Measurement of the flexural damping capacity and dynamic Young's modulus of metals and reinforced plastics

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Abstract
An apparatus is described which is suitable for measuring the flexural damping and dynamic Young's modulus of beam specimens at stress levels up to 200 MN m−2. Symmetric free-free flexural modes of vibration are excited by a coil/magnet pair, the coil being attached to the midpoint of the beam. Extraneous sources of damping have been reduced to a low level despite the difficulties of producing high-amplitude vibration. Low-damping specimens must be tested in vacuo (05 Torr was usually sufficient) if the effects of air damping are not to be significant. Specific damping capacities from 01 to 50% can be accurately measured over a frequency range of 100 to 800 Hz and a temperature range -50 to +200°C.