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RISS 인기검색어
- 검색키워드
- 저자 : Toshiro Matsumoto (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
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A simple method to detect cracks in beam-like structures
Jiawei Xiang,Toshiro Matsumoto,Jiangqi Long,Yanxue Wang,Zhansi Jiang 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.9 No.4
This study suggests a simple two-step method for structural vibration-based health monitoring for beam-like structures which only utilizes mode shape curvature and few natural frequencies of the structures in order to detect and localize cracks. The method is firstly based on the application of wavelet transform to detect crack locations from mode shape curvature. Then particle swarm optimization is applied to evaluate crack depth. As the Rayleigh quotient is introduced to estimate natural frequencies of cracked beams, the relationship of natural frequencies and crack depths can be easily obtained with only a simple formula. The method is demonstrated and validated numerically, using the numerical examples (cantilever beam and simply supported shaft) in the literature, and experimentally for a cantilever beam. Our results show that mode shape curvature and few estimated natural frequencies can be used to detect crack locations and depths precisely even under a certain level of noise. The method can be extended for health monitoring of other more complicated structures.
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A simple method to detect cracks in beam-like structures
Xiang, Jiawei,Matsumoto, Toshiro,Long, Jiangqi,Wang, Yanxue,Jiang, Zhansi Techno-Press 2012 Smart Structures and Systems, An International Jou Vol.9 No.4
This study suggests a simple two-step method for structural vibration-based health monitoring for beam-like structures which only utilizes mode shape curvature and few natural frequencies of the structures in order to detect and localize cracks. The method is firstly based on the application of wavelet transform to detect crack locations from mode shape curvature. Then particle swarm optimization is applied to evaluate crack depth. As the Rayleigh quotient is introduced to estimate natural frequencies of cracked beams, the relationship of natural frequencies and crack depths can be easily obtained with only a simple formula. The method is demonstrated and validated numerically, using the numerical examples (cantilever beam and simply supported shaft) in the literature, and experimentally for a cantilever beam. Our results show that mode shape curvature and few estimated natural frequencies can be used to detect crack locations and depths precisely even under a certain level of noise. The method can be extended for health monitoring of other more complicated structures.
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Md. Robiul Awall,Toshiro Hayashikawa,Xingwen He,Takashi Matsumoto 한국강구조학회 2013 International Journal of Steel Structures Vol.13 No.2
The torsional stiffness of curved twin I-girder bridges is very low, which may lead to a vulnerability to eccentric dynamic loads. This study is intended to investigate the improvement effect of bottom lateral bracings on dynamic performance of curved twin I-girder bridges under running vehicles, using a developed numerical approach. In this approach, to conduct the running vehicle-bridge interaction analysis, finite element method is used to create the detailed models of both the curved bridge and the running vehicle. Parametric studies are carried out using these numerical models to investigate the effect of bottom lateral bracings on the dynamic performance of the curved bridge under running vehicles. The numerical results indicate that the proposed bottom lateral bracing systems can increase the torsional stiffness of the bridge, whose increasing rate depends on the type of bracing configuration. The bottom lateral bracings can also distribute dynamic loads smoothly between the two main girders, which leads to a more stable structure.
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Evidence of a Rattling Transition in the Caged Compounds LaRu2Zn20 and LaIr2Zn20: 139La NMR Studies
Hideki Tou,Kenji Asaki,Hisashi Kotegawa,Takahiro Onimaru,Keisuke T. Matsumoto,Yukihiro F. Inoue,Toshiro Takabatake 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
We report a study of 139La(I=7/2) nuclear magnetic resonance (NMR) to investigate the structuralphase transition in the two caged compounds LaIr2Zn20 and LaRu2Zn20 from microscopic viewpoints. The former compound shows a second-order structural phase transition around Ts = 200 Kwhereas the latter one shows a first-order structural phase transition at Ts = 150 K. For both compounds,quite narrow La-NMR lines of less that 10 kHz without any electric field gradient (EFG) atthe La site were observed at temperatures above Ts, indicating that the local symmetry at the Lasite holds a cubic symmetry. On the other hand, an EFG at La site appears at temperatures belowTs, evidencing symmetry lowering occurs at the La site at temperatures below Ts. At temperaturesaround Ts, both the nuclear spin-lattice relaxation rate (1/T1) and the nuclear spin-spin relaxationrate (1/T2) show unusual enhancements associated with the slowing down of the EFG fluctuations. However, the temperature dependences of 1/T1T and 1/T2 are different from the typical slowingdownphenomena of the EFG fluctuations due to the classical motional narrowing. The lowering ofthe local symmetry at the La site is ascribed to a freezing of the rattling motion.
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