scholarly journals The Study on Improvement about Vibration Absorption Plate Spring for Rotorcraft

2021 ◽  
Vol 22 (9) ◽  
pp. 729-735
Author(s):  
Jeong-Mo Koo ◽  
Gwang-Eun Lee ◽  
Jeong-Mi Seo ◽  
Tae-Hoon Won
2021 ◽  
pp. 116010
Author(s):  
Zbyněk Šika ◽  
Tomáš Vyhlídal ◽  
Zdeněk Neusser

2012 ◽  
Vol 502 ◽  
pp. 441-445
Author(s):  
Jin Bo Ren ◽  
Xiang Zhang ◽  
Bing Le Hu

This paper mainly talks about the structure of new-energy autos batteries’ cooling fan. It gives the reasons for vibration in theory. It also improved the structure of damping pads for vibration absorption by comparing vibration absorption effect of damping pads made of two different kinds of material. In the end, the better-effect structure and material for vibration absorption is selected after the experimental comparison. In addition, the assembly technique is advanced for fan, which left a notable alleviation of vibration.


Author(s):  
Nejat Olgac ◽  
Martin Hosek

Abstract A novel active vibration absorption technique, the Delayed Resonator, has been introduced recently as a unique way of suppressing undesired oscillations. It suggests a control force on a mass-spring-damper absorber in the form of a proportional position feedback with a time delay. Its strengths consist of extremely simple implementation of the control algorithm, total vibration suppression of the primary structure against a harmonic force excitation and full effectiveness of the absorber in a semi-infinite range of disturbance frequency, achieved by real-time tuning. All this development work was done using the absolute displacements of the absorber in the feedback. These displacement measurements may be difficult to obtain and for some applications impossible. This paper deals with a substitute and easier measurement: the relative motion of the absorber with respect to the primary structure. Theoretical foundations for the Delayed Resonator (DR) are briefly recapitulated and its implementation on a single-degree-of-freedom primary structure disturbed by a harmonic force is introduced utilizing both absolute and relative position measurement of absorber mass. Methods for stability range analysis and transient behavior are presented. Properties acquired for the same system with these two different feedback are compared. Relative position measurement case is found to be more advantageous in most applications of the Delayed Resonator method.


2001 ◽  
Author(s):  
Giulio Grillo ◽  
Nejat Olgac

Abstract This paper presents an influence region analysis for an actively tuned vibration absorber, the Delayed Resonator (DR). DR is shown to respond to tonal excitations with time varying frequencies [1–3]. The vibration suppression is most effective at the point of attachment of the absorber to the primary structure. In this study we show that proper feedback control on the absorber can yield successful vibration suppression at points away from this point of attachment. The form and the size of such “influence region” strongly depend on the structural properties of the absorber and the primary system. There are a number of questions addressed in this paper: a) Stability of vibration absorption, considering that a single absorber is used to suppress oscillations at different locations. b) Possible common operating frequency intervals in which the suppression can be switched from one point on the structure to the others. A three-degree-of-freedom system is taken for as example case. One single DR absorber is demonstrated to suppress the oscillations at one of the three masses at a given time. Instead of an “influence region” a set of “influence points” is introduced. An analysis method is presented to find the common frequency interval in which the DR absorber operates at all three influence points.


2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Ryan Jenkins ◽  
Nejat Olgac

This paper offers two interlinked contributions in the field of vibration absorption. The first involves an active tuning of an absorber for spectral and spatial variations. The second contribution is a set of generalized design guidelines for such absorber operations. “Spectral” tuning handles time-varying excitation frequencies, while “spatial” tuning treats the real-time variations in the desired location of suppression. Both objectives, however, must be achieved using active control and without physically altering the system components to ensure practicality. Spatial tuning is inspired by the concept of “noncollocated vibration absorption,” for which the absorber location is different from the point of suppression. This concept is relatively under-developed in the literature, mainly because it requires the use of part of the primary structure (PS) as the extended absorber—a delicate operation. Within this investigation, we employ the delayed resonator (DR)-based absorber, a hybrid concept with passive and active elements, to satisfy both tuning objectives. The presence of active control in the absorber necessitates an intriguing stability investigation of a time-delayed dynamics. For this subtask, we follow the well-established methods of frequency sweeping and D-subdivision. Example cases are also presented to corroborate our findings.


