The Evaluation of Fatigue Caused by Plane-Bending Stress on Stainless Steel Using the Stacked-Coil Type Magnetic Sensor

To prevent an accident due to the metal degradation of stainless steels, we have previously proposed fatigue evaluation methods (such as the remnant magnetization method using a thin-film flux-gate magnetic sensor [1] and the inductance method using a pan-cake type coil [2]). These two fatigue evaluation methods demonstrated a good correlation between the magnetic sensor output signal and the amount of plane-bending fatigue damage in stainless steels. We developed a stacked-coil type magnetic sensor shown in Fig. 1(a) in order to achieve a magnetic sensor for an accurate fatigue evaluation. This magnetic sensor was composed of two detection coils that are connected differentially, an excitation coil, and a ferrite core. Fig. 1(b) shows the connection of the excitation coil and the two detection coils. Fig. 2 shows the detection result of fatigue and crack using this magnetic sensor. The material used for this specimen was an austenitic stainless steel (SUS304), and plane-bending stress was applied. From Fig. 2, it can be seen that this magnetic sensor detected defects well. The evaluation results of plane-bending fatigue damage distribution will be shown in in detail the complete paper

Effects of root radius and pitch difference on fatigue strength and anti-loosening performance for high strength bolt–nut connections

The fatigue strength improvement and anti-loosening performance are studied experimentally and analytically for JIS M16 bolt–nut connections. Three different root radii are considered coupled with three different pitch differences. The enlarging the bolt root radius improves the fatigue limit of the bolt by more than 30% because both stress amplitude and mean stress can be reduced. Furthermore, suitable pitch difference improves the fatigue limit by more than 25%. This is because under no pitch difference the crack initiation always occurs at No.1 or No.2 threads close to the bolt head causing the final failure; however, under a suitable pitch difference the crack initiation occurs at No.6 or No.7 threads far away from the bolt head. Good anti-loosening performance can be expected for the bolt–nut connections having enlarged root radius because the prevailing torque TP = 19 Nm and the residual prevailing torque TuP=10Nm are not smaller compared to other special bolt–nut connections

The Evaluation of Fatigue Caused by Plane-Bending Stress on Stainless Steel Using the Stacked-Coil Type Magnetic Sensor

To prevent an accident due to the metal degradation of stainless steels, we have previously proposed fatigue evaluation methods (such as the remnant magnetization method using a thin-film flux-gate magnetic sensor [1] and the inductance method using a pan-cake type coil [2]). These two fatigue evaluation methods demonstrated a good correlation between the magnetic sensor output signal and the amount of plane-bending fatigue damage in stainless steels. We developed a stacked-coil type magnetic sensor shown in Fig. 1(a) in order to achieve a magnetic sensor for an accurate fatigue evaluation. This magnetic sensor was composed of two detection coils that are connected differentially, an excitation coil, and a ferrite core. Fig. 1(b) shows the connection of the excitation coil and the two detection coils. Fig. 2 shows the detection result of fatigue and crack using this magnetic sensor. The material used for this specimen was an austenitic stainless steel (SUS304), and plane-bending stress was applied. From Fig. 2, it can be seen that this magnetic sensor detected defects well. The evaluation results of plane-bending fatigue damage distribution will be shown in in detail the complete paper.</p

深絞り性の優れた熱延鋼板の製造法と疲労強度に関する研究

第1章 序論 第2章 高r値熱延綱板を製造するための冶金学的検討 第3章 高r値熱延鋼板を製造するための機械的因子の検討 第4章 疲労強度におよぼす集合組織の影響 第5章 疲労き裂停留におよぼすひずみ時効の影響 第6章 応力勾配のある場におけるき裂発生過程 第7章 炭素鋼焼なまし材の回転曲げ疲労強度に及ぼす表面加工層の影響 第8章 総括Made available in DSpace on 2012-07-10T07:35:54Z (GMT). No. of bitstreams: 4 yakushiji1.pdf: 9558926 bytes, checksum: 1b4093af00e95b1286ddbf9876088cf2 (MD5) yakushiji2.pdf: 14267096 bytes, checksum: ec42931463bb60b69aa23b5d31110824 (MD5) yakushiji3.pdf: 10723371 bytes, checksum: 97ec9bff66883f678d130483e2888686 (MD5) yakushiji4.pdf: 7231929 bytes, checksum: ce82615b0d0f74e6e6a10f0a7423283a (MD5) Previous issue date: 1994-12-26主1-参1工学_機械科

Effect of loading type on fatigue property of specimens treated by cutting and rubbing process

Aiming for a result to improve fatigue strength, “cutting and rubbing process” which is a kind of surface treatment was used for forming a round-bar smooth-specimen, showing drastically enhanced rotating-bending fatigue strength. On the other hand, actual machine components and structures invariably contain geometrical irregularities, such as fillets, keyways, screw threads, and holes. Fatigue cracks initiated from such stress raisers, indicating that the validity of the cutting and rubbing process on fatigue strength of specimen with a stress raiser should be examined. In this study, fatigue tests of smooth and notched specimens finished by the cutting and rubbing process were conducted under some loading types including rotating-bending, tension-compression and torsion loading. Results showed that fatigue strength of notched specimens was significantly enhanced compared to that of smooth specimens under rotating-bending and tension-compression loads. In other words, the cutting and rubbing processing was more effective in stress raisers than the smooth surface. The physical background on the effect of loading type on the fatigue strength of the cutting and rubbing processed specimen was discussed based on the fracture origin, microstructure in the surface layer, stress gradient caused by both loading type and notch