| Continuous Measurements of Eyeball Area and Their Spectrum Analyses -- Toward the Quantification of Rest Rhythm of Horses by Image Processing |
25 OCT 2001 |
|
| Authors:
T. Ohnishi; W. Chen; T. Kobayashi; Y. Honda; T. Saito; SOKA UNIV HACHIOJI TOKYO (JAPAN) DEPT OF BIOENGINEERING
|
 | The motion of eyelids and eyeballs in domestic animals had been recognized well agreement with the sleep depth estimated by spectrum analyses of electroencephalogram at half closed eye and fully closed eye. This study aimed at quantitative estimating rest rhythm of horses by the analyses of eyeball movement. The mask attached with a miniature CCD camera was newly developed. The continuous images of the horse eye for about 24 hours ... |
|
| Improvement in Stress Corrosion Resistance of 7075 Aluminum Alloy by RRA Process |
FEB 90 |
|
| Authors:
T. Ohnishi; Y. Ibaraki
|
| The RRA (retrogression and reaging) process was investigated in order to reduce the susceptibility of 7075 Al alloy to stress corrosion cracking, and to keep high strength due to T6. The process includes the first low temperature aging, the second retrogression at higher temperature, and the third reaging at low temperature. For the first aging the usual T6 treatment is practically suitable. For the second retrogression the higher the temperature ... |
|
| Work-Hardening and Annealing Characteristic of Mg-Li Binary Alloys |
JAN 89 |
|
| Authors:
T. Ohnishi; T. Ito
|
| Work-hardening, annealing characteristic, tensile properties and corrosion resistance of Mg-Li binary alloys, containing 8, 12 and 20 wt% lithium, were investigated. The 8Li alloy, which has (alpha + beta) eutectic structure, shows relatively high initial strength and high ability to work- hardening, while beta single phase alloys of 12Li and 20Li have lower strength and limited ability to work-hardening. However, plastic formability of these beta phase alloys is extremely superior ... |
|
| Corrosion Fatigue of 7075 Aluminum Alloy, |
FEB 1987 |
|
| Authors:
T. Ohnishi; K. Yoshimura
|
| Fatigue tests of 7075-T651 aluminum alloy were carried out in laboratory air and in aerated 3.5% NaCl aqueous solution. In both S-N and da/dN-delta K measurements, fatigue properties in NaCl were considerably inferior to those in air. A number of laminated cracks, which were intergranular cracks along pan-cake-like grain boundaries, were formed in a lower delta K region in NaCl, while these were not observed in air at all. In ... |
|
| Heat Treatment to Reduce the Susceptibility of Al-Zn-Mg-Cu Alloy to Stress Corrosion Cracking, |
OCT 1986 |
|
| Authors:
T. Ohnishi; H. Shiota
|
| A three-step aging process to reduce the susceptibility of 7475 aluminum alloy to stress corrosion cracking, and to keep high strength, was investigated. This process includes the first low temperature aging, the second retrogression at higher temperatures, and the third reaging at low temperature once again. For the condition applied to the first step the usual T6 treatment is most suitable. For the second step the higher the retrogression temperature ... |
|
| The Superplastic Behavior and Structural Changes during Hot Deformation of Al-Cu-Zr Alloys, |
JUN 1986 |
|
| Authors:
K. Higashi; S. Nagai; M. Maeda; T. Ohnishi
|
| The superplastic behavior of Al-4.5Cu-0.5Zr and Al-5.9Cu-0.5Zr alloys was studied. Both the alloys 20 to 30 microns in grain size at initial recrystallization and 40 to 60 microns after hot deformation show superplastic elongation only up to 250% at any temperatures and strain rates. Significantly fine grained structures 5 microns in size are achieved after an initial straining stage only by deformation at temperatures being elevated. This microstructural change is ... |
