shukuji ASAKURA1988 Volume 26 Issue 1 Pages 44-54
Published: January 25, 1988
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSA method evaluating the electrical equivalence of a corroding metal in a solution was proposed. The electrical responses of corroding systems to the square wave current stimuli were analyzed by the present method. The new method can not only evaluate the deviation of electrical response of the corroding system from the idealized one but also determine the necessary parameters without any arbitrariness. It was demonstrated that an idealized equivalent circuit was acceptable only for high conductive solutions in acidic media.View full abstractDownload PDF (1017K)
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