| Shigeru Hamada | Last modified date：2024.04.23 |
Professor /
Strength of Materials /
Department of Mechanical Engineering /
Faculty of Engineering
Presentations
| 1. | Shigeru HAMADA, Fatigue Crack Extension by Damage Accumulation, 13th International Fatigue Congress (FATIGUE 2022+1), 2023.11. |
| 2. | Pengxu REN Daisuke ITOH Shigeru HAMADA, Carbon content effect on fatigue crack extension behavior and extension mode in 18%Ni martensitic steels, 13th International Fatigue Congress (FATIGUE 2022+1), 2023.11. |
| 3. | Shun KINO Daisuke ITOH Shohei UEKI Shigeru HAMADA, Fatigue Crack Extension Mode for 18Ni Martensitic Steel and Its Effect on Fatigue Limit, 13th International Fatigue Congress (FATIGUE 2022+1), 2023.11. |
| 4. | Ren Pengxu Daisuke Itoh Shigeru Hamada, FATIGUE CRACK EXTENSION MODE OF 18%Ni MARTENSITIC STEEL, 15th International Conference on Fracture (ICF15), 2023.06. |
| 5. | Bryan Proaño Hirofumi Miyahara Kohei Morishita Toshiharu Matsumoto Hitoshi Sakai Shigeru Hamada, INFLUENCE OF THE CONTOUR PARAMETER IN MICROSTRUCTURE DUALITY AND FRACTURE INITIATION IN NON-COMBUSTIBLE MAGNESIUM ALLOYS FABRICATED BY LASER POWDER BED FUSION, 15th International Conference on Fracture (ICF15), 2023.06. |
| 6. | Taeseul PARK Bryan Steve PROAÑO SARAUZ Shigeru HAMADA, EVALUATION OF STRENGTH CHARACTERISTICS FOR NON-COMBUSTIBLE MAGNESIUM ALLOY PRODUCTS FABRICATED BY LASER POWDER BED FUSION UNDER AS-BUILT CONDITION, 15th International Conference on Fracture (ICF15), 2023.06. |
| 7. | Shigeru Hamada Yudai Yamaguchi Yudai Okawa Yamato Araki, DAMAGE ACCUMULATION MODE FATIGUE CRACK PROPAGATION AND PROPAGATION BEHAVIOR PREDICTION METHOD, 15th International Conference on Fracture (ICF15), 2023.06. |
| 8. | Taeseul Park, Bryan Steve Proaño Sarauz, Shigeru Hamada, Fracture Toughness Measurement of Non-Combustible Mg Products Fabricated by Selective Laser Melting in As-Built Conditions, ECF23, the 23rd European Conference on Fracture 2022, 2022.06. |
| 9. | Akihiro Kurafuji, Bryan Steve Proaño Sarauz, Shigeru Hamada, Effect of Surface Microstructure on Fatigue Strength of Non-combustible Mg Products Fabricated by Selective Laser Melting, ECF23, the 23rd European Conference on Fracture 2022, 2022.06. |
| 10. | Shun KINO, Daisuke ITOH, Shigeru HAMADA, Fatigue Strength Properties of 18Ni Martensitic Steels as a Function of Microstructure Size, ECF23, the 23rd European Conference on Fracture 2022, 2022.06. |
| 11. | Pengxu REN, Shigeru HAMADA, Fatigue Crack Extension Mode Analysis in 18%Ni Steel, ECF23, the 23rd European Conference on Fracture 2022, 2022.06. |
| 12. | Bowen Chen, Shigeru Hamada, Quantification of fatigue damage and its effect on fatigue limit, ECF23, the 23rd European Conference on Fracture 2022, 2022.06. |
| 13. | Bryan S. Proano; Hitoshi Sakai; Shigeru Hamada; Toshiharu Matsumoto; Hirofumi Miyahara; Kohei Morishita, Microstructure Duality Influence in Plastic Strain Formation from an Artificial Defect in As-Built Non-Combustible Mg Products Fabricated by Selective Laser Melting, ASTM International Conference on Additive Manufacturing, ICAM2021, 2021.11. |
| 14. | Virendra Kumar Verma, Shigeru Hamada, Motomichi Koyama, Understanding the damage initiation mechanism of precipitation-strengthened Fe-Ni-Cr based austenitic steel, 10th International Conference on Materials Processing and Characterization, 2020.02. |
| 15. | He Liu, Shigeru Hamada, Hiroshi Noguchi , Harmless preexisting crack in structures made of hydrogen-embrittlement sensitive materials under monotonic tension, 2020 4th International Conference on Material Science and Technology (ICMST 2020), 2020.01, [URL]. |
| 16. | He Liu, Shigeru Hamada, Hiroshi Noguchi , Harmless preexisting crack in structures made of hydrogen-embrittlement sensitive materials under monotonic tension, International Conference on Engineering & Technology (ICET-19), 2019.12. |
| 17. | Ren Pengxu, Hamada Shigeru, Noguchi Hiroshi, Effect of hardness HV on plastic strain gradient around sharp stress concentration source of S45C Steel with a mechanically long crack, 日本機械学会 M&M2019材料力学カンファレンス, 2019.11. |
| 18. | Chen Tingshu, Liu He, Zhang Kejin, Koyama Motomichi, Hamada Shigeru, Noguchi Hiroshi, Notch sensitivity in pure nickel determined by two mechanisms of hydrogen-assisted crack extension: sub-/main-crack coalescence versus main-crack growth, 日本機械学会 M&M2019材料力学カンファレンス, 2019.11. |
| 19. | Verma Virendra Kumar, He Liu, Shigeru Hamada, Tatsuo Yokoi, Hiroshi Noguchi, Effect of initial crack length on the transition of fatigue properties for precipitation hardened steel, 日本機械学会 M&M2019材料力学カンファレンス, 2019.11. |
| 20. | Liu He, Chen Tingshu, Verma Virendra Kumar, Hamada Shigeru, Koyama Motomichi, Noguchi Hiroshi, Similarity between shallow notch and crack effects on structure strength governed by plastic instability, 日本機械学会 M&M2019材料力学カンファレンス, 2019.11. |
| 21. | Bryan PROANO, Tomoya YAMAGUCHI, Hirofumi MIYAHARA, Toshiharu MATSUMOTO, Shigeru HAMADA, Hitoshi SAKAI, Kiyoshi OGAWA, Suyalatu and Hiroshi NOGUCHI , Weakest Region Analysis and Size Effects on the Nature and Distribution of Defects and Their Influence on Strength of Noncombustible Mg Products Fabricated by Selective Laser Melting, First European Conference on Structural Integrity of Additively Manufactured Materials (ESIAM19), 2019.09. |
| 22. | Virendra Kumar Verma, He Liu, Shigeru Hamada, Hiroshi Noguchi, Fatigue crack propagation study of precipitation hardened steels, International Conference on Advances in Materials and Manufacturing Applications [IConAMMA 2019], 2019.08. |
| 23. | Kejin Zhang, Shigeru Hamada, Motomichi Koyama, Tatsuo Yokoi and Hiroshi Noguchi, Influence of shear-affected-zone due to punching in tensile characteristics of steel plate, 22nd European Conference on Fracture - ECF22, 2018.08. |
| 24. | Temma Sano, Daisuke Sasaki, Motomichi Koyama, Shigeru Hamada and Hiroshi Noguchi, Proposal and verification of novel fatigue crack propagation simulation method by finite element method, 22nd European Conference on Fracture - ECF22, 2018.08. |
