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Bending fatigue strength of case-carburized helical gears (In the case of large helix angles)
Kengo Nojima,Kengo Ogata,Motomu Tanaka,Ryosuke Nishi,Yuichi Ono,Takao Koide 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.12
Case-carburizing enlarges the depth of the hardened layer at the tooth width end on the acute angle side of helical gears. For the helical gears with large helix angles (Exceeding 25°), this hardened layer may lower their bending fatigue strength. Therefore, we investigated the influence of this hardened layer on their bending fatigue strength through the bending fatigue tests. Our results suggest that this hardened layer might reduce the case-carburizing’s effect to enhance their bending fatigue strength. Thus, using only the maximum tooth root stress would be inadequate for evaluating their bending fatigue strength, and it would be necessary to consider the relationship between the hardened layer and the tooth root stress distribution (Especially, the stress applied at the tooth width end on the acute angle side) from the beginning of meshing to the end.
Kengo Yoshida,Mitsutoshi Kuroda 한국소성가공학회 2011 기타자료 Vol.2011 No.8
Plastic deformation characteristics and limit strains are simulated for textured face-centered cubic polycrystalline sheets using a generalized Taylor-type crystal plasticity model. The r-values are predicted to be 1.04, 7.74 and 0.17 for the random, {111}〈uvw〉 and {001}〈uvw〉 textures, respectively. The {111}〈uvw〉 texture gives limit strains as large as the random texture, whereas the {001}〈uvw〉 texture yields limit strains evidently higher than the other two even though its r-value is extremely low. Thus, the r-value cannot act as an indicator to the stretchability of sheet metals. For the {001}〈uvw〉 texture, a superior strain-hardening ability under plane-strain stretching mode is found to be responsible for the increase in the limit strains under plane-strain and equi-biaxial stretching modes. We conclude that the enhancement of the strain-hardening ability for plane strain mode is one of the key factors for high stretchability sheets.
Kengo Fujii,Masataka Sakane,Tetsuya Abe,Tsukasa Nakagawa,Shinsuke Sakai,Masaki Tatsumura,Toru Funayama,Masashi Yamazaki 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.6
Study Design: Retrospective, radiological study. Purpose: To determine the relationship between clinical symptoms and the extent of tumor occupation of the spinal canal by cauda equina schwannoma. Overview of Literature: Little is known about the relationship between the size of tumors of the cauda equina and the manifestation of clinical symptoms. We analyzed this relationship by estimating the percentage of tumor occupation (PTO) in the spinal canal in cauda equina schwannomas and by correlating this parameter with the presence and severity of clinical symptoms. Methods: Twenty-two patients (9 men and 13 women; age, 19–79 years; mean age, 55.3 years) who were radiologically diagnosed with schwannomas of the cauda equina between April 2004 and July 2014 were retrospectively analyzed. PTO was measured in axial and sagittal magnetic resonance imaging slices in which the cross-sectional area of the tumor was the largest. Data regarding clinical symptoms and results of physical examinations were collected from patient medical records. PTO differences between symptompositive and -negative groups were analyzed for each variable. Results: In the 4 cases in which tumor presence was not related to clinical symptoms, PTO was 5%–10% (mean, 9%) in axial slices and 23%–31% (mean, 30%) in sagittal slices. In the 18 cases in which symptoms were associated with the tumor, PTO was 11%–86% (mean, 50%) in axial slices and 43%–88% (mean, 71%) in sagittal slices. PTO in axial slices was significantly higher in the presence of Déjèrine symptoms and/or muscle weakness, a positive straight leg raise test, and a positive Kemp sign. Conclusions: PTO >20% in axial slices and >40% in sagittal slices can be an indication of symptomatic cauda equina schwannoma.
Behavior of GDI fuel spray adhered on a wall
( Kengo Jinnai ),( Yoshihiro Kobayashi ),( Masataka Arai ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-
Impingement behavior of iso-octane spray injected from GDI nozzle was investigated. Ground glass plate was used as an impingement wall to observe trace-mark of liquid film on the wall. When fuel spray adhered on the ground glass plate, the light transmitted only through adhesion area of liquid fuel. This light-transmitted liquid film area was observed from bottom side of the impingement plate. The trace-mark image of liquid film was taken by high-speed camera during and after injection period. It was binarized and evaluated as the adhered area of liquid film. Adhesion area was measured under two injection pressure conditions (P<sub>inj</sub>=0.6MPa and 3.0MPa) and two impingement distances (z= 30 mm and 50 mm) with dry wall and wet wall conditions. The total injection period was 15 ms for single shot injection. As for the split injection (10ms x 3 shots), interval of split injection was 5ms but total injected mass was kept to be same as the single injection. Fuel adhesion started when spray tip arrived at the impingement plate, its area expanded with injection elapsed however it was always narrower than the wall spray area that was observed as a general top view image of impingement spray. Further, adhesion area still increased during a few milli-seconds after injection finished. During the interval period of split injection, adhesion area was also expanded. Adhesion area on wet wall was narrower than that on dry wall because of secondary splash from wet wall. Since the continuous increase of adhesion area during the interval period was cancelled by the splash caused by following split spray, there was no apparent difference on adhesion film behaviors of single and split fuel injection. Larger increase rate of adhesion area was obtained at P<sub>inj</sub>=3.0MPa than that at P<sub>inj</sub>=0.6MPa, but qualitative behavior of adhesion area was not affected by the injection pressure.