Vibration Insulation Research Articles

Effect of Heavy Filler on Dynamic Mechanical Properties of Polymer Composites

Experimental studies on the effect of frequency and temperature on the dynamic mechanical properties of filled composites are studied poorly and require further research. The purpose of theresearch is to study the effect of heavy fillerbarite (BaSO4), on the dynamic characteristics of a highly filled composite based on butyl rubber, and to compare the efficiency of barite in the composite with similar light filler. The conclusions are made on the basis of a comparative analysis of the temperature-frequency dependences of the loss tangent and the storage modulusat various percentages of filler, obtained by the DMA method. It has been established that while increasing barite concentration the elasticity of the composite material decreases, the glass transition temperature shifts upwards, and the reverse occurs in the zone of highly elastic state of the composite: the higher the barite concentration, the higher the damping properties. The authors provided a rationale that the heavy filler shows the effect only in the highly elastic zone if compared with the light one. The article is of practical value for the development of new vibration insulation materials.

Integrated Dynamic Characterization of Thermorheologically Simple Viscoelastic Materials Accounting for Frequency, Temperature, and Preload Effects.

In vibration insulation projects, a parameter affecting the dynamic properties of the viscoelastic materials is the previous static load acting on the supports, denominated here as the ‘preload’. Most of the currently-used methodologies obtain the dynamic properties by considering only the effects of temperature and frequency. The additional effect of preload can be added to the usual methodologies by employing the hyperelastic theory developed by Mooney–Rivlin. The current work proposes an integrated approach to characterize thermorheologically simple viscoelastic materials, including the preload effect along with the influence of temperature and frequency. The proposed method uses a hybrid optimization process, combining a genetic algorithm (GA) and a non-linear optimization technique—named ‘simplex’—in an inverse problem structure applied to all experimental data at hand. A set of samples of elastomer BT-806 55 (butyl rubber) was tested at various temperatures, frequencies, and preloads. The comparison between the results of the present methodology and traditional approaches to a variation in the dynamic properties at all frequencies and temperatures for a constant vibration amplitude. The present results prove that the proposed methodology is a viable alternative to represent the dynamic properties of materials used in vibration isolation.

A Magnetic-Dependent Vibration Energy Harvester Based on the Tunable Point Defect in 2D Magneto-Elastic Phononic Crystals

In this work, an innovative vibration energy harvester is designed by using the point defect effect of two-dimensional (2D) magneto-elastic phononic crystals (PCs) and the piezoelectric effect of piezoelectric material. A point defect is formed by removing the central Tenfenol-D rod to confine and enhance vibration energy into a spot, after which the vibration energy is electromechanically converted into electrical energy by attaching a piezoelectric patch into the area of the point defect. Numerical analysis of the point defect can be carried out by the finite element method in combination with the supercell technique. A 3D Zheng-Liu (Z-L) model which accurately describes the magneto-mechanical coupling constitutive behavior of magnetostrictive material is adopted to obtain variable band structures by applied magnetic field and pre-stress along the z direction. The piezoelectric material is utilized to predict the output voltage and power based on the capacity to convert vibration energy into electrical energy. For the proposed tunable vibration energy harvesting system, numerical results illuminate that band gaps (BGs) and defect bands of the in-plane mixed wave modes (XY modes) can be adjusted to a great extent by applied magnetic field and pre-stress, and thus a much larger range of vibration frequency and more broad-distributed energy can be obtained. The defect bands in the anti-plane wave mode (Z mode), however, have a slight change with applied magnetic field, which leads to a certain frequency range of energy harvesting. These results can provide guidance for the intelligent control of vibration insulation and the active design of continuous power supply for low power devices in engineering.

Is anything radically new in noise control research?

