KOIDE Takao Faculty of Eng., Tottori Univ., Assoc.Prof., 工学部, 助教授 (60127446)
ODA Satoshi Faculty of Eng., Tottori Univ., Professor, 工学部, 教授 (50032016)
|Budget Amount *help
¥2,400,000 (Direct Cost : ¥2,400,000)
Fiscal Year 1995 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1994 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1993 : ¥1,400,000 (Direct Cost : ¥1,400,000)
Research was conducted on AE signals, AE cumulative event count, AE event count rate, AE cumulative energy count, AE energy rate, AE amplitude, frequency spectra of AE signals and crack propagation in the bending fatigue process of SCM415 case-hardened, S45C normalized, two kinds of ADI [astempered ductile iron, ADI1 : T_<LAMBDA> = 875ﾟC,T_I = 375ﾟC,ADI2 : T_<LAMBDA> = 875ﾟC,T_I = 235ﾟC,(T_<LAMBDA> : temperature of austemper treatment, T_I : temperature of isothermal transformation)] and SACM645 ion-nitrided gear teeth under different tooth loads. The relationship between the AE parameters and the fatigue crack propagation as well as the effects of the gear material and the tooth load on the AE characteristics in the bending fatigue process were determined. Basic data were obtained for the prediction and the diagnosis of bending fatigue failure of the gear tooth by means of AE method.
The main results obtained from this investigation are summarized as follows.
1. AE cumulative event coun
t and AE cumulative energy count in the bending fatigue process of gear teeth increase markedly just before the crack initiation and become almost constant in the crack growth in the cases of the case-hardened and the ADI1 gear. In the case of the ion-nitrided gear, the change of these AE parameters in the fatigue process shows the same tendency as the case of the case-hardened gear, but the increasing rate is considerably smaller than in the case of the case-hardened gear. In the case of the ADI2 gear, these AE parameters increase after the crack initiation. In the case of the normalized gear, the changes of these AE parameters with the crack initiation can hardly be observed. Hence, the prediction of the crack initiation using these AE parameters is possible in the cases of the case-hardened, the ADI1 and the ion-nitrided gear, but difficult in the cases of the ADI2 and the normalized gear. 2.AE amplitudes in the bending fatigue process of the case-hardened, the ADI1 and the ion-nitrided gear are small in the early stage of the fatigue process, become larger just before the crack initiation, smaller in the crack growth and larger just before the tooth breakage. In the case of the ADI2 gear, AE amplitude becomes larger after the crack initiation. In the case of the normalized gear, AE signals with large amplitude can not be almost observed. 3. Maximum amplitudes of AE signals in the bending fatigue process of the ion-nitrided, the case-hardened, the ADI and the normalized gear tooth become smaller in the order mentioned. Less