A novel piezo-actuated flapping mechanism based on inertia drive

2020 ◽  
Vol 31 (15) ◽  
pp. 1782-1792
Author(s):  
Yangkun Zhang ◽  
Yuxin Peng ◽  
Yang Cheng ◽  
Haoyong Yu
Keyword(s):  
Frictional Contact ◽  
Transmission Mechanism ◽  
Arbitrary Form ◽  
Flapping Motion ◽  
Flapping Mechanism

In this article, a novel piezo-actuated flapping mechanism based on inertia drive is proposed and developed. In comparison with the existing flapping mechanisms, the proposed one has a more direct driving form simply via a frictional contact without using any transmission mechanism like crank-rocker or crank-slider, making it easier for miniaturization. In addition, it could principally allow for an arbitrary form of flapping motion with unlimited stroke. The flapping principle and the rationale for an arbitrary form of flapping motion with unlimited stroke are presented. A prototype of the proposed flapping mechanism was constructed and tested. The ability in various modulations of flapping motion, including flapping amplitude, position, asymmetry between downstroke and upstroke flapping speeds, and frequency, is demonstrated.

Nonlinear Interaction of an Elastic Pulse With a Frictional Contact Interface Between Two Anisotropic Dissimilar Media

2004 ◽  
Vol 126 (1) ◽  
pp. 108-117 ◽  
Author(s):  
Yue-Sheng Wang ◽  
Hui-Hui Dai ◽  
Gui-Lan Yu
Keyword(s):  
Critical Angle ◽  
Frictional Contact ◽  
Singular Integral Equations ◽  
Arbitrary Form ◽  
Algebraic Equations ◽  
Contact Interface ◽  
Non Linear ◽  
Cauchy Singular Integral ◽  
Open Question ◽  
Separation Zones

The paper analyses the interaction of an elastic pulse of arbitrary form with a frictional contact interface between two anisotropic solids which are pressed together and at the same time loaded by the in-plane and anti-plane shearing tractions. The incident pulse is assumed strong enough to break friction so that localized separation and slip take place. Coulomb friction, which causes the non-linear coupling between the in-plane and anti-plane motions, is supposed along the contact interface. The sub-critical angle incidence is first considered. By using Fourier analysis, the problem is reduced to a set of algebraic equations. A method to get the solution of the equations with determination of the slip/stick/separation zones is developed. As an example, the detailed computation for the case of an incident parabolic stress pulse is carried out. Numerical results of the interface tractions and the slip velocities are presented for two contacting half-spaces of the same materials in the same orientation. The super-critical angle incidence is discussed. In this case the problem is cast to a set of non-linear Cauchy singular integral equations whose solution is still an open question in mathematics.

Design of a Bio-Inspired Spherical Four-Bar Mechanism for Flapping-Wing Micro Air-Vehicle Applications

2008 ◽  
Author(s):  
Matt McDonald ◽  
Sunil K. Agrawal
Keyword(s):  
Three Dimensional ◽  
Micro Air Vehicles ◽  
Aerodynamic Performance ◽  
Flapping Wing ◽  
Micro Air Vehicle ◽  
Aerodynamic Forces ◽  
Flapping Motion ◽  
Wing Motion ◽  
Air Vehicle ◽  
Flapping Mechanism

Design of flapping-wing micro air-vehicles presents many engineering challenges. As observed by biologists, insects and birds exhibit complex three-dimensional wing motions. It is believed that these unique patterns of wing motion create favorable aerodynamic forces that enable these species to fly forward, hover, and execute complex motions. From the perspective of micro air-vehicle applications, extremely lightweight designs that accomplish these motions of the wing, using just a single, or a few actuators, are preferable. This paper presents a method to design a spherical four-bar flapping mechanism that approximates a given spatial flapping motion of a wing, considered to have favorable aerodynamics. A spherical flapping mechanism was then constructed and its aerodynamic performance was compared to the original spatially moving wing using an instrumented robotic flapper with force sensors.

scholarly journals EXPERIMENTAL STUDY OF GROUND EFFECT ON THREE-DIMENSIONAL INSECT-LIKE FLAPPING MOTION

2014 ◽  
Vol 34 ◽  
pp. 1460384 ◽  
Author(s):  
XIAOHU ZHANG ◽  
KIM BOON LUA ◽  
RONG CHANG ◽  
TEE TAI LIM ◽  
KHOON SENG YEO
Keyword(s):  
Three Dimensional ◽  
Ground Effect ◽  
Flapping Wing ◽  
Water Tank ◽  
Force Measurements ◽  
Flapping Motion ◽  
Large Water ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Flapping Mechanism

This paper focuses on an experimental investigation aimed at evaluating the aerodynamics force characteristics of three-dimensional (3D) insect-like flapping motion in the vicinity of ground. The purpose is to establish whether flapping wing insects can derive aerodynamic benefit from ground effect similar to that experienced by a fixed wing aircraft. To evaluate this, force measurements were conducted in a large water tank using a 3D flapping mechanism capable of executing various insect flapping motions. Here, we focus on three types of flapping motions, namely simple harmonic flapping motion, hawkmoth-like hovering motion and fruitfly-like hovering motion, and two types of wing planforms (i.e. hawkmoth-like wing and fruitfly-like wing). Results show that hawkmoth-like wing executing simple harmonic flapping motion produces average lift to drag ratio [Formula: see text] similar to that of fruitfly wing executing the same motion. In both cases, they are relatively independent of the wing distance from the ground. On the other hand, a hawkmoth wing executing hawkmoth flapping motion produces [Formula: see text] characteristic different from that of fruitfly wing executing fruitfly motion. While the [Formula: see text] value of the former is a function of the wing distance from the ground, the latter is minimally affected by ground effect. Unlike fixed wing aerodynamics, all the flapping wing cases considered here do not show a monotonic increase in [Formula: see text] with decreasing wing distance from the ground.

2008 Economy Results: The End of the "Fat" Years

2009 ◽  
pp. 4-25 ◽  
Author(s):  
B. Zamaraev ◽  
A. Kiyutsevskaya ◽  
A. Nazarova ◽  
E. Sukhanov
Keyword(s):  
Economic Crisis ◽  
National Economy ◽  
Banking System ◽  
Housing Markets ◽  
Transmission Mechanism ◽  
Economic Conditions ◽  
Basic Change ◽  
Russian Economy ◽  
The World

The article analyzes the current economic conditions in Russia. Succession, distribution and the transmission mechanism of the world financial and economic crisis to the Russian economy are considered in this article as well as the changes in the banking system, share and housing markets. Production, consumption and investment on the boundary of 2008-2009 are described. The conclusion about the basic change of conditions of national economy development is presented.

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