Vibration Damping Characteristics Research Articles

Study of the Vibration Isolation Properties of a Pneumatic Suspension System for the Seat of a Working Machine with Adjustable Stiffness

This paper presents a study of the vibration isolation properties of pneumatic suspension systems for work machinery seats, with a particular focus on adjustable stiffness. It highlights the contribution that semi-active seat suspension systems make to vibration reduction, ultimately leading to improved passenger comfort levels and increased safety for vehicle users. The primary objectives of the research were twofold: firstly, to identify the key parameters of the apneumatic vibration isolation system; and secondly, to evaluate its performance in improving vibration damping. This entailed the development of a mathematical model that would foreground the movement through simulations based on different initial pressures, thus enabling the accurate prediction of real-life scenarios concerning the vibration-damping characteristics of the seating system, taking into account the different design options available for working machine technology applied at the test bed level, of which the pneumatic isolator is an integral component. In the cognitive process, the verification and validation of the formulated theoretical model play an important role. This approach enables the behaviour of the actual system to be inferred from the results of simulation studies, thus allowing the design of an appropriate vibration control system. By simulating different air bellow pressures, the characteristics of the seat suspension system can be assessed. This study provides valuable insights into optimising the vibration-damping capability of the air suspension system.

Influence of chemical treatment of Bamboo fibers on the vibration and acoustic characterization of Carbon/Bamboo fiber reinforced hybrid composites

In the pursuit of sustainable materials, natural fibers are gaining attention because of their renewable nature and low environmental impact. However, their application in composites has been hindered by their hydrophilicity and non-homogeneity in the properties. To address these issues, chemical treatments such as Sodium Hydroxide and Potassium Permanganate have been utilized. This study explored the impact of chemical treatments on Bamboo fibers and their subsequent influence on the vibration and acoustic properties of Carbon/Bamboo fiber-reinforced hybrid composites. This study investigates the vibration damping and acoustic characteristics of hybrid composites, considering the synergistic advantages of Bamboo’s natural damping properties and Carbon fiber’s mechanical strength. The damping factor of Sodium Hydroxide treated Bamboo fiber reinforced hybrid composites is 34.55% higher than that of untreated Bamboo fiber reinforced hybrid composites. It is also 11.95% higher than that of Potassium Permanganate treated Bamboo fiber reinforced hybrid composites. The flexural modulus of untreated Bamboo fiber reinforced hybrid composites was 164.36% and 157.77% higher than that of Sodium Hydroxide treated and Potassium Permanganate treated Bamboo fiber reinforced hybrid composites, respectively. The effect of chemical treatment on the fiber properties were analysed using the FTIR spectrum. Acoustic characterization revealed that untreated Bamboo fiber composites have higher sound absorption coefficients at lower frequencies, whereas Sodium Hydroxide-treated composites have higher sound absorption coefficients at medium and high frequencies. The results indicated that chemical treatment enhanced fiber-matrix adhesion, reduced stiffness, and influenced the damping and acoustic performance of the hybrid composites.

Synergistic effect of graphene and carbon black on the mechanical and vibration damping characteristics of styrene-butadiene rubber

Synergistic effect of graphene and carbon black on the mechanical and vibration damping characteristics of styrene-butadiene rubber

Vibrations and thermoelastic quality factors of hemispherical shells with fillets

In engineering applications, hemispherical shell resonators are typically machined with fillets to reduce stress concentration and enhance structure strength. The fillets will inevitably affect the dynamic properties and the mechanical quality factor of hemispherical shell resonators, which has been seldom investigated before. In this paper, an effective analytical method is developed to explore the free vibration and thermoelastic damping (TED) characteristics of the hemispherical shell with fillets. The fillets are characterized by the variation in the thickness of the hemispherical shell during modelling. The first-order shear deformation theory (FSDT) is used to describe the theoretical formulas of the hemispherical shell with fillets. By employing the unified Jacobi polynomials and Fourier series as the assumed mode shape functions, the equation of motion of the structure is established by Hamilton's principle and the assumed mode method. The analytical model for thermoelastic quality factor (QTED) which is determined by TED is obtained by computing the dissipated energy and the maximum elastic potential energy of the hemispherical shell with fillets. The validity and accuracy of the present method are confirmed by comparing the present solutions with the published results and those obtained from the finite element method (FEM). The influences of fillets on the vibration behaviors and QTED characteristics of the hemispherical shells are analyzed in detail. The present model can be used to optimize the design of the fillets of the hemispherical shell resonators with high quality factors.