| 25. | Taketo Kaida, Motomichi Koyama, Shigeru Hamada, Hiroshi Noguchi, Eisaku Sakurada, Tatsuo Yokoi, Kousaku Ushioda, Proposal of fractographic analysis method coupled with EBSD and ECCI, 22nd European Conference on Fracture - ECF22, 2018.08. |
| 26. | Shigeru Hamada, Taro Suemasu, Motomichi Koyama, Masaharu Ueda and Hiroshi Noguchi, Re-examination of fatigue crack propagation mechanism under cyclic Mode II loading, 22nd European Conference on Fracture - ECF22, 2018.08. |
| 27. | Taro Suemasu, Motomichi Koyama, Shigeru Hamada, Masaharu Ueda and Hiroshi Noguchii, The influence of fracture surface contact in fatigue crack propagation of material having texture under Mode II loading, 22nd European Conference on Fracture - ECF22, 2018.08. |
| 28. | M. Aibara, M. Koyama, S. Hamada, H. Noguchi,, Analysis of fatigue crack configuration influence on fatigue life, 22nd European Conference on Fracture - ECF22, 2018.08. |
| 29. | Saburo OKAZAKI, Junichiro YAMABE, Hisao MATSUNAGA, Shigeru HAMADA, Saburo MATSUOKA, Influence of hydrogen on tensile and fatigue life properties of 304/308 austenitic stainless steels butt welded joints, 2018 ASME Pressure Vessels & Piping Conference, 2018.07. |
| 30. | Fatigue life properties of austenitic stainless steel weld metals in high-pressure hydrogen gas. |
| 31. | Saburo Okazaki, Shigeru Hamada, Hisatake Itoga, Hisao Matsunaga, Masami Nakamura, Saburo Matsuoka, A case study of a cooling pipe for a pre-cooler used in a 70-MPa hydrogen station, ASME 2017 Pressure Vessels and Piping Conference, PVP 2017, 2017.01, A case study was conducted on the cooling pipe of a pre-cooler which had been used in a 70-MPa hydrogen station demonstration project. The cooling pipe consisted of a main pipe, a mechanical joint pipe and a mechanical joint. The main and mechanical joint pipes had been joined using TIG welding. Through chemical composition analysis, microstructure observation and Vickers hardness measurement, it was revealed that the main and mechanical joint pipes had been manufactured from SUS316L and that 316L was the filler metal used for TIG welding. Round-bar specimens were machined out of the main pipe in order to investigate the tensile properties of the base metal. On the other hand, both round-bar specimen without reinforcement and square-bar specimens with reinforcement were fabricated from the weld-joint. Using the three types of specimens, slow strain rate tensile tests were performed in 0.1 MPa nitrogen gas and in 115 MPa hydrogen gas at a temperature of -40 °C. Reduction of area (RA), φ, for the round base-metal specimen, the round weld-joint specimen and the square weldjoint specimen were respectively, 83.5 %, 71.3 % and 81.4 % in nitrogen gas, whereas the related values in hydrogen gas were 60.1 %, 61.3 % and 40.1 %. In other words, the RA for the three types of specimens was smaller in hydrogen gas than in nitrogen gas. Dimples were formed on the fracture surfaces of the three specimen types in nitrogen gas, whereas both dimples and quasi-cleavages were formed in hydrogen gas.. |
| 32. | A case study of a cooling pipe for a pre-cooler used in a 70-MPa hydrogen station Copyright © 2017 ASME. A case study was conducted on the cooling pipe of a pre-cooler which had been used in a 70-MPa hydrogen station demonstration project. The cooling pipe consisted of a main pipe, a mechanical joint pipe and a mechanical joint. The main and mechanical joint pipes had been joined using TIG welding. Through chemical composition analysis, microstructure observation and Vickers hardness measurement, it was revealed that the main and mechanical joint pipes had been manufactured from SUS316L and that 316L was the filler metal used for TIG welding. Round-bar specimens were machined out of the main pipe in order to investigate the tensile properties of the base metal. On the other hand, both round-bar specimen without reinforcement and square-bar specimens with reinforcement were fabricated from the weld-joint. Using the three types of specimens, slow strain rate tensile tests were performed in 0.1 MPa nitrogen gas and in 115 MPa hydrogen gas at a temperature of -40 °C. Reduction of area (RA), φ, for the round base-metal specimen, the round weld-joint specimen and the square weldjoint specimen were respectively, 83.5 %, 71.3 % and 81.4 % in nitrogen gas, whereas the related values in hydrogen gas were 60.1 %, 61.3 % and 40.1 %. In other words, the RA for the three types of specimens was smaller in hydrogen gas than in nitrogen gas. Dimples were formed on the fracture surfaces of the three specimen types in nitrogen gas, whereas both dimples and quasi-cleavages were formed in hydrogen gas.. |
| 33. | Test method for threshold of hydrogen-induced crack growth KI,H of SCM435 in 115 MPa hydrogen gas. |
| 34. | Case Study on Cooling Pipe of Pre-cooler Used for Verification Test of 70 MPa Hydrogen Station. |
| 35. | Punching process effects on fatigue strength properties. |
| 36. | Relationship between hardness and fatigue limit focusing attention on the plastic strain similarity between indentation and fatigue crack growth. |
| 37. | Effect of Hydrogen on SSRT Properties of 304/308 Weld Metal. |
| 38. | Shuto FUKUDOME, Shigeru HAMADA, Masaharu UEDA, Hiroshi NOGUCHI, Shear mode crack propagation along with plastic flow of small area, 12th International Conference on the Mechanical Behavior of Materials (ICM12), 2015.05. |
| 39. | Hisao MATSUNAGA, Michio YOSHIKAWA, Hisatake ITOGA, Junichiro YAMABE, Shigeru HAMADA, Saburo MATSUOKA, Tensile- and fatigue-properties of low alloy steel JIS-SCM435 and carbon steel JIS-SM490B in 115 MPa hydrogen gas, 2014 ASME Pressure Vessels & Piping Conference, 2014.07. |
| 40. | Junichiro YAMABE, Hisatake ITOGA, Torhu AWANE, Hisao MATSUNAGA, Shigeru HAMADA, Saburo MATSUOKA, Fatigue-life and leak-before-break assessments of Cr-Mo steel pressure vessels with high-pressure gaseous hydrogen, 2014 ASME Pressure Vessels & Piping Conference, 2014.07. |
| 41. | Toshiyuki Ishina, Shigeru Hamada, Hiroshi Noguchi, Derivation of Non-dimensional Number for Elastic-perfectly Plastic Continuum Body and Elastic-perfectly Plastic Solid Materials in Linear Elastic Fracture Mechanics, The 20th European Conference on Fracture, 2014.07. |
