Experimental and numerical characterisation of fibre‐metal‐elastomer laminates by using DMA regarding its damping behaviour

Abstract

Hybrid carbon fibre-elastomer-metal laminates consist of alternating layers of carbon fibre reinforced plastics, elastomer layers and aluminium sheets. These laminates offer great potential for a lightweight structural material with adjustable damping properties. The material damping is strongly influenced by the viscoelastic properties of the elastomer layers which damp by the principle of constrained layer damping when the laminate is vibrated. In this study the material damping was experimentally characterised by three point bending dynamic mechanical analysis (DMA). In this regard, HyCEML specimens were tested on different frequencies and temperatures. The loss factor, storage-and loss modulus were measured to characterise the damping over the temperature and the frequency range. Time-temperature superposition was applied to determine the damping characteristics at higher and lower frequencies. The experimental results were compared to numerical studies on the basis of a characterisation of the single constituents. A test setup with a cantilever beam under free vibration was chosen for the comparison of experimental and numerical results. Detailed multi-layer finite element models were generated offering high flexibility in terms of type and number of finite elements especially in the direction of laminate thickness. For this purpose, existing material models were used to investigate the influence of each component on the system's damping behaviour. The damping in the free vibration experiments was determined with the logarithmic decrement at the free end. Also the numerically and experimentally determined first eigenfrequencies were compared. It could be shown that the laminate damping is strongly dependent on the glass transitions of both the carbon-fibre reinforced plastics and the elastomers. The numerically determined first eigenfrequency matched the experimental with a deviation of 10 %, the logarithmic decrement of the experimental results was more than 50 % higher. The damping behaviour of the HyCEM laminate, however, is underestimated by the numerical investigation, since nonlinear viscoelastic effects are not yet considered.

Temperature Dependency of the Deformation Behavior of Hybrid CFRP/Elastomer/Metal Laminates under 3-Point Bending Loads

“…Since an excessive characterization of the individual materials would go beyond the scope of this study, results published by the authors on the deformation behavior at room temperature [8] and the temperature-and frequency-dependent material behavior of the elastomer are used to discuss the results [9].…”

On the Influence of Low-Velocity Impact Damage on Constrained-Layer Damping in Hybrid Cfrp-Elastomer-Metal Laminates

“…This study presents a thorough investigation on the influence of impact damage on CLD in HyCEMLs with a differentiation of type and extent of damage, which makes the results presented here a novelty within research on FMELs. In contrast to previous works on HyCEMLs investigating its damping behavior [40,21] or impact resistance [10], this paper's focus lies on the materials' tolerance to damage with regard to its damping capabilities. Different laminate layups and choices of viscoelastic material for the damping plies are investigated.…”

Application of a mixed variational higher order plate theory towards understanding the deformation behavior of hybrid laminates

“…The introduction of a highly viscoelastic layer in the interface can significantly damp these vibrations by means of constrained layer damping. The application of this mechanism to hybrid CFRP elastomer metal laminates (HyCEMLs) has previously been investigated by Liebig et al [1] and Sessner et al [2,3]. However, in order to accurately depict the damping behavior of more complex structures on component level, quantitative knowledge of the stress and strain states in the elastomeric damping layer is necessary.…”