日本航空宇宙学会誌
Online ISSN : 2424-1369
Print ISSN : 0021-4663
ISSN-L : 0021-4663
44 巻 , 515 号
選択された号の論文の9件中1~9を表示しています
  • 金子 義彦
    1996 年 44 巻 515 号 p. 681-690
    発行日: 1996/12/05
    公開日: 2010/12/16
    ジャーナル フリー
  • 石原 昌文
    1996 年 44 巻 515 号 p. 691-697
    発行日: 1996/12/05
    公開日: 2010/12/16
    ジャーナル フリー
    Finite element analysis of 3-dimensional large rotation problem of a beam is possible by means of the nonlinear beam model by Simo. His beam model is regarded as geometrically exact, and described by a configuration manifold which involves the special orthogonal group SO (3). Then, the tangent stiffness matrix becomes nonsymmetric away from equilibrium. By the way, Argyris describes that the exchanges of the rotations of both fixed axes and follower axes are impossible, but the exchange of the rotations of semitangential axes is possible and the moment becomes conservative. In this paper, it will be shown that the exchanges of the rotations of both fixed axes and follower axes are impossible, but the exchange of the rotations of semitangential axes is possible from Argyris. And the beam model by Simo will be also shown. In the upcoming paper, it will be shown that the tangent stiffness of fixed rotation ΔδΠr is nonsymmetric, and the tangent stiffness of follower rotation ΔδΠf is in reverse order of ΔδΠr, and the tangent stiffness of semitangential rotation ΔδΠs becomes symmetric. Fundamental problems of 3-dimensional large rotation of a beam are solved with three kinds of tangent stiffnesses, that is, ΔδΠr, ΔδΠf and ΔδΠs And the results are compared with theoretical solution and other finite element solutions, so it will be proved that symmetric tangent stiffness is the most effective.
  • 石原 昌文
    1996 年 44 巻 515 号 p. 698-704
    発行日: 1996/12/05
    公開日: 2010/12/16
    ジャーナル フリー
    Finite element analysis of 3-dimensional large rotation problem of a beam is possible by means of the nonlinear beam model by Simo. His beam model is regarded as geometrically exact, and described by a configuration manifold which involves the special orthognal group SO (3). Then, the tangent stiffness matrix becomes nonsymmetric away from equilibrium. By the way, Argyris describes that the exchanges of the rotations of both fixed axes and follower axes are impossible, but the exchange of the rotations of semitangential axes is possible and the moment becomes conservative. In the previous paper, it was shown that the exchanges of the rotations of both fixed axes and follower axes were impossible, but the exchange of the rotations of semitangential axes was possible from Argyris. And the beam model by Simo was also shown. In this paper, it will be shown that the tangent stiffness of fixed rotation ΔδΠr is nonsymmetric, and the tangent stiffness of follower rotation ΔδΠf is in reverse order of ΔδΠr, and the tangent stiffness of semitangential rotation ΔδΠs becomes symmetric. Fundamental problem of 3-dimensional large rotation of a beam are solved with three kinds of tangent stiffnesses, that is, ΔδΠr, ΔδΠf and ΔδΠs And the results are compared with theoretical solution and other finite element solutions, so it will be proved that symmetric tangent stiffness is the most effective.
  • 宮下 純一
    1996 年 44 巻 515 号 p. 705-711
    発行日: 1996/12/05
    公開日: 2010/12/16
    ジャーナル フリー
    Economical power generation is expected from a jet stream since it has about 30 times higher energy density than other renewable energies. Moreover, Japan is most blessed with the jet stream energy in the world. We started research on jet stream power generation in 1993. Experiments with small-scale flying platforms are included in it. A summary of the studies and the experiments is described.
  • 三木 光範, 室津 義定, 田合 弘幸
    1996 年 44 巻 515 号 p. 712-719
    発行日: 1996/12/05
    公開日: 2010/12/16
    ジャーナル フリー
    In order to perform the structural and geometric analyses of variable geometry trusses a knowledgebased approach is adopted. A truss structure is divided into small elements, and their responses are extracted and a knowledgebase is constructed in an object-oriented manner. The object-oriented structural analysis is capable of treating any material and geometric nonlinearlities since the method is based on the iterative relaxation of nodal unbalanced forces by moving the nodes. The object-oriented geometric analysis where a kinematic problem is converted into a problem for a force equilibrium at the nodes is also found to be effective for determining the geometry of variable geometry trusses.
