Electrodynamic vibration supression

2003 ◽  
Author(s):  
Sam Behrens ◽  
Andrew J. Fleming ◽  
S. O. R. Moheimani
Keyword(s):  
Electrodynamic Vibration

The ESS Muddle: Physics vs. Relics

1995 ◽  
Vol 38 (2) ◽  
pp. 21-26
Author(s):  
Hank Caruso
Keyword(s):  
Environmental Stress ◽  
Military Service ◽  
Development Process ◽  
Thermal Response ◽  
Change Rate ◽  
Current State ◽  
Hardware Development ◽  
Air Change Rate ◽  
Electrodynamic Vibration ◽  
Common Vision

This paper examines the history and evolution of environmental stress screening (ESS) to show how uncoordinated initiatives from each military service contributed to the current state of array in the ESS community. The lack of a common vision for ESS is examined as a continuing handicap in efforts to integrate ESS more fully into the hardware development process. Common areas of confusion regarding effective ESS procedures and facilities are discussed, including: temperature air change rate vs. hardware thermal response; the number of vibration axes needed; simultaneous vibration in combined axes vs. sequential vibration in each; and pneumatic vs. electrodynamic vibration facilities. A "checklist" of considerations to apply in developing a successful ESS program is presented. The June, 1994, DoD initiative regarding possible elimination or replacement of military specifications and standards with commercial standards is reviewed with respect to ESS.

scholarly journals On the Force Drop Off Phenomenon in Shaker Testing in Experimental Modal Analysis

2002 ◽  
Vol 9 (4-5) ◽  
pp. 165-175 ◽  
Author(s):  
Paulo Sergio Varoto ◽  
Leopoldo Pisanelli Rodrigues de Oliveira
Keyword(s):  
Input Signal ◽  
Modal Testing ◽  
Analytical Models ◽  
Vibration Exciter ◽  
Electromechanical Device ◽  
Vibration Tests ◽  
Operational Modes ◽  
Electrodynamic Vibration ◽  
Force Drop

The Electrodynamic Vibration Exciter (shakers) has been one of the most employed excitation sources in modal tests. The shaker is an electromechanical device that provides a mechanical motion due to the input signal sent to its coil. Despite being widely used, it is well known that the shaker interacts with the structure under test. In particular, when the structure passes through a given resonance, the force delivered by the shaker abruptly decreases, causing the so called drop off phenomenon. This paper aims to study this force drop off phenomenon in the single shaker modal testing. Analytical models are developed to help in understanding the physical principles involved in the interaction between the shaker and the structure under test. Experimental analyses are performed using different shakers as well as excitation signals, in order to evaluate the effects of the input signal, as well as the power amplifier operational modes, on the structure dynamics. Preliminary tests revealed that significant distortions might occur during vibration tests using shakers and these distortions significantly affect the determination of the structure response.

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