Abstracts of Journal Articles - Accepted for Publication


A Nonlocal Finite Element Model for Buckling and Vibration of Functionally Graded Nanobeams

Authors
A Imani Aria (Tabriz University, Iran) & MI Friswell (Swansea University)
Journal
Composites Part B: Engineering
accepted for publication
Abstract
In this paper, a nonlocal (strain-driven) finite element model is presented to examine the free vibration and buckling behaviour of functionally graded (FG) nanobeams on the basis of first-order shear deformation theory (FSDBT). The proposed beam element has five nodes and ten degrees of freedom. The material properties of the FG nanobeam are assumed to vary in the thickness direction according to the power-law form. The stretching-bending coupling effect is eliminated by employing the neutral axis concept. Governing equations are deduced with the aid of Hamilton's principle. Buckling loads and natural frequencies are calculated for different nonlocal coefficients, boundary conditions (BCs), power-law indices, and span-to-depth ratios. The accuracy of the proposed element is verified by comparing with available benchmark results in the literature.

Composite Rotor Blade Twist Modification in Flight by Using a Moving Mass and Stiffness Tailoring

Authors
MR Amoozgar, AD Shaw, J Zhang & MI Friswell (Swansea University)
Journal
AIAA Journal
accepted for publication
Abstract
In this paper, a new concept for morphing composite blades is proposed, and how this concept changes the twist distribution of the blade is explained. A change in the blade twist is obtained by adding a mass to the blade which produces an extra centrifugal force. This centrifugal force then may produce a moment that can change the blade twist via the extension-twist or bend-twist coupling of the composite lamination. These types of couplings are present in anti-symmetrically and symmetrically laminated beams, respectively. The dynamics of the rotating composite blade is modeled by using the geometrically exact fully intrinsic beam equations. The concentrated mass is considered as a non-structural concentrated mass which has offsets with respect to the beam reference line. The nonlinear partial differential equations are discretized by using a time-space scheme, and the converged results are compared with those reported in the literature and very good agreement is observed. It is found that for an antisymmetric lamination, the spanwise location of the concentrated mass affects the twist while in the symmetric case the chordwise position of the concentrated mass is the source of twist change. It is also found that introducing the concentrated mass to a real blade can change the twist dramatically.