|
| Relationship Between Fracture Toughness and Impurity Elements in Al-Zn-Mg-Cu Alloys, |
SEP 1985 |
|
| Authors:
K. Higashi; Y. Hirai; T. Ohnishi
|
| A relationship between fracture toughness or critical crack tip opening displacement (CTODc) and Fe- and Si-rich insoluble inclusions in 7000 type alloys was studied. The magnitude of crack tip plastic blunting or fracture toughness is determined by forming characteristic dimples just in advance of the stretched zone. The dimples on fracture surfaces are classified into two types of populations by scanning electron micrography and energy dispersion spectroscopy analysis. One population ... |
|
| Stress Corrosion Cracking of 7075 Series Aluminum Alloys |
JUN 85 |
|
| Authors:
T. Ohnishi; H. Kojima; N. Seko; K. Higashi
|
| The stress corrosion resistance of commercial 7075, 7175 and 7475 alloys plates 60 mm in thickness was investigated. The resistance of these specimens strongly depends on the orientation of specimen, T-L specimens are highly superior in resistance to S-L specimens. The overaging treatment (T7) is extremely effective for improving the resistance of these alloys. The residual stress removing treatment (TX51) has a considerable effect to improve the resistance of S-L ... |
|
| Relationship between Fracture Toughness and Tensile Properties in Al-Zn- Mg-Cu Alloys |
JUN 85 |
|
| Authors:
K. Higashi; Y. Hirai; T. Ohnishi
|
| Effect of alloy purity and aging on the fracture toughness of three type alloys has been examined to clear the relationship between the fracture toughness and tensile properties. The fracture toughness was evaluated by the critical crack tip opening displacement (CTOD(sub c)) derived from stretched zone analysis. The general magnitude of CTOD(sub c) increases with reduction in iron and silicon contents. The value of CTOD(sub c) depends on the aging ... |
|
| Effects of Orientation of Specimen on Hydrogen Embrittlement in 7075 Aluminum Alloy |
APR 85 |
|
| Authors:
T. Ohnishi; K. Inagaki; K. Higashi
|
| Hydrogen embrittlement of 7075 specimens aged at 120 C for 1 hour, which were prepared to have various orientations, was investigated by a tensile test of cathodically charged ones. Hydrogen permeation behaviors for these specimens are similar to each other, but permeation from T or S plane of rolled alloys is seemed to be somewhat easier than that from L plane. Embrittlement of the specimens with S-L or S-T direction ... |
|
| RELATIONSHIP BETWEEN FRACTURE TOUGHNESS AND TENSILE PROPERTIES IN ALUMINUM-ZINC-MAGNESIUM-COPPER ALLOYS. |
1985 |
|
| Authors:
K. HIGASHI ; Y. HIRAI ; T. Ohnishi
|
|
| Application of Fracture Mechanics to Propagation of Stress Corrosion Crack Based on Localized Hydrogen Embrittlement |
DEC 84 |
|
| Authors:
T. Ohnishi; K. Higashi
|
| In order to estimate quantitatively and theoretically, the SCC test results for Al-8Mg alloy were analyzed by applying the fracture mechanics, based on the presumption that the principal determining parameter in SCC is the localized hydrogen embrittlement near the crack tip. Theoretically, the high hydrogen concentration appears to be unable to produce through the hydrostatic stress induced diffusion only, in the case of lower yield strength materials such as the ... |
|
| Propagation of Stress Corrosion Crack in Al-8%Mg Alloy |
NOV 84 |
|
| Authors:
T. Ohnishi; K. Higashi
|
| The growth rate of stress corrosion cracks, size of hydrogen embrittled zone (HEZ) and width of stretched zone (SZW) in the area ahead of SCC region through an overload test after SCC were measured for Al-8%Mg alloy aged at 200 C for 1 h. K(sub ISCC) is 67 kg/mm(super 3/2). HEZ size is nearly constant at about 4 mm in the regions I and II of da/dt-K(sub I) curve and ... |
