This paper presents the new method for controller design. It is based on Generalized Kalman-Yakubovich-Popov (GKYP) lemma which provides a unified LMI characterization for finite frequency range properties of dynamic system. Firstly, we will represent the restriction of controller synthesis using GKYP lemma, then propose the new method for controller synthesis based on GKYP lemma combined with H∞ method in order to make up for restriction of GKYP lemma based controller synthesis. Then we will present the design example of ALFLEX longitudinal controller and confirm the character and effectiveness of our method. Furthermore, we will propose the Embedded Model Matching method which realizes the desired response with a small precompensator.
In this study, we succeeded to develop a very low power miniaturized ion engine powered by microwave discharge. The accomplished performance was ion production cost of 240W/A and propellant utilization efficiency of 39% by input microwave power 1.0W and mass flow rate of 0.15sccm. In order to realize this very low power operation, we have proposed an antenna design method for miniaturized microwave ion engines. The effectiveness of this method was verified by plasma observation inside the discharge chamber and ion beam extraction characteristics of the engine. Based on this method, antenna of the engine was designed and improved. As a result we have achieved to our goal.
Carbon fiber reinforced plastics (CFRP) have been used in structural components for newly developed aircraft and spacecraft. The main structures of an airframe, such as the fuselage and wings, are essentially composed of stiffened panels. Therefore, in the structural design of airframes, it is important to evaluate the buckling strength of the composite stiffened panels. Widely used finite element method (FEM) can analyzed any stiffened panel shape with various boundary conditions. However, in the early phase of airframe development, many studies are required in structural design prior to carrying out detail drawing. In this phase, performing structural analysis using only FEM may not be very efficient. This paper describes a simple buckling analysis method for composite stiffened panels, which is based on finite strip method. This method can deal with isotropic and anisotropic laminated plates and shells with several boundary conditions. The accuracy of this method was verified by comparing it with theoretical analysis and FEM analysis (NASTRAN). It has been observed that the buckling coefficients calculated via the present method are in agreement with results found by detail analysis methods. Consequently, this method is designed to be an effective calculation tool for the buckling analysis in the early phases of airframe design.
Present paper is an analytical study on a patch repair problem. An exact solution based on a simplified plate model is obtained for single-patch-repaired circular plates with axisymmetric debondings between the patch and the base plate subjected to a uniform radial displacement, where significant bending deformation occurs owing to asymmetric configuration of the repaired plate. The debondings locate both at the outside edge of the patch and at the edge of the hole. The theoretical solution agreed well with a finite element solution. The basic mechanism of debonding problem of two dimensional patch repaired plate is discussed through the present theoretical solution and the finite element solutions. The nonlinear finite element results show that nonlinear effect is significant, while the nonlinear solution finally approaches the linear solution obtained by neglecting bending deformation. The linear solutions of energy release rate of the debonding crack with and without considering bending effect gives an upper and a lower limit. The linear exact solution neglecting bending deformation is applicable as a rough estimate at an early design stage since not only the solution gives upper limit but also the effect of the bending deformation on energy release rate of debonding crack decays quickly with the increase of the applied inplane displacement.
In the Reynolds number region lower than approximately 1.0 × 105, which corresponds to the Reynolds number region of a Micro Air Vehicle, thinner and sharper leading edge airfoil performs better than thicker and blunter one. This research focuses on the difference in flowfields which are clarified by means of streamline calculation and surface pressure distribution measurement. Numerical studies were performed to the blunt type NACA0012 airfoil and both numerical and experimental studies were performed to the thinner type 4% cambered-plate airfoil. The performance of the NACA0012 airfoil is deteriorated with decreasing Reynolds number, whereas that of the 4% circular arc cambered-plate airfoil is not affected. The deterioration of the NACA0012 airfoil performance is mainly due to the laminar boundary layer separation near the trailing edge; such phenomena are not essential to the performance in the cambered-plate airfoil results. This paper also demonstrates that the flow separation at the trailing edge can be estimated from the temporal amplification factor of the oscillatory mode which is calculated by the global linear stability analysis.