| 42. | Fatigue-life and leak-before-break assessments of CR-MO steel pressure vessels with high-pressure gaseous hydrogen Copyright © 2014 by ASME. Pressure cycle tests were performed on two types of Cr-Mo steel pressure vessels with inner diameters of 306 mm and 210 mm and notches machined on their inside under hydrogen-gas pressures, varied between 0.6 and 45 MPa at room temperature. One of the Cr-Mo steels had a fine microstructure with tensile strength of 828 MPa, while the other had a coarse microstructure with tensile strength of 947 MPa. Fatigue-crack growth (FCG) and fracture-toughness tests of the Cr-Mo steels were also carried out in gaseous hydrogen. The Cr-Mo steels showed accelerated FCG rates in gaseous hydrogen compared to ambient air with an upper bound corresponding to an approximately 30-times higher FCG rate. Furthermore, in gaseous hydrogen, the fracture toughness of the Cr-Mo steel with coarse microstructure was significantly smaller than that of the steel with fine microstructure. Four pressure vessels were tested; then, all of the pressure vessels failed by leak-before-break (LBB). Based on the fracture-mechanics approach, the LBB failure of one pressure vessel could not be estimated by using the fracture toughness in gaseous hydrogen. The fatigue lives could be estimated by using the upper bound of the accelerated FCG rates in gaseous hydrogen.. |
| 43. | Tensile-and fatigue-properties of low alloy steel JIS-SCM435 and carbon steel JIS-SM490B in 115 MPA hydrogen gas Copyright © 2014 by ASME. Slow strain rate tests using smooth specimens of two types of steels, low alloy steel JIS-SCM435 and carbon steel JIS-SM490B, were carried out in nitrogen gas and hydrogen gas under a pressure of 115 MPa at three different temperatures: 233 K, room temperature and 393 K. In nitrogen gas, these steels exhibited the so-called cup-and-cone fracture at every temperature. On the other hand, in hydrogen gas, in both steels a number of cracks initiated on the specimen surface and coalesced with each other at every temperature, which led to a marked reduction in ductility. Nonetheless, even in hydrogen gas, JIS-SCM435 exhibited a certain reduction of area after the stress-displacement curve reached the tensile strength (TS), whereas JIS-SM490B exhibited little, if any, necking in hydrogen gas. In addition, tension-compression fatigue testing at room temperature revealed that in both steels there was no noticeable difference between the fatigue strengths in air and 115MPa hydrogen gas, especially in a relatively long life regime. Considering that there was little or no hydrogen-induced degradation in either TS or fatigue strength in JIS-SCM435, it is suggested that JIS-SCM435 is eligible for fatigue limit design on the basis of a safety factor (i.e. TS divided by the allowable design stress) for mechanical components used in hydrogen gas up to 115 MPa.. |
| 44. | Proposal of New Constitutive Equation for Realizing Hydrogen-Enhanced-Localized-Plasticity and It’s Application to Hydrogen Embrittlement Mechanism. |
| 45. | Fatigue Limit Prediction Method for a Material with an Arbitrary Shaped Flaw and Verification Using 5056 Aluminum Alloy. |
| 46. | Effect of the Defect Shape on the Fatigue Crack Non-Propagation behavior Using Quenched and Tempered 0.45% Carbon Steel. |
| 47. | Shigeru Hamada, Minjian Liu, Measurement of effective stress intensity factor range of mode II fatigue crack growth using hysteresis loop, 13th International Conference on Fracture, 2013.06, A method was proposed for measuring the effective stress intensity factor ranges of Mode II fatigue crack growth by using the hysteresis loop for a specimen's surface strain. Many cases of rolling contact fatigue failure, such as those that occur in railway rails, bearings and gears are due to repeated high shear loads. In order to prevent such fatigue failures, the resistance of a material to repeated high shear loads must be determined. The fatigue crack growth characteristics are dependent on the Mode II stress intensity factor range. However, conventionally measured Mode II fatigue crack growth characteristics vary according to the measurement methods. Therefore, the authors improved the experimental measurement method proposed by Murakami, and proposed a way to measure the Mode II effective stress intensity factor range. Improvements to the jigs and specimen were made based on the ideal mechanical model of the experimental method. Furthermore, to measure the Mode II fatigue crack growth behavior, strain gauges were applied to the specimen and the hysteresis loop of the strain was measured with high accuracy by using a newly developed subtraction circuit.. |
| 48. | Shigeru Hamada, Minjian Liu, Measurement of effective stress intensity factor range of mode II fatigue crack growth using hysteresis loop, 13th International Conference on Fracture 2013, ICF 2013, 2013.01, A method was proposed for measuring the effective stress intensity factor ranges of Mode II fatigue crack growth by using the hysteresis loop for a specimen's surface strain. Many cases of rolling contact fatigue failure, such as those that occur in railway rails, bearings and gears are due to repeated high shear loads. In order to prevent such fatigue failures, the resistance of a material to repeated high shear loads must be determined. The fatigue crack growth characteristics are dependent on the Mode II stress intensity factor range. However, conventionally measured Mode II fatigue crack growth characteristics vary according to the measurement methods. Therefore, the authors improved the experimental measurement method proposed by Murakami, and proposed a way to measure the Mode II effective stress intensity factor range. Improvements to the jigs and specimen were made based on the ideal mechanical model of the experimental method. Furthermore, to measure the Mode II fatigue crack growth behavior, strain gauges were applied to the specimen and the hysteresis loop of the strain was measured with high accuracy by using a newly developed subtraction circuit.. |
