Warping Model Research Articles

Analytical studies on static aeroelastic behavior of forward-swept composite wing structures

An exact methodology allowing one to determine the aeroelastic lift distribution and the divergence instability of swept cantilevered composite wing structures is developed in this paper. The approach based on the Laplace transform technique enables one to solve, in a unified manner, both aeroelastic problems. The analysis encompasses the cases of free and constrained warping models for the wing twist. Numerical results are presented to demonstrate the effects played by the fiber orientation, ply lay-up, warping inhibition, and wing geometry on the subcritical static aeroelastic response and on the divergence instability of composite swept wings.

Warped Fermi Surface in GaSb from Shubnikov-de Haas Measurements

The frequencies of Shubnikov-de Haas oscillations in $n$-type tellurium-doped GaSb have been obtained as a function of magnetic field direction in samples with electron concentrations $n\ensuremath{\approx}{10}^{18}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. Field-modulation and phase-sensitive detection techniques were employed in the measurements. A frequency anisotropy of \ensuremath{\sim}1% has been unambiguously determined. These results are explained by the warping contribution to the $k=0$ conduction-band energy expression derived by Kane using k\ifmmode\cdot\else\textperiodcentered\fi{}p perturbation theory. By fitting the frequency anisotropy to the theoretical prediction, it is found that the warping parameter $L\ensuremath{-}M\ensuremath{-}N=(11\ifmmode\pm\else\textpm\fi{}2)\frac{{\ensuremath{\hbar}}^{2}}{2{m}_{0}}$. A small (\ensuremath{\sim}2%) effective-mass anisotropy has been observed; the symmetry of the result is predicted from the warping model, i.e., ${m}^{*}(111)g{m}^{*}(110)g{m}^{*}(100)$.