NOVEL HIGH-RESOLUTION INTERFEROMETRIC MATERIALS TESTING DEVICE FOR THE DETERMINATION OF THE VISCOELASTIC BEHAVIOUR OF HIGH-TECH PLASTICS

Michael Kühnel, Falko Hilbrunner, Gerd Jäger

Abstract

The use of high-tech plastics in the field of mechanical engineering is increasing dramatically. The time-dependent change of strain <i>&epsilon;</i>(<i>t</i>) during constant load (viscoelasticity, creeping) is a fundamental property of plastics and exact knowledge of these properties is required for the design of plastic parts. A novel high-resolution materials testing device is presented in this paper. It offers reaction-free interferometric measurement of the viscoelastic behaviour of plastics at a constant bending load. The resolution of the deflection is 1 nm.<br />Therefore, unlike the three point bending test described in the ISO 899-2:2003 standard, the device is suitable for the measurement of viscoelasticity <i>&epsilon;</i>(<i>t</i>) at very small strain values (<i>&epsilon;</i>_max &lt; 0.1 %) and after a very short loading time (<i>t</i> &lt; 1 d).<br />A detailed description of the device and the parameters is shown as well as measurements of the time-dependent strain <i>&epsilon;</i>(<i>t</i>) of a high-tech plastic. Very good reproducibility of the measurements was achieved, which makes the device very suitable for measuring viscoelastic behaviour.

Keywords

plastic, viscoelasticity, creep

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IMEKO-WC-2009-TC3-212.pdf

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IMEKO TC

TC3 - Measurement of Force, Mass, Torque, and Gravity

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