scholarly journals Vibration Control of Linear Split Stirling Cryogenic Cooler for Airborne Infrared Application

2000 ◽  
Vol 7 (6) ◽  
pp. 363-379 ◽  
Author(s):  
A.M. Veprik ◽  
V.I. Babitsky ◽  
N. Pundak ◽  
S.V. Riabzev
Keyword(s):  
Experimental Testing ◽  
Vibration Isolator ◽  
Harmonic Force ◽  
Linear Compressor ◽  
Environmental Vibration ◽  
Combined Action ◽  
Passive Isolation ◽  
Dynamic Absorber ◽  
Cryogenic Cooler ◽  
Theoretical Results

Modern infrared imagers often rely on the split Stirling cryogenic coolers the linear compressors of which are the well-known sources of harmonic disturbance. The traditional method of their passive isolation fails to meet the restraints on the static and dynamic deflections which are originated by the combined action of the airborne g-loading and harsh random vibration.The vibration protection system, which combines a stiff and heavily damped vibration isolator with tuned dynamic absorber, is studied and optimised for use in the design of an airborne infrared device.Such a design is aimed, primarily, at essential dynamic suppression of the harmonic force which is produced by the linear compressor and, secondarily, at minimisation of environmental vibration loads transmitted through the infrared device to the linear compressor. Experimental testing backed up the theoretical results.

Novel concept for driving the linear compressor of a micro-miniature split Stirling cryogenic cooler

2009 ◽  
Author(s):  
V. Maron ◽  
A. Veprik ◽  
L. Finkelstein ◽  
H. Vilenchik ◽  
I. Ziv ◽  
...  
Keyword(s):  
Linear Compressor ◽  
Novel Concept ◽  
Cryogenic Cooler

scholarly journals Some remarks on tile effect of dynamic absorber

1989 ◽  
Vol 11 (4) ◽  
pp. 10-13
Author(s):  
Nguyen Van Dao
Keyword(s):  
Linear Systems ◽  
Degrees Of Freedom ◽  
Harmonic Force ◽  
Two Degrees Of Freedom ◽  
Dynamic Absorber ◽  
Tile Effect

In order to limit the vibration of mass m2 (fig. 1) while the mass m1 is subject ted to a harmonic force Q0sinωt, the dynamic absorber can be used. In this case the  system considered is of more than two degrees of freedom. The article presented dealer with some linear systems of this kind with various methods of attaching the dynamic absorbers. It seams that advantageous absorbers are those given in figures 2 and 3. Whereas two absorbers acting simultaneously as shown in figs 4, 5, 6 do not give more effectiveness.

scholarly journals Selected aspects of a cold forging process for hollow balls

2021 ◽  
Author(s):  
Grzegorz Samołyk ◽  
Grzegorz Winiarski
Keyword(s):  
Numerical Model ◽  
Numerical Modelling ◽  
Wall Thickness ◽  
Experimental Testing ◽  
Wide Spectrum ◽  
Cold Forging ◽  
Hole Size ◽  
Forging Process ◽  
Experimental Findings ◽  
Theoretical Results

AbstractThis paper presents the results of a study investigating a cold forging process for producing hollow balls with different wall thicknesses. The study was performed by FEM numerical modelling, which made it possible to obtain a wide spectrum of results. For the analysis of FEM results obtained for problematic cases (shape defects in forged balls), novel hypotheses for results interpretation are proposed. The FEM numerical model and hypotheses are then verified via experimental testing, and selected theoretical results are compared with experimental findings. Finally, obtained results are discussed (e.g. the effect of billet dimensions on forging conditions, wall thickness and hole size), a method for FEM results interpretation is presented, and design-related solutions ensuring the production of defect-free hollow balls are proposed.

