Measuring and testing – Vibration – Mechanical impedance
Patent
1990-04-12
1992-01-21
Snow, Walter E.
Measuring and testing
Vibration
Mechanical impedance
G01H 100, G01M 700, G01N 2900
Patent
active
050818708
ABSTRACT:
A method and apparatus is provided for dynamic mechanical measurements of materials in which a plurality of coplanar coils are disposed transversely with respect to a magnetic flux field. The coils are rigidly mounted to a plate and arranged so as to eliminate inductive coupling between the coils. Alternating current is passed through some of the coils so as to vibrate or oscillate the plate because of the alternating force resulting from the interaction of the electrical current and the magnetic field. Other of the coils have an alternating motional electromotive force (voltage) generated in them because of their vibration. The mechanical impedance of the plate is determined from the vector ratio of the vibration forcing current to the velocity sensing voltage. When the plate is connected to the material to be tested in vibration, measurements of the vector ratio of electrical current to motional voltage then provide determinations of dynamic mechanical properties at vibration frequencies from 0.1 to 100,000 Hz.
REFERENCES:
patent: 2774239 (1956-12-01), Fitzgerald
patent: 3830099 (1974-08-01), Ichihawa
Automated Measurement System for Dynamic Mechanical Properties of Viscoelastic Materials, Polymer Bulletin, 18, 1, 167-174 (1987), Edwin R. Fitzgerald and Roger E. Fitzgerald.
Method for Determining the Dynamic Mechanical Behavior of Gels and Solids at Audio Frequencies, J. Colloid Sci. 8, 1, 1-34 (1953) Fitzgerald, Ferry.
Temperature Magnitude Superposition of the Dynamic Mechanical Response of Tire Stocks, Polymer Bulletin, 8, 339-346, 1982, Fitzgerald and Ferry.
Audio-Frequency Mechanical Spectra of a Butadiene Terpolymer, J. Appl. Polymer Sci. 19, 2015-2031, 1975, Edwin R. Fitzgerald.
Viscoelastic Response of Intervertebral Disks at Audiofrequencies, Med. and Biol. Engr. 9, 459-478, 1970, Edwin Fitzgerald and Alan Freeland.
Dynamic Mechanical Properties of Stretched Natural Rubber, J. Accoust. Soc. Am. 33, 10, 1305-1314, 1961, Edwin Fitzgerald.
Yield Strength of Crystalline Solids from Dynamic Mechanical Measurements Developments in Mechanics, 1, pp. 10-38, 1961, Edwin Fitzgerald.
Dynamic Mechanical Measurements on Portland Cement Pastes During Setting and Curing, Materials Science and Engr. 7, 318-334, 1971, Edwin Fitzgerald.
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