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山口, 誉夫 ; 竹前, 康徳 ; 黒沢, 良夫 ; 松村, 修二
概要:
application/pdf<br />Journal Article<br />Body panels in automobiles are usually stiffened by beads and are covered with viscoelastic damping layers. In the first report, method of numerical analysis for modal loss factors of the bead
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panels were verified by experimental results. In the analysis, asymptotic method was applied to complex eigenvalue problem using three-dimensional FEM in consideration with complex material parameter. In the second report, influences of geometry (height, length, interval) of the beads on modal loss factors were clarified. In this report, layouting the viscoelastic materials on the surface of the bead panels using damping contributions of positions of the materials to modal loss factor properly, modal loss factors can be improved. Further, by investigating bead shapes which can concentrate distribution of dissipated energy on local area in the panels, effective shape of beads is proposed in consideration with modal loss factor, light weight and rigidity.
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黒沢, 良夫 ; 山口, 誉夫 ; 榎本, 秀喜 ; 松村, 修二
概要:
application/pdf<br />Journal Article<br />We have developed a technique for estimating vibrations of vehicle body struct
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ures with damping materials using large-scale finite element (FE) model, which will enable us to grasp and to reduce high-frequency road noise (200～500Hz). In the new technique, first order solutions for modal loss factors are derived applying asymptotic method. This method saves calculation time to estimate modal damping as a practical tool in the design stages of the body structures. Frequency responses were calculated using this technique and the results almost agreed with the test results. This technique can show the effect of damping materials on automotive body panels, and it enables the more efficient layout of the damping materials. Further, we clarified damping properties of car structures under coupled vibration between frames and panels with viscoelastic layers.
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NARUSAWA, Kazuyuki ; HAYASHIDA, Morimasa ; KURASHIMA, Daisuke ; WAKABAYASHI, Katsuhiko ; KAMIYA, Yushi
概要:
application/pdf<br />Journal Article<br />This paper covers our investigation into a decline in FC performance resulting from hydrogen fuel containing CO. Several investigations were conducted into the dependence of CO poisoning on
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types of catalyst using Pt and Pt-Ru alloy. The investigations are summarized as follows : 1) The poisoning prediction formulas and the poisoning estimation coefficient to predict and estimate the performance were derived theoretically. 2) The actual process of CO poisoning was scrutinized by focusing on adsorption of CO and desorption of CO_2 molecules, and changes of several polarizations caused by CO poisoning were estimated. 3) Investigations into the relationship between the CO concentration, operating pressure, operating temperature and the CO poisoning were carried out. If the FC was operated at a high CO concentration, no significant improvement could be expected when using increased pressure, and further, the effects of the operating temperature is almost the same for the two types of catalyst.
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山口, 誉夫 ; 黒沢, 良夫 ; 松村, 修二 ; 野村, 章
概要:
application/pdf<br />Journal Article<br />This paper describes vibration phenomena for stiffened elastic panels having viscoelastic damping layer. The panels are stiffened by beads. The laminated panels are modeled using
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three-dimensional finite elements in consideration with complex modulus of elasticity. Further, applying asymototic method to the discreted equations of motion, explicit expressions of modal loss factors for the laminates are derived. Consequently, the expressions have similar form to Modal Strain Energy Method, which is proposed by Jonson. Numerical code is developed related to the expressions. Vibration damping properties of the bead panels, which are calculated by the code, is consistent with experimental results. Temperature dependence of the damping properties by FEM also agreed well with the experiments. These investigations reveal that modal damping decreases due to beads of the panels.
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山口, 誉夫 ; 黒沢, 良夫 ; 松村, 修二 ; 村上, 聡 ; 澤田, 耕吉
概要:
application/pdf<br />Journal Article<br />Viscoelastic damping materials are laminated on car body panels to reduce structure borne noise. In usual, these panels are stiffened by beads. Damping properties of the panels are sensitively
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affected by their complicated configurations. In the first report, we studied about prediction methods of damping properties for both bead panels and actual vehicle models having non-constraint viscoelastic layer. Applying asymototic method to the discreted equations of FEM, explicit expressions of modal loss factors for the laminates were derived, and then were verified by experiment. In this report, sensitive effects of geometry of beads (e.g. length of beads, height of beads and so on) on modal damping were revealed in detail. Applying Inoue's method, we also analized damping phenomena on the bead panels using distribution of dissipated energy between inplane deformation and out of plane deformation.
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紙屋, 雄史 ; 成澤, 和幸 ; 林田, 守正 ; 倉嶌, 大輔 ; 若林, 克彦
概要:
application/pdf<br />Journal Article<br />This paper covers our investigation into a decline in Fuel Cell performance resulting from hydrogen fuel containing CO. Here, we had several investigations into CO poisoning on dependence of types
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of catalyst between Pt and Pt-Ru alloy. The results are summarized as follows: 1) The poisoning prediction formulas and the poisoning estimation coefficient to predict and estimate the FC performance were derived theoretically. 2) The actual process of CO poisoning was scrutinized by focusing on adsorption of CO and desorption of CO_2 molecules, and changing of several polarizations of FC caused by CO poisoning were estimated. 3) Investigations into the relationship between the CO concentration, operating pressure, operating temperature and the CO poisoning were carried out. If FC underwent at a high CO concentration, no significant improvement could be expected by operating at increased pressure, and effects of the operating temperature is almost the same between two types of catalyst.
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山口, 誉夫 ; 黒沢, 良夫 ; 松村, 修二
概要:
application/pdf<br />Journal Article<br />This paper deals with analysis for acoustic properties of three-dimensional closed sound fields having sound absorbing materials. In this analysis, the sound absorbers can have arbitrary
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shapes and can be located anywhere in the fields. The fields involve gas and sound absorbers which are modeled using Finite Element Method. A new three-dimensional element are developed for the absorbers. This element has two damping parameters which are complex density and complex volume elasticity. The elements are constructed, and then the corresponding simultaneously coupled equations are solved to obtain the frequency response. Further, a new expression is also derived to get distribution of contribution to modal damping for each element. These approachs are applied to three-dimensional rooms where the absorbers exist in different positions. The results are compared with the experiments carried out by Utsuno and are discussed.
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永井, 健一 ; 松村, 修二 ; 池澤, 龍 ; 山口, 誉夫 ; 石田, 光之
概要:
application/pdf<br />Journal Article<br />Experimental results are presented for self-excited vibration of an automotive wiper. The self-excited vibration is generated by a stick-slip motion. It is of practical importance to suppress the
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self-excited vibration of the wiper. To find out modal coupling in the vibration of the wiper, simplified wiper is constructed. Movement of simplified wiper is separated into horizontal and vertical directions to simulate a motion of the actual wiper. The simplified wiper and the actual wiper are used for experiments. Static deformation of a wiper blade is measured. The blade is pressed on a glass surface. The wiper blade shows characteristics of soft-hardening spring involving a buckled deformation. Modal coupling in the self-excited vibration is examined by sweeping the wiper on a rotating glass table with constant angular velocity. Increasing a load pressed on the blade, coupling vibration is generated due to self-excitations along glass surface and parametric movements in vertical direction. The vibration amplitude is suppressed extremely when the load is close to the buckling load. Moreover, the maximum Lyapnov exponent of the dynamic response shows least number of the modes contributed to the self-excited vibration.
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