This paper attempts to review the state of art of noise control research globally and answer a key question: Has anything been radically new in noise control research lately? There is anecdotal evidence that no radical noise control solution has emerged from noise control research since the invention of active noise control by Paul Lueg in 1936 (U.S. Patent 2,043,416). Among passive noise control solutions used for sound absorption the market is dominated by mineral wool and fibreglass (43% in 2017, Global Insulation Market Report, 2024). Technical foams used for acoustic absorption cover pretty much of the rest. Similar situation is for common solutions used for noise and vibration insulation. Their acoustical properties and in-situ performance can be predicted within experimental and material parameter uncertainties using a commercial package such as Comsol or semi-empirical models such as by Delany and Bazley. There seem no radical solutions has emerged recently to challenge this status quo. Metamaterials are one promising solution for the future, but they remain largely in the realm of academic laboratories or fancy theories. Therefore, another key question is: What has true impact of noise control research been so far and what fundamental ideas need to emerge to radically improve this situation?

Dynamical mechanical characterization of a nanostructured vibration damping layer

A vibration damping layer can dissipate relatively large amounts of energy. A known effect of this dissipation of energy is the reduction of the response of a structure to sound and vibration excitation and the reduction of the transmission of sound through structures at high frequencies. Added damping also increases the impedances of structures at their resonances and thus may improve the effectiveness of vibration isolation at these resonances. It has been observed that the molecular behavior of new nanomaterial composites may have significant influence on their shock and vibration insulation properties. Dynamical mechanical characterization of these nanostructured materials is important for determining the potential application as a viscoelastic vibration damping layer. In this work, inclusion of several nanostructures to thermostable polyurethane has been made and their main elastic properties have been measured using current standard methods. It is observed that specific amounts of nanostructures can improve the impact damping capabilities of the material, with the advantage of reduced thickness and weight as compared to traditional materials.

Resilient pads with custom designed stiffness

The paper deals with examples of using vibration insulation in project documentation. The research methodology and the results of measurements of elastic characteristics of rail fastening components in the form of rail pads and baseplate pad was presented. High precision of designing and manufacturing of elastic elements with a specific characteristic was emphasized. Shortcomings of national legislation in this area have been pointed out. In the summary, the desired directions of changes in this unfavorable situation were defined.

Research on the Vibration Insulation of High‐Speed Train Bogies in Mid and High Frequency

According to a large amount of the test data, the mid and high frequency vibrations of high‐speed bogies are very notable, especially in the 565~616 Hz range, which are just the passing frequencies corresponding to the 22nd to 24th polygonal wear of the wheel. In order to investigate the main cause of wheel higher‐order polygon formation, a 3D flexible model of a Chinese high‐speed train bogie is developed using the explicit finite element method. The results show that the couple vibration of bogie and wheelset may lead to the high‐order wears of wheel. In order to reduce the coupled resonance of the wheelset and the bogie frame, the effects of the stiffness and damping of the primary suspensions, wheelset axle radius, and bogie frame strength on the vibration transmissibility are discussed carefully. The numerical results show that the resonance peaks in high frequency range can be reduced by reducing the stiffness of axle box rotary arm joint, reducing the wheelset axle radius or strengthening the bogie frame location. The related results may provide a reference for structure improvement of the existing bogies and structure design of the new high‐speed bogies.

Proposal of new vibro-acoustic floor

Human perception of vibration could be the basic parameter in designing a new buildings located close to public transport. It is also one of parameter that is considered in diagnosis of building vibration. People perceived vibrations through the floor. The problem of floor vibration appear especially in old historical buildings with wooden floor when source of transport vibration change because of infrastructure development. During years road, tramway or railway infrastructure is more expanded that it was when the old buildings were built. That is why new solutions of protection against noise and vibration are needed. One of that kind solution could be vibro-acoustic floor which can reduce impact sounds and vibrations. A flooring system that insulates both acoustically and vibrantly is a common solution to reduce noise coming from impact sounds or to propagate from lower levels to higher ones and to limit the influence of vibration on people receiving vibration in buildings passively. The flooring system should therefore be capable to damp vibrations up to 100 Hz and have sound insulation of min. 25 dB. The composition of vibration insulation materials and their material parameters will be selected to optimize the acoustic and vibration protection. At the same time, the acoustic and vibration-insulating flooring system should have all the functional features that are common to the floor: ease of installation and adequate rigidity. In paper three types of vibro-acoustic floors will be considered: with full vibro-insulation, with insulation strips and with point insulation. Advantages and disadvantages of these three considered solutions will be presented. The paper is pilot study to in-situ measurement which will be held under the project of EU commission support.

