13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Development and Several Additional Performances of Dual-Spindle Rotating Bending Fatigue Testing Machine GIGA QUAD Taizoh Yamamoto1,*, Akio Kokubu1, Tatsuo Sakai2, Yuki Nakamura3 1 Yamamoto Metal Technos Co. Ltd., 4-7 Setoguchi 2-chome, Hirano-ku, Osaka, 547-0034 Japan 2 Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577 Japan 3 Toyota National College of Technology, 2-1 Eiseicho, Toyota, Aichi, 471-8525 Japan * Corresponding author: yamakin@mx1.alpha-web.ne.jp Abstract In order to investigate the fatigue characteristics of metallic materials experimentally, a long period of time is required to get sufficient number of S-N data. In recent years, in order to overcome this difficulty, multi-type rotating bending fatigue testing machine whose name is GIGA QUAD have been developed by Yamamoto Metal Technos Co., Ltd., in which four specimens can be tested simultaneously. In this time, some additional new functions have been developed as follows; (1) 'high and low temperature environmental testing unit' whose target temperature is in a range of 600℃ and -150deg.C, (2) 'constant temperature/humid environmental testing unit' combined with the conventional corrosive cell, (3) ‘fracture alarm unit’, and (4) ‘2-step variable loading unit’. By combining these new functions with the machine of GIGA QUAD, one can perform the fatigue tests efficiently corresponding to the respective requirements for researchers in both of academic and industrial sectors. Keywords High temperature environmental testing unit, Low temperature environmental testing unit, Constant temperature/humid environmental testing unit, Fracture alarm unit, 2-step variable loading unit 1. Introduction One of difficulties in fatigue tests for structural materials is to take a long time to perform the fatigue test. Fatigue tests are usually conducted toward the loading cycles of N=107, but the fatigue property in gigacycle regime is also focused as an important subject in recent years[1]-[8]. In such a long life region, a tremendous long period is required to perform fatigue tests. If the fatigue test is performed at the loading frequency of 50Hz, it takes more than 200 days to reach 109 cycles of the load application. It means that it takes very long term for us to obtain one S-N curve. In addition, since the fatigue life of any metallic material has a distinct scatter, sufficient number of specimens should be tested to obtain the reliable fatigue property. An example of such fatigue test data for a bearing steel in very high cycle regime are shown in Figure 1 as an S-N diagram[5]. Type I indicates the conventional bearing steel, whereas Type II indicates the high purity bearing steel. Figure 1. Typical example of fatigue test data for bearing steel in very high cycle regime 103 104 105 106 107 108 109 1010 800 1000 1200 1400 1600 1800 TypeⅠ surface slip TypeⅠ fish-eye TypeⅡ surface slip TypeⅡ fish-eye Number of cycles to failure Nf , cycles Stress amplitude a , MPa
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