Vibration analysis of a smart viscoelastic porous sandwich micro-shell with magnetorheological fluid core using the modified couple stress theory

In the current study, for the first time, the size-dependent vibration of a functionally graded (FG) porous sandwich cylindrical microshell with magnetorheological fluid core is investigated using modified couple stress theory (MCST) and the first-order shear deformation theory (FSDT). The microshell is made of FG porous material and for investigating the material properties, two types of porous distributions are considered. Based on FSDT and the MCST, the governing equations are derived using Hamilton’s principle regarding the energy dissipation due to the shear deformation of the magnetorheological core layer and the interaction between all layers. Different assumptions, based on the continuity in transverse shear stresses and slope of in-plane displacements, are considered in the theoretical formulation. The natural frequency and loss factor of the microshell with sliding simply supported boundary conditions are determined using Navier’s solution method. Finally, the influence of some parameters such as material length scale(l/h: 0-1), types of porous distributions (symmetric-asymmetric), porosity volume fraction (e0: 0-1), magnetic field intensity (B: 0-800) and aspect ratio (L/R: 1-8, R/h: 10-100) on the vibration damping characteristics of microshell, is investigated and validity of the results is studied.

Multi-Body Dynamic Analysis of Hydrostatic Bearing with the MMC Material in Micro-Nano Machining.

This study focuses on the analysis of a linear hydrostatic bearing using harmonic frequency response and harmonic response simulations. The aim is to evaluate the feasibility of replacing the existing alloy steel material with a metal matrix composite (MMC) in terms of its performance and dynamic characteristics for both the base and carriage parts. The simulation results indicate that the MMC material exhibits higher resonant frequencies and improved damping capabilities compared to the structural steel material. The higher resonant frequencies observed in the MMC material are attributed to its stiffness and structural properties. These properties contribute to increased natural frequencies and improved vibration damping characteristics. This suggests that incorporating the MMC material in the bearing design could enhance motion control, improving the ability to precisely control and manipulate the movement of components or systems. In the context of ultraprecision machining applications, incorporating the MMC material in the hydrostatic bearing design can also lead to a more accurate and controlled motion, resulting in improved precision and finer machining outcomes. The displacement analysis confirms that both materials meet the specifications provided by the manufacturer, supporting the viability of using MMC as an alternative. However, further experimental validation and considerations of material feasibility, manufacturing factors, and cost-effectiveness are necessary before implementing the MMC material in practical applications. Overall, this research highlights the potential benefits of MMC in the design of linear hydrostatic bearings, paving the way for enhanced performance in ultraprecision machining processes.

Enhancing vibration damping properties of additively manufactured viscoelastic structures through process parameter optimization

With the increasing use of additive manufacturing (AM) in diverse fields, printed structures are inevitably exposed to vibrations, which can result in fracture, fatigue, and noise. Present study aims to enhance the damping characteristics of the final part by incorporating viscoelastic materials into the primary structure using multi-material AM. The effects of process parameters on the vibration damping characteristics of printed viscoelastic structures were investigated through modal analysis and design of experiments. Results show that higher nozzle temperature, smaller layer height, lower deposition speed and smaller raster angle contribute to higher resonant frequencies and loss factors of the final parts.

Analysis of Vibration-Damping Characteristics and Parameter Optimization of Cylindrical Cavity Double-Plate Phononic Crystal.

For the application of low-frequency vibration damping in industry, a cylindrical cavity double-layer plate-type local resonance phononic crystal structure is proposed to solve low-frequency vibration in mechanical equipment. Initially, using COMSOL 5.4 software, the bending wave band gap is calculated in conjunction with elastic dynamics theory and the BOLOCH theorem to be 127-384 Hz. Then the mechanism of bending wave gap is analyzed by combining element mode shape and an equivalent model. Subsequently, the bending vibration transmission characteristics of the crystal plate are explained, and the vibration-damping characteristics are illustrated in combination with the time-frequency domain. An experimental system is constructed to verify the vibration-damping properties of crystal plates; the experimental results and simulation results are verified with each other. Finally, the element structural parameters are optimized using the RSM. Fifty-four sets of experiments are designed based on six structural factors and three levels, and the expressions between the bending wave band gap and six structural factors are obtained. Combining the particle swarm algorithm, the optimization is performed with the band gap width as the target. This method is shown to be more accurate than the commonly used interior point method. The structure of cylindrical-cavity-type phononic crystal and the parameter optimization method proposed in this paper provide a certain reference for the design of local-resonance-type phononic crystal.

