Interfacial Damping Research Articles

Damping capacity of Al–12Si composites effected by negative thermal expansion of Y2W3O12 particle inclusions

Effects of Y2W3O12 particle inclusions and content on damping capacity of Al–12Si composites have been investigated. The Y2W3O12, which is a kind of negative thermal expansion material, can generate high local strain in the composites. Thermal expansion testing shows that the coefficient of thermal expansion (CTE) of Y2W3O12 has obvious changes between 100 and 200 °C The Y2W3O12/Al–12Si composites show damping peaks and display higher damping capacities than the pure Al–12Si alloy. The damping capacities of composites strongly depends on the content of Y2W3O12 inclusions. A thermal strain damping model is also established. Based on the model analysis results, there is a significant contribution of thermal strain to the damping capacity in the composites; the change in CTE of Y2W3O12 could cause the generation of damping peaks. Moreover, dislocation damping and interfacial damping are also main damping mechanisms in the investigated composites.

Characterization of spherical cell porous aluminum alloy-polyurethane interpenetrating phase composites at different temperatures

The characterization, including deformation process, damping mechanisms within the plastic plateau region, damping and stiffness properties, of spherical cell porous aluminum alloy-polyurethane interpenetrating phase composites (SCPAA/PU composites) at different temperatures were investigated. Compressive tests show that seven distinct regions for the composites under the given loading pattern are exhibited. Then, the damping mechanisms for the composites within the plastic plateau region are found to be attributed to the following aspects, including the damping of the matrix and filler phase, the interfacial friction damping between the matrix phase and filler phase, and the macroscopic interface dislocation friction damping along macro-interface in the debonded region. Furthermore, no clear regularity between the loss factor and temperature is observed, while the secant stiffness decreases with the increment of temperature. Both loss factor and secant stiffness declines rapidly in the first few cycles, and reduces slowly until a stable state is achieved. At last, the variation of loss factor/secant stiffness with the number of cycles can be described by a power function model. The proposed model works well with the testing data.

Polyurethane/poly(vinylidene fluoride)/MWCNT composite foam for broadband airborne sound absorption

ABSTRACTA polyurethane/poly(vinylidene fluoride)/multi‐walled carbon nanotubes (PU/PVDF/MWCNT) (83/15/2) composite foam was designed and fabricated. The foam exhibited high airborne sound absorption performance in a wide‐frequency range. The sound absorption coefficient reached the value of 0.85 at 1 kHz, which is a significant improvement over PU foam. It was found that PVDF formed a separate immiscible phase and part of it was crystallized in a polar phase in the PU scaffold in the PU/PVDF/MWCNT composite, which could benefit the sound absorption performance by introducing interfacial damping and local piezoelectric damping effects. The introduction of the conductive MWCNT filament in the composite foam further improved sound absorption, possibly by facilitating the dissipation of the electrical charges generated from local piezoelectric effect and enhancing both the interfacial damping effect and local piezoelectric damping effect. With PU as the main ingredient, the fabrication scalability of the foam can be improved with significantly reduced material and production cost in comparison with PVDF foam. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47868.

Strong interfacial perpendicular anisotropy and interfacial damping in Ni0.8Fe0.2 films adjacent to Ru and SiO2

We report detailed investigations of a strong perpendicular magnetic anisotropy in Ni0.8Fe0.2 thin films originating from interfaces with adjacent Ru and SiO2 layers. The anisotropy is quantified using broadband ferromagnetic resonance measurements for three types of layered heterostructures, namely an asymmetric structure of SiO2/Ni0.8Fe0.2/Ru and symmetric structures of Ru/Ni0.8Fe0.2/Ru and SiO2/Ni0.8Fe0.2/SiO2. The results show a stronger perpendicular anisotropy at the Ni0.8Fe0.2/SiO2 interface than at the Ni0.8Fe0.2/Ru interface and a lower interfacial damping contribution for the Ni0.8Fe0.2/SiO2 interface compared to the Ni0.8Fe0.2/Ru interface.