A Dynamic Method of Nanoindentation

A new dynamic method of measuring the local value of hardness and contact stiffness at the nanoscale range using a probe in self-oscillation mode at resonant eigenfrequency is proposed. The possibility is shown of measuring the force of contact interaction of a probe with a sample in a range from ten to several hundred μN with shift of the probe’s resonant eigenfrequency, at a resolution up to one hundred nN. The advantage of this method is the absence of a drift component of the measuring signal during the time interval of a test cycle. This ensures operability of the method without special conditions of vibration insulation and thermal insulation that are necessary for instrumental indentation.

Dynamic properties of carbon aerogel/epoxy nanocomposite and carbon fiber-reinforced composite beams

Carbon aerogels are a promising candidate for vibration insulation due to their three-dimensional networked structures interconnected with carbon nanoparticles. However, the effect of adding carbon aerogels to polymer-based composites on their dynamic properties remains unclear. In this study, an epoxy polymer matrix was modified with carbon aerogels, and this modified matrix was used to manufacture nanocomposite plates and carbon fiber-reinforced polymer composite laminates to investigate its dynamic properties. Force vibration tests were performed on cantilever beams of the composite beams. The frequency responses of the composite beams were measured experimentally and analytically; the half-power method was used to calculate the damping ratio for each vibration mode. According to the experimental results, the presence of carbon aerogel in the nanocomposites and laminates steadily increased the natural frequencies. Differences within 10% of the natural frequencies were obtained between the experimental and numerically. Furthermore, the damping ratios of the nanocomposite and laminate beams increased significantly with the increase in aerogel loading. For a nanocomposite with 0.3 wt% aerogel, a damping ratio approximately 44% greater than that of unmodified nanocomposite was obtained. The maximum damping ratio was 4.682% for the laminate with 0.5 wt% aerogel—an 88% increase compared with the unmodified laminate.

Frequency graded 1D metamaterials: A study on the attenuation bands

Depending on the frequency, waves can either propagate (transmission band) or be attenuated (attenuation band) while travelling through a one-dimensional spring-mass chain with internal resonators. The literature on wave propagation through a 1D mass-in-mass chain is vast and continues to proliferate because of its versatile applicability in condensed matter physics, optics, chemistry, acoustics, and mechanics. However, in all these areas, a uniformly periodic arrangement of identical linear resonating units is normally used which limits the attenuation band to a narrow frequency range. To counter this limitation of linear uniformly periodic metamaterials, the attenuation bandwidth in a one-dimensional finite chain with frequency graded linear internal resonators are investigated in this paper. The result shows that a properly tuned frequency graded arrangement of resonating units can extend the upper part of the attenuation band of 1D metamaterial theoretically up to infinity and also increases the lower part of the attenuation bandwidth by around 40% of an equivalent uniformly periodic metamaterial without increasing the mass. Therefore, the frequency graded metamaterials can be a potential solution towards low frequency and wideband acoustic or vibration insulation. In addition, this paper provides analytical expressions for the attenuation and transmission frequency limits for a periodic mass-in-mass metamaterial and demonstrates the attenuation band is generated by the high absolute value of the effective mass not only due to the negative effective mass.

Gaussian closure technique for chain like structures with elasto-plastic elements described by the Bouc hysteresis

Hysteretic materials can be described using the Bouc model. Based on this model, analytic solutions for the Gaussian closure technique for one mechanical degree of freedom were presented previously. The solution is based on classical moments of a multivariate Gaussian distribution and, for the non-linear portion of the model, analytic solutions can be derived when the necessary multi-dimensional integrals are solved in the correct order. These results can be extended to multiple degrees of freedom as long as a description in relative coordinates is possible. This is true for chain-like structures of which the model of a multi storey building under wind or earthquake excitation or the vertical displacements of a vibration insulation are examples. A procedure is presented that allows the solution of all integrals by a sequence of substitutions similar to the single degree-of-freedom model. The method is evaluated using a two and a five storey frame and the results are in good agreement with Monte-Carlo results although a slight underestimation occurs for larger loads. As no numerical integration is necessary, the method is very fast. Furthermore, contrary to statistical linearization the method takes also the covariances between the nodes into account and allows the calculation of the transient case using a fast explicit time step procedure. Finally, the high number of moment equations which increases almost with the square of degrees of freedom does not seem to lead to instabilities.

