Dynamic Analysis of a Flapper-Nozzle Valve

1991 ◽  
Vol 113 (1) ◽  
pp. 163-167 ◽  
Author(s):  
S. J. Lin ◽  
A. Akers
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Nonlinear Theory ◽  
Previous Analysis ◽  
Experimental Results ◽  
Piston Flow ◽  
Good Agreement

A previous analysis into the dynamic behavior of the flapper-nozzle component of the electrohydraulic servovalve was performed after linearization of the equations relating to control piston flow (Lin and Akers, 1989a). This paper reports results for first-stage gain and for dynamic behavior when linearization has not been performed. Good agreement has been achieved between results calculated from the nonlinear theory presented and experimental results.

Effect of the Wave Amplitude on the Dynamic Behavior of a Wave Journal Bearing

2008 ◽  
Author(s):  
Nicoleta M. Ene ◽  
Florin Dimofte ◽  
Fred B. Oswald
Keyword(s):  
Dynamic Behavior ◽  
Wave Amplitude ◽  
Journal Bearing ◽  
Experimental Results ◽  
Transient Method ◽  
Poincaré Maps ◽  
Poincare Maps ◽  
Bearing Clearance ◽  
Bearing Behavior ◽  
Good Agreement

The effect of the wave amplitude on the dynamic behavior of a three-wave journal bearing is analyzed. A transient method was used to predict the wave bearing behavior after Fractional Whirl Frequency (FFW) occurs. Dynamic trajectories, Poincare´ maps, and FFT analyses are used to study the dynamic behavior of the journal bearing. It was found that the threshold of stability is strongly influenced by the wave amplitude. However, even when FFW occurs, the journal maintains its trajectory inside the bearing clearance. The predicted data were found to be in good agreement with the experimental results obtained at the NASA GRC.

An Analytical and Experimental Study of the Dynamic Behavior of a Quick-Acting Hydraulic Fuse

1989 ◽  
Vol 111 (3) ◽  
pp. 528-534 ◽  
Author(s):  
S. R. Lee ◽  
K. Srinivasan
Keyword(s):  
Experimental Study ◽  
Response Time ◽  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Dynamic Models ◽  
Operating Conditions ◽  
Experimental Setup ◽  
Hydraulic Circuit ◽  
Short Response Time ◽  
Good Agreement

The dynamic behavior of a quick-acting hydraulic fuse is investigated here by analysis and experiment. The fuse has a very short response time and is designed to respond to pressure and flow transients that immediately follow a line rupture. In view of the short response time, a proper dynamic analysis of the entire hydraulic circuit is necessary, in addition to analysis of the fuse behavior. Dynamic models of the fuse and other hydraulic circuit elements used in the experimental setup are presented. The experiments consist of simulating line leaks and measuring fuse response, under a variety of operating conditions. Experimental and analytical results are in very good agreement if the leak transients are properly characterized.

Breathing Vibrations of a Horizontal Circular Cylindrical Tank Shell, Partially Filled With Liquid

1995 ◽  
Vol 117 (2) ◽  
pp. 187-191 ◽  
Author(s):  
M. Amabili ◽  
G. Dalpiaz
Keyword(s):  
Dynamic Behavior ◽  
Theoretical Approach ◽  
Cylindrical Shells ◽  
Horizontal Axis ◽  
Experimental Results ◽  
Liquid Level ◽  
Mode Shapes ◽  
Cylindrical Tank ◽  
Qualitative Explanation ◽  
Good Agreement

A theoretical approach to study breathing vibrations of cylindrical shells with horizontal axis, partially filled with liquid, is delineated and the results of some modal tests conducted on an industrially-manufactured tank are presented and discussed. The good agreement between theoretical and experimental results is preliminarily verified in the case of both an empty and completely full shell, in order to confirm that it is possible to apply the theoretical approach to real structures. The modal properties of a partially-filled shell as a function of liquid level are then experimentally studied, the mode shapes are compared using the Modal Assurance Criterium and a qualitative explanation of the dynamic behavior is proposed.

On the Dynamic Analysis of Roller Chain Drives: Part I — Theory

1992 ◽  
Author(s):  
Nicholas M. Veikos ◽  
Ferdinand Freudenstein
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Span Length ◽  
Additional Insight ◽  
Roller Chain ◽  
Computer Aided ◽  
Chain Dynamic ◽  
Chain Drives ◽  
Insight Into ◽  
Good Agreement

Abstract A generally applicable, computer-aided procedure has been developed for the dynamic analysis of roller chain drives. This approach addresses important factors of chain dynamic behavior such as impact, discontinuities in span length, chain elasticity, coupling between longitudinal and transverse motions, as well as coupling between motion and boundary conditions. The procedure has been used to study various chain configurations. The results show good agreement with experimental observations and indicate some general trends, which provide additional insight into the dynamic behavior of these systems.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

