Viscoelastic Damping Material Research Articles

High strength and high damping CFRP composites with co‐curing viscoelastic sandwich film

AbstractThe high temperature co‐curing damping composite was investigated by co‐curing technology to improve the mechanical property and damping performance of the traditional fiber reinforced resin matrix composite. Fluororubber with stable chemical properties and high‐temperature resistance was used as the core layer of novel carbon fiber reinforced bismaleimide resin matrix High‐temperature Co‐curing Damping Sandwich Composites (HCDSC). The curing temperature and curing time of fluororubber were consistent with that of bismaleimide resin by adjusting the formula. The viscoelastic damping properties and thermal stability of zinc methacrylate reinforced fluororubber were investigated in detail. Static mechanical tests, modal tests and interfacial shear tests prove that HCDSC display excellent mechanical and damping properties. The interfacial microscopic analysis reveals that viscoelastic sandwich materials are closely bonded with the composites. The dynamic characteristics of damping sandwich composite plate with fixed support on four sides is analyzed theoretically, and the vibration equilibrium equation of composite plate is derived by combining first‐order shear deformation theory, variational principle, and Hamilton principle. The damping performance of the composite plate are discussed through modal tests to verify the accuracy of theoretical derivation. This research is of great significance to solve the problem of structural dynamics, and provides a new idea for the design of structural and functional composite materials.Highlights A viscoelastic damping material with large damping and high strength was prepared. The dynamic performance of co‐curing sandwich composite structures was studied. The free vibration of composite structures was explored via experiment and theory.

A generalized mechanical model with high-flexibility of viscoelastic damping materials and devices considering frequency and amplitude dependence effects

Owing to the complex mechanical properties influenced by excitation frequency and amplitude, the modeling of viscoelastic damping materials and devices faces the challenge of poor coordination among simplicity, accuracy, generality and flexibility. To address this issue, a nonlinear frequency–amplitude model was established by combining the proposed generalized complex stiffness model with the Berg friction model. The generalized complex stiffness model was proposed to characterize the frequency dependence, and the Berg friction model was employed to study the amplitude dependence. A dynamic analysis method was proposed based on a state space approach to realize a complete and accurate representation of the proposed mechanical model. Property tests of a viscoelastic damper and viscoelastic isolator were then conducted to study the dynamic mechanical performance under different excitation frequencies and amplitudes. Finally, the accuracy of the nonlinear frequency–amplitude model was validated using experimental data.

Experimental investigation of novel pre-compressed viscoelastic dampers with different matrix materials

In this paper, a novel pre-compressed viscoelastic damper with polyurethane-based piezoelectric damping composite material matrix is proposed. The damper mainly consists of the piezoelectric damping material matrix, steel plates, splints, and bolts, in which the pre-compression can be provided by bolts between the splints. By varying three influencing parameters of displacement amplitude, excitation frequency, and temperature, the dynamic mechanical properties of a total of 6 viscoelastic dampers (VEDs) were cyclically tested. The seismic behavior and vibration-resilient performance were evaluated by varying the viscoelastic damping material matrix and structural form. The experimental results show that the VED based on piezoelectric composite material matrix has a plumper hysteresis loop and better energy dissipation capacity. Moreover, the analyses illustrate that the pre-compression can improve the mechanical properties of the VED. In addition, the study of signal-to-noise ratio also reveals that the VED based on piezoelectric composite material matrix has excellent energy dissipation capability. The novel pre-compressed VED based on piezoelectric composite material matrix shows promising application prospects in vibration control.

