scholarly journals Vibration Isolation Review: II. Shock Excitation

1996 ◽  
Vol 3 (6) ◽  
pp. 451-459 ◽  
Author(s):  
F.C. Nelson
Keyword(s):  
Vibration Isolation ◽  
Shock Velocity ◽  
Shock Excitation ◽  
Shock Mitigation ◽  
Flexible Connections

This is the second part of a two part review of shock and vibration isolation. It covers three distinct categories of shock excitation—pulselike shock, velocity shock, and complex shock—and discusses the means that are available in each case to measure the effectiveness of shock mitigation by the imposition of flexible connections between the isolated system and its base.

Optimal Control of Vertically Stroking Crew Seats Employing Magnetorheological Energy Absorbers

2009 ◽  
Author(s):  
Harinder J. Singh ◽  
Young-Tai Choi ◽  
Norman M. Wereley
Keyword(s):  
Optimal Control ◽  
Impact Velocity ◽  
Vibration Isolation ◽  
Viscous Force ◽  
Bingham Number ◽  
Shock Mitigation ◽  
Feasible Range ◽  
Shock Event ◽  
Damper Design ◽  
Energy Absorbers

Nondimensional analyses of vertical stroking crew seats with adaptive nonlinear magnetorheological energy absorbers (MREA) and magnetorheological shock isolation (MRSI) were addressed in this study. Under consideration were single-degree-of-freedom vertically stroking seat systems consisting of a rigid occupant mass falling with prescribed initial impact velocity (sink rate). The governing equations of the vertical stroking crew seats were derived using nondimensional variables such as nondimensional stroke, velocity, acceleration and time constant, as well as nondimensional Bingham number (i.e., the ratio of MR yield force to viscous force). The critical Bingham number was defined as that Bingham number for which the available stroke was fully utilized and the seat reaches zero velocity at the end of stroke. This was done in order to maximize shock mitigation performance. Two cases were studied: (1) the MREA problem, or the case where no spring was employed in the suspension, so that the seat was used for a single shock event, (2) the MRSI problem, or the case where a spring was employed in the suspension, so that after the initial shock event, the suspension could be used for either vibration isolation or mitigation of subsequent shock events. Nondimensional displacement, velocity and acceleration were analyzed for MREA and MRSI vertical stroking crew seats for three different payload masses of 47, 77 and 97 kg corresponding to 5th percentile (%tile) female, 50th %tile and 95th %tile male, respectively, with initial impact velocities of 4, 5 and 6 m/s. An optimal control solution was derived for both the MREA and MRSI cases. The effects of payload mass and initial impact velocity on the optimal responses of the vertical stroking crew seats were analyzed for a feasible range of Bingham number based on a realistically constrained (in diameter and volume) MR damper design.

The Application of State Feedback Control in Double-Stage Vibration Isolation System

2012 ◽  
Vol 152-154 ◽  
pp. 1006-1009
Author(s):  
Shu Yong Liu ◽  
Qing Chao Yang ◽  
Ai Bo Yang ◽  
Liang Deng
Keyword(s):  
State Feedback ◽  
Vibration Isolation ◽  
State Feedback Control ◽  
Acceleration Response ◽  
Maximum Displacement ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Shock Excitation ◽  
Auxiliary Power ◽  
Safety Range

Double-stage vibration isolation system can attenuate structure-born noise in media and high frequency band effectively, which improves the ship’s capability of concealment greatly. At the same time, this vibration control system can decrease the isolated equipment’s acceleration response while subjected to foundation shock excitation effectively. Hence ensure the isolated equipment’s acceleration response in a safety range. But the maximum displacement response of the isolated equipment will increase greatly at the same time. This requires that those flexible connecting components between the equipment and the environment should have great permitted displacement. If an auxiliary power system which can adjust the characteristics of the vibration isolations in the main system according to the vibration state is mounted on the middle mass block, it will output suitable force to attenuate the oscillation quickly to protect both the isolated equipment and the flexible connecting components under shock excitation condition. Simulation results show that this method is effective.

Comparison of TEM and STM observations of small silver clusters on different carbon supports

1990 ◽  
Vol 48 (4) ◽  
pp. 264-265
Author(s):  
Bernd Tesche ◽  
Tobias Schilling
Keyword(s):  
Vibration Isolation ◽  
Pyrolytic Graphite ◽  
Carbon Film ◽  
Silver Clusters ◽  
Carbon Supports ◽  
Stacking Order ◽  
System P ◽  
High Resolution Tem ◽  
High Degree ◽  
Degree Of Order

The objective of our work is to determine:a) whether both of the imaging methods (TEM, STM) yield comparable data andb) which method is better suited for a reliable structure analysis of microclusters smaller than 1.5 nm, where a deviation of the bulk structure is expected.The silver was evaporated in a bell-jar system (p 10−5 pa) and deposited onto a 6 nm thick amorphous carbon film and a freshly cleaved highly oriented pyrolytic graphite (HOPG).The average deposited Ag thickness is 0.1 nm, controlled by a quartz crystal microbalance at a deposition rate of 0.02 nm/sec. The high resolution TEM investigations (100 kV) were executed by a hollow-cone illumination (HCI). For the STM investigations a commercial STM was used. With special vibration isolation we achieved a resolution of 0.06 nm (inserted diffraction image in Fig. 1c). The carbon film shows the remarkable reduction in noise by using HCI (Fig. 1a). The HOPG substrate (Fig. 1b), cleaved in sheets thinner than 30 nm for the TEM investigations, shows the typical arrangement of a nearly perfect stacking order and varying degrees of rotational disorder (i.e. artificial single crystals). The STM image (Fig. 1c) demonstrates the high degree of order in HOPG with atomic resolution.

Vibration isolation of power tool operators

1983 ◽  
Author(s):  
C. W. Suggs ◽  
C. F. Abrams
Keyword(s):  
Vibration Isolation

An hourglass-type electromagnetic isolator with negative resistance electromagnetic shunt circuit

2020 ◽  
Vol 64 (1-4) ◽  
pp. 549-556
Author(s):  
Yajun Luo ◽  
Linwei Ji ◽  
Yahong Zhang ◽  
Minglong Xu ◽  
Xinong Zhang
Keyword(s):  
Vibration Isolation ◽  
Electromechanical Coupling ◽  
Coupling Effect ◽  
Negative Resistance ◽  
Isolation System ◽  
Amplitude Vibration ◽  
Vibration Responses ◽  
The Stability ◽  
Isolation Performance ◽  
Shunt Circuit

The present work proposed an hourglass-type electromagnetic isolator with negative resistance (NR) shunt circuit to achieve the effective suppression of the micro-amplitude vibration response in various advanced instruments and equipment. By innovatively design of combining the displacement amplifier and the NR electromagnetic shunt circuit, the current new type of vibration isolator not only can effectively solve the problem of micro-amplitude vibration control, but also has significant electromechanical coupling effect, to obtain excellent vibration isolation performance. The design of the isolator and motion relationship is presented firstly. The electromechanical coupling dynamic model of the isolator is also given. Moreover, the optimal design of the NR electromagnetic shunt circuit and the stability analysis of the vibration isolation system are carried out. Finally, the simulation results about the transfer function and vibration responses demonstrated that the isolator has a significant isolation performance.

Performance testing for an active/passive vibration isolation and steering system

1996 ◽  
Author(s):  
Jeanne Sullivan ◽  
James Gooding ◽  
Michelle Idle ◽  
Alok Das ◽  
Terance Hoffman ◽  
...  
Keyword(s):  
Vibration Isolation ◽  
Performance Testing ◽  
Steering System ◽  
Passive Vibration Isolation
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