2021 ◽  
Author(s):  
Xingbao Huang ◽  
Xiao Zhang ◽  
Bintang Yang

Abstract This paper introduces an energy conversion inspired vibration control methodology and presents a representative prototype of tunable bi-stable energy converters. This work is concerned on improving the vibration absorption and energy conversion performance of tunable bi-stable clustered energy conversion inspired dynamic vibration absorbers (EC-DVAs). The deterministic parametric analysis of the energy transfer performance of clustered EC-DVAs is conducted. Firstly, nonlinear vibration behaviors including transient energy transfer and snap-through motions are studied, and then effects of EC-DVA number on vibration control is investigated. Furthermore, the optimal computation based on adjusting the length ratio (namely bi-stable potential barrier height) is developed to obtain the maximum energy conversion efficiency of clustered EC-DVAs and the minimum residual kinetic energy of the primary system considering different number of clustered EC-DVAs. Moreover, the optimal calculation based on optimal EC-DVA number is also developed to achieve the most excellent vibration absorption and energy conversion performance. Finally, the optimal calculation based on optimal mass ratio is conducted. Numerical simulations show that when the total mass ratio is constant the snap-through motions of each EC-DVA depend remarkably on EC-DVA number; the energy conversion efficiency and residual kinetic energy after dynamic length ratio optimization is independent on ambient input energy and EC-DVA number; The energy conversion efficiency and vibration absorption performance based on optimal EC-DVA number maintain high efficiency and stable when the ambient input energy or the potential energy of clustered EC-DVAs varies. The optimal mass ratio is large when the system’s potential barrier is too large and the ambient input energy is small. Therefore, the presented tunable bi-stable system of clustered EC-DVAs with appropriate bi-stable potential function and proposed optimization strategies is a potential alternative for vibration control of mechanical components exposed to varying impulses.


2011 ◽  
Vol 471-472 ◽  
pp. 975-980
Author(s):  
Takahiko Yoshi ◽  
Kazuya Okubo ◽  
Toru Fujii

Significant stiffness reduction of the plate spring due to delaminations around the interwoven cloths could be prevented by using CFRTP (carbon fiber cloth and Polyethylene Terephthalate (PET)) rather than that by using CFRP (carbon fiber cloth and epoxy), when ultra high cyclic loading was applied to the plate spring under high humidity condition. To explain the result, the prediction model of stiffness reduction was introduced considering time-dependent crack propagation accompanying with creep deformation around the crack tip. Stiffness reduction of CFRP under high humidity condition was not only determined by cyclic crack propagation but also by time-dependent crack propagation accompanying with creep deformation around the crack tip. It was found that CFRTP was effective material of the plate springs on vibration conveyer for the uses under high humidity condition to prevent significant stiffness reduction, where the crack propagation accompanying with creep deformation should be prevented around the crack tip.


2012 ◽  
Vol 220-223 ◽  
pp. 543-548
Author(s):  
Meng Jie ◽  
Hai Feng Xie ◽  
Yan Liu ◽  
Zhi Gang Yang

In order to measure the fatigue property of the small and hard brittle components working under conditions of the little amplitude, high frequency force, a novel kind of resonant high frequency fatigue testing machine which is driven by the piezoelectric vibrator (PZT、PLZT or PMN) has been proposed. Firstly, the working principle of the piezoelectric resonance high frequency fatigue testing machine is analyzed, and the dynamic model of the fatigue testing machine is established to get the systemic dynamic characteristics. Then a prototype is designed and produced. Finally, the maximum load on the sample is measured by the test with the machine. The results indicate that the maximum load on the sample is 23.4N-98.1N when changing the voltage (100V-250V) and the thickness of the plate spring (1.1mm-0.6mm). The prototype made in this paper is suitable for the tensile and fatigue testing with the load level mentioned above under the condition of little amplitude and high frequency force.


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