On nonlinear damping effects with nonlinear temperature-dependent properties for an axial thermo-viscoelastic rod

The present manuscript develops a new axisymmetric model of thermo-viscoelastic rods to account for uniform temperature effects and nonlinear terms, which are induced by Kelvin–Voigt damping. A fundamental relationship between the damping of viscoelastic material and nonlinear geometry are researched through the application of Galerkin and multiple scale (MS) methods to the new model. Then, the MSM-based solutions are confirmed with a numerical integration method, and a good agreement between the approximate analytical and numerical results is observed. Free axial vibrations based on the standard linear solid model in uniform thermal rises with nonlinear material properties as a function of temperature is considered. The temperature of the viscoelastic rod remains constant under conditions of uniform temperature rise. Studying the behavior of the dynamic system in the presence of uniform temperatures increases the effect of nonlinear damping on its vibration behavior. Approximate analytical results are presented for use as a reference point in future analysis of nonlinear thermo-viscoelastic rods with a weak hardening system. Also, the results of this research can be useful and practical for finding the modal damping ratio of the system as well as the dynamic analysis of damping in the presence of thermal environment.

Nonlinear Dynamics Study of Giant Magnetostrictive Actuators with Fractional Damping

Since the structural mechanics of the super magnetostrictive actuator (GMA) system involves problems related to viscoelastic damping materials, the fractional order is more accurate than the integer order calculus to characterize the viscoelastic features in the structure. In order to further investigate the intrinsic mechanism and dynamical characteristics of the GMA dynamical system, the dynamical equations of the nonlinear GMA system containing fractional damping terms are established and the main resonance of the system is analyzed using the averaging method. The mechanism of the influence of some parameters on the GMA system is analyzed by MATLAB numerical simulation to study the bifurcation and chaotic motion phenomena of the system from the qualitative and quantitative perspectives. The results show that the fractional damping coefficient, external excitation amplitude and fractional order have significant effects on the amplitude-frequency characteristics of the system; the fractional order has a greater influence on the bifurcation and chaotic behavior of the system; the dynamic behavior of the system caused by the change of external excitation amplitude and fractional damping coefficient at different damping orders is similar but the chaotic region is different.

Buckling Analysis of a Composite Honeycomb Reinforced Sandwich Embedded with Viscoelastic Damping Material

In this study, the buckling loads of a composite sandwich structure, which is reinforced by a honeycomb layer and filled with viscoelastic damping material, are analyzed. By applying von Karman anisotropic plate equations for large deflection, the governing equation of the composite sandwich structure is determined, and the deflection of the structure is further defined by a double triangular series. According to the dynamic equivalent effective stiffness obtained by the homogenous asymptotic method and Hill’s generalized self-consistent model based on the Halpin–Tsai model, limiting the dynamic load buckling of the composite honeycomb reinforced sandwich structure embedded with viscoelastic damping material under axial compression can be achieved. The factors that influence the composite sandwich’s buckling loads are discussed and compared, such as the load and geometry parameters, the thickness of the honeycomb reinforcement layer and the honeycomb’s width. Finally, the results obtained by the present method are validated by the existing literature.

A novel design of vibration isolator with high and frequency dependent damping characteristics based on a Large Negative Poisson’s Ratio (LNPR) structure

In this paper, a biconcave-lens shaped structure with a large value of negative Poisson’s ratio (LNPR) is proposed. By filling viscoelastic damping materials inside this LNPR structure, a novel vibration isolator with frequency dependent damping characteristics is designed. With this integrated design of negative Poisson’s ratio structural element and viscoelastic materials, the compression and tension of the filled viscoelastic materials will be enlarged by the LNPR structure during a vibration process, which can effectively dissipate the vibrational energy. This proposed novel vibration isolator can achieve large damping characteristics and low vibration transmissibility, particularly when applying in micro-level vibration isolation. Finite element simulation is performed to predict the static and dynamic characteristics of this proposed novel vibration isolator, and characterize the hyperelastic and viscoelastic properties of the damping rubber. Finally, a vibration isolation platform using four proposed vibration isolators is established to perform frequency-sweep testings, with which our proposed design concept of this novel vibration isolator is demonstrated.