Equivalence study on hollow extruded aluminum alloy profile plates based on vibroacoustic behavior

For noise simulation of a high-speed train passenger compartment, an equivalence study of vehicle body hollowaluminumprofiles is imperative for reducing the finite element calculation in the simulation process and adapting to the requirements of statistical energy analysis. From the perspective of structural vibration and acoustic radiation, hollow aluminum flooring was used as an example. This study provides a noise-, vibration-, harshness-(NVH) equivalent plate acquisition method for hollow profiles and plates and studies the engineering application conditions and deviations of the equivalent structure. In accordance with the NVH-equivalent method for hollow profiles, a basic process is furnished for acquiring the properties and parameters of the equivalent plate. The consistency of vibration and noise insulation between the equivalent plate and hollow profiles plate has been validated through simulation. An electric multiple unit (EMU) interior noise simulation example showed that for an interior noise simulation model using equivalent plates, the prediction accuracy of interior noise can meet the requirements of engineering applications while significantly reducing the simulation time.

Optimization of the protection against railway vibrations on the example of railway control building in Biała Rawska

The work presents the design process of vibration isolation for a building subjected to the influence of railway vibrations. This process is illustrated on the example of the railway control building in Biała Rawska, realized within the framework of the investment whose the general contractor was PORR Poland Construction S.A. Measurements of railway vibrations at the site of the planned building were made. The building calculation model was performed and then the vibration isolation parameters of the building were calculated based on the simulation calculations of this model. The purpose of the described design work was to limit the impact of vibration on the people and the equipment in the computer server room located in this building. The original design of the rail track vibration insulation was replaced by the building vibration project. This allowed to optimize work time, reduced railway traffic interruptions and the cost of vibration isolation.

Vibration transmission through an impacting mass-in-mass unit, an analytical investigation

Impacting events are discontinuous and non-smooth in nature; thus, resulting in various forms of complex nonlinear dynamics. A numerical algorithm has been developed based on the analytical solution to distinguish different classes of impacting responses. The main advantages of the solver are that it can either stop the integration process after automatically identifying the steady state solution or continue until the maximum time is reached in case of the chaotic type response. To identify the frequency of higher periodic response, a periodicity coefficient has been defined as the frequency ratio of excitation and the system's response. The effect of coefficient of restitution on the different dynamic responses is also discussed within the scope of the paper. The amplitude of the vibration of the main mass is reduced due to the presence of the multi-periodic and chaotic impacting responses for a wide range of excitation frequencies. These characteristics make impact dampers ideal for applications in wideband vibration insulation and a unit of wideband nonlinear metamaterial.

Prediction and Experimental Analysis of the Effectiveness of Vibration-Isolating Tramway

In Krakow during last time, it is seen the development of tram and bus infrastructure. This is to improve the mobility of the residents as well as the comfort of using the means of mass communication. Besides this, the municipal authorities do not neglect the development works relating to the future construction of the metro. New network of tramways and roads are planned, designed and built. Many exploited for years’ tramway tracks and the road is repaired due to their poor technical condition. Insufficient technical condition of the existing tramway tracks and streets makes it necessary to repair them. The work concerns the influence of vibration induced by traffic crossing trams in one of the main streets of Krakow on people staying in buildings and passively receiving these vibrations. The study was carried out in three stages. In the first stage, before the renovation of the tramway, the measurements of vibration were done in a number of selected residential buildings with various constructions. The recorded vibrations were analyzed according to the procedure given in ISO 2631-2 due to human exposure. In a second step numerical analyzes were performed using the database of registered communication vibrations and dynamic models of buildings. The results of calculations were used for selection of the appropriate parameters (thickness, stiffness) of vibration isolation of the analyzed tramway due to the comfort of the people staying in buildings. In a third step, the checking measurements were carried out in the same places as in the first stage and from the same types of trams. Re-analyzes were made for assessing the impact of vibration on people. Comparative analysis has shown that applied vibration insulation met expectations and helped to reduce the level of vibration felt by the people.