Dynamic Modeling and Experimental Testing of a Piano Action Mechanism With a Flexible Hammer Shank

2007 ◽  
Author(s):  
Adel Izadbakhsh ◽  
John McPhee ◽  
Stephen Birkett
Keyword(s):  
Experimental Testing ◽  
Rigid Bodies ◽  
Beam Model ◽  
Action Mechanism ◽  
Rayleigh Beam ◽  
Hammer Head ◽  
Main Components ◽  
The Impact ◽  
Grand Piano ◽  
Theoretical Results

The piano action is the mechanism that transforms the finger force applied to a key into a motion of a hammer that strikes a piano string. This paper presents a state-of-the-art model of a grand piano action, which is based on the five main components of the action mechanism (key, whippen, jack, repetition lever, and hammer). Even though Askenfelt and Jansson [1] detected some flexibility for the hammer shank in their experiments, all previous piano models have assumed the hammers to be rigid bodies. In this paper, we have accounted for the hammer shank flexibility using a Rayleigh beam model. It turns out that the flexibility of the hammer shank does not significantly affect the rotation of the other parts of the piano mechanism, compared with the case that the hammer shank has been modeled as a rigid part. However, the flexibility of the hammer shank changes the impact velocity of the hammer head, and also causes a greater scuffing motion for the hammer head during the contact with the string. To validate the theoretical results, experimental measurements were taken by two strain gauges mounted on the hammer shank, and by optical encoders at three of the joints.

scholarly journals Characteristics of Dynamic Absorber Using Rubber Vibration Isolator.

1994 ◽  
Vol 60 (580) ◽  
pp. 4116-4122
Author(s):  
Kouichi Ozaki ◽  
Kazuhiro Hashimoto ◽  
Yasuo Jimbo
Keyword(s):  
Vibration Isolator ◽  
Dynamic Absorber

Application of a dynamic antiresonant vibration isolator to minimize the vibration transmission in underwater vehicles

2017 ◽  
Vol 24 (17) ◽  
pp. 3819-3829 ◽  
Author(s):  
Niuniu Liu ◽  
Chenyang Li ◽  
Caiyu Yin ◽  
Xingjian Dong ◽  
Hongxing Hua
Keyword(s):  
Power Flow ◽  
Thrust Bearing ◽  
Vibration Mode ◽  
Underwater Vehicle ◽  
Vibration Isolator ◽  
Harmonic Force ◽  
Vibration Transmission ◽  
Force Transmissibility ◽  
Isolation Performance ◽  
Analytical Dynamic

Harmonic axial force resulting from a propeller’s first vibration mode is a major cause of tonal sound radiation of an underwater vehicle. To reduce the harmonic force, we employ a dynamic antiresonant vibration isolator (DAVI) in parallel with thrust bearing of the shafting system to attenuate vibration transmitted to the hull. The methods of transfer matrices and substructure synthesis are used to create a semi-analytical dynamic model of the propeller–shaft–hull system with DAVI. In this model, the elastic properties of the propeller and foundation are taken into consideration. The force transmissibility and power flow are then used to evaluate the isolation performance of the DAVI. For the purpose of comparison, a resonance changer (RC) proposed in the published literature is also used to reduce the axial vibration transmission. It is demonstrated numerically that by using DAVI, the vibration and power flow of the underwater vehicle are greatly attenuated at the designed frequency without obviously changing the axial fundamental resonance frequency of the shafting system, which is superior to the RC isolator.

scholarly journals THEORETICAL STUDY OF THE EFFECT OF PROBE SHAPE ON ADHESION FORCE BETWEEN PROBE AND SUBSTRATE IN ATOMIC FORCE MICROSCOPE EXPERIMENT

2013 ◽  
Vol 43 (4) ◽  
pp. 61-72 ◽  
Author(s):  
Li Yang ◽  
Junhui Hu ◽  
Lingjiang Kong
Keyword(s):  
Atomic Force Microscope ◽  
Theoretical Study ◽  
Adhesion Force ◽  
Quantitative Description ◽  
Fundamental Parameters ◽  
Atomic Force ◽  
Combined Action ◽  
Theoretical Results ◽  
Good Agreement ◽  
Manipulation Experiment

Abstract The quantitative description of adhesion force dependence on the probe shape is of importance in many scientific and industrial fields. We performed a theoretical study on the influences of the probe shape (the sphere and parabolic probe) on the adhesion force at different humidity in order to elucidate how the adhesion force varied with the probe shape in atomic force microscope manipulation experiment. We found that the combined action of the triple point and the Kelvin radius is the guiding trend of the adhesion force, and these two fundamental parameters are closely related to the probe shape. Meanwhile, the theoretical results demonstrated that the adhesion force are in a good agreement with the experiment data if the van der Waals force is take into account.

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