| 49. | Measurement of effective stress intensity factor range of mode II fatigue crack growth using hysteresis loop A method was proposed for measuring the effective stress intensity factor ranges of Mode II fatigue crack growth by using the hysteresis loop for a specimen's surface strain. Many cases of rolling contact fatigue failure, such as those that occur in railway rails, bearings and gears are due to repeated high shear loads. In order to prevent such fatigue failures, the resistance of a material to repeated high shear loads must be determined. The fatigue crack growth characteristics are dependent on the Mode II stress intensity factor range. However, conventionally measured Mode II fatigue crack growth characteristics vary according to the measurement methods. Therefore, the authors improved the experimental measurement method proposed by Murakami, and proposed a way to measure the Mode II effective stress intensity factor range. Improvements to the jigs and specimen were made based on the ideal mechanical model of the experimental method. Furthermore, to measure the Mode II fatigue crack growth behavior, strain gauges were applied to the specimen and the hysteresis loop of the strain was measured with high accuracy by using a newly developed subtraction circuit.. |
| 50. | shigeru hamada, Strength Evaluation for Micro Polycrystalline Silicon Structure and Hermetic Seal of MEMS package, The Sixth KAIST-Kyushu University Joint Workshop on Frontiers in Mechanical and Aerospace Engineering, 2012.09, There are two important points to develop MEMS package from the view point of reliability. The first one is the strength reliability of micro polycrystalline silicon structure, and the second one is bonding strength reliability for hermetic seal. In order to evaluate strength of micron size polycrystalline silicon (poly-Si) structure for MEMS considering surface morphology difference between top and sidewall and effective surface area, bending strength tests of cantilever beam, surface roughness measurement and fracture surface analysis are performed. The specimens are made by CVD process for poly-Si deposition and deep RIE process for sidewall formation, and then the surface morphology of the top and the sidewall surface are different. The various size notches on the specimen are introduced in order to change effective surface area. By the fracture surface analysis, it was found that the fracture initiation point was not always maximum stress point; this is because there exist stress concentration on the surface. Surface roughness was measured using atomic force microscope (AFM). Then the maximum stress concentration of the specimen on the top and the sidewall surface respectively were presumed using extreme statistics, and effective surface area was defined. Then, bending strength and effective surface area shows good correlation. In order to secure the certain operation of MEMS devices, it is very important to design a hermetically sealed package which protects the device from wet environments, taking into account the reliability of cap bonding of MEMS packages. Anodic bonding is a popular cap bonding method. In this process, glass and single crystal silicon are bonded at high temperature under high voltage conditions. In this study, the new production method of device size specimen with an interface crack by wafer process is proposed. And an attempt is made to establish a method of testing the cap bonding strength of packages and to make clear the interface strength of anodic bonding between the glass and single crystal silicon.. |
| 51. | , [URL]. |
| 52. | , [URL]. |
| 53. | , [URL]. |
| 54. | , [URL]. |
| 55. | , [URL]. |
| 56. | Proposal of evaluation method of fatigue limits in cast non-combustible Mg alloy at high temperature. |
| 57. | Relation between fatigue crack initiation and structure in pearlitic steel. |
| 58. | Determination of effective stress intensity factor range of mode ii fatigue crack propagation using improved experimental method Many cases of rolling contact fatigue failure, such as those that occur in railway rails, rolling bearings, and gears, are due to repeated high shear load. In order to prevent such fatigue failures, the resistance of a material against to repeated high shear load must be determined. The fatigue crack growth rate is dependent on the stress intensity factor range of Mode II ΔK II. However, Mode II crack propagation characteristics vary according to the method by which they are determined. We improved the experimental method proposed by Murakami and measured the effective stress intensity factor range of Mode II AK IIeff. Changes to the jigs and specimen were made and the experimental method was such that the ideal mechanical model was expected to be approached. Furthermore, to measure the ΔKIIeff, several strain gauges were applied to the specimen around the crack tip. Using the improved method, some ΔK IIeff values during the Mode II fatigue crack propagation tests can be measured.. |
| 59. | Ductile to brittle transition in magnesium alloy with a crack We evaluated the strength of a cast non-combustible magnesium alloy that is intended for use in automobile engines. This alloy contains thin sheet-like oxides because of its production process. The size of these thin sheet-like oxides varies, and this means that the temperature dependency of the strength characteristics of the alloy cannot be determined by a tensile test alone. Initially, specimens of the alloy having an artificial pre-crack of 5 [mm] to simulate the sheet-like oxides were subject to tensile testing. The testing was carried out at room temperature (23 [°C]), 150 [°C], 200 [°C] and 250 [°C]. 250 [°C] is the temperature of the environment in which the alloy will be used in automobile engines. All the fractures propagated from the artificial pre-crack and the alloy exhibited its maximum strength at 150 [°C]. To investigate the temperature dependency of the fracture mechanism, a scanning electron microscope (SEM) was used to observe the region near the tip of the pre-crack on the fracture surface of the specimens tested at room temperature and at 250 [°C]. On the fracture surface of the specimen tested at 250 [°C], some dimples were observed over some of the surface near the tip of the artificial pre-crack; however, the fracture surface of the specimen tested at room temperature showed brittle fracture surface morphology over the entire area. For the magnesium alloy, the critical resolved shear stress for non-basal slip, which is a characteristic of a hexagonal close-packed metal, is dependent on temperature. Therefore, ductile to brittle transition was considered to be occurred at a temperature between room temperature and 250 [°C]. Mechanical restraint is also considered to be affected the ductile to brittle transition.. |