A new way to investigate the damping properties of NR/CIIR blends characterized by the rebound behaviors

AbstractIn this work, effects of natural rubber (NR) content on the vulcanization and damping properties of chlorinated butyl rubber (CIIR) were studied. A new method to characterize the damping performance of the NR/CIIR blends by the rebound behavior of rubber ball was proposed. And an optical laser‐based measurement was used to follow the movement of the rubber sample. The DMA results showed that better damping properties of the blends was obtained at higher proportion of CIIR in the blends at room temperature (20°C) and a frequency of 0.1–100 Hz. Furthermore, a propose was made that the damping properties of the blends can be characterized by the rebound behavior of the rubber ball, and two methods were developed to characterize the damping properties of the blends according to the rebound experimental results of the rubber ball. The functional relationship between the height of the nth bounce of the rubber ball and NR content was obtained by experimental fitting. The damping index (DI) was defined by combining the parameters such as bounce height, bounce times and bounce time of the rubber ball. It was expected that this study could provide a new idea for the characterization and testing of viscoelastic damping materials.

Concurrent Topology Optimization for Maximizing the Modal Loss Factor of Plates with Constrained Layer Damping Treatment.

Damping performance of the plates with constrained layer damping (CLD) treatment mainly depends on the layout of CLD material and the material physical properties of the viscoelastic damping layer. This paper develops a concurrent topology optimization methodology for maximizing the modal loss factor (MLF) of plates with CLD treatment. At the macro scale, the damping layer is composed of 3D periodic unit cells (PUC) of cellular viscoelastic damping materials. At the micro scale, due to the deformation of viscoelastic damping material affected by the base and constrained layers, the representative volume element (RVE) considering a rigid skin effect is used to improve the accuracy of the effective constitutive matrix of the viscoelastic damping material. Maximizing the MLFs of CLD plates is employed as the design objectives in optimization procedure. The sensitivities with respect to macrodesign variables are formulated using the adjoint vector method while considering the contribution of eigenvectors, while the influence of macroeigenvectors is ignored to improve the computational efficiency in the mesosensitivity analysis. The macro and meso scales design variables are simultaneously updated using the Method of Moving Asymptotes (MMA) to find concurrently optimal configurations of constrained and viscoelastic damping layers at the macro scale and viscoelastic damping materials at the micro scale. Two rectangular plates with different boundary conditions are presented to validate the optimization procedure and demonstrate the effectiveness of the proposed concurrent topology optimization approach. The effects of optimization objectives and volume fractions on the design results are investigated. The results indicate that the optimized layouts of the macrostructure are dependent on the objective mode and the volume fraction on the meso scale. The optimized designs on the meso scale are mainly related to the objective mode. By varying the volume fraction on the macro scale, the optimized designs on the meso scale are different only in their detailed size, which is reflected in the values of the equivalent constitutive matrices.

Study on the Damping Dynamics Characteristics of a Viscoelastic Damping Material

Viscoelastic damping materials are an effective means to control structural vibration, and are widely used in various fields. In this paper, we use the Dynamic Mechanical Analysis (DMA) characterization data of viscoelastic damping materials and dynamic characteristics experiments to study the dynamic characteristics of structural damping, analyze and summarize the relationship between the performance of damping materials with temperature and frequency, and explore the influencing factors of damping materials on structural vibration. The research shows that temperature and frequency have great influence on the performance of damping material, and the storage modulus and loss factor change regularly. The modal experiment analysis verifies that the viscoelastic damping material has a good suppression effect on structural vibration, which provides a theoretical basis for the development of damping materials with controllable temperature and frequency domains.

Variable-order fractional dynamic behavior of viscoelastic damping material

Abstract Viscoelastic damping material has been widely used in engineering machinery to absorb vibration and noise. Dynamic behavior of the viscoelastic damping 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 Laplace transform of the VOFC model. The dynamic thermomechanical analysis tests by the three-point bending mode are carried out at variable temperatures and frequencies, and the frequency spectrum of the dynamic behavior, i.e. the loss modulus, storage modulus and loss factor are obtained. Against the test data, the VOFC model is compared with classical models such as the integer-order Maxwell model, constant fractional-order Kelvin-Voigt model, constant fractional-order Maxwell model and constant fractional-order standard linear solid model. The results show that the VOFC model can describe dynamic behavior of the viscoelastic damping material at different temperatures and frequencies more accurately. And the VOFC model has simpler structure and only two parameters with clearly physical meaning. Finally, a calculation software is designed and developed, which simplifies the process of predicting viscoelastic dynamic behavior in a wide frequency range.

