A novel model of dipteran flight mechanism

Cao, Qingjie; Xiong, Yeping; Wiercigroch, Marian

doi:10.1007/s40435-013-0001-5

Cited by 40 publications

(10 citation statements)

References 33 publications

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“…An experimental prototype is built to demonstrate the unique dynamic characteristics of the ZS system based upon the schematic shown in Fig. 3(a), which with the trajectory S of point P is an ellipse, which can be regarded as the coupling of a positive and a negative stiffness components 30,40,41 . The prototype with the adjustable loading 27kg ≤ M + m ≤ 37kg, the total stiffness of the vertical springs k 0 = 1.04N/mm, the total stiffness of the horizontal springs k/4 = 1N/mm, maximum stroke l 0 = R x = 200mm, minimum pre-stretch of horizontal springs B = 0mm, and the semi-minor axis R y = 102mm.…”

Section: Experimental Investigationsmentioning

confidence: 99%

Road to entire insulation for resonances

Cao

Zhu

Wang

et al. 2022

Preprint

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The effective solution to avoid machinery damage caused by resonance has been perplexing the field of engineering as a core research direction since the resonance phenomenon was discovered by Leonhard Euler in 1750. Numerous attempts have been performed to reduce the influence of resonance since the middle of last century, by introducing a nonlinear structure or a closed-loop control system. However, the existed methodologies cannot eliminate the resonance completely even extra problems were introduced inevitably, which means the technical choke-point of resonance-free remains unsolved. Here we propose an inverse method based upon the requirements of dynamic characteristics of the supporting system to construct a passive archetypal model with zero-stiffness within a designable distance to avoid the resonance. The reliability of the inverse method is demonstrated theoretically and experimentally, which indicate that the constructed system with zero-stiffness can outright eliminate the mechanical resonance by completely isolating the energy transfer between the load and environment. The distinctive geometric characteristics of the zero-stiffness system leads to a new inspiration for the design of resonance-free passive mechanisms or metamaterials, and the inverse method can even adapt the design for a more targeted application based on an arbitrary complex dynamic requirement.

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Section: Experimental Investigationsmentioning

confidence: 99%

Road to entire insulation for resonances

Cao

Zhu

Wang

et al. 2022

Preprint

Self Cite

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“…Write the dimensionless dynamic Eq. ( 9) into the form of two simultaneous first-order differential equations in horizontal and vertical directions, obtained by (10) and (11) separately, (8) The phase diagrams of the non-conservative autonomous systems are shown in Fig. 4.…”

Section: Sqzs Analysismentioning

confidence: 99%

“…Traditional scheme is mainly based on the linear theory to separate the structure from the basement [5][6][7][8][9][10], which is just effective for high-frequency waves. Recently, attentions have been made on nonlinear lowfrequency vibration isolation structure, which significantly improves the isolation performance [11][12][13][14][15][16]. However, these works mainly focus on vertical damage using stable quasi-zero stiffness (SQZS) system with single degree-of-freedom (DOF), which is invalid for horizontal direction.…”

Section: Introductionmentioning

confidence: 99%

An Archetypal Vibration Isolator with Quasi-zero Stiffness in Multiple Directions

Zhu

Cao

et al. 2022

J Nonlinear Math Phys

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To avoid the failure under the longitudinal, shear, and mixed wave from earthquake, an archetypal vibration isolator based on a smooth and discontinuous (SD) oscillator is proposed. This model comprises a lumped mass mounted by a vertical spring and a horizontal elastic continuum, which separately provides positive and the negative stiffness forming the stable quasi-zero stiffness (SQZS) in all vertical and horizontal directions. The equation of motion is formulated by employing the Lagrange equation, and the SQZS condition is obtained by optimizing the geometrical parameters of the system. The analysis shows that the system admits remarkable performance in vibration isolation with low resonant frequency and a large stroke of SQZS interval. The results also demonstrate the system has improved aseismic behaviour under the complex excitation of seismic wave significantly.

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“…These elements, usually referred to as Quasi-Zero-Stiffness (QZS) mechanisms [5] or Negative Stiffness Mechanisms (NSM) [6], can generate a negative restoring force or negative stiffness so that low dynamic stiffness of the overall system is achieved while keeping its static stiffness high and the static deflection small. Such mechanisms are often created by springs [7][8][9][10], magnets [11,12], bars [13,14], circular rings [15], or composite plates [16]. By transforming a linear system into a nonlinear system with NSMs, it has been shown that the natural frequency of the linearized system can be reduced.…”

Section: Introductionmentioning

confidence: 99%

Enhancing Vibration Isolation Performance by Exploiting Novel Spring-Bar Mechanism

Shi

Yang

2021

Applied Sciences

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This study investigates the use of a spring-bar mechanism (SBM) in a vibration suppression system to improve its performance. The SBM, comprising bars and springs, is configured with a conventional linear spring-damper isolator unit. The dynamic response, force transmissibility, and vibration energy flow behaviour are studied to evaluate the vibration suppression performance of the integrated system. It is found that the SBM can introduce hardening, softening stiffness, or double-well potential characteristics to the system. By tuning the SBM parameters, constant negative stiffness is achieved so that the natural frequency of the overall system is reduced for enhanced low-frequency vibration isolation. It is also found that the proposed design yields a wider effective isolation range compared to the conventional spring-damper isolator and a previously proposed isolator with a negative stiffness mechanism. The frequency response relation of the force-excited system is derived using the averaging method and elliptical functions. It is also found that the system can exhibit chaotic motions, for which the associated time-averaged power is found to tend to an asymptotic value as the averaging time increases. It is shown that the time-averaged power flow variables can be used as uniform performance indices of nonlinear vibration isolators exhibiting periodic or chaotic motions. It is shown that the SBM can assist in reducing force transmission and input power, thereby expanding the frequency range of vibration attenuations.

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A novel model of dipteran flight mechanism

Cited by 40 publications

References 33 publications

Road to entire insulation for resonances

Road to entire insulation for resonances

An Archetypal Vibration Isolator with Quasi-zero Stiffness in Multiple Directions

Enhancing Vibration Isolation Performance by Exploiting Novel Spring-Bar Mechanism

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