Abstract
Using low-modulus foam materials of lower density leads to significantly higher protection of personnel (from noise and harmful vibrations) and structures (from corrosion), while only slightly increasing the weight of an object. But the main intended purpose of such a filler which is capable of actively absorbing the energy of vibrations caused by external dynamic forces is to reduce their number and amplitude. To achieve a similar effect, the building industry and aircraft construction have a long and successful history of utilizing three-layer plates and shells coated with a thin foam material. Theoretical studies, supported by experiments, make one come to the conclusion that volume damping of such elements has quite a low efficiency. The goal of the research was to preliminarily estimate how appropriate it is to use artificial low-modulus elastic materials to damp thin-walled elements of metal structures. It was achieved by running computational experiments in Solid Works software environment and plotting, on the basis of the experiments, vibrograms of damped vibrations of a cantilever beam. The results obtained during the testing showed that the volume damping using a foam material could be an efficient tool for damping free vibrations of a metal structure affected by bending.
Highlights
Dissipation of energy in a material is caused by its elastic imperfections and manifests itself in the formation of a certain hysteresis loop under cyclic strain [1]
Regardless of what causes the energy losses, damping properties of an elastic system are thought to be characterized by a relative dissipation of energy ψ, which is considered in terms of a relation between a dissipated energy ΔW during one cycle of steady-state vibration and an amplitude value of a potential energy W in the elastic system [1,2,3]: ψ = ∆W
An envelope of vibrations is shown for the unfilled beam, allowing to visually demonstrate a damping effect of the foam material
Summary
Dissipation of energy in a material is caused by its elastic imperfections and manifests itself in the formation of a certain hysteresis loop under cyclic strain [1]. The relative energy dissipation ψ, expressed by (1) and often called a coefficient of dissipation or absorption, is utilized to estimate the damping properties of a material. An expression which describes the absorption coefficient ψR of a three-layer coated rod under pure bending is known [2]: ψR = ψ + ψA (2). Where ψ, ψA are absorption coefficients for an uncoated rod and a coating material, V, VA and E, EA are volumes and moduli of elasticity for the rod and coating material. It was noted that the absorption-coefficient correction for a coated rod defined by the second summand depends on the product of ψAEA. Coatings made of low-modulus materials with quite high damping properties often turn out to be inefficient [4,5]
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