| 60. | Effect of friction stir welding condition on fatigue limit of welded non-combustible Mg alloy The atigue strength of Friction Stir Welding is affected by the structure and the welding defect size. The welding defect sizes have a scatter. Therfore, the effect of Friction Stir Welding condition on fatigue limit of welded noncombustible Mg alloy was investigated with the specimen which has a controlled defect size. As a result, the good correlation between the fatigue limit and the hardness of the welding area was clarified. © (2012) Trans Tech Publications.. |
| 61. | Evaluation of joint defects on FSW of mg alloy using statistical method To select the welding conditions that can ensure a particular fatigue strength for safe use in a structure produced by the FSW (Friction Stir Welding) of Mg alloys, this paper proposes a method for determining the range of welding conditions that can ensure a particular joint defect size limit. The welding parameters used are the rotation speed of the tool ω and the welding speed v. Generally, a welding condition is selected using only the fatigue strength as an index. However, ensuring the fatigue strength in a particular welding condition does not insure the strength and reliability of a welded part, because actual welding is not typically carried out in a particular welding condition. Therefore, a range of conditions that can ensure a particular fatigue strength is required. Moreover, we also consider parameters that represent the factors that decrease fatigue strength, namely, √area, HV, and R, because the welding conditions that can ensure a particular fatigue strength are determined by an evaluation of these factors, as well. Therefore, in this study, a method for determining a range of welding conditions that can ensure a welding defect size limit is proposed. Furthermore, FSW welding tests were carried out and the validity of the proposed method was evaluated. X-ray transmission measurements were carried out to measure the welding defect size obtained using the method. Then, the prediction of the maximum welding defect size was carried out for a welding length of 25 [m], which is representative of body of a the Shinkansen rolling stock car.. |
| 62. | Relation between fatigue crack initiation and structure in pearlitic steel To clarify the relation between fatigue crack initiation and the crystal structure in pearlitic steel used for railroad rails, fatigue tests are performed, focusing on crack initiation. Then, the fracture surfaces are analysed using a scanning electron micro-scope (SEM). To observe the crystal structure, before the fatigue is performed, the specimen surface is etched chemically. The crystal structure of pearlitic steel, is comprised of "pearlite colonies" which have the same lamellar structure direction, and "pearlite blocks" which have the same ferrite crystal direction. A fatigue crack initiation region should be affected by the crystal structure; however, the relation between the crack initiation region and the crystal structure in pearlitic steel has not been clarified. From the fatigue test results, the fatigue crack of the pearlitic steel was initiated at a very early stage of the fatigue test. To determine the unit of fatigue crack initiation in pearlitic steel, the relation between the crack initiation region and crystal structure was clarified by using SEM analysis.. |
| 63. | The effect of prestrain on fatigue property of precipitation strengthening stainless steel SUH660 In precipitation-strengthened steel, precipitation particles are considered to be cut by the prestrain treatment and affect the fatigue property of the steel. In this study, fatigue tests on prestrained specimens were performed to investigate the effect of the prestrain and precipitate cutting on the crack initiation and propagation characteristics of precipitation-hardened stainless steel (SUH660). Plain specimens were used to observe the process of crack initiation and propagation. The fatigue life was divided into the crack initiation life and the crack propagation life. The results of the fatigue test showed that the crack initiation life of a prestrained specimen was longer than that of a nonstrained specimen. The observed crack propagation mode was mainly Mode II. The measured crack propagation life of the prestrained specimen was shorter than that of the non-strained specimen, which was the opposite of the results observed for carbon steel. It was assumed that this was because Mode II crack propagated more easily and faster in the prestrained specimen, where the precipitates were cut, than in the non-strained specimen. Therefore, the relationship between the fatigue life of the prestrained specimen and the non-strained specimen is considered to be dependent on the stress level. When the crack propagation life governed the fatigue life, the fatigue life of the prestrained specimen was shorter than that of the non-strained specimen. However, when the crack initiation life governed the fatigue life, the fatigue life of the prestrained specimen would be longer than that of the non-strained specimen.. |
| 64. | Proposal of evaluation method of fatigue limit with small crack under mean stress, taking non-combustible Mg alloy as an example. |
| 65. | The effects of distribution of hardness on fatigue property of precipitation strengthening stainless steel A286. |
