High damping and nonlinear vibration of sandwich beams with entangled cross-linked fibres as core material

Abstract

This article investigates the use of a recently developed fibrous core material to increase vibration damping in sandwich beams. The entangled cross-linked fibre (ECF) material is made of short carbon fibres cross-linked with epoxy resin. Dry friction between fibres provides energy dissipation when the material is deformed. Previous measurements on the material are post-processed to provide a simplified viscoelastic description of the material, for an easier interpretation of subsequent structural testings. Two sandwich beams are compared with reference honeycomb beams: a sandwich beam with an ECF core, and a hybrid beam with a honeycomb core and an ECF insert. Steady-state tests are performed on both types of beams to obtain their frequency responses for different excitation levels, and the corresponding apparent loss factors are computed. The beam with a full ECF core shows an apparent loss factor more than ten times higher than the reference honeycomb beam. The hybrid sandwich beam provides an apparent loss factor four times higher than the reference honeycomb beam. All beams exhibit nonlinear softening responses consistent with a dry friction phenomenon in the material: the resonance frequencies decrease with increasing excitation amplitude, and damping increases then decreases again at very high amplitudes while remaining largely superior to that of the honeycomb beams. Transient impact testings are also presented for a qualitative comparison of the ECF and reference beams, and the ECF beams lead to shorter decay times compared to the reference beams.

Improving damping capabilities of composites structures by electroactive films containing piezoelectric and conductive fillers

“…Both structures, the sandwich beams and panels containing the nanocomposite, were poled under an electric field above the glass transition temperature of the polymer matrix but below the Curie temperature of particles for 1 min. More details about the poling process used for filled polymers are described by Capsal et al [31,33]. Composite panels were polled by corona effect.…”

Damping contribution of the glass reinforced aluminum laminates epoxy to the aluminum based-sandwich structures

“…On the other hand, use of fiber reinforced polymer matrix composites is a good option for relatively higher damping, being used as face sheets in the constructions of the sandwich structures. [5][6][7] Unfortunately, these materials too are not exempt from some disadvantages such as being prone to deterring in high temperature and humidity environments, to fragile behavior resulting in cracks, 8,9 delamination, 10,11 and debonding. 12,13 In order to overcome the relevant disadvantages of these materials (aluminum and polymer composites), a concept of hybrid material system has been proposed; Fiber Metal Laminates (FML) interlacing fiber reinforced polymer (FRP) and metal sheets were initially designed for the aerospace industry.…”

Static and dynamic characteristics of nano-reinforced 3D-fiber metal laminates using non-destructive techniques

“…A notable example would be the approach adopted by Berthelot [6,30], Piollet et al. [31], and Fotsing et al. [32,33], who investigated the effect of entangled cross-linked fibers and interleaved viscoelastic layers (as inherently damped materials) in damping the vibration response of laminate and sandwich composites.…”