Design and validation of metamaterials for multiple structural stop bands in waveguides

Environmental and economic requirements lead to a constantly increasing application of lightweight designs. Fulfilling the conflicting goals of favorable noise and vibrational behavior and lightweight design is a challenging tasks, requiring novel low mass and compact volume solutions. Vibro-acoustic metamaterials come to the fore as possible lightweight solutions with superior noise and vibration insulation properties in targeted and tunable frequency ranges, referred to as stop bands. They typically consist of (often periodic) assemblies of unit cells of non-homogeneous material composition and/or topology, adding local resonant behavior to the host structure. Metamaterials targeting different stop bands can be combined to suppress vibrations over a larger frequency zone. This paper investigates various metamaterial layouts for reducing vibrations along a known transmission path, being a duct with a square section. The efficiency of the considered metamaterial designs for vibration attenuation are evaluated and compared both numerically and experimentally. Due to the typical periodic nature of this class of materials, the numerical prediction of the stop band behavior is modeled using unit cell models for the duct; both a one dimensional (1D) waveguide as well as a two dimensional (2D) infinite periodic structure. The efficiency and accuracy of both approaches are evaluated and compared to measurements. It is demonstrated that different resonant structures can be combined to merge stop bands, either using a mixed, checkered pattern, or a sequential pattern. Depending on the transmission path and the targeted frequency zone, either approach or a combination of both can be used. Furthermore it is shown that the 2D unit cell analyses gives an accurate prediction of the stop band locations.

Evaluation of Basic Oxygen Furnace (BOF) material into slag-based asphalt concrete to be used in railway substructure

The endurance of a high-speed railway asphalt concrete reinforced trackbed is improved through the use of various percentages of Basic Oxygen Furnace (BOF) slag to replace the coarse natural gravel aggregate of asphalt concrete (replacement rate is 0%, 25%, 50%, 75% and 100%, respectively). We evaluated the performance of BOF-asphalt concrete (which is used as a reinforced trackbed) by performing a modified penetration test, dynamic triaxial test, tensile stress restrained specimen test (TSRST), thermal conductivity test, and dynamic model test. The results show that the penetration time is an alternative index, and all of the BOF-asphalt concretes have a waterproof function. With the increase in the BOF replacement rate, the vibration attenuation, bearing capability, antifreeze capability, and insulation effect are improved, while with the BOF replacement rate increase, the flexural tensile strength loss rate is increased during the long term freeze-thaw cycles.

Comparative Analysis of the Efficiency of Fiber Winding Types Used in the Fiber-Optic Gyro Sensor Coil Under Temperature Variation Conditions

Background. The paper is devoted to the study of the effectiveness of different types of coil fiber winding of fiber optic gyro (FOG) in reducing of the impact of Shupe effect under temperature changes. Objective. The objective of the study is to evaluate the effectiveness of different types of FOG fiber coil winding under temperature changes. Methods. Based on the analysis of existing types of winding, and formulae for non-reciprocal phase shift calculation, a method for evaluation of the impact of temperature gradient on coils with different types of winding is created. Method mentioned is applied to 9 different types of coil winding. Results. The dependencies of zero shift vs time for nine types of winding under the impact of axial, radial temperature gradients and combinations thereof are obtained. Conclusion. Overall, use of quadruple windings seems to be optimal; for low precision sensors one can recommend centered unipolar winding while ensuring good thermal and vibration insulation of the coil. The use of pads (or frameless coils) is justified when simple winding is used (e.g., in devices for short-living objects, for automotive industry, etc.), or for high-precision sensors.

Testing Equipment Location on Springing Base Plate

When is the hydropulser running, is a source of broad-band vibrations. Removing these unfavourable influences, which act negatively on environment and especially on human beings, is by an elastic support possible. Rubber or air springs are inserted between the frame of the hydropulser and the floor. Under these conditions, the transmission of vibration transferred to the floor declines according to values of natural frequencies. In this paper are discussed two possibilities of base plate (base) support. Especially using of air springs shows high efficiency of vibration insulation springing base