| 66. | Systematization of Analysis Method of Fatigue Crack Initiation Site in Pearlitic Steel Smooth Specimen. |
| 67. | Strength Evaluation Method in Magnesium Alloy with Defect. |
| 68. | Measurement of Effective Stress Intensity Factor Range of Mode II Fatigue Crack Propagation. |
| 69. | Fatigue limit evaluation considering crack initiation for lamellar pearlitic steel, [URL]. |
| 70. | , [URL]. |
| 71. | , [URL]. |
| 72. | , [URL]. |
| 73. | Proposal of evaluation method of fatigue limits of non-combustible Mg alloy with small crack under mean stress. |
| 74. | Characteristic of threshold stress intensity factor range for small crack on magnesium alloys In order to propose a prediction expression of a threshold stress intensity factor range (AKlh) for magnesium alloys with small crack, rotating bending fatigue tests in three magnesium alloys which have a different hardness and low carbon steel (JIS S10C) were carried out. In these tests, the AK of a crack propagation lower limit from an annealed pre-crack as the AKlh was measured. One of the three magnesium alloys have the same Vickers hardness (HV) as the low carbon steel, however the AKth was half of the low carbon steel. In order to make this difference clear, the authors focused on an effective threshold stress intensity factor range (AKeffth), because there is large difference in the AKeffth which is not negligible to evaluate the AKlh between magnesium alloys and steel. Considering the difference in the AKefflh, a prediction expression was proposed based on Murakami's prediction expression which can predict the AKlh in various metals by applying only two parameters i.e. the HV and an initial crack size. However, the prediction expression cannot evaluate the AK th of the magnesium alloys. In this expression, Young's modulus which is proportional to the AKeffth was used to modify Murakami's prediction expression. In addition the new prediction expression was speculated to be accurate. © 2011 Published by Elsevier Ltd.. |
| 75. | Fatigue limit evaluation considering crack initiation for lamellar pearlitic steel In order to evaluate the fatigue limit of lamellar pearlitic steel used for railroad rails, tensile tests and fatigue tests are performed. Although the fatigue ratio of the lamellar pearlitic steel is lower than that of general steels, the reason for this has not been clarified. The fatigue cracks of the pearlitic steel initiate at a very early stage during the fatigue test. It is speculated that the steel should be treated as a steel with initial defects. In order to determine the initial defect size of the ultra-low cycle fatigue test, tensile tests are performed. Based on the test results, it was clarified that the crack initiation size depends on the crystal structure. In order to predict the fatigue limit of the pearlitic steel, Murakami's prediction method is applied to the steel. The measured defect sizes are applied to the method, and the fatigue tests are performed. The predicted fatigue limits and the test results have good agreement. In addition, from the SEM observations, the initial crack causing the fatigue failure was found to be a pearlite block. We then concluded that the fatigue limit of the pearlitic steel can be predicted by Murakami's method and the defect size is the pearlite block size. If the pearlite block sizes then become small, the fatigue limit of the pearlitic steel will increase. © 2011 Published by Elsevier Ltd.. |
| 76. | Fatigue strength properties of precipitation strengthening stainless steel A286 focused attention on small fatigue crack behaviour In order to safely use precipitation strengthening type A286 stainless steel in high cycles, the fundamental fatigue strength characteristics were investigated using fatigue tests at room temperature. During the fatigue test, the author paid attention to the behaviour of small fatigue cracks in order to clarify the fatigue strength properties in more detail than the usual fatigue test. As a result of the fatigue test, the fatigue strength characteristic of the A286 steel became clarified as shown below. The fatigue strength ratio of the A286 steel is lower than 0. 5 which is the ratio value of most steels. The cracks propagate which result in a failure even after 107 cycles. It was found that there are two crack mechanisms propagation of the A286 steel; i.e., in a high load-stress, the cracks monotonously propagate and result in failure. Under a low load-stress, the cracks intermittently propagate even after 107 cycles. The non-propagating cracks coalesce with a new crack which initiates near the crack tip and it becomes longer, finally resulting in a failure. This is the reason why the fatigue failures occur even after 10 7 cycles. © 2011 Published by Elsevier Ltd.. |
| 77. | Measurement of effective stress intensity factor range of Mode II fatigue crack propagation Many rolling contact fatigue failures, such as those that occur in railway rails, rolling bearings and gears, is due to the high repeated shear load. In order to prevent such fatigue a failure, the resistance of the material against such a load must be determined. The fatigue crack growth rate is dependent on the stress intensity factor range of the Mode II Δ KII. However, the Mode II crack propagation characteristic varies according to different experiment methods. Therefore, in this study, we measured the effective stress intensity factor range of the Mode II Delta; KIIeff. As it is difficult to carry out the Mode II fatigue crack propagation in the laboratory, this test was carried out using a bending load in this study. This bending load was applied to the tips of a double cantilever specimen and the Mode II fatigue crack propagation could be carried out between the two cantilevers. Furthermore, in order to measure the Δ KIIeff, several strain gauges were applied to the specimen around the crack tip. Using this technique, some Δ KIIeff value during the Mode II fatigue crack propagation tests will be reported. © 2011 Published by Elsevier Ltd.. |
| 78. | Proposal of distribution characteristic evaluation method of flaky inclusion (examination by simulation), [URL]. |