High temperature damping behavior and dynamic Young's modulus of magnesium matrix composite reinforced by Ti2AlC MAX phase particles

The evolutions with the temperature of damping capacities and dynamic Young's moduli of ternary Ti2AlC particles reinforced AZ91D composites were investigated. This work has highlighted that Ti2AlC significantly contributes to the damping capacity and to dynamic moduli of composites. With increasing temperature, especially above 200 °C, the interfacial damping capacity becomes dominant and dynamic moduli of composites decrease. These trends were revealed from the transformed tensile fracture mechanisms. At room temperature, Ti2AlC particles delaminated without any decohesion between Ti2AlC particles and the Mg matrix. However, the interfacial decohesion occurred above 200 °C. One explanation of this change of decohesion mechanism could be ascribed to the inherent structure of the Ti2AlC MAX phase and to the formation of a robust amorphous magnesium layer at the interface between Ti2AlC and magnesium matrix that was evidenced by HRTEM. This amorphous layer further gives rise a high activation energies (H) of damping peaks for composites, which was calculated to 128 kJ/mol. This value is higher than those calculated for SiC or graphite reinforced AZ91D composites, making Ti2AlC particles particularly interesting for application in reinforcing magnesium composites.

Influence of the thickness of an antiferromagnetic IrMn layer on the static and dynamic magnetization of weakly coupled CoFeB/IrMn/CoFeB trilayers.

The static and dynamic magnetization response of the CoFeB/IrMn/CoFeB trilayer system with varying thickness of the antiferromagnetic (AF) IrMn layer is investigated using magnetization hysteresis (M–H) and ferromagnetic resonance (FMR) measurements. The study shows that the two CoFeB layers are coupled via a long-range dynamic exchange effect through the IrMn layer up to a thickness of 6 nm. It is found that with the increase in IrMn layer thickness a nearly linear enhancement of the effective magnetic damping constant occurs, which is associated with the simultaneous influence of spin pumping and interlayer exchange coupling effects. An extrinsic contribution to the linewidth originating from the two-magnon scattering is also discussed. The AF-induced interfacial damping parameter is derived by studying the evolution of damping with inverse CoFeB thickness. The static magnetic measurements also reveal the interlayer exchange coupling across the IrMn layer both at room temperature and low temperature. The asymmetric hysteresis loop and training effect observed at low temperature is related to the presence of a metastable AF domain state. We show that both the static and dynamic magnetic properties of trilayer films can be adjusted over a wide range by changing the thickness of the IrMn spacer layer.

On the Measurement of Energy Dissipation of Adhered Cells with the Quartz Microbalance with Dissipation Monitoring.

We previously reported the finding of a linear correlation between the change of energy dissipation (Δ D) of adhered cells measured with the quartz crystal microbalance with dissipation monitoring (QCM-D) and the level of focal adhesions of the cells. To account for this correlation, we have developed a theoretical framework for assessing the Δ D-response of adhered cells. We rationalized that the mechanical energy of an oscillating QCM-D sensor coupled with a cell monolayer is dissipated through three main processes: the interfacial friction through the dynamic restructuring (formation and rupture) of cell-extracellular matrix (ECM) bonds, the interfacial viscous damping by the liquid trapped between the QCM-D sensor and the basal membrane of the cell layer, and the intracellular viscous damping through the viscous slip between the cytoplasm and stress fibers as well as among stress fibers themselves. Our modeling study shows that the interfacial viscous damping by the trapped liquid is the primary process for energy dissipation during the early stage of the cell adhesion, whereas the dynamic restructuring of cell-ECM bonds becomes more prevalent during the later stage of the cell adhesion. Our modeling study also establishes a positive linear correlation between the Δ D-response and the level of cell adhesion quantified with the number of cell-ECM bonds, which corroborates our previous experimental finding. This correlation with a wide well-defined linear dynamic range provides a much needed theoretical validation of the dissipation monitoring function of the QCM-D as a powerful quantitative analytical tool for cell study.

