The most famous Euler-Buckling equation is that of Bernoulli-Euler beam. But, Timoshenko showed 2 kinds of Euler-Buckling equations of Timoshenko beam, which are allowed shear deformation, in his study.1) Each equation has different rotation defined for axial force. One is defined as the slope of the deflection of the neutral axis. The other is defined as the rigid rotation of the section. For mathematical modeling of the structure for finite element analysis, the definition of the spin is important. Then, by the variational method, which is based on 2-dimensional continuum mechanics with green-lagrange strain, Euler-Buckling equation is led. And it is shown that there are 4 kinds of variations by hypotheses of deformations. And those 4 kinds of equations are compared with 2 kinds of those of Timoshenko.1)
This paper proposes a new digital redesign method for linear state-feedback control systems with fixed gain matrices. The method is based on the discretization of the closed-loop control input signal, and then the principle of equivalent area is applied to this discretization. In the closed-loop system the proposed method achieves second-order approximation to the underlying continuous-time state-feedback control system. The proposed method is applied to a digital CCV flight control system design based on the decoupling control. Since from a characteristics of the step invariance discrete-time model the discrete-time approach which designs discrete-time controllers for the discrete-time plant model cannot be applied to the decoupling control, the digital redesign approach is used. The simulation results indicate that the proposed method redesigns the continuous-time state-feedback control system more satisfactorily in control performance than other methods.
Numerical studies of MHD supersonic flow are important to estimate the performance of electric thrusters. Here, we have developed a code taking account of sonic-inlet conditions of 1-dimensional flow given by Lawless et al. For the purpose of analyzing a flow in a realistic geometry, the code allows ionization and recombination processes in a 2-dimensional axisymmetric MHD flow. By calculating 2-dimensional flows (i) satisfying the sonic-inlet conditions and (ii) having the geometry and parameters identical to the experiment, the steady flowfields generating an oblique shock wave are obtained. The shock wave is analyzed by the Rankine-Hugoniot relation having the effect of source terms in momentum and energy equations, confirming that the source terms could quantitatively explain the shock strength.
Temperature distributions around two fundamental-shaped bodies, a sphere and a wedge, in hypersonic fluid flow were measured by laser-induced fluorescence (LIF) taking advantage of three absorption lines of NO. In either instance, the temperature distributions measured in the free stream (up to 70K), behind the shock wave, and at the stagnation point (up to 600K) invariably showed a high degree of agreement with the calculated values
New ground transport system, Ground Effect Transport System (GETS), which has potential for solving the green house problem of the earth by saving fuel to transport because the system is expected to have high lift-to-drag ratio, had been newly proposed, and fundamental investigations needed to develop such transport system has been conducted in university laboratory level. In the present study, some of the essential aerodynamic characteristics of an wing-in-ground effect of the GETS is investigated experimentally. Namely, effect of the tandem wing height from the ground and the wing interference are investigated. The results are compared with the numerical simulation results. It was shown that the effect of the interference of the wings could be ignored when the distance became more than 2.5 times the chord length of the wings. It was also found to be important that the boundary layer of the ground plate should be eliminated in the experimental study of such system that required very small gap between the wing and the ground plate.
Translational energy dependence of the atomic oxygen reactivity with polyimide films is reported. An ion beam type atomic oxygen source was used to study atomic oxygen reactivity in a wide range of translational energies. Mass change of polyimide films was measured by a frequency shift of the quartz crystal microbalance during atomic oxygen beam exposures. The experimental result showed strong translational energy dependence of mass change of the polyimide film, i.e., mass gain was observed at the translational energies below 30eV whereas mass loss was observed at the higher translational energies. X-ray photoelectron spectra indicated that pyromelliticdianhydride in the polyimide structure was degradated by the 5eV atomic oxygen reaction. Decomposition of oxydianiline was also obvious at higher translational energies. The mass gain observed in this study was explained by the absence of adsorbed oxygen at the polyimide surfaces due primarily to the low flux of the beam, which may lead to the suppression of debonding of polymer backbones.