記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IOP Conference Series: Materials Science and Engineering  

This research concerns the detection method of contact-type failure based on nonlinear wave modulation utilizing ultrasonic vibration driven by self-excitation. When the structure is vibrating by environmental force or forced excitation, the contact area is fluctuated by vibration. In this condition, the vibration transfer characteristics of ultrasonic vibration have fluctuated in synchronization with vibration (non-linear wave modulation). The detection method based on non-linear wave modulation can detect contact-type failure. In this paper, the novel detection method based on nonlinear wave modulation is presented. Firstly, the self-excitation method using local feedback control is introduced. Local feedback control can oscillate at the natural frequency automatically. Secondly, the concept of a novel detection method is introduced. When the structure with contact-type failure is vibrating, the frequency of the ultrasonic vibration excited by local feedback control will fluctuate in synchronization with natural frequency fluctuation. To explain the detection method, non-linear wave modulation is expressed 1 degree of freedom model. In this model, the local stiffness fluctuation is modelled by the spring element of which spring coefficient is fluctuated in synchronization with structural vibration. We regard the transfer function of this model as a linear time-varying system. The amplitude of the fluctuation of natural frequency caused by stiffness fluctuation can be the novel index of failure level. Lastly, the result of the experiment using the uniform beam specimen is shown. From the relationship between forcing pressure of the contact-type failure and the amplitude of the frequency modulation, it is proved that the novel index is associated with failure level.

DOI： 10.1088/1757-899X/886/1/012032

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85090295091&origin=inward

記述言語：日本語   出版者・発行元：一般社団法人 日本機械学会  

<p>This research concerns sound transmission characteristic analysis for human middle ear lesions using finite element method. A large number of patients are suffering from the middle ear lesions, such as the tympanic membrane perforation, the arthrosclerosis, and the tympanosclerosis. These lesions can change the dynamic properties of middle ear, cause various kinds of hearing problems, as well as the decline of the quality of life. For an early detection of illness and the improvement of the cure, it is important to clarify the influence on hearing ability at the time of lesion of the middle ear. However, it is difficult to grasp the dynamic properties of the auditory organ of a human body by an experiment. In this paper, the dynamic analysis of the middle ear at the time of lesions using the finite element method was conducted. Firstly, a finite element model of a healthy middle ear was built up, and used to verify the validity of the model. The analysis results showed good correspondence to the experiment results of other study. Secondly, the influences of tympanic membrane perforations with different size and position are investigated. The analysis results showed that the decrease of hearing ability is proportional to the size of the tympanic membrane perforation. Especially, the perforation at lower part showed an obvious decrease of hearing ability. Thirdly, the influences of arthrosclerosis and tympanosclerosist occurring at different positions are investigated. The results showed that the arthrosclerosis of incudostapedial joint and the tympanosclerosist at upper part of the TM can obviously decrease the hearing ability.</p>

DOI： 10.1299/jsmedmc.2020.402

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：VSP BV  

In the fabric shaping process during resin transfer molding, fabrics are deformed due to inter-fiber sliding and buckling of yarns. We have observed inter-fiber sliding and yarn buckling in the deep drawing of fabrics by a cylindrical punch. The amount of punch traveling and the molding die radius affect the occurrence of inter-fiber sliding and yarn buckling. Comparing simulation results and actual deformation of fabrics, we should take account of inter-fiber-sliding and buckling of yarns.

DOI： 10.1163/156855103322320356

Web of Science

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：オンライン  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：オンライン開催  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：オンライン開催  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：オンライン開催  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：オンライン開催  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：オンライン開催  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：オンライン開催  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：オンライン開催  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：高知  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：高知  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：高知  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：秋田  

DOI： 10.1299/jsmemecj.2019.J10101P

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：福岡  

This research concerns high efficiency propulsion method of multi-articulated robot by decentralized control using local feedback control. Recently, various robots which are useful when disasters happened have been studied. At the time of disaster, these robots need to promote with high efficiency. To answer this demand, the propulsion method using resonance was proposed. On the other hand, natural frequencies of propulsion robot are varying in synchronization with the change of external environment. In this paper, the control method of propulsion robot which drives at the resonance point automatically is proposed. Especially, investigation of the proposed method for large degree of freedom robot is done. Firstly, vibration propulsion mechanism is introduced. This device promotes using the difference of friction coefficient between moving forward and moving backward. It is easy to measure natural frequencies of the device without the difference of friction coefficient. Secondly, the design method controller of decentralized control is shown. The proposed decentralized control uses the local feedback control. The driving method using local feedback control can oscillate natural vibration of vibration propulsion mechanism by self-excited vibration. The decentralized control realizes the synchronization of the actuators through natural vibration mode by the force entrainment of the self-excited oscillator. The propulsion experiment by centralized control and decentralized control is examined to evaluate propulsion efficiency. As the result, the propulsion method by decentralized control is high efficiency as compared with the method by centralized control.

DOI： 10.1299/jsmedmc.2019.136

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：福岡  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：福岡  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：福岡  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：福岡  

記述言語：日本語  

Saint-Venant's principle is generally interpreted as the rapid decay of end effects, but we know some systems where the local stress decays slowly. The whole stress field of an elastic body can be expressed as superposition of stress fields, which corresp

記述言語：日本語  

記述言語：日本語  

The authors developed the finite element method (FEM) for micropolar elastic solids and applied it to the problem of topology optimization. The weighted residual method and 8-node isoparameteric elements were employed for the FEM analysis. The solid isotropic material with penalization (SIMP) method and the gravity control function were employed in the optimization procedure. To test the numerical solutions, the bending problem of the cantilever was used. In this analysis, the effects of the engineering material constants for micropolar elasticity, the coupling number N, which is related to stresses, and the characteristic length 1, which is related to couple stresses, are researched. The optimal structures of micropolar materials are strongly influenced by material properties of bending. Though the optimal topologies of classical elastic solids are truss frames, in general, those of micropolar materials are rigid frames. Since the checkerboard structures are more apt to appear in the optimization process for micropolar solids than in classical elasticity, filtering (the gravity control function employed in this paper) or other techniques are required to obtain practical solutions. The proposed method could potentially solve the optimization problems of biomaterials such as bone tissue.

記述言語：日本語  

記述言語：日本語  

記述言語：日本語  

記述言語：日本語  

The impact phenomena between golf clubs and golf balls are studied in order to examine the possibility of the shape optimization of clubs. The release velocity and side spin of the ball after impact with golf clubs, whose shapes are arbitrarily changed, are evaluated through FEM simulations. The following results are obtained from some simulations. First, the shape of the club is greatly related to the performance of the release velocity and side spin of the ball as well as the sweet area of clubs. Therefore, effectiveness of the shape optimization of the clubs is confirmed. Secondly, the kind of the club shapes having good performance is clarified from the viewpoint of mechanical energy.