Viscoelastic granular dampers under low-amplitude vibration

Abstract

This paper considers dampers comprising collections of viscoelastic particles that are subjected to vibrations whose amplitude is such that slip between particles is negligible. Energy dissipation occurs primarily by viscoelastic processes within each particle and is maximised when standing waves are set up in the granular medium. In this work, the medium is represented as an equivalent viscoelastic solid and predictions of performance employ models constructed using standard finite element software. Two numerical approaches are considered: one uses the Direct Frequency Response and the other uses standard modal analysis in conjunction with analytical expressions for energy dissipation based on the wave equation. The performance of these prediction techniques is compared with measured behaviour from experiments on a box-shaped structure and a hollow composite tube assembly. The computational efficiency of the modal technique allowed a brief investigation of the effects of uncertainties in the actual nature of the granular arrangement. Results show that both prediction methods give a reasonable level of accuracy. Differences between predicted and measured behaviour are shown to be of the same order as the uncertainty in the prediction itself. For the systems considered, it is shown that the methods are appropriate for acceleration amplitudes up to almost that of gravity.

Viscoelasticity of new generation thermoplastic polyurethane vibration isolators

“…A sketch of such Granular damping element (GDE) is shown Fig.1, whereas Fig.2 schematically presents its working principle. Described GDE elements differ from the similar elements, devices and patents 30-33 that use sand 34,35 , granulated polymers [36][37][38][39] or metals [40][41][42][43][44][45] for enhanced damping, since in our case enhanced damping is not only the result of friction between particles but also result of changed material properties.…”

Particle impact dampers: Past, present, and future

“…This type of variant mainly includes the buffered impact damper, [61] the fine particle impact damper, [62] the polymeric particle damper, [63,64] the elastomer particle damper, [65] the soft hollow particle damper, [66] the metal swarf damper, [67] and the metallic wires particle damper. [68][69][70] Li et al [61] covered the inner wall of the particle damper with thin rubber material, which formed the buffered impact damper.…”

“…The material improved type improves the materials of particles and cavities by employing novel materials or using traditional materials skillfully, in order to reduce noise levels, impact forces, and increase plastic deformation, thus increasing the energy absorption. This type of variant mainly includes the buffered impact damper, the fine particle impact damper, the polymeric particle damper, the elastomer particle damper, the soft hollow particle damper, the metal swarf damper, and the metallic wires particle damper . Li et al covered the inner wall of the particle damper with thin rubber material, which formed the buffered impact damper.…”

Design of micro-vibration isolation system for a remote-sensing satellite payload using viscoelastic materials

“…Viscoelastic (VE) dampers are among the earliest types of passive control devices that have been effectively utilized to solve dynamic problems in many fields, including space applications. Thanks to their advantages of simple construction, easy manufacturing process, low cost and excellent energy dissipation capacity, viscoelastic micro-vibration dampers have been developed to attenuate micro-vibrations (Darabi et al, 2016;Rao, 2003;Soong & Spencer, 2002;Xu et al, 2016). Sorbothane is a viscoelastic polymer (polyurethane) that has low transmissibility verifying a high damping coefficient over a very wide temperature range compared to any other polymer (Sorbothane, 2015a).…”