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Title: Eddy-current system for the vibration-testing of blades

Abstract

This invention is an improved system for the vibration-testing of cantilevered non-ferrous articles by inducing eddy currents therein. The principal advantage of the system is that relatively little heat is generated in the article being vibrated. Thus, a more accurate measurement of the fatigue characteristics of the article is obtained. Furthermore, the generation of relatively little heat in the blade permits tests to be conducted in low-pressure atmospheres simulating certain actual processes environments. Heat-generation in the vibrated article is minimized by utilizing eddy currents which are generated by an electromagnet whose magnetic field varies but does not change polarity. The typical winding for the electromagnet is excited with pulsating d.c. That is, the winding is alternately charged by connecting it across a d.c. power supply and then discharged by connecting it across a circuit for receiving current generated in the winding by self-induction. Preferably, the discharge circuit is designed so that the waveform of the discharging current approximates that of the charging current.

Inventors:
 [1]
  1. Chillicothe, OH
Issue Date:
OSTI Identifier:
862838
Patent Number(s):
4026142
Assignee:
United States of America as represented by United States Energy (Washington, DC)
Patent Classifications (CPCs):
G - PHYSICS G01 - MEASURING G01M - TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES
DOE Contract Number:  
E(33-2)-1
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
eddy-current; vibration-testing; blades; improved; cantilevered; non-ferrous; articles; inducing; eddy; currents; therein; principal; advantage; relatively; heat; generated; article; vibrated; accurate; measurement; fatigue; characteristics; obtained; furthermore; generation; blade; permits; tests; conducted; low-pressure; atmospheres; simulating; processes; environments; heat-generation; minimized; utilizing; electromagnet; magnetic; field; varies; change; polarity; typical; winding; excited; pulsating; alternately; charged; connecting; power; supply; discharged; circuit; receiving; current; self-induction; preferably; discharge; designed; waveform; discharging; approximates; charging; eddy current; magnetic field; power supply; eddy currents; accurate measurement; pressure atmosphere; charging current; charge circuit; inducing eddy; accurate measure; currents therein; /73/

Citation Formats

Jacobs, Martin E. Eddy-current system for the vibration-testing of blades. United States: N. p., 1977. Web.
Jacobs, Martin E. Eddy-current system for the vibration-testing of blades. United States.
Jacobs, Martin E. Sat . "Eddy-current system for the vibration-testing of blades". United States. https://www.osti.gov/servlets/purl/862838.
@article{osti_862838,
title = {Eddy-current system for the vibration-testing of blades},
author = {Jacobs, Martin E},
abstractNote = {This invention is an improved system for the vibration-testing of cantilevered non-ferrous articles by inducing eddy currents therein. The principal advantage of the system is that relatively little heat is generated in the article being vibrated. Thus, a more accurate measurement of the fatigue characteristics of the article is obtained. Furthermore, the generation of relatively little heat in the blade permits tests to be conducted in low-pressure atmospheres simulating certain actual processes environments. Heat-generation in the vibrated article is minimized by utilizing eddy currents which are generated by an electromagnet whose magnetic field varies but does not change polarity. The typical winding for the electromagnet is excited with pulsating d.c. That is, the winding is alternately charged by connecting it across a d.c. power supply and then discharged by connecting it across a circuit for receiving current generated in the winding by self-induction. Preferably, the discharge circuit is designed so that the waveform of the discharging current approximates that of the charging current.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1977},
month = {1}
}

Patent:

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