Simulation of the Dynamic Response to Sinusoidal Excitation of the Elastic Porous Metal Mesh Damper

As a promising device of vibration isolation for rocket engine turbopumps, turbine engines, and other kinds of rotordynamic applications, the elastic porous metal mesh damper (MMD) has drawn large attention from researchers. It exhibits higher load capacity and environmental adaptivity than traditional viscoelastic damping materials owing to the excellent combination of metallic properties and the rubber-like damping performance. However, the design of a metal mesh damper relies heavily on the trial-and-error methodology for tuning fabrication parameters, which prevents it from widespread use in rotor-bearing applications. Therefore, efforts are directed toward forging an explicit link between fabrication parameters and the dynamic behaviors of MMDs in the present work. Quasistatic and dynamic mechanical tests are carried out to help determine the primary factor that influences the damping performance of the MMD and to demonstrate how the dynamic behaviors of MMDs evolve with the fabrication parameters. Furthermore, two different modeling methodologies, i.e., the FE method and the mixed damping approach, are used to predict the hysteresis behaviors of the dampers. The latter method not only properly reproduces the experimental results but also makes it possible to build an intuitive connection between the fabrication procedures and the dynamic mechanical behaviors of the MMDs. The orthogonal test results determine that the mesh density plays a dominant role in controlling both the load capacity and damping performance of the MMDs. By integrating mesh density and motion amplitude into the expression of parameters including stiffness coefficient, damping coefficient, and damping component factor, the mixed damping model demonstrates excellent predictive accuracy under different excitation conditions.

Nonlinear Vibration Analysis of a Hinged–Clamped Beam Moving with Pulsating Speed and Subjected to Internal Resonance

This work focuses on the revelation of nonlinear characteristics of a hinged–clamped beam moving with pulsating speed. Cubic geometric nonlinearity, viscous damping due to intervening medium, and viscoelastic material damping are considered in the governing equation of motion. Parametric excitation is induced in the system due to pulsating speed amid 3:1 internal resonance between the first two modes. A perturbation technique-direct method of multiple scales is applied to solve the problem. Nonlinear features like various stability and bifurcation phenomena are extracted by applying a continuation algorithm. Trivial state stability plot and the impacts of viscous and material damping have been studied. The consequence of alterations of the amplitude of pulsating speed constituent, internal frequency detuning parameter, axial stiffness, and parametric detuning parameter on the vibration responses have been analyzed in detail. The analytic-numeric approach reveals rich and interesting nonlinear phenomena under united parametric and internal resonances in the study of the hinged–clamped beam that are not available in the existing literature.

Research on damping addition and vibration reduction technology of frame aerospace electronic chassis

This paper poses a box instrumentation in aerospace electronic chassis TO-5 encapsulation relay under the action of impact environmental load state of reverse fault mode, by reasonable single frames of viscoelastic damping materials added, increasing box style structure between the PCB mechanical installation interface damping ratio and frequency ratio, finally realizes the transfer rate is reduced, achieve instrumentation relay PCB, lower impact acceleration response. By adding damping cushion to the frame machine installation interface, the load transfer path of impact mechanics is optimized to reduce the installation stiffness and change the fundamental frequency characteristics of the whole machine.

Experimental study on the application of metamaterials in low frequency vibration reduction of thin plates

In order to validate the damping effect of metamaterials, the low frequency damping effect of the spring oscillator metamaterials was used to test the vibration of thin plates. And the damping effect was compared with the viscoelastic damping materials. The results show that, with lighter additional weight, the low frequency damping effect of the spring oscillator metamaterials for plate was better than that of the viscoelastic damping materials.

