Flying insects and robots that mimic them flap and rotate (or ‘pitch’) their wings with large angular amplitudes. The reciprocating nature of flapping requires rotation of the wing at the end of each stroke. Insects or flapping-wing robots could achieve this by directly exerting moments about the axis of rotation using auxiliary muscles or actuators. However, completely passive rotational dynam...

This paper introduces an approach to effectively model the nonlinear aeroelastic behavior of fully flexible aircraft. The study is conducted based on a nonlinear strainedbased finite element framework in which the developed low-order formulation captures the nonlinear (large) deflection behavior of the wings, and the unsteady subsonic aerodynamic forces acting on them. Instead of merely conside...

We present computations of membrane airfoil behavior subject to aerodynamic loading and compare them with in vivo measurements of membrane wings of bats during flight. The computational method assumes an inviscid potential flow (with net circulation determined by a Kutta condition), is computed using XFOIL and iteratively coupled with a finite element model describing the membrane behavior. We ...

Airplanes and helicopters use high aspect ratio wings to reduce the power required to fly, but must operate at low angle of attack to prevent flow separation and stall. Animals capable of slow sustained flight, such as hummingbirds, have low aspect ratio wings and flap their wings at high angle of attack without stalling. Instead, they generate an attached vortex along the leading edge of the w...

Females of the tussock moth Orgyia recens have vestigial wings, whereas the males have normal wings. During early pupal development, female wings degenerate drastically compared with those of males. To examine whether ecdysteroid is involved in this sex-specific wing development, we cultured pupal wings just after pupation with ecdysteroid (20-hydroxyecdysone, 20E). In the presence of 20E, the ...

Simulation analyses for in-situ cyclic loading tests in cohesive soil were conducted to indicate that finite element models considering nonlinearity of material , pile-soil separation and a loosened layer valid evaluating lateral resistance steel pipe piles with wings driven by rotational penetration. The results analytical studies demonstrated pile head load approached without when displacemen...