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Advanced Materials Structures for Sound and Vibration Damping
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Advanced Materials Structures for Sound and Vibration Damping

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Materials Physics".

Deadline for manuscript submissions: closed (20 August 2023) | Viewed by 25432

Special Issue Editor

Dr. Martin Vašina

E-Mail Website
Guest Editor
Department of Physics and Materials Engineering, Tomas Bata University in Zlín, Vavrečkova 5669, 760 01 Zlín, Czech Republic
Interests: vibration damping; sound absorption; viscoelasticity; mechanical properties of materials; 3D printing; light absorption

Special Issue Information

Dear Colleagues,

Noise and mechanical vibration belong to negative environmental factors in many cases. They can have an adverse effect on human health, accuracy of manufacture, service life of processing equipment and tools, labor protection and so on. For these reasons, it is necessary to eliminate undesirable noise and mechanical vibration by appropriate means. There are different possibilities to reduce excessive noise and mechanical vibrations.

The aim of this Special Issue is to develop advanced material structures for noise and vibration damping. The articles presented in this Special Issue will cover various topics that have a significant influence on sound absorption and mechanical vibration damping of material structures, ranging from but not limited to manufacturing technologies of materials, composite and multilayer structures, mathematical simulations and experimental investigation of vibroacoustic properties, production efficiency, mechanical properties, and practical applications of advanced material structures, among others. Topics are also open to utilization of different types of recycled materials for these purposes, which can be also beneficial to our environment.

Dr. Martin Vašina
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • sound absorption
  • mechanical vibration
  • material structures
  • mechanical properties
  • viscoelasticity
  • manufacturing technologies
  • composite materials
  • mathematical simulations
  • porosity
  • excitation frequency
  • multilayer structures
  • microscopy

Published Papers (15 papers)

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Editorial

Jump to: Research

2 pages, 174 KiB  
Editorial
Advanced Materials Structures for Sound and Vibration Damping
by Martin Vašina
Materials 2022, 15(4), 1295; https://doi.org/10.3390/ma15041295 - 10 Feb 2022
Cited by 2 | Viewed by 1782
Abstract
The studies of sound and vibration are closely related [...] Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)

