Search

Vibration analysis of wing-box structures is a crucial aspect of the aeronautic design to avoid aeroelastic effects during normal flight operations. The deformation of a wing structure can induce nonlinear couplings, causing a different dynamic behavior from the linear counterpart, and nonlinear effects should be considered for more realistic simulations. Moreover, composite materials and aeroelastic tailoring require new simulation tools to include bending–torsion coupling effects. In this research, a beam finite element with bending–torsion coupling formulation is used to investigate the effects of the deflection of beam structures with different aspect ratios. The nonlinear effects are included in the finite element formulation. The geometrical effect is considered, applying a deformation dependent transformation matrix. Stiffness effects are introduced in the stiffness matrix with Hamilton's Principle and a perturbation approach. The results obtained with the beam finite element model are compared with numerical and experimental evidence. [ABSTRACT FROM AUTHOR]

Current CubeSats usually exhibit a low structural mass efficiency and a low internal volume for their payloads. The present work aims to propose an advanced structural architecture for CubeSats that addresses the issues of low structural mass efficiency and payload volume. The starting concept is the smart tiles architecture for satellites developed for the ARAMIS (an Italian acronym for a highly modular architecture for satellite infrastructures) CubeSat project. By introducing multifunctional structures and lightweight, composite materials in the design of smart tiles, the volumetric and structural mass efficiency of the entire CubeSat are enhanced. The advantages of the chosen approach are preliminarily analyzed in terms of the volumetric efficiency and amplitude of the payload design space. A 1U battery tile design is then selected to investigate the multifunctional structures design aspects in the project of space structures. A battery tile prototype is designed, produced, and tested. The CubeSat volumetric increment and the payload volume gain with respect to the traditional architecture is shown to reach a maximum of 37%. The CubeSat structural mass ratio can be reduced to 16.7%. [ABSTRACT FROM AUTHOR]

CubeSats primary structures are usually made with aluminium alloys, with few examples of CFRP primary structures under study. Power system battery arrays usually occupy spacecraft internal volume and mass that should be available to the payload. A CFRP structural/battery array configuration has been designed, allowing to integrate the electrical power system in the bus primary structure. Its configuration has been developed with the modular design philosophy of the AraMiS CubeSat. It is sized as a tile, mounted on an external face of the 1U CubeSat. It accommodates two solar cells, while the opposite face accommodates power system circuitry. Following a cellular structure concept, a set of commercial LiPo batteries has been placed between two CFRP panels and spaced out with CFRP ribs. Compliance with launch mechanical loads has been evaluated with a finite element analysis. A preliminary thermal analysis has been performed to simulate a LEO orbit environment. The results indicate that even with a low degree of structural integration, more volume and mass can be allocated to the payload, with respect to traditional, functionally separated designs in aluminium alloy. The low degree of integration allows to employ relatively cheap, commercial off-the-shelf components.

This paper presents the design and manufacture of the first European Very Long-Endurance Stratospheric Unmanned Air Vehicle, HeliPlat[R] (HELIos PLATform). This vehicle is a monoplane with eight brushless motors, a twin-boom tail type and two rudders. A computer program has been developed to carry out the platform design. To minimize airframe weight, high modulus carbon fiber composite material has been used extensively. Airfoil coordinates and wing planform have been optimized in order to achieve the best possible aerodynamic efficiency by using integral panel/boundary-layer methods and also to obtain the minimum possible induced drag with respect to local Reynolds airfoil. To this effect, several wind-tunnel tests were carried out so as to compare the analytically predicted airfoil performances. After an initial configuration had been worked out, a scale technological demonstrator (wing span 24 m) was designed, manufactured, and tested under shear, bending, and torsion loads. Finite element analysis was also carried out in order to predict the static and dynamic behavior of both the full-size and scale model versions of the HeliPlat structure. The preliminary static test resulted in a high correspondence.

The recent advances in battery energy density and electric propulsion systems for automotive applications are enabling the development of the electric vertical take-off and landing (VTOL) aircraft. The electric VTOL is a new means of transport that can fly like an aircraft and take off and land vertically like a helicopter, sometimes called personal aerial vehicle. This paper compares it to the existing vehicles that may compete with it and addresses the estimation of its performances in hover, cruise flight, and the transition phase. The main parameters affecting performances are then discussed. Considerable space is dedicated to the battery mass to total mass ratio. [ABSTRACT FROM AUTHOR]