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Predecessor
Volume 28, Issue 1
Displaying 1-5 of 5 articles from this issue
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Takashi MACHIDA, Hiroshi MIYATA, Hiroyuki OHTA, Saburo USAMI1990 Volume 28 Issue 1 Pages 4-12
Published: January 25, 1990
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSThe fatigue behavior of structural ceramics was examined at elevated temperature. The fatigue of silicon carbide depends on the loading time, but does not depend on the number of loading cycles. The fatigue is observed in air and the lifetime can be represented using Larson-Miller plots, but the fatigue behavior is observed in a vacuum. These results show that the thermal activated oxidation seems to be dominant in the elevated temperature fatigue process.
The crack growth in the fatigue process consists of three stages. In the first stage the crack shows a rapid growth rate, but the growth rate decreases in the second stage. In the third stage, a rapid growth rate or an arrested behavior of the crack is observed according to the level of loading stress. Under a certain level of stress, the crack can not become unstable because of healing effect, so that the existence of fatigue limit is recognized.
A new design rule for fatigue at elevated temperature is proposed based on the fatigue limit.View full abstractDownload PDF (2698K) -
Noriyuki MIYAZAKI1990 Volume 28 Issue 1 Pages 13-19
Published: January 25, 1990
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSThe dynamic fracture toughness KId of material is used to assess the integrity of a structure under impact loading. It is evaluated from instrumented impact tests such as pre-cracked Charpy tests or pre-cracked drop weight tests together with a numerical analysis of the dynamic stress intensity factor using a load-time history obtained from the tests. A two-dimensional dynamic finite element analysis is often utilized for this purpose. It requires large computer storage and run time. Therefore, it is inadequate to the quick evaluation of test data.
In the present paper, a method for calculating the dynamic stress intensity factor of a pre-cracked bending specimen used in instrumented impact tests is newly proposed by making use of a line-spring model. A pre-cracked bending specimen is modeled by one-dimensional beam finite elements and a line-spring representing the stiffness or compliance of a cracked part. The present method enables the one-dimensional analysis of a two dimensional crack problem and thus the time variation of the dynamic stress intensity factor of a pre-cracked bending specimen can be obtained by making use of a personal computer within a few minutes. The present method is applied to the dynamic stress intensity factor analysis of a pre-cracked three-point bending specimen and a pre-cracked four-point bending specimen. The results obtained from the present method are in reasonably good agreement with the two-dimensional finite element solutions or the experimental results. A quick evaluation system for dynamic fracture toughness can be made by combining an instrumented impact test apparatus with a computer program based on the present method which runs on a personal computer.View full abstractDownload PDF (652K) -
Masanori SHUKU1990 Volume 28 Issue 1 Pages 20-29
Published: January 25, 1990
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSFloating oil storage system has recently been realized at Aokata Bay Area, Kamigotocho, Nagasaki, Japan.
The system, which is a kind of offshore storage and suited to Japanese conditions, was proposed and developed as a new method for stockpiling emergency oil reserves since 1974.
The system consists mainly of five (5) oil storage barges capable of holding abt. 880, 000kl (Total amount abt. 4.4 million kl) of crude oil, mooring dolphins, and other facilities.
This paper describes special features of the oil storage barge and its mooring system.View full abstractDownload PDF (1351K) -
by Static Tilt Tests Using a Large Model of Exact Similitude (2nd Report)Fujikazu SAKAI, Akira ISOE, Hajime HIRAKAWA, Yukio MENTANI1990 Volume 28 Issue 1 Pages 30-40
Published: January 25, 1990
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSIn order to investigate the uplifting behavior of large-scaled LNG, LPG and oil tanks, which has recently been said to be closely related with the earthquake damages, the authors conducted a series of static tilt tests using a very big model made of aluminum alloy with about 10m diameter and 8m height. This model is characteristic of satisfying almost perfectly the similitude law between actual largescaled tanks, and the tilt test made it possible to conduct such big experiments and to measure in detailes the behaviors.
In the previous paper, the authors introduced the outline of the static tilt tests, and discussed the influences of anchor rigidity. In this paper, the influences of anchor rigidity and prestress are discussed, and in addition to it the loosely anchored cases are investigated, in which the gap length is artificially taken as 3.5mm. Finally based on the synthetical consideration of the results obtained in this paper and the first one, we proposed a new methodology to design anchor straps rationally.View full abstractDownload PDF (958K) -
Yuuji YOSHITOMI, Hideaki KAMOHARA, Hisanobu KANAMARU, Hitoshi KONNO1990 Volume 28 Issue 1 Pages 41-48
Published: January 25, 1990
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSA joining technique with high accuracy and reliability is required in mechatronics parts. However, sufficient accuracy and joining strength can not be achieved by conventional methods such as staking and fitting.
A joining technique called Metal Flow Joining has been developed and applied to several mechatronics parts and car parts. In principle two parts are joined together by plastic metal flow into circumferential grooves on the surface of once part during pressing the other with a punch.
The effects of the position and the number of the grooves on the plastic flow formability and the strength of the joints have been studied by FEM analysis and some experiments.
The joining strength equal to the shear strength of the base metal can be obtained in the range of the ratio L/B (L: the distance between the loading surface and the circumferential grooves, B: the loading width) from 0.5 to 0.75.
It is also found that optimum number of the grooves is two or three.
The coaxiality and the parallelism of the joints made by the Metal Flow Joining are less than 0.02mm and in the range from 0.005 to 0.015mm respectively.
Higher accuracy of the joints can be also assured compared with those made by the conventional staking.
It is concluded that the designing die and the controll of the joining conditions are very important to achieve higher accuracy and reliability, and wide application of this technique can be expected.View full abstractDownload PDF (2864K)
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