Dynamic analysis of a helical gear reduction by experimental and numerical methods

2020 ◽  
Vol 68 (1) ◽  
pp. 48-58
Author(s):  
Chao Liu ◽  
Zongde Fang ◽  
Fang Guo ◽  
Long Xiang ◽  
Yabin Guan ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Fourth Order ◽  
Numerical Models ◽  
Helical Gear ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Lumped Mass ◽  
Gear Mesh

Presented in this study is investigation of dynamic behavior of a helical gear reduction by experimental and numerical methods. A closed-loop test rig is designed to measure vibrations of the example system, and the basic principle as well as relevant signal processing method is introduced. A hybrid user-defined element model is established to predict relative vibration acceleration at the gear mesh in a direction normal to contact surfaces. The other two numerical models are also constructed by lumped mass method and contact FEM to compare with the previous model in terms of dynamic responses of the system. First, the experiment data demonstrate that the loaded transmission error calculated by LTCA method is generally acceptable and that the assumption ignoring the tooth backlash is valid under the conditions of large loads. Second, under the common operating conditions, the system vibrations obtained by the experimental and numerical methods primarily occur at the first fourth-order meshing frequencies and that the maximum vibration amplitude, for each method, appears on the fourth-order meshing frequency. Moreover, root-mean-square (RMS) value of the acceleration increases with the increasing loads. Finally, according to the comparison of the simulation results, the variation tendencies of the RMS value along with input rotational speed agree well and that the frequencies where the resonances occur keep coincident generally. With summaries of merit and demerit, application of each numerical method is suggested for dynamic analysis of cylindrical gear system, which aids designers for desirable dynamic behavior of the system and better solutions to engineering problems.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

scholarly journals Full-dimensional quantum stereodynamics of the non-adiabatic quenching of OH(A2Σ+) by H2

2021 ◽  
Author(s):  
Bin Zhao ◽  
Shanyu Han ◽  
Christopher L. Malbon ◽  
Uwe Manthe ◽  
David. R. Yarkony ◽  
...  
Keyword(s):  
Quantum Dynamics ◽  
Previous Analysis ◽  
Branching Ratio ◽  
Energy Matrix ◽  
Elastic Channel ◽  
Electronically Excited ◽  
Oppenheimer Approximation ◽  
Electronic Motion ◽  
Adiabatic Dynamics ◽  
Good Agreement

AbstractThe Born–Oppenheimer approximation, assuming separable nuclear and electronic motion, is widely adopted for characterizing chemical reactions in a single electronic state. However, the breakdown of the Born–Oppenheimer approximation is omnipresent in chemistry, and a detailed understanding of the non-adiabatic dynamics is still incomplete. Here we investigate the non-adiabatic quenching of electronically excited OH(A2Σ+) molecules by H2 molecules using full-dimensional quantum dynamics calculations for zero total nuclear angular momentum using a high-quality diabatic-potential-energy matrix. Good agreement with experimental observations is found for the OH(X2Π) ro-vibrational distribution, and the non-adiabatic dynamics are shown to be controlled by stereodynamics, namely the relative orientation of the two reactants. The uncovering of a major (in)elastic channel, neglected in a previous analysis but confirmed by a recent experiment, resolves a long-standing experiment–theory disagreement concerning the branching ratio of the two electronic quenching channels.

scholarly journals Comparison of Experimental and Numerical Transient Drop Deformation during Transition through Orifices in High-Pressure Homogenizers

2021 ◽  
Vol 5 (3) ◽  
pp. 32
Author(s):  
Benedikt Mutsch ◽  
Peter Walzel ◽  
Christian J. Kähler
Keyword(s):  
High Pressure ◽  
Visual Analysis ◽  
Imaging Technique ◽  
Extensional Flow ◽  
Droplet Breakup ◽  
Experimental Results ◽  
Drop Deformation ◽  
Droplet Deformation ◽  
Shadow Imaging ◽  
Good Agreement

The droplet deformation in dispersing units of high-pressure homogenizers (HPH) is examined experimentally and numerically. Due to the small size of common homogenizer nozzles, the visual analysis of the transient droplet generation is usually not possible. Therefore, a scaled setup was used. The droplet deformation was determined quantitatively by using a shadow imaging technique. It is shown that the influence of transient stresses on the droplets caused by laminar extensional flow upstream the orifice is highly relevant for the droplet breakup behind the nozzle. Classical approaches based on an equilibrium assumption on the other side are not adequate to explain the observed droplet distributions. Based on the experimental results, a relationship from the literature with numerical simulations adopting different models are used to determine the transient droplet deformation during transition through orifices. It is shown that numerical and experimental results are in fairly good agreement at limited settings. It can be concluded that a scaled apparatus is well suited to estimate the transient droplet formation up to the outlet of the orifice.

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