Reynolds-averaged modeling of turbulence damping near a large-scale interface in two-phase flow

The two-fluid Euler-Euler model can be used for the description of co-existing stratified and dispersed multiphase flow within one flow domain. For realistic engineering applications, turbulence is often modeled in the Reynolds-averaged Navier-Stokes (RANS) framework where closure of the Reynolds stresses is mostly achieved using the turbulent viscosity formulation. It is a well-known problem that at large-scale interfaces between two phases such turbulence modeling breaks down as turbulent viscosity in the vicinity of an interface is over-predicted. To address this issue, we adopt the Egorov approach (Egorov et al., 2014) which locally damps turbulence near the interface. This model is based upon the idea that at a large-scale interface the lighter phase may see the heavier phase much like a solid wall, suggesting a wall-like treatment of turbulent dissipation at the interface. The implementation of the model inside a two-phase formulation of the k–ω model is discussed, and shown to give good predictions of interfacial turbulence in co-current stratified two-phase flow. The Egorov approach is extended to the k–ε model, which may be relevant for a large array of engineering applications in which the k–ε model is more effective than the k-ω model. It is shown that the non-dimensional Egorov approach coefficient is grid dependent. We introduce a new formulation of the interfacial damping term in the two-fluid Euler-Euler model which gives more consistent results for different computational grids in comparison to the original formulation of the Egorov approach. This feature, as well as its straightforward implementation in both the k–ω and k–ε models, make the new model useful to a large array of multiphase engineering problems in which interfacial turbulence damping is relevant.

Microstructure and properties of SiC/Gr composite reinforced aluminum matrix composites material

SiC/Gr/ZL101 aluminum-based composites were prepared by semi-solid stirring and gravity pouring method. The effects of SiC/Gr with different volume fractions on the microstructure and property of aluminum-based composites were studied by means of microstructure observation, tensile test, fracture scanning analysis and damping capacity test. The results show that the primary phase α-Al of ZL101 alloy prepared by semi-solid stirring and gravity pouring method is fragmented dendrite, along with the rising SiC volume fractions, the tensile strength of the composites first increases and then decreases while its elongation gradually decreases, the maximum tensile strength of the material can reach 168 MPa, up to 16% than that of ZL101 alloy, the fracture morphology is obviously brittle fracture. They also show that the addition of SiC and Gr improves the damping capacity of ZL101 alloy, the internal dissipation Q-1 of the composites is obviously higher than that of matrix alloy and gradually increases along with the rising SiC volume fractions. The damping mechanism of the composites is mainly the combined effects of both dislocation damping and interfacial damping.

Normal Damping Model of Mechanical Joints Interfaces Considering Asperities in Lateral Contact

A mechanical interface behaves as the stiffness and damping when the interface is bearing a static normal force and a sine normal exciting force. For the interfacial normal damping, a calculating model was proposed. This proposed model studied the lateral contact (shoulder–shoulder contact) between upper and lower asperities in the elastic and elastic-perfectly plastic stages, which is neglected by other classical models. The normal force can be divided into a normal component and a tangential component when two asperities are contacting in dislocation. The relation between the loading–unloading normal component forces and deformation can be calculated, and then the strain energy dissipation between asperities can be gotten by integral. The friction energy dissipation also can be calculated based on the relation between loading–unloading tangential component forces and the slippage. Furthermore, the total interfacial energy dissipation can be obtained according to the statistical theory. Finally, the equivalent viscous damping is estimated using the vibration theory. The proposed model and classical models are compared by simulation and experiment, and it was found that the interfacial damping of the proposed model is more than the damping of the classical models. Moreover, the proposed model is consistent with the experimental results.

Experimental Investigation of Energy Dissipation in Presliding Spherical Contacts Under Varying Normal and Tangential Loads

Interfacial damping in assembled structures is difficult to predict and control since it depends on numerous system parameters such as elastic mismatch, roughness, contact geometry, and loading profiles. Most recently, phase difference between normal and tangential force oscillations has been shown to have a significant effect on interfacial damping. In this study, we conduct microscale (asperity-scale) experiments to investigate the influence of magnitude and phase difference of normal and tangential force oscillations on the energy dissipation in presliding spherical contacts. Our results show that energy dissipation increases with increasing normal preload fluctuations and phase difference. This increase is more prominent for higher tangential force fluctuations, thanks to larger frictional slip along the contact interface. We also show that the energy dissipation and tangential fluctuations are related through a power law. The power exponents we identify from the experiments reveal that contacts deliver a nonlinear damping for all normal preload fluctuation amplitudes and phase differences investigated. This is in line with the damping uncertainties and nonlinearities observed in structural dynamics community.