Experimental Study and Damping Effect Analysis of a New Tuned Liquid Damper Based on Karman Vortex Street Theory

In order to solve the shortcomings of traditional TLDs (tuned liquid dampers), such as their narrow frequency bands and their occupation of large amounts of space, based on deep-water theory, a new type of TLD incorporating Karmen vortex street theory is proposed and named as KV-TLD. A shaking table experimental test is conducted to fully analyze its vibration damping characteristics and its effectiveness in terms of vibration control is confirmed. Through comparison with a traditional TLD, the superiority of KV-TLD is verified. By analyzing parameters such as the mass ratio and the frequency ratio, it is found that a larger mass ratio means a better damping effect. When the frequency ratio is close to 1.0, the damping effect is better, while the vibration damping advantage of KV-TLD is much lower. Good performance in terms of installation, a wide frequency band, and damping effect means that KV-TLD is superior in terms of actual engineering application possibilities, and can also act as a good reference for subsequent engineering projects.

Imparting Reprocessability, Quadruple Shape Memory, Self-Healing, and Vibration Damping Characteristics to a Thermosetting Poly(urethane-urea)

The advent of dynamic covalent bond chemistry (DCBC) has sparked renewed research interest in reprocessability of thermosetting polymers. However, combining reprocessability with stimuli-responsiveness remains a challenge for futuristic applications. Usually, a combination of complementary DCBCs is employed to integrate reprocessability with shape memory as well as self-healing (SH) attributes in a single polymeric system. In the present work, we report two-component poly(urethane-urea) (PUU) networks, with varied hard segment (HS) concentrations, that exhibit quadruple shape memory (QSM), efficacious vibration damping, thermally activated intrinsic SH as well as multiple cycles of thermal reprocessability. The component A is an isocyanate capped bi-soft segment blend of polybutadiene diol and polypropylene glycol, while the second component comprises an aromatic diamine chain extender solubilized in an oligomeric polyoxypropylene triol. The networks characterized through FTIR as well as small- and wide-angle X-ray scattering (SAXS and WAXD) revealed a phase-separated morphology with extensive hydrogen-bonding (H-bonding) interactions in the HS domains of the PUU networks. Dynamic mechanical analysis (DMA) measurements revealed broad dissipation factor (tan δ) vs temperature and frequency profiles of the networks, which could be leveraged for efficacious passive vibration damping applications. A dissociative mechanism of urethane and urea bond exchange, evidenced from temperature-dependent FTIR studies enabling facile stress relaxation, is proposed to be the mechanistic origin of the reprocessability and SH of the networks. A broad dissipation factor (tan δ) vs temperature profiles endowed the networks with QSM characteristics. We posit that the study is relevant for expanding the scope of DCBCs for development of reprocessable thermosetting polyurethanes with multiple smart functionalities.

Effect of infill pattern and ratio on the flexural and vibration damping characteristics of FDM printed PLA specimens

3D printing technology has started to be used in many different areas of our lives. In this study, the panels' flexural behaviors and vibration-damping capabilities produced in different infill patterns (Grid, Cross, and Tri-hexagon) and different infill ratios (0%, 20%, 40%, 60%, 80%, and 100%) were investigated. The specimen dimensions were 12.7 mm in width, 127 mm in length, and 3.2 mm in thickness. A biopolymer polylactic acid (PLA) filament with Ø 1.75 mm was used to produce test specimens. Fused Deposition Modeling is a modern additive manufacturing technique; however, optimization is needed to enhance the properties of 3D-printed parts. The flexural properties, as well as vibration-damping characteristics of the 3D-printed specimen, were evaluated experimentally. The results show that the infill pattern and ratio significantly affect flexural behavior and vibration-damping properties. The flexural tests showed that the highest flexural strength was obtained in the Tri-hexagon pattern, while the highest damping capability was obtained on Cross pattern specimens. Additionally, with the increasing infill ratio, the flexural modulus, and flexural strength increase. The specific strength value obtained for the 20% fill rate for all patterns was observed as maximum Best damping properties were obtained on a 40% infill ratio with all the different tested patterns. This study also showed that infill pattern and ratio design could improve the plastic parts' properties, and 3D printing provides an easy way to test the properties of different infill patterns and ratios.