Homogenous asymptotic analysis on vibration energy dissipation characteristics of periodical honeycomb reinforced composite laminate filled with viscoelastic damping material

In this paper, free transverse vibration energy dissipation properties of honeycomb reinforced composite laminated structures are studied. By applying the homogenous asymptotic method (HAM) and representative unit cell (RUC) approach, considering the frequency- and temperature-dependent properties of the viscoelastic damping material (VDM), the constitutive equations of the laminated composite structure is obtained. Based on the transverse wave energy propagation and transmission theory in solid structures, the structural loss factor (SLF) of the composite structure can be ultimately determined, which is a frequency- and temperature-dependent variable according to the same properties of VDM’s physical parameters that were applied. Several geometry factors including the thickness of the VDM layer, the width and the inner angle of the honeycomb reinforcements, influence on the vibration energy dissipation characteristics of the composite structure are investigated qualitatively and quantitatively. The results are validated by the Galerkin method based asymptotic approach, which shows consistency with each other, especially when the external excitation frequency larger than 500 Hz in the considered frequency ranges.

Hybrid composite shaft of High-Speed Rotor-Bearing System - A rotor dynamics preview

In this present study, the detailed rotor dynamic evaluation of hybrid composite material rotating shaft of a power turbine high-speed rotor-bearing system is presented. The slender power turbine shaft of front driving turboshaft engine powering the rotorcraft requires a stiffer and lighter material to exhibit better rotor dynamics. Based on the preliminary investigation which predicted substantial rotor dynamic advantages, the laminated composite material shaft is proposed in the compressor section of the rotor-bearing system. To avoid the direct exposure of composite material to the harsh environment of gas turbine engine, hybrid metal fiber form of rotating shaft is employed. The hybrid metal fiber shaft is comprised of a core laminated carbon-epoxy tube sandwiched by steel tubes both inside and outside. The effect of parametric variation in the laminate and length of the hybrid shaft is evaluated and compared with the existing steel shaft. The viscoelastic material damping of carbon-epoxy laminate is also included as a rotating internal damping to evaluate the rotor dynamic instability threshold of the rotor-bearing system. From the analysis, it is found that the combination of metal and fiber-reinforced material can effectively leverage the combined strengths of both materials.

Study on dynamic mechanical properties of viscoelastic damping materials based on finite element theory

The relationship between the vibration parameters and the dynamic mechanical properties of the rubber material is established through the vibration reduction experiment and the finite element theory of the ZN-35 silicon rubber damper, which provides a new method for the prediction of the wide-band dynamic mechanical properties of the viscoelastic damping material.

Design of a disc-shaped viscoelastic damping material attached to a cylindrical pipe as a dynamic absorber or Houde damper

The vibration of pipes and cylindrical shells leading to noise and damage is an important engineering problem in plant systems and air conditioners, among others. To attenuate such vibration, a viscoelastic material is attached to a pipe as a damping material. Generally, the viscoelastic material covers the entire pipe to provide damping due to elongation of the material, but this requires a large amount of viscoelastic material. To overcome this problem, the approach adopted in this paper is to attach the viscoelastic material to only part of the pipe. The vibration of the pipe is then attenuated by not only the damping due to the viscoelastic material but also by the viscoelastic material acting as either a dynamic absorber or Houde damper. The disc-shaped viscoelastic material attached to the pipe is modeled as either a mass–spring–damper system or mass–damper system, and design guidelines are proposed for the material based on invariant-point theory. To assess the validity of the proposed design method, hammering tests are performed involving designed silicone attached to a pipe. The first- and second-order resonances of the pipe are attenuated by the silicone as a dynamic absorber and a Houde damper, respectively.

Interface bonding mechanisms of co-cured damping carbon fiber reinforced epoxy matrix composites

The ingredients of viscoelastic damping material were designed according to polymerization theory. It was different from traditional damping material. The curing process of resin matrix and vulcanized performance of viscoelastic material were taken into account during manufacturing process. The new co-cured damping composites were prepared via co-curing method. The feasibility of ingredients was verified by interfacial shear test and microstructure analysis. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis both indicated that the interface between the viscoelastic material and the resin matrix had chemical bonding interaction. The rationality of those designed ingredients was further proved. Plenty of results reveal that such co-cured damping composites possess excellent interfacial bonding strength. This work is aimed to explore the bonding mechanisms between damping materials and resin matrix to improve its interfacial bonding performance. The work also provides a theoretical basis for development of functional composites.