Magnetic properties in ultrathin 3d transition-metal binary alloys. II. Experimental verification of quantitative theories of damping and spin pumping

A systematic experimental study of Gilbert damping is performed via ferromagnetic resonance for the disordered crystalline binary 3d transition metal alloys Ni-Co, Ni-Fe and Co-Fe over the full range of alloy compositions. After accounting for inhomogeneous linewidth broadening, the damping shows clear evidence of both interfacial damping enhancement (by spin pumping) and radiative damping. We quantify these two extrinsic contributions and thereby determine the intrinsic damping. The comparison of the intrinsic damping to multiple theoretical calculations yields good qualitative and quantitative agreement in most cases. Furthermore, the values of the damping obtained in this study are in good agreement with a wide range of published experimental and theoretical values. Additionally, we find a compositional dependence of the spin mixing conductance.

Modelling of the interfacial damping due to nanotube agglomerations in nanocomposites

Nanocomposites reinforced with carbon nanotube fibers exhibit greater stiffness, strength and damping properties in comparison to conventional composites reinforced with carbon/glass fibers. Consequently, most of the nanocomposite research is focused in understanding the dynamic characteristics, which are highly useful in applications such as vibration control and energy harvesting. It has been observed that those nanocomposites show better stiffness when the geometry of nanotubes is straight as compared to curvilinear although nanotube agglomeration may exist. In this work the damping behavior of the nanocomposite is characterized in terms of loss factor under the presence of nanotube agglomerations. A micro stick-slip damping model is used to compute the damping properties of the nanocomposites with multiwall carbon nanotubes. The present formulation considers the slippage between the interface of the matrix and the nanotubes as well as the slippage between the interlayers in the nanotubes. The nanotube agglomerations model is also presented. Results are computed based on the loss factor expressed in terms of strain amplitude and nanotube agglomerations. The results show that although-among the various factors such as the material properties (moduli of nanotubes and polymer matrix) and the geometric properties (number of nanotubes, volume fraction of nanotubes, and critical interfacial shear stresses), the agglomeration of nanotubes significantly influences the damping properties of the nanocomposites. Therefore the full potential of nanocomposites to be used for damping applications needs to be analyzed under the influence of nanotube agglomerations.

Electron Energy Loss Spectroscopy of Hot Electron Transport between Gold Nanoantennas and Molybdenum Disulfide by Plasmon Excitation

Hot electron transport from single gold nanoantennas to underlying monolayer molybdenum disulfide (MoS2) is examined using electron energy loss spectroscopy (EELS). EELS allows nanometer‐scale resolution and avoids confounding effects of optical excitation. Experimental EELS measures of plasmon bandwidth in the presence and absence of MoS2 are compared with calculated bandwidth contributions from radiative, nonradiative, and interfacial damping. Transport of plasmon hot electrons from 80 nm gold nanospheres to underlying MoS2 is estimated. A 6 ± 1% hot electron transport quantum efficiency is inferred from a measured 0.08 eV increase in plasmon damping in the presence of MoS2. Hot electron transport can contribute to reported enhancements in catalysis and photodetection of MoS2 decorated with gold nanoantennas. Improved understanding of resonant electric interactions between noble metal nanoantennas and transition metal dichalcogenides can benefit emerging optoelectronics.

Theoretical study of interfacial damping in perpendicular anisotropy superlattices along multiple crystal orientations

Damping, representing the loss of magnetic energy from the electrons to the lattice through the spin-orbit interaction, is calculated for Co/Pt and Co/Pd superlattices grown along the (001), (111), and (011) orientations. The damping consists of two contributions: interfacial and, usually, bulk. The interfacial damping shows dependence on the superlattice orientation. The origin of the interfacial damping is due to both the distorted electronic states at the interface and the spin-orbit interaction in the weakly polarized nonmagnetic Pt/Pd layers deposited on Co layers. The density of states around the Fermi level provides the spin-flip channels and closely correlates with the damping value. The damping shows asymmetry in the two transverse directions of the spin for spins at most angles. The damping for out-of-plane magnetization can be as much as 1.7 times larger than that of in-plane magnetization.