Investigating the free vibration of viscoelastic FGM Timoshenko nanobeams resting on viscoelastic foundations with the shear correction factor using finite element method

This article intends to investigate the free vibration damping characteristics of functionally graded viscoelastic nanobeams embedded in viscoelastic foundations using the infinite Kelvin–Voigt model of the Winkler–Pasternak type. This model is based on the nonlocal strain-driven gradient elasticity theory of Eringen. A power law model is then adopted to describe the continuous variation in the material properties of functionally graded material nanobeams. The study was carried by means of the first-order shear deformation theory with the shear correction factor using the finite element method. For the purpose of validating the developed model, it was decided to compare the results obtained with those reported about elastic nanobeams in the literature. Moreover, the influence of the power law exponent, structural damping coefficient, foundation coefficient, nonlocal parameter, and boundary conditions on the free frequency response of viscoelastic nanobeams was also investigated.

Shape Memory Hybrid Composites.

Smart structures can help to resolve many issues related to conventional materials that are being used in different industries. Shape memory alloys (SMAs) are smart materials with better actuation response, vibration damping characteristics, and large strain recovery, making them good candidates due to their high strength and corrosion resistance for various engineering applications. The performance of fiber-reinforced polymer (FRP) composite materials that are replacing many conventional materials due to their good strength, stiffness, and lightweight potential especially in fuel-consuming industries such as aerospace and automotive, can further be improved by impregnation with SMAs. This review discusses the SMA-reinforced FRP composites, leading to shape memory hybrid composite materials, the issues and limitations in composite manufacturing, and their uses in different research arenas including impact and damping applications, seismic protection applications, crack closure applications, shape morphing applications, and self-deployable structures.

Vibro-acoustic characteristics of multifunctional carbon fiber reinforced panel

This paper deals with the assessment of vibro-acoustic properties of a multifunctional carbon fiber reinforced panel manufactured by bulk infusion, a modified resin film infusion process. The components of the epoxy resin were chosen to contrast the electrical insulating property and poor flame resistance of the epoxy resins impregnating carbon woven fabric. To confer electrical conductivity to the resin a percentage of 0.5 wt% of Multi-Wall Carbon Nanotubes (MWCNTs) was dispersed in the resin, whereas to increase flame resistance a percentage of 5 wt% of Glycidil Polyhedral Oligomeric Silsesquioxanes (GPOSS) was solubilized in the epoxy mixture. Furthermore, as hardener agents, a mixture of 4,4’-DiaminoDiphenyl Sulfone (DDS) (53.4 wt%) and Bis(3-Aminophenyl) Methyl Phosphine Oxide (BAMPO) (46.7 wt%) was used. The values of the electrical conductivity were found satisfactory enough, being 4.02 × 10−2 S/m for the multifunctional resin and 1.39 × 104 S/m for the in-plane conductivity of the panel, whereas the Limiting Oxygen Index (LOI) value of the multifunctional resin was found to increase from 27% to 36%. Considering these promising results, an experimental assessment of the vibro-acoustic properties of the manufactured multifunctional panel was also performed. The panel was tested mainly to evaluate its low-frequency vibration damping and sound insulation characteristics. The manufactured panel demonstrated an improved efficiency if compared to a baseline configuration, presenting almost the double modal damping and a gain of 10 dB on the global noise reduction.