|
| Superplastic Behavior of 5083 Aluminum Alloy |
OCT 84 |
|
| Authors:
T. Ohnishi; K. Higashi; Y. Nakatani
|
| Superplastic behaviors were observed in a commercial JIS A5083 aluminum alloy which had been heat-treated to have an equiaxed recrystallization structure with a grain size of about 7 microns. In the optimum condition in this work, at 763 K and at 1.11 x 10(super -3)s(super -1), the specimen showed the maximum elongation of 460%. The plots of the maximum engineering stress against the initial strain rate in the temperature range ... |
|
| Microstructures and Mechanical Properties of Al-Mg(sub 2)Si Eutectic Alloys Unidirectionally Solidified |
OCT 84 |
|
| Authors:
Y. Nakatani; T. Ohnishi; T. Hatanaka; M. Maeda
|
| Monovariant Al-Mg(sub 2)Si eutectic alloys having quasibinary eutectic composition were unidirectionally solidified. Al-8.3Mg-3.8Si alloy containing slightly excess Mg shows the most suitable structure for an aligned composite material. Eutectic cell structures form and Mg(sub 2)Si plates transform into rods at faster solidification rates decreasing their interspacings. The non-cell alloy solidified at a low rate has the maximum strength 45.4 kg/sq mm at room temperature and is stable at elevated temperatures. ... |
|
| Structures and Mechanical Properties of Ternary Al-6%Ni-X (Ti, Cu, Mg, Fe, Cr and Mn) Alloys Unidirectionally Solidified |
OCT 84 |
|
| Authors:
Y. Nakatani; T. Ohnishi; T. Hatanaka; H. Kozima
|
| The in situ composite Al-6Ni eutectic alloys containing such third elements as Ti, Cu, Mg, Fe, Cr and Mn were unidirectionally solidified at solidification rates R = 15 to 600 micrometers/s at temperature gradients G = 60 to 70 C/cm to strengthen the alloys. Additions of Cr and Mn are effective to improve the properties. Micro-Vickers hardness in the eutectic region increases with Cr and Mn contents. An Al-6Ni-1.0Cr alloy ... |
|
| Formation and Disappearance of the Hydrogen Embrittled Zone Pre-Existing Ahead of the Stress Corrosion Crack |
APR 82 |
|
| Authors:
T. Ohnishi; K. Higashi
|
| The investigations were carried out on an Al-8Mg alloy cut from the rolled alloy of 10 mm thickness. The hydrogen uncharged and charged specimens were tensile-tested in air in order to confirm that the specimen suffers an intergranular brittle failure by hydrogen addition. The specimen aged at 200 C for 1 hour was stress-corrosion-tested in 3.5% NaCl solution at room temperature for 120 hours by loading to 65% of the ... |
|
| Temperature Dependence of Fracture Characteristics of 5083 Alloy |
JAN 82 |
|
| Authors:
K. Higashi; T. Ohnishi; K. Komatsu; Y. Nakatani
|
| The temperature dependence of fracture toughness of 5083-O and 5083-T were estimated by measuring the critical crack tip opening displacement (CTOD(sub c)) derived from stretched zone analysis. These alloys have an excellent property in a static tensile test and show appreciable low temperature embrittlement in a dynamic test. CTOD(sub c) significantly depends on temperature. The CTOD(sub c) values of 5083-O at room temperature and -196 C are 70 and 21 ... |
|
| Evaluation of Fracture Toughness of 5083 and 7075 Alloys by Stretched Zone Analysis |
NOV 81 |
|
| Authors:
K. Higashi; T. Ohnishi; K. Komatsu; Y. Nakatani
|
| An attempt to evaluate the fracture toughness of 5083 and 7075 alloys is made by observing the stretched zone (SZ) formed ahead of the pre-crack in a Charpy test. The width and height of the stretched zone was analyzed stereographically from fracture toughness. Twice SZH corresponds to the critical crack tip opening displacement. |
