Yoshikazu Sano

Convenient Adhesive Strength Evaluation Method in Terms of the Intensity of Singular Stress Field

A convenient evaluation method is proposed for the debonding adhesive strength in terms of the intensity of singular stress field (ISSF) appearing at the end of interface. The same FEM mesh pattern...

Strain Rate Concentration Factor for Round and Flat Test Specimens

In this study, the strain rate concentration is considered for high speed tensile test, which is now being recognized as a standard testing method. To evaluate the impact strength of engineering materials, Izod and Charpy tests are unsuitable since they cannot control the impact speeds and therefore the testing results do not coincide with the real failure of real products. For smooth specimens, the strain rate can be determined from the tensile speed \( u/t \) and specimen length \( l \) as \( \dot{\varepsilon }_{smooth} = u/tl \). For notched specimens, however, the strain rate at the notch root \( \dot{\varepsilon }_{notch} \) should be analyzed accurately. In this study, therefore, the strain rate concentration factor defined as \( K_{{t\dot{\varepsilon }}} = \dot{\varepsilon }_{notch} /\dot{\varepsilon }_{smooth} \) is studied with varying the notch geometry and specimen length for round and flat test specimens.

Intensity of singular stress fields of wedge-shaped defect in human tooth due to occlusal force before and after restoration with composite resins

Wedge-shaped defects are frequently observed on the cervical region of the human tooth. Previously, most studies explained that improper tooth-brushing causes such defects. However, recent clinical observation suggested that the repeated stress due to occlusal force may induce the formation of these wedge-shaped defects. In this study, therefore, two-dimensional human tooth models are considered with and without a wedge-shaped defect by applying the finite element method. To evaluate large stress concentrations accurately, a method of analysis is discussed in terms of the intensity of singular stress fields appearing at the tip of the sharp wedge-shaped defect. The effects of the position and direction of occlusion on the intensity of singular stress fields are discussed before and after restoration with composite resins.

Dependency of tensile strength of ductile cast iron on strain rate and temperature

The dependency of the tensile strength and the notch strength on strain rate and temperature were investigated for conventional ferrite-pearlite type ductile cast iron (JIS-FCD500) to make clear the applicability of ductile cast iron to components for welded steel structures. High speed tensile tests were conducted on notched and smooth specimens with varying strain rate and temperature. Charpy absorbed energy was also evaluated on notched specimen with varying temperature. It is found that the tensile strength is in a good relationship with strain rate-temperature parameter R for the wide range of strain rate and temperature. With decreasing R parameter, both and increase even when Charpy absorbed energy starts decreasing. It should be noted that the notch strength is always larger than the tensile strength at room temperature in the range of R parameter required for the welded structures. Therefore, the tensile strength is confirmed to be useful for the structural design.

Coming out prevention by stopper for the shrink fitted sandwiched shaft from the ceramic sleeve

Ceramic roller can be used in the heating furnace conveniently because of its high temperature resistance. The roller consists of sleeve and steel shaft connected only under a small shrink fitting ratio because of the brittleness. However, the coming out of the shaft may often happen from the ceramic sleeve under repeated bending load. Therefore, how to prevent the coming out failure becomes an important issue. Based on the previous study, a two-dimensional shrink fitted structure is considered by replacing the shaft with the inner plate and by replacing the sleeve with the outer plate. Then, this research focuses on preventing the inner plate coming out from the outer plate by introducing a newly designed stopper on the outer plate. The simulation results shows that the coming out phenomenon can be prevented effectively due to the contact between the inter plate and the stopper installed on the outer plate. In order to evaluate the contact force between the inner plate and the stopper, the coming out mechanism is clarified. To prevent the coming out by stopper safely, the effects of the magnitude of repeated load and the friction coefficient upon the contact compressive force are investigated under large number of loading cycles by using 2D simulation.

Simulation of Coming out of the Shaft from the Ceramics Sleeve During Rotation of the Rollers Connected under Small Shrink Fitting Ratio

自動車用鋼板をはじめとする高級鋼材を生産するための 熱処理炉(Fig.1参照)では,ローラーを用いて鋼材の搬送 が行われている。現在,Fig.2(a)のようなステンレス耐熱 鋼にセラミック溶射でコーティングされた胴部と,ステン レス耐熱鋼の軸部を溶接,焼嵌め等で接合し,中空部を水 冷する構造のローラー(ハースロールと呼ばれる)が,主 として用いられている。このローラーは,炉内の高温環境 下において使用中に,耐熱鋼とセラミックコーティング層 の線膨張係数の違いや,コーティング層の微小欠陥や密着 強度の限界等に起因し,ローラー表面にき裂や剥離 ,そ れに伴う肌あれ,摩耗等の発生を招き,ローラーの寿命を 短くしている。また,ローラー内部を水冷するために熱損 失が無視できない。 そこで,Fig.2(b)のように胴部材料全体をセラミックと し,その両端に鋼製軸を用い,中空部を空冷するローラー 構造を検討している。胴部材料を耐熱性・耐摩耗性 ・耐 腐食性 に優れたセラミックにすることで,現状のコー ティングに起因する欠陥を防止でき,ローラー寿命を飛躍 高温炉中で使われる セラミックローラー稼動中におけるシャフトの抜け

OS1210 Fatigue Strength Analysis for Bolts and Nuts Which Have Slightly Different Pitches Considering Clearance

5.3. エコドライブによる CO2削減効果 1 台あたりのエコドライブ効果とエコドライブ普及率を乗 じることで,各地域のエコドライブによる CO2削減率を推計 した.1 台あたりのエコドライブ効果については,国内外の 6 機関が公表した平均値~である 13%を採用し,普及率はエ ネルギーITS 研究会のシナリオに沿って 70%を採用した.そ の結果,中国,インド,ASEAN いずれも 2050 年のエコドラ イブ普及による CO2削減効果は 9%とした. 5.4. 統合対策を考慮した CO2削減効果シナリオ 5.1~5.3 節で推計した交通流対策およびエコドライブによ る CO2削減効果を考慮し,統合対策における CO2排出量の推 計を行った.その結果,CO2排出量は統合対策にて 20%減(道 路整備:8%,ITS:9%,エコドライブ:4%)となり,技術進 化(次世代車普及含む)および統合対策をそれぞれ単独で実 施すると 31%,20%の CO2削減が可能であり,両者を併せて 実施すると 45%と推計された(図 22).