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Instrument for Measuring Dynamic Viscoelastic Properties.

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Patent, Filed 28 Jul 80, patented 5 Oct 82,

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In the present invention there is provided a method and apparatus for measuring the dynamic material constants for rubber compounds. A rubber compound such as nitrile, neoprene or polyurethane is tested to determine the Youngs modulus and loss factor. One end of the strip is attached to an electromechanical shaker while the opposite end of the strip is suspended under constant tension. The electromechanical shaker propagates an acoustic wave in the test strip and a piezoelectric transducer positioned at a first point on the strip measures the mechanical response of the strip for relative phase and amplitude. The shaker is programmed to step piecewise over the frequency range from 100Hz to 40KHz a frequency synthesizer. The source signal from the synthesizer is prefiltered, to provide a constant output level at the network analyzer, and then amplified by a 20-W power amplifier. The signal from the piezoelectric transducer is amplified and routed to the network analyzer which measures and digitizes the phase angle and amplitude difference between the synthesizer and the transducer. A programmable calculator controls the frequency sweep of the frequency synthesizer and collects and stores the data obtained by the transducer at the first point strip. After the data is accumulated at the first point, the shaker is adjusted relative to the transducer so as to position the transducer at a second point on the strip where a second set of data is obtained over the frequency range. The data obtained at the first and second points is used to calculate the Youngs modulus and loss factor at a given frequency for the strip tested.

Subject Categories:

  • Adhesives, Seals and Binders

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