|
| Energy Dispersion Spectroscopy of Pre-Existing Hydrogen Embrittled Zone Ahead of Stress Corrosion Cracks |
OCT 81 |
|
| Authors:
K. Higashi; T. Ohnishi; Y. Nakatani
|
| Scanning electron microscopy and energy dispersion spectroscopy were made on the fracture of Al-8Mg alloy failed under tensile loading after stress corrosion testing. When the alloy failed immediately after stress corrosion testing, a wide range of intergranular cracking area is observed which consists of two zones with and without trace chloride. The latter disappears when the alloy is aged at room temperature after stress corrosion testing, because the permeated hydrogen ... |
|
| Effect of Temperature and Strain Rate on Hydrogen Embrittlement of an Al-8%Mg Alloy |
SEP 81 |
|
| Authors:
T. Ohnishi; K. Higashi; N. Inoue; Y. Nakatani
|
| The temperature and strain rate dependence of hydrogen embrittlement of an Al-8%Mg alloy have been investigated. Marked embrittlement is observed in a certain temperature range around room temperature, and is increased with decreasing strain rate. The recovery of the embrittlement occurs in two temperature regions. One is the region in which the recovery proceeds more rapidly with increasing temperature above 300 K and is independent of the strain rate. The ... |
|
| Formation and Disappearance of Pre-Existing Embrittled Zone Ahead of Stress Corrosion Crack |
JUN 81 |
|
| Authors:
K. Higashi; T. Ohnishi; Y. Nakatani; K. Okabayashi
|
| Tensile loading tests were carried out on pre-cracked Al-8%Mg alloy specimens hydrogen charged or stress corrosion tested. Fractography and measurements of crack propagation and stretched zone widths show formation of pre-existing embrittled zone ahead of stress corrosion cracks. This zone disappears when the specimen stress corrosion tested is aged at room temperature. The pre-existing embrittled zone is a sequence of hydrogen embrittlement from the facts that formation and disappearance of ... |
|
| Effect of Thermomechanical Treatment on Hydrogen Embrittlement and Stress Corrosion Cracking of Al-8%Mg Alloy |
APR 81 |
|
| Authors:
T. Ohnishi; K. Higashi; Y. Nakatani
|
| In the conventional aging of Al-8%Mg alloy, the hydrogen embrittlement and the decrease of stress corrosion cracking life by hydrogen permeation are markedly produced in the hardening region of aging process. The step aging hardly alters these behaviors, because this treatment brings about an insignificant change in the microstructure. The thermomechanical treatment effectively depresses the embrittlement and the decrease of life by hydrogen permeation over the whole range of testing ... |
|
| Influence of Microstructure on Hydrogen Embrittlement of Al-8%Mg Alloy |
OCT 80 |
|
| Authors:
K. Higashi; T. Ohnishi; Y. Nakatani; K. Okabayashi
|
| When hydrogen is charged to the Al-8%Mg alloy, a large amount of hydrogen is penetrated not only in the age-hardened state, but a small amount is penetrated in the under and over-aged states. The maximum penetration state nearly agrees with the maximum hardened state. This is attributed to the correspondence of hydrogen penetration to distribution of precipitates owing to preferred penetration into grain boundaries and interfaces of precipitates. The alloy ... |
|
| Effects of Hydrogen on Stress Corrosion Cracking of Al-8%Mg Alloy |
OCT 80 |
|
| Authors:
K. Higashi; T. Ohnishi; Y. Nakatani; K. Okabayashi
|
