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CONTENTS
Volume 2, Number 1, January 2015
 

Abstract
In this paper, geometrical and mechanical approaches are proposed for the simulation of the draping of woven fabric onto complex parts. The geometrical discrete approach allows to define the ply shapes and fibres orientation in order to optimize the composite structural properties and the continuum meso-structural mechanical approach allows to take into account the mechanical properties of fibres and resin and the various dominating mode of deformation of woven fabrics during the forming process. Some numerical simulations of forming process are proposed and compared with the experimental results in order to demonstrate the efficiency of our approaches.

Key Words
woven fabric; draping, geometrical approach; continuum finite element analysis

Address
Abel Cherouat and Houman Borouchaki: University of Technology of Troyes, Charles Delaunay Institute/GAMMA3-INRIA Project Team, 12 rue Marie-Curie, BP 2060, 10010 Troyes, France

Abstract
A modular multidisciplinary analysis and optimization framework has been built with the goal of performing conceptual design of an advanced efficient supersonic air vehicle. This paper addresses the specific challenge of designing this type of aircraft for a long range, supersonic cruise mission with a payload release. The framework includes all the disciplines expected for multidisciplinary supersonic aircraft design, although it also includes disciplines specifically required by an advanced aircraft that is tailless and has embedded engines. Several disciplines have been developed at multifidelity levels. The framework can be readily adapted to the conceptual design of other supersonic aircraft. Favorable results obtained from running the analysis framework for a B-58 supersonic bomber test case are presented as a validation of the methods employed.

Key Words
aircraft design; multidisciplinary design optimization; supersonic air vehicle; conceptual design; embedded engine and airframe integration

Address
Darcy L. Allison, Craig C. Morris, Joseph A. Schetz, Rakesh K. Kapania: Department of Aerospace and Ocean Engineering, Virginia Tech, Blacksburg, VA, 24061, USA
Layne T. Watson: Department of Computer Science and Mathematics, Virginia Tech, Blacksburg, VA, 24061, USA
Joshua D. Deaton: Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH, 45435, USA

Abstract
The attitude aerodynamic control is an important subject in the design of an aerospace plane. Usually, at high altitudes, this control is fulfilled by thrusters so that the implementation of an aerodynamic control of the vehicle has the advantage of reducing the amount of thrusters fuel to be loaded on board. In the present paper, the efficiency of a wing-flap has been evaluated considering a NACA 0010 airfoil with a trailing edge flap of length equal to 35% of the chord. Computational tests have been carried out in hypersonic, rarefied flow by a direct simulation Monte Carlo code at the altitudes of 65 and 85 km, in the range of angle of attack 0-40 deg. and with flap deflection equal to 0, 15 and 30 deg.. Effects of the flap deflection have been quantified by the variations of the aerodynamic force and of the longitudinal moment. The shock wave-boundary layer interaction and the shock wave-shock wave interaction have been also considered. A possible interaction of the leading edge shock wave and of the shock wave arising from the vertex of the convex corner, produced on the lower surface of the airfoil when the flap is deflected, generates a shock wave whose intensity is stronger than those of the two interacting shock waves. This produces a consistent increment of pressure and heat flux on the lower surface of the flap, where a thermal protection system is required.

Key Words
hypersonic; rarefied Aerodynamics; effects of wing-flap deflection; shock wave-boundary layer interaction; shock wave-shock wave interaction; direct simulation Monte Carlo method

Address
Gennaro Zuppardi: Department of Industrial Engineering, University of Naples \"Federico II\", Piazzale Tecchio 80, 80125 Naples, Italy