  • 藤森 篤, 中野 准也, 太田 裕文
    1996 年 44 巻 515 号 p. 720-728
    発行日: 1996/12/05
    公開日: 2010/12/16
    ジャーナル フリー
    This paper presents a robust control design for a two-dimensional airfoil active flutter suppression (2D-AFS) from the viewpoint of uncertainty model representation. Multiplicative, additive and coprime factor uncertainty models are used to present the perturbation due to change of the flight velocity in the 2D-AFS system. Controllers are then designed by μ synthesis technique in the frame of the robust stability and robust control performance problems. The controllers are reduced by the extended coprime factorization (weighted) (ECFW) controller reduction technique. As a result, the multiplicative uncertainty model is the most suitable for the robust control design of the 2D-AFS in case of the flight velocity change. A controller designed with the multiplicative uncertainty model increases the flutter velocity by 34% and shows the robustness against gust disturbance under the perturbation. Furthermore, a 7th-order controller is obtained by the ECFW controller reduction technique, which shows the same control performances as the original controller.
  • 瓜田 明, 中村 佳朗, 川添 博光
    1996 年 44 巻 515 号 p. 729-734
    発行日: 1996/12/05
    公開日: 2010/12/16
    ジャーナル フリー
    The objectives of the present study are to obtain unsteady pressure distributions on a freely oscillating body and to examine its relation with the body motion. In the present experiment, a low speed wind tunnel was used, where the exit was directed in a vertical direction. The shape of the model is similar to a Chinese pan with a diameter of 480mm. This experiment was performed at two flow velocities: 10m/s and 20m/s, and the model was suspended from a bar above the wind tunnel exit. The model was freely oscillated in the wind tunnel flow under the gravity and aerodynamic forces. The amplitude of this oscillation was damped due to the aerodynamic forces. The pressure distributions on the body were successfully measured, which clarified the damping mechanism of the body motion. To compare with the experimental result, the unsteady numerical calculations were also performed with the boundary element method.
  • 麻生 茂, 前川 昌三, 辛島 桂一, 佐藤 清
    1996 年 44 巻 515 号 p. 735-740
    発行日: 1996/12/05
    公開日: 2010/12/16
    ジャーナル フリー
    Three-dimensional shock wave/turbulent boundary layer interaction region induced by a blunt protuberance is experimentally investigated. Experiments are performed under the testing condition of freestream Mach number of 2, 3 and 4 with almost adiabatic wall condition. The primary separation lines locate almost same position irrespective of freestream Mach number, and freestream Mach number independence on the primary separation region is revealed. However, detailed flow structures for each Mach number are different. Pressure begins to rise at slightly ahead of the primary separation line where stream lines begin to deflect outward. As freestream Mach number is increased, the maximum pressure becomes higher but locations, where the pressure begins to rise and reaches to its maximum level, exist at almost same locations respectively regardless of freestream Mach numbers. The oscillating separated shock waves are observed in the interaction region by instantaneous shadow graph technique and significant unsteady flow structure is captured.
  • 辻井 利昭, 村田 正秋, 張替 正敏
    1996 年 44 巻 515 号 p. 741-743
    発行日: 1996/12/05
    公開日: 2010/12/16
    ジャーナル フリー
    An airborne attitude determination system using GPS phase interferometry has been developed by National Aerospace Laboratory (NAL) and flight tested. Two GPS antennas are mounted 6.41 meters apart on the fuselage of the aircraft so that the pitch and yaw angles can be determined. An INS (Inertial Navigation System) is also installed to provide an independent attitude reference. Results of post-flight analyses are presented showing that the attitude estimated by GPS agrees with that of INS within 0.1 degrees in pitch and 0.2 degrees in yaw angle.
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