| The susceptibility of the Al-8%Mg alloy to stress corrosion cracking changes with an aging state and reaches to its maximum at the state in which precipitates are distributed the most densely at grain boundaries. Hydrogen penetration reaches to its maximum at the maximum aging state. Hydrogen has the most remarkable effect on stress corrosion cracking at the slightly under-aged state of maximum susceptibility. The fracture of stress corrosion cracking is ... |
|
| Structures of Monovariant Al-Fe-Ni Eutectic Alloys Unidirectionally Solidified |
SEP 80 |
|
| Authors:
Y. Nakatani; T. Ohnishi; C. Okada; S. Kaminishi; T. Hatanaka
|
| Twenty Al-Fe-Ni alloys were unidirectionally solidified at temperature gradients G = 60 to 70 C/cm and solidification rates R = 15 to 1000 micrometers/s. The coupled growth regions of monovariant Al-T (ternary compound) eutectics were determined. Cellular eutectics are formed in the coupled growth region except at extremely slow rates of solidification. The shape of the eutectics transforms from elongated to square cell in accordance with solidification rates. Excess Ni ... |
|
| Mechanical Properties of Monovariant Al-Fe-Ni Eutectic Alloys Unidirectionally Solidified |
SEP 80 |
|
| Authors:
Y. Nakatani; T. Ohnishi; C. Okada; S. Kaminishi; T. Hatanaka
|
| Microhardness and tension tests at room and elevated temperatures were carried out on Al-T (ternary compound) regular eutectic alloys in the coupled growth region. The eutectics are hardened linearly in proportion to gamma(super -1) (gamma: interphase spacing) and Fe + Ni%. The tensile strength at room temperature depends on the microstructure and volume fraction of fibers. The maximum strength is 31 kg/mm(super 2). The non-cellular rod-like eutectic has a modulus ... |
|
| Effects of Additional Elements on Hydrogen Embrittlement of Al-8%Mg Alloy |
MAY 80 |
|
| Authors:
T. Ohnishi; K. Higashi; N. Inoue; Y. Nakatani
|
| HYDROGEN EMBRITTLEMENT AND STRESS CORROSION CRACKING IN AL-8%MG ALLOYS CONTAINING 0.3%ZR, CR, MN, FE, BE, AS, TE AND ZN WERE INVESTIGATED. THE ALLOYS ARE EMBRITTLED BY HYDROGEN CHARGING AND ARE MORE SUSCEPTIBLE TO STRESS CORROSION CRACKING CORRESPONDING TO A PENETRATED HYDROGEN CONTENT. THE ADDITIONAL ELEMENTS HAVE INFLUENCES BOTH ON INITIAL AND PENETRATED HYDROGEN CONTENTS. THE ORDER OF RESISTANCE TO PENETRATION IS; (STRONG) ZR>CR>MN>FE BASE ALLOY>BE>AS>TE>ZN (WEAK). DECREASE IN TENSILE STRENGTH ... |
|
| Growth Conditions and Mechanical Properties of Metastable Al-Fe Regular Eutectic Alloys |
JAN 80 |
|
| Authors:
Y. Nakatani; T. Ohnishi; C. Okada; S. Kaminishi
|
| Al-1.1 to 4.1%Fe alloys were directionally solidified at solidification rates 30 to 1,000 micrometers/sec under temperature gradient 50 to 70 C/cm. Seven ranges of microstructures are classified depending on compositions and solidification rates. A metastable Al-FeAl(sub 6) eutectic grows at the rate above 130 micrometers/sec depending on compositions. A coupled region of Al-FeAl(sub 6) eutectic lies at Fe 2.5 to 3.2%, in which the shape of FeAl(sub 6) changes from ... |
|
| EFFECTS OF MANGANESE AND CHROMIUM ON STRESS CORROSION CRACKING OF Al-Mg ALLOYS |
JAN 79 |
|
| Authors:
T. Ohnishi; Y. Nakatani
|
| This work has been performed to clarify the origin of an effect of manganese and chromium additions on SCC susceptibility of Al-Mg alloys. Both elements added in the alloys have a remarkable effect for improving SCC in maximum aging state, but have a little effect in over-aging and especially under-aging states. This fact is attributed to lowering the development of susceptibility resulted from depression of grain boundary precipitation. |
|
| MICROSTRUCTURES AND MECHANICAL PROPERTIES OF UNIDIRECTIONALLY SOLIDIFIED Al-Fe EUTECTIC ALLOYS |