Abstract
We investigated complex damped modes in beams in the presence of a viscoelastic layer sandwiched between two elastic layers. The problem was solved using two approaches, (1) Rayleigh beam theory and analyzed using the Ritz method, and (2) by using 2D plane stress elasticity based finite-element method. The damping in the layers was modeled using the complex modulus. Simply-supported, cantilever, and viscously supported boundary conditions were considered in this study. Simple trigonometric functions were used as admissible functions in the Ritz method. The key idea behind sandwich structure is to increase damping in a beam as affected by the presence of a highly-damped core layer vibrating mainly in shear. Different assumptions are utilized in the literature, to model shear deformation in the core layer. In this manuscript, we used FEM without any kinematic assumptions for the transverse shear in both the core and elastic layers. Moreover, numerical examples were studied, where the base and constraining layers were also damped. The loss factor was calculated by modal strain energy method, and by solving a complex eigenvalue problem. The efficiency of the modal strain energy method was tested for different loss factors in the core layer. Complex mode shapes of the beam were also examined in the study, and a comparison was made between viscoelastically and viscously damped structures. The numerical results were compared with those available in the literature, and the results were found to be satisfactory.

Key Words
finite element method; damping; sandwich beam; complex modes; viscoelasticity; constrained damping treatment; modal strain energy method

Address
Naveed Ahmad: Department of Engineering Science and Mechanics, Virginia Tech, Blacksburg, VA, USA
Rakesh K. Kapania: Department of Aerospace and Ocean Engineering, Virginia Tech, Blacksburg, VA, USA

Abstract
The paper focuses on the integration of a non-linear one-dimensional model of Synthetic Jet (SJ) actuator in a well-assessed numerical simulation method for turbulent compressible flows. The computational approach is intended to the implementation of a numerical tool suited for flow control simulations with affordable CPU resources. A strong compromise is sought between the use of boundary conditions or zero-dimensional models and the full simulation of the actuator cavity, in view of long-term simulation with multiple synthetic jet actuators. The model is integrated in a multi-domain numerical procedure where the controlled flow field is simulated by a standard CFD method for compressible RANS equations, while flow inside the actuator is reduced to a one-dimensional duct flow with a moving piston. The non-linear matching between the two systems, which ensures conservation of the mass, momentum and energy is explained. The numerical method is successfully tested against three typical test cases: the jet in quiescent air, the SJ in cross flow and the flow control on the NACA0015 airfoil.

Key Words
synthetic jet; active flow control; virtual shaping

Address
Michele Ferlauto and Roberto Marsilio: Department of Mechanical and Aerospace Engineering, Politenico di Torino, Corso Duca degli Abruzzi, 24, 10129, Turin, Italy

Abstract
Automatic Dependent Surveillance Broadcast (ADS-B) is quickly being adopted by aviation safety authorities around the world as the standard for aircraft tracking. The technology provides the opportunity for live tracking of aircraft positions within range of an ADS-B receiver stations. Currently these receiver stations are bound by land and local infrastructural constraints. As such there is little to no coverage over oceans and poles, over which many commercial flights routinely travel. A low cost space based ADS-B receiving system is proposed as a constellation of small satellites. The possibility for a link between aircraft and satellite is dependent primarily on proximity. Calculating the likelihood of a link between two moving targets when considering with the non-periodic and non-uniform nature of actual aircraft flight-paths is nontrivial. This analysis of the link likelihood and the performance of the tracking ability of the satellite constellation has been carried out by a direct simulation of satellites and aircraft. Parameters defining the constellation (satellite numbers, orbit size and shape, orbit configuration) were varied between reasonable limits. The recent MH370 disappearance was simulated and potential tracking and coverage was analysed using an example constellation. The trend of more satellites at a higher altitude inclined at 60 degrees was found to be the optimal solution.

Key Words
low-earth orbit, satellite constellation, aircraft tracking, MH370

Address
Thien H. Nguyen, Ediz Cetin, Barnaby Osborne and Thomas F Dixon: Australian Centre for Space Engineering Research (ACSER), School of Electrical Engineering
and Telecommunications, UNSW Australia, 2052, Australia
Naomi Tsafnat: School of Mechanical and Manufacturing Engineering, UNSW Australia, 2052 Australia


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