Effect of interface type on the static and dynamic mechanical properties of 3D braided SiCf/SiC composites

The static and dynamic mechanical properties of three dimensional (3D) braided SiCf/SiC composites with pycrocarbon (PyC) and SiC and without an interphase layer prepared by polymer infiltration and pyrolysis (PIP), were investigated using static and dynamic bending tests as well as microstructural characterization. Test results indicated that the interfacial shear stress, flexural strength, elastic modulus, and storage modulus of 3D braided SiCf/SiC composites with an interphase layer were superior to those the composites without an interlayer; the former also showed a lower internal friction than the latter. Results from Weibull statistical analysis also indicated that the scale parameter σ0 (337.1MPa and 630.6MPa, respectively) and Weibull modulus m (16.85 and 19.91, respectively) of 3D braided SiCf/SiC composites with SiC and PyC interphase were higher than those of composites without an interphase (103.2MPa, 14.02). The composite with the PyC interphase presented the highest flexural strength and the most ductile fractures because it featured relatively ideal interfacial bonding and a layered interphase structure, leading to effective energy-dissipation mechanisms, such as fiber pull-out. The composite with the SiC interphase exhibited highest elastic and dynamic moduli because of strong interfacial bonding and a non-layered rough interphase structure, which enhanced its ability to resist strain. The ideal interface improves load transfer and did not contribute to damping. The occurrence of interfacial damping in the 3D braided SiCf/SiC caused the internal friction to become more sensitive to temperature, frequency and amplitude. The static and dynamic mechanical properties, including internal friction and storage modulus, as well as failure behavior of the 3D braided composites were remarkably affected by the interface type.

A new analytical model for vibration of a cylindrical shell and cardboard liner with focus on interfacial distributed damping

This paper proposes a new analytical model for a thin cylindrical shell that utilizes a homogeneous cardboard liner to increase modal damping. Such cardboard liners are frequently used as noise and vibration control devices for cylindrical shell-like structures in automotive drive shafts. However, most prior studies on such lined structures have only investigated the associated damping mechanisms in an empirical manner. Only finite element models and experimental methods have been previously used for characterization, whereas no analytical studies have addressed sliding friction interaction at the shell–liner interface. The proposed theory, as an extension of a prior experimental study, uses the Rayleigh–Ritz method and incorporates material structural damping along with frequency-dependent viscous and Coulomb interfacial damping formulations for the shell–liner interaction. Experimental validation of the proposed model, using a thin cylindrical shell with three different cardboard liner thicknesses, is provided to validate the new model, and to characterize the damping parameters. Finally, the model is used to investigate the effect of the liner and the damping parameters on the modal attenuation of the shell vibration, in particular for the higher-order coupled shell modes.

Carbon nano-ink coated open cell polyurethane foam with micro-architectured multilayer skeleton for damping applications

Carbon nanotube ink coated multilayered polyurethane open cell foams utilize the CNT–CNT interfacial frictional damping mechanism, thus dramatically improving the foam energy dissipation capability by 270%.

Investigation and modelling of damping mechanisms of magnetorheological elastomers

ABSTRACTDamping in MREs is considered to be ascribed to viscous flow of the rubber matrix, interfacial damping at the interface between the magnetic particles and the matrix and magnetism induced damping. In this study, individual components in MREs that contribute to material damping were investigated. A model was developed to include viscous flow of the rubber matrix, interfacial damping and magnetism induced damping to give the total damping capacity of MREs()It was found thatdepends on frequency, iron sand content, strain amplitude andis independent of the applied magnetic field over saturation magnetization. The proposed model was assessed experimentally using a series of isotropic and anisotropic MREs. Comparison between tan δ withshowed thatmatched the experimental trends with average percentage difference of 8.1% and 21.8% for MREs with modified iron sand unmodified iron sand, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43247.

Exponential stability for a structure with interfacial slip and frictional damping

In this work we prove the exponential stability for a laminated beam consisting of two identical layers of uniform density, which is a system closely related to the Timoshenko beam theory, taking into account that an adhesive of small thickness is bonding the two layers and produce the interfacial slip. It is assumed that the thickness of the adhesive bonding the two layers is small enough so that the contribution of its mass to the kinetic energy of the entire beam may be ignored.