JUL 78 |
|
| Authors:
Y. Nakatani; T. Ohnishi
|
| Al-2.7 wt%Fe and Al-3.25 wt%Fe alloys were unidirectionally solidified where the temperature gradient G and solidification rate R were controlled and uncontrolled, respectively. The Al-2.7 wt%Fe alloy has three types of structures i.e. platelet eutectic, mixture of platelet and fibrous eutectics and flaky eutectic having primary alpha corresponding to G and R. The interphase spacing lamba of FeAl(sub 3) is R lambda(super 2) equals 5.8 X 10(super -3) (cm(super 3)/sec). ... |
|
| EFFECTS OF HYDROGEN ON TENSILE PROPERTIES OF Al-8%Mg ALLOY |
OCT 77 |
|
| Authors:
T. Ohnishi; T. Hara; Y. Mohri; Y. Nakatani
|
| Hydrogen charging and room temperature aging were carried out on the Al-8%Mg alloy aged at 170 C for 24 hr. Tensile tests were made under a constant rate 0.05 cm/min. The ultimate tensile strength and elongation are decreased with increasing the time of hydrogen charging, namely the hydrogen content, but the 0.2% proof stress is unchanged. The ductility is completely recovered during aging at room temperature. Penetration of hydrogen results ... |
|
| PENETRATION OF HYDROGEN INTO AN Al-8%Mg ALLOY |
AUG 77 |
|
| Authors:
T. Ohnishi; T. Hara; Y. Nakatani
|
| The cathodic charge method was used in which cathodic currents 5 mA/ sq cm was applied in 2N-sulfuric acid solution at room temperature. Hydrogen content increases with charging time and saturates at about 10 min. Hydrogen is appreciably evolved during aging at room temperature but not so completely to recover the original level. No hydride is formed. Aluminum lattices are expanded and lattice strain is relaxed by penetration of hydrogen ... |
|
| OBSERVATIONS OF STRESS CORROSION CRACKING OF Al-Mg ALLOYS |
MAY 77 |
|
| Authors:
T. Ohnishi; Y. Nakatani
|
| stress corrosion cracking tests were carried out in 3.5% nacl solution. in a normal stress corrosion test, hydrogen bubbles generated at grain boundaries after some period from a start of testing and cracks were visualized. cracks propagated along the grain boundary with increasing the number and size of bubbles. as a corrosion reaction was activated by anodic current in an accelerated test, hydrogen bubbles generated earlier and larger, and generated ... |
|
| EFFECT OF THERMOMECHANICAL TREATMENT ON STRENGTH AND STRESS CORROSION OF Al-8%Mg ALLOY |
FEB 77 |
|
| Authors:
T. Ohnishi; M. Uekado; F. Oriishi; Y. Nakatani
|
| the tensile and stress corrosion tests were made on the al-8%mg alloy aged at 200 c for various periods after aging at 150 c for 24 hr followed cold rolling by 0.30 and 50%. the stress corrosion behavior was tested in the 3.5% nacl solution by loading of 80% of 0.2% proof stress of the alloy with the anodic current of 5ma/cm(super 2). the two-step aging is not effective, but ... |
|
| EFFECT OF MICROSTRUCTURE ON STRESS CORROSION SUSCEPTIBILITY |
JAN 76 |
|
| Authors:
T. Ohnishi; Y. Nakatani; H. Sakamoto
|
|
| EFFECTS OF SOME FACTORS ON STRESS CORROSION SUSCEPTIBILITY OF AL-MG ALLOYS |
JAN 76 |
|
| Authors:
T. Ohnishi; Y. Nakatani
|
|
| EFFECTS OF HYDROGEN ON STRESS CORROSION CRACKING OF Al-8%Mg ALLOY |
|
|
| Authors:
T. Ohnishi; Y. Nakatani
|
| The mechanism for stress corrosion in the Al-Mg alloy is investigated. Charged hydrogen has an influence to the susceptibility to stress corrosion and lowers the life. The upper and lower critical concentrations are found. Increase in the susceptibility is saturated beyond the former at the amount of hydrogen increase 0.35 cc/100g and the susceptibility is unchanged below the latter at 0.15 cc/100g. The amount of hydrogen absorbed in the alloy ... |
|
Reports by Author