Vibration damping characteristics of the cork-based composite material in line to frequency analysis

1. A WWF Report, 2006, Cork Screwed? Environmental and Economic Impacts of the Cork Stoppers Market. Minnesota University, WWF Mediterranean Programme Office. Google Scholar

Physical, thermal, mechanical, sound absorption and vibration damping characteristics of natural fiber reinforced composites and hybrid fiber reinforced composites: A review

Physical, thermal, mechanical, sound absorption and vibration damping characteristics of natural fiber reinforced composites and hybrid fiber reinforced composites: A review

Comparative Research on Vibration Characteristics of Cast-In-Place Steel-Spring-Floating Slab Track under Different Subway Line Conditions

Purpose: Steel-spring-floating slab tracks are widely used in subway lines. It is necessary to analyze and study the vibration damping and transmission characteristics of the steel-spring-floating slab track in various frequency bands under the action of train loads. Method: A steel-spring-floating slab track and ordinary monolithic track tunnel sites with similar line conditions on straight and curved segments were selected. The vibration signals of rail, track bed, and tunnel walls were collected and the analysis results of vibration damping and vibration transmission between the steel-spring-floating slab track and the ordinary monolithic track were compared. Results: The dynamic responses of the rail in the four working conditions are relatively close, and the acceleration of the steel-spring-floating slab track bed is significantly larger than that of the ordinary monolithic track. The vibration response generated in the curved segment is significantly greater, and each frequency band will generate more peak points, and the high-frequency vibration will be more severe. Conclusions: The steel-spring-floating slab track can significantly reduce the acceleration response of the tunnel wall; the bottom constraint of the steel-spring-floating slab track is less, and the vibration response of the track bed is more severe.

Effect of Fiber Content on Mechanical, Morphological, and Vibration Damping Characteristics of Natural Fiber-reinforced Composite Fuel Tanks

ABSTRACT Rotational molding is a powder processing technology widely used to manufacture hollow plastic products. It is a well-known process used for the manufacturing of large containers, water tanks, fuel tanks, refrigerated containers, etc. This study aimed at the incorporation of Tampico and Palmyra fibers as reinforcement in Linear Low-Density Polyethylene (LLDPE) tanks produced by the rotational molding process. The effect of fiber content on various properties like mechanical, morphological, and vibration damping characteristics of the composites were investigated. The fibers were initially treated with 5% NaOH solution for better reinforcing efficiency and to improve the degradation temperature. Thermo Gravimetry Analysis (TGA) reported that a sufficient increment in degradation temperature is achieved by NaOH treatment on fibers. The short fiber composites considered for the study have obtained better mechanical strength than long fiber reinforced LLDPE composites. The results proved that fiber length has less effect on the vibration damping characteristics of the composites, but the percentage of fiber content is a significant factor for improving the natural frequency of the composites.

Effect of Device Positions on the Vibration Damping Characteristics of Bead Panels Using a New Vibration Damping Device Consisting of a Constraint Frame and a Viscoelastic Layer

This paper describes numerical simulation of the dynamic characteristics of a bead panel equipped with a new vibration control device. The device includes two blocks of viscoelastic gels and a constraint layer having a box cross section. The gel blocks are sandwiched between the constraint layer and the test structure. The modal analysis is carried out numerically using the finite element method with modal strain energy method. Effects of device positions on the vibration damping characteristics of the bead panel were evaluated using eigenmodes, modal loss factors and resonance frequencies.

A comparative study of Mechanical, morphological and vibration damping characteristics of wood fiber reinforced LLDPE processed by rotational moulding

The present work investigates the mouldability of Linear Low-Density Polyethylene (LLDPE) with Wood Dust (WD) as a potential reinforcement with enhanced mechanical, morphological, and vibration damping characteristics. This was achieved by incorporating treated wood particles in rotomoulded grade into the LLDPE matrix with the help of a lab model rotomoulding machine. The incorporation of natural fibers finds difficult in the processing of rotomoulded parts since the process itself is a powder processing technique. The rotomoulded parts developed here is distinct from the previous works reported as it utilizes melt-compounded composite granules of a significantly larger size than the matrix material which is in the powder form. The need for natural fiber composite is come into existent because of its availability in abundance and is cheap. This project aims to come up with a solution of the best polymer composite material with a given percentage of natural fiber as filler. In rotational molding, several natural fibers have been used such as coir, flax, agave, sisal, palymira, etc. In the present study, LLDPE powder is used as a base material and mixed with a different weight percentage of WD fillers. The mechanical characterization and morphological study results proved that a sufficient hike in strength is obtained for 10% WD fiber added composites. The Experimental Modal Analysis (EMA) results also prove that the incorporation of WD is effective in improving the vibration damping characteristics of the composites developed.