| 79. | Fatigue strength evaluation method of lamellar pearlite rail steel, [URL]. |
| 80. | Proposal of Distribution Characteristic Evaluation Method of Flaky Inclusion (Examination by Simulation). |
| 81. | Fatigue Characteristics of Lamellar Pearlite Steel Considering Pearlite Block and Colony. |
| 82. | Hydrogen exposure effect on tensile strength of high strength steel sharp notched specimen. |
| 83. | Strength evaluation of polycrystalline silicon structure considering sidewall morphology In order to evaluate strength of micron size polycrystalline silicon (poly-Si) structure for MEMS considering surface morphology difference between top and sidewall and effective surface area, bending strength tests of cantilever beam, surface roughness measurement and fracture surface analysis are performed. The specimens are made by CVD process for poly-Si deposition and deep RIE process for sidewall formation, and then the surface morphology of the top and the sidewall surface are different. The various size notches on the specimen are introduced in order to change effective surface area. By the fracture surface analysis, it was found that the fracture initiation point was not always maximum stress point; this is because there exist stress concentration on the surface. Surface roughness was measured using atomic force microscope (AFM). Then the maximum stress concentration of the specimen on the top and the sidewall surface respectively were presumed using extreme statistics, and effective surface area was defined. Then, bending strength and effective surface area shows good correlation.. |
| 84. | Hydrogen Exposure Effect on Tensile Strength of High Strength Steel Sharp Notched Specimen. |
| 85. | Strength Evaluation of Polycrystalline Silicon Structure Considering Sidewall Morphology. |
| 86. | Evaluation of Fracture Strength for Poly-Si in various shape and size. |
| 87. | Proposal of Strength Evaluation Method based on Fracture Mechanism in New Mg Casting Alloy. |
| 88. | Microscopic deformation behavior of lamellar pearlite steel Fatigue ratio of lamellar pearlite steel used for railroad rail is lower than the ratio of general steels. The reason is not clarified. It is reported the direction of lamellar microstructure in lamellar pearlite steel effects fatigue characteristics. In order to clarify microscopic deformation behavior of lamellar microstructure considered to effect fatigue characteristics, static tensile tests of lamellar pearlite steel was conducted, in this report. Using the plastic replica technique, microscopic deformation behavior, the initiation and propagation of micro crack was observed. By the observation, it is clarified that the crack initiates but does not propagate during static tensile test. The authors presume the fatigue of lamellar pearlite steel as follow: The grain size crack initiate at initial stage of fatigue process, and the crack act as initial defect of the lamellar pearlite steel. Based on the presumption, the fatigue limit of the lamellar pearlite steel was predicted, and the fatigue limit was confirmed by fatigue tests. As the result, the predicted fatigue ratio are 0.32~0.33 which show good agreement with the fatigue test result.. |
| 89. | Proposal of estimation method for notched specimen fatigue limit of commercially pure titanium In order to identify the fatigue limit for a sharp notched specimen of commercially pure titanium, rotating bending fatigue tests on smooth and notched specimens were curried out. In previous studies, it was found that the fatigue limit for a sharp notched specimen of commercially pure titanium could not be determined and it is not sure whether it fail over N=10 7 cycles or not. Based on the experimental results, in the smooth specimen and notched specimen (p=1.0mm), they have fatigue limits and knee points, while the sharp notched specimen (p=0.1mm) does not. As an estimation method, the fatigue crack initiation of each specimen was then investigated. The investigation results are as follows. (1) The proportional relationship exists between the maximum stress K iωa at the notch root and logarithm of the number of cycles to fatigue crack initiation N i. (2) Based on the slope of the relationship between the maximum stress K iωa and the number of cycles to fatigue crack initiation N i at the notch root, there is no possibility that the fatigue crack in the same mechanism initiates over N=10 7 cycles. Therefore, the stress amplitude that is not initiated the fatigue crack at N=10 7 cycles is the fatigue limit.. |
| 90. | Strength Evaluation Method of Micro Polycrystalline Silicon. |
| 91. | Size effect of micro polycrystalline silicon structure with stress concentratio. |
| 92. | The effect of hydrogen on tensile strength of high strength steel SCM435 notched specimen. |
| 93. | , [URL]. |
| 94. | , [URL]. |
| 95. | ○S. Hamada and K. Hashizume, Strength Reliability of Micro Polycrystalline Silicon Structure, 10th International Conference on The Mechanical Behavior of Materials (ICM10), 2007.05. |
| 96. | Strength reliability of micro polycrystalline silicon structure In order to evaluate strength reliability of micron size polycrystalline silicon (poly-Si) structure, bending tests of cantilever beam and Weibull analysis are performed. Recently, the importance of microelectromechanical systems (MEMS) in society is increasing, and the number of production is also increasing. The MEMS devices, which contain mechanical movement, have to maintain their reliability in face of external shock, thermal stress and residual stress from manufacturing processes. In greeting the mass production era of the MEMS, in case the material strength design of MEMS is performed, required strength data is not average value but the variation, especially minimum value of the material. Micron size poly-Si structure is widely employed in the MEMS such as microsensor, switching device and so on. Then, in order to evaluate strength reliability of micron size poly-Si structure, tests and analysis are performed. The specimen is made by chemical vapor deposition (CVD) process and thickness is 3.5, 6.4 and 8.3 micrometer and the specimen has notch. The test specimen used for the test changed characteristics of (1) film thickness (2) stress concentration, and investigation about the influence each effects of the variation in a bending strength are discussed.. |
