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Home>Products>Journal and Reviews>I.RE.AS.E.>Latest issue International Review of Aerospace Engineering - June 2009 - Papers
International Review of Aerospace Engineering - Papers
Vol. 2. n. 3, pp. 123-132
Abstract - This paper addresses the problem of path planning for a Low Earth Orbit satellite. The main contribution of the paper is a comparison of the flatness approach with more classical linear approaches such as bang-bang and jerk profiles generation. The comparison is performed on satellite benchmark provided by Alcatel Space. The conclusion is that flatness approach allows a reduction of actuator consumption, settling time and oscillations during the tranquilization phase of the manoeuvre. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Flat system, satellite path planning, nominal trajectory generation.
Vol. 2. n. 3, pp. 133-138
Abstract - In this paper, the active magnetic control technique is applied for controlling the attitude and nutation of roll/yaw axes as well as unloading the excess wheel angular momentum for a small biased-momentum satellite in a nominal operation. Two control structures are configured using 2 and 3 magnetic torquers. The proportional controller is used for the attitude and nutation control of roll/yaw axes while the proportional-integral controller is used for the wheel momentum unloading task. Both systems are evaluated through numerical treatments and compared particularly during the momentum unloading process. The performance from simulations exhibits that both systems fulfill the mission requirements. However, the system that uses 3 magnetic torquers gives a better attitude performance. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Magnetic Control, Momentum Biased, Momentum Unloading.
Vol. 2. n. 3, pp. 139-144
Abstract - The prediction of the separation movements of the external store weapons carried out on military aircraft wings under transonic conditions is an important task in the aerodynamic design area in order to define the operational-release envelopes. The development of computational fluid dynamics techniques has successfully contributed to the prediction of the flowfield through the aircraft/weapon separation problems. The numerical solution of the discretized three-dimensional, inviscid and compressible Navier-Stokes equations over an unstructured grid is accomplished with a commercial CFD finite-volume code. This analysis is applied for pressure distribution, flowfield calculations and aerodynamic coefficients distributions during the entire separation trajectory. The efficiency of the applied computational analysis gives satisfactory results compared, when possible, against the published data of verified experiments. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Computational Fluid Dynamics, Ejector Forces and Moments, External Stores, Moving-Body Trajectories, Store Separation.
Vol. 2. n. 3, pp. 145-153
Abstract - On the base of p-set function definition the solution of two airframe reliability problems are considered: the choice of both the Specified Maximum Permitted Life and inspection program for fatigue-prone airframe. The problems should be solved by processing of the lifetime test data. Instead of the use of confidence intervals for lifetime distribution parameters new approach based on the p-set function is offered. Then we do not need to solve the problem how to choose two values: confidence probability in conjunction with the required reliability. In fact we only need to know permissible probability of failure in service. For the case of approval test the minimax approach is offered. Some numerical examples are given. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Inspection program, P-set function, Minimax.
Vol. 2. n. 3, pp. 154-161
Abstract - The present article presents the Explicit Force Method (EFM) in the analysis of beams and frames. Based on complementary work a 2-node beam element is developed in three dimensions with 3 Forces and 3 Moments as unknowns at each node. The element force matrix and global force equilibrium are formulated. The right hand side of equilibrium are nodal displacements and rotations. Applied loads/moments can be inserted as boundary conditions. The general formulation leads to the estimation of global nodal forces and moments which compose the internal loads. In a postprocessing mode, nodal displacements and rotations can be computed on an element basis. The method applies also to general beam cross-sections that may yield coupling and three dimensional deformation. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Explicit Force Method EFM, Beam element, Complementary work, Force matrix, Cross sections, Coupling deformation.
Vol. 2. n. 3, pp. 162-166
Abstract - In aerospace structures, panels with variously shaped cutout are often used. The understanding of the effects of cutout on the buckling behavior of such plates has grown in importance with the increasing need for lightweight structures. The excellent mechanical properties of advanced composite materials make them prime candidates for a wide variety of application in aerospace and other branches of engineering. The correct and effective use of advanced composite materials requires a complex analysis in order to achieve good understanding of the system response characteristics to external causes. A finite element analysis, using commercial finite element software, is used to study the buckling behavior of plates with different central cutout. Particular emphasis is placed on flat square plates subjected to a uni-axial compression load. The main objective of this study is to demonstrate the buckling behavior of composite plates with central cutout. The effect of cutout geometry (circular, square, or triangular cutouts), cutout bluntness, and material properties are considered. In addition, the effect of fiber angle, stacking sequences, and cutout size are discussed. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Buckling, Perforated Plates, Cutout, Unixaial Load, Finite Element.
Vol. 2. n. 3, pp. 167-174
Abstract - Laser Doppler measurements are presented for a highly curved flow generated by the collision of plane wall turbulent jet with a low-velocity boundary layer. The experiments were performed for a wall jet-to-boundary layer velocity ratio of 2, and include mean and turbulent velocity characteristics along the two normal directions contained in planes parallel to the nozzle axis. The results, which have relevance to flows encountered by powered-lift aircraft operating in ground effect, quantify the structure of the complex ground vortex flow resulting from the collision of a wall jet with a boundary layer. The results revealed the existence of a very low-frequency instability. The source of this low frequency unsteadiness is probably associated with a small vortex located near the separation point. In the central zone of the upwash flow where the maximum values of the vertical velocity component occurs, additional distinct high frequency peaks were also identified. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: VSTOL, Ground effect, Highly curved flow
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