Optimization of Damping Configurations in a Plate Embedded with ABH Array

Owing to its broadband and lightweight features, the Acoustic Black Hole (ABH) effect has attracted increasing interests in the structural dynamics and vibration-acoustic communities in recent years. And damping material is essential to achieve effective ABH phenomena. To explore effective vibration and noise control in thin-walled structures such as vehicle body panel using ABH effect, aiming at the plate embedded with two-dimensional ABH array, this paper investigates the coupling between ABH structure and damping material. First, the energy dissipation mechanism of viscoelastic damping material is analyzed to obtain the deformation characteristic that leads to effective energy dissipation. Next, the bending deflection of a plate with a single ABH under harmonic excitation is investigated, and the damping material configuration is optimized to obtain an optimal vibration suppression. Finally, the above-mentioned configuration is applied to a plate embedded with the ABH array and compared with the conventional damping arranging method. And the advantages of this damping material configuration scheme in vibration and noise control are investigated and summarized. This paper provides a reference for the damping material configuration and optimization of the thin plates embedded with ABHs.

Variable-Order Fractional Dynamic Behavior of Viscoelastic Damping Material

Viscoelastic damping material has been widely used in engineering machinery to absorb vibration and noise. In engineering, the dynamic behavior of the viscoelastic material is mainly affected by temperature and frequency. Classical dynamic behavior equations of the viscoelastic damping material have complex structures with multiple and ambiguous parameters. So a novel variable-order fractional constitutive model (VOFC) is established based on the variable-order fractional operator. Then the viscoelastic dynamic equations are derived by the Laplace transform of the VOFC model. The DMA test by the three-point bending mode is carried out at variable temperatures and frequencies and the frequency spectrum of the dynamic behaviors, i.e., the loss modulus, the storage modulus and the loss factor are obtained. Against the test data ,the VOFC model is compared with classical models such as the integer-order Maxwell model (IOM), the constant fractional-order Kelvin-Voigt model (CFK), the constant fractional-order Maxwell model (CFM) and the constant fractional-order standard linear solid model (CFS). Through the comparison , it can be found that the VOFC model can describe dynamic behaviors of the viscoelastic damping material at different temperatures and frequencies more accurately. Furthermore, the VOFC model has simpler structure and only two parameters with clearly-physical meanings.

Experimental investigation of the dissipation characteristic of sandwich structures with periodically perforated viscoelastic damping material core

Wave energy can be dissipated gradually when it is propagated in viscoelastic damping material (VDM) composite structures. In this paper, after the specimens with different opening ratios (ORs) of VDM layer are prepared, the elastic wave energy propagation and dissipation characteristic of periodically perforated VDM cored sandwich structures are investigated by an experimental method. The sandwich structures are discretized into several testing points in our experiment. When the complex velocity, equivalent effective mass, and external excitation forces have been obtained at each testing point by sensors, the energy dissipation in the sandwich structure is determined based on the energy dissipation mechanism of wave transmission in solid. The experimental results are then compared with theoretical and numerical simulation results. By analyzing the computational accuracy of theoretical and numerical results using experimental data, it is shown that high consistency between theoretical, numerical, and experimental results can be achieved, especially in the medium-frequency and high-frequency ranges. Thus, our experimental results demonstrate that periodically perforated VDM sandwich structures can be applied to engineering practice for their good performance of dissipation characteristics in the middle-frequency and high-frequency ranges.

Synthesis and Characterization of Novel Styrene-Butadiene Damping Rubber with Tunable Glass Transition Temperature and Excellent Dynamic Properties

A new type of viscoelastic vibration damping rubber matrix, styrene-butadiene block copolymer with designed molecular weight, unit sequence, mass ratio of styrene/butadiene and content of bound styrene synthesized through anionic solution polymerization method with more excellent damping properties than the current commercialized SBR is exhibited. In addition, the glass transition temperature (Tg) of the new type of SBR can be tunable to the suitable temperature region according to the application requirements. In this paper, we put the emphasis on the synthesis and properties characterization of this new type material, and try to provide a new method to fabricate a viscoelastic damping material (VDM) with tunable Tg and excellent dynamic mechanical properties usable for applications in the field of vibration reduction industry.