Compression and frequency dependence of the viscoelastic shear properties of flexible open-cell foams

The shear dynamic mechanical behaviour of selected melamine resin and polyurethane open-cell foam materials in a broad range of static uniaxial compression up to almost full material densification was investigated. In situ computed tomography (CT) and stereo light microscopy images were qualitatively analysed to study the foam deformation kinematics. Using a rotational rheometer, storage and loss shear moduli were measured at different temperatures and the results were then transformed to an extended frequency range of up to 104 Hz using the frequency-temperature superposition. A different and in some cases strong dependence of storage and loss shear moduli upon frequency and compression was found. As a potential possibility of using the results, a novel idea of the so called Compressible Constrained Layer Damping (CCLD) as an adaptive vibration damping element was briefly presented. The findings could be also relevant for any application of precompressed foam materials under shear dynamic load.