| 97. | Strength reliability of poly-silicon for MEMS, [URL]. |
| 98. | Fatigue strength characteristics of non-combustible Mg alloy welded joint, [URL]. |
| 99. | Fatigue Strength Characteristic of Notched Specimen of Noncombustible Magnesium Alloy, [URL]. |
| 100. | Fractography Web Database System (Macroscopic Fatigue Fracture Surface). |
| 101. | Fatigue Strength of Notched Specimen of Non-combustible Magnesium Alloy. |
| 102. | Strength reliability of micro polycrystalline silicon structure. |
| 103. | Stress concentration and surface roughness effect on strength of polycrystalline silicon structure In order to clarify the stress concentration and surface roughness effect on strength of the polycrystalline silicon (poly-Si) structure, bending tests of poly-Si microcantilever beam specimen and surface roughness measurement is performed. The bending test results are analyzed by means of maximum stress at the notch root calculated by FEM models, and it is found that this approach cannot describe the test results. Therefore, modified approach is taken into account by use of two parameters that are the maximum stress and area where stress is larger than 50% of the maximum stress, which indicates stress extension around the position of maximum stress representatively. By this two parameters approach, the test results are explained quantitatively and a strength design chart for stress concentration area of the poly-Si structure is obtained. On the other hand, relationship between strength and surface roughness are confirmed and useful information for the process quality control are obtained. Copyright © 2005 by ASME.. |
| 104. | Prediction of lifetime of solder joints by heat cycle accelerated test. |
| 105. | Bonding strength reliability of MEMS packages. |
| 106. | Development strength reliability of micro-materials for MEMS. |
| 107. | Bond strength reliability evaluation for hermetic seal of MEMS package. |
| 108. | Stress Concentration and Surface Roughness Effect on Strength of Polycrystalline Silicon Structure. |
| 109. | Prediction of lifetime of solder joints by heat cycle accelerated test. |
| 110. | Relationship between strength and surface roughness about micro polycrystalline silicon structure. |
| 111. | The fatigue-breaking example of rotating machines. |
| 112. | The application and the subject to a real product of a micro material. |
| 113. | Strength evaluation of micro-polycrystalline silicon structure. |
| 114. | Eiji Yoshikawa, Masahiro Tsugai, Makio Horikawa, Hiroshi Otani, Shigeru Hamada, Influence of RTA parameters on residual stress and stress gradient of multilayered LPCVD polysilicon film, 15th IEEE International Conference on Micro Electro Mechanical Systems MEMS 2002, 2002.01, This paper reports the experimental results of examining the residual stress and stress gradient of LPCVD multilayered polysilicon film according to various rapid thermal annealing (RTA) in a nitrogen atmosphere. In particular the stress gradient of multilayered polysilicon film ranging from -17.1 to +1.5 MPa/μm as the RTA processing time increased could be reduced to nearly zero by selecting the appropriate RTA time. The mechanism responsible for this dependence was examined by using both experimental data and material analysis using secondary ion mass spectroscopy (SIMS) and transmission electron microscopy (TEM). It is concluded that the shift of the stress gradient is mainly caused by the thin nitride layers at surface and interface of multilayered polysilicon film.. |
| 115. | Influence of RTA parameters on residual stress and stress gradient of multilayered LPCVD polysilicon film This paper reports the experimental results of examining the residual stress and stress gradient of LPCVD multilayered polysilicon film according to various rapid thermal annealing (RTA) in a nitrogen atmosphere. In particular the stress gradient of multilayered polysilicon film ranging from -17.1 to +1.5 MPa/μm as the RTA processing time increased could be reduced to nearly zero by selecting the appropriate RTA time. The mechanism responsible for this dependence was examined by using both experimental data and material analysis using secondary ion mass spectroscopy (SIMS) and transmission electron microscopy (TEM). It is concluded that the shift of the stress gradient is mainly caused by the thin nitride layers at surface and interface of multilayered polysilicon film.. |
| 116. | NOTCH EFFECT OF MICRO POLYCRYSTALLINE SILICON CANTILEVER. |
| 117. | Notch Effect of Micro Polycrystalline Silicon Structure. |
| 118. | Notch Effect of Micro Polycrystalline Silicon Structure. |
| 119. | Notch and size effect of micro scale structure. |
| 120. | Reliability of BGA SOlder Joints Strength under Mechanical Loading. |
| 121. | Fractgraphy analysis of electric devices. |
| 122. | The influence of joint shape between solder ball and land on thermal fatigue life of BGA package. |
| 123. | The influence of joint shape between solder ball and land on thermal fatigue life of BGA package. |
| 124. | Y Murakami, C Sakae, S Hamada, Mechanism of rolling contact fatigue and measurement method of DKIIth for steels, International conference on the importance of understanding the fundamentals of the fatigue process in counteracting its effects in engineering components and structures, and to reflect on the contributions of K.J.Miller, 1997.03. |
| 125. | Analysis of spot welds by the combination of thermoelastic stress analyzer and FEM. |
| 126. | New measurement method of Mode II threshold stress intensity factor range ΔKτth and its application. |
| 127. | New measurement method of Mode II threshold stress intensity factor range DKIIth and its application. |
| 128. | New measurement method of Mode II threshols stress intensity factor range and its application. |
Unauthorized reprint of the contents of this database is prohibited.