This paper presents a new design for the core of a lightweight tail section of an unmanned aerial vehicle (UAV) with camber-morphing horizontal and vertical stabilizers. The core of each stabilizer is composed of an aluminum spar, two active end ribs, and multiple inactive ribs. Each active end rib is composed of a solid leading compartment connected to a flexible corrugated trailing segment. Thermally activated shape memory alloy (SMA) wire actuators along the length of the corrugated segment are used to control the camber of each active rib. The SMA wires are extended through the hollow spar to increase the amount of actuation and are guided using polycarbonate pulleys. A parametric CAD model was created to automatically regenerate the corrugated trailing segment geometry based on trough height, width and angle, as well as the used NACA airfoil. The locations of the vertical webs are adjusted with each parameter set so that the webs are always at the trough centers for consistency. COMSOL's LiveLink was used to pass the generated CAD geometry to COMSOL, where finite element structural analysis is performed to study the effect of the geometric parameters on the camber deformation under SMA wire actuation and applied loads. The deformed shape of the trailing segment is then approximated as a third-degree polynomial and used to modify the four-digit NACA airfoil equation, generating a deformed shape for the airfoil. 2D computational fluid dynamics simulations are then performed to compute the lift-to-drag ratio for each structural configuration, from which the geometric parameters that maximize the performance of the stabilizer at the design speed can be selected. The proposed UAV SMA-based camber-morphing rear control section has been successfully manufactured and tested. Camber morphing up to 10.7°was successfully achieved and showed very good agreement with the numerical prediction.

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The Magnetorheological fluid, as one of the smart materials, is the focus of many researches running nowadays and is getting to replace many materials in several engineering applications. This fluid is characterized by its ability to change from liquid into semi-solid gel in few milliseconds as a result of applying magnetic field. This paper deals with a magnetorheological fluid embedded in an Aluminum sandwich beam to give the whole sandwich structure relevant controllability of various parameters such as natural frequencies, vibration amplitudes, and damping factors. This paper presents Finite Element (FE) formulation of the MR sandwich beam, and uses the finite element model to solve for various beam boundary conditions, various magnetic field levels and configurations. The paper also compares the finite element results with published analytical results. Finally, the paper checks the suitability of the spectral element (SE) method in dealing with the MR sandwich beam, and compares the spectral results with the finite element results.

This paper presents a new design for the core of a span-morphing unmanned aerial vehicle (UAV) wing that increases the spanwise length of the wing by fifty percent. The purpose of morphing the wingspan is to increase lift and fuel efficiency during extension, to increase maneuverability during contraction, and to add roll control capability through asymmetrical span morphing. The span morphing is continuous throughout the wing, which is comprised of multiple partitions. Three main components make up the structure of each partition: a zero Poisson’s ratio honeycomb substructure, telescoping carbon fiber spars and a linear actuator. The zero Poisson’s ratio honeycomb substructure is an assembly of rigid internal ribs and flexible chevrons. This innovative multi-part honeycomb design allows the ribs and chevrons to be 3D printed separately from different materials in order to offer different directional stiffness, and to accommodate design iterations and future maintenance. Because of its transverse rigidity and spanwise compliance, the design maintains the airfoil shape and the cross-sectional area during morphing. The telescoping carbon fiber spars interconnect to provide structural support throughout the wing while undergoing morphing. The wing model has been computationally analyzed, manufactured, assembled and experimentally tested.

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Available online xxx Keyword: Porous material Cowin-Nunziato model Local integral equations Moving least square method Micro-dilatation Stress intensity factor (SIF) a b s t r a c t A meshless local Petrov-Galerkin (MLPG) model of porous elastic materials based on micro-dilatation theory by Cowin and Nunziato (1983) is developed. . This theory describes properties of homogeneous elastic materials with voids free of fluid. The primal fields (mechanical displacements, and change in matrix volume fraction which is also called micro-dilatation) are coupled in the constitutive equations. The governing differential equations are satisfied in the weak form on small circular subdomains for 2D problems. Only one node is lying at the center of each subdomain spread on the analyzed domain. A Heaviside step function is applied as test functions in the weak-form to derive local integral equations on subdomains. The spatial variation of the displacements and micro-dilatation are approximated by the moving least-squares (MLS) scheme. After performing the spatial integrations, a system of ordinary differential equations for certain nodal unknowns is obtained.

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