Research

Jump to: Editorial

18 pages, 8752 KiB  
Article
Theoretical and Experimental Analyses on the Sound Absorption Coefficient of Rice and Buckwheat Husks Based on Micro-CT Scan Data
by Shuichi Sakamoto, Kentaro Toda, Shotaro Seino, Kohta Hoshiyama and Takamasa Satoh
Materials 2023, 16(16), 5671; https://doi.org/10.3390/ma16165671 - 17 Aug 2023
Cited by 1 | Viewed by 761
Abstract
In this study, the sound absorption coefficients of rice and buckwheat husks were estimated. Computed tomography (CT) images were processed to determine the circumference and surface area of voids in the granular material, and the normal incident sound absorption coefficients were derived. In [...] Read more.
In this study, the sound absorption coefficients of rice and buckwheat husks were estimated. Computed tomography (CT) images were processed to determine the circumference and surface area of voids in the granular material, and the normal incident sound absorption coefficients were derived. In addition, the tortuosity, which expresses the complexity of the sound wave propagation through the structure, was measured for each material. The theoretical sound absorption coefficients were then compared to the measured sound absorption coefficients with and without consideration of the tortuosity. A correction factor was used to bring the surface area of the granular material closer to the actual surface area and observed that the tortuosity obtained theoretical values that matched the trend of the measured values. These results indicate that using CT images to estimate the sound absorption coefficient is a viable approach. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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17 pages, 6508 KiB  
Article
Experimental Validation of Dynamic Response of Small-Scale Metaconcrete Beams at Resonance Vibration
by Meisam Ansari, Fabiola Tartaglione and Carsten Koenke
Materials 2023, 16(14), 5029; https://doi.org/10.3390/ma16145029 - 16 Jul 2023
Cited by 1 | Viewed by 655
Abstract
Structures and their components experience substantially large vibration amplitudes at resonance, which can cause their failure. The scope of this study is the utilization of silicone-coated steel balls in concrete as damping aggregates to suppress the resonance vibration. The heavy steel cores oscillate [...] Read more.
Structures and their components experience substantially large vibration amplitudes at resonance, which can cause their failure. The scope of this study is the utilization of silicone-coated steel balls in concrete as damping aggregates to suppress the resonance vibration. The heavy steel cores oscillate with a frequency close to the resonance frequency of the structure. Due to the phase difference between the vibrations of the cores and the structure, the cores counteract the vibration of the structure. The core-coating inclusions are randomly distributed in concrete similar to standard aggregates. This mixture is referred to as metaconcrete. The main goal of this work is to validate the ability of the inclusions to suppress mechanical vibration through laboratory experiments. For this purpose, two small-scale metaconcrete beams were cast and tested. In a free vibration test, the metaconcrete beams exhibited a larger damping ratio compared to a similar beam cast from conventional concrete. The vibration amplitudes of the metaconcrete beams at resonance were measured with a frequency sweep test. In comparison with the conventional concrete beam, both metaconcrete beams demonstrated smaller vibration amplitudes. Both experiments verified an improvement in the dynamic response of the metaconcrete beams at resonance vibration. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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23 pages, 8833 KiB  
Article
Fretting Fatigue Life Prediction of Dovetail Structure Based on Plastic Effect and Sensitivity Analysis of Influencing Factors
by Jianjun Zhou, Bowen Yang, Shuaiyuan Li and Junzhou Huo
Materials 2023, 16(9), 3521; https://doi.org/10.3390/ma16093521 - 04 May 2023
Viewed by 1196
Abstract
Micro relative sliding exists on the contact surface of the main primary equipment’s surface structures, resulting in serious fretting fatigue. The plastic effect causes serious fatigue to the structure under alternating loads. Existing fatigue life prediction models fail to fully consider the shortcomings [...] Read more.
Micro relative sliding exists on the contact surface of the main primary equipment’s surface structures, resulting in serious fretting fatigue. The plastic effect causes serious fatigue to the structure under alternating loads. Existing fatigue life prediction models fail to fully consider the shortcomings of fretting and plastic effects, which causes the prediction results to be significantly different to real-lifeworld in engineering situations. Therefore, it is urgent to establish a fretting damage fatigue life prediction model of contact structures which considers plastic effects. In this study, a plastic fretting fatigue life prediction model was established according to the standard structural contact theory. The location of dangerous points was evaluated according to a finite element simulation. The cyclic load maximum stress value was compared with the fretting fatigue test data to confirm the error value, and the error between the proposed fretting fatigue life model and the test value was within 15%. Concurrently, we combined this with mass data analysis and research, as it is known that the contact zone parameters have an impact on fretting fatigue and affect the structural lifespan. With the help of ABAQUS, the fretting numerical calculation of the dovetail tenon model was carried out to analyze the sensitive factors affecting the fretting fatigue life of the dovetail tenon structure. By keeping the fretting load unchanged, the contact area parameters such as contact surface form, contact area width and friction coefficient were changed in order to calculate the fretting stress value, σfretting and the dovetail structure was improved to extend its fretting fatigue life. Finally, it was concluded that fretting fatigue was most sensitive to the width and contact form of the contact area. In actual engineering design, multiple factors should be considered comprehensively to determine a more accurate and suitable width and form of the contact area. For the selection of friction coefficient, on the premise of saving costs and meeting the structural strength requirements, the friction coefficient should be as small as possible, and the problem can also be solved through lubrication during processing. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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19 pages, 9100 KiB  
Article
Mathematical Model for Estimating the Sound Absorption Coefficient in Grid Network Structures
by Takamasa Satoh, Shuichi Sakamoto, Takunari Isobe, Kenta Iizuka and Kastsuhiko Tasaki
Materials 2023, 16(3), 1124; https://doi.org/10.3390/ma16031124 - 28 Jan 2023
Cited by 1 | Viewed by 1257
Abstract
Although grid network structures are often not necessarily intended to absorb sound, the gaps between the rods that make up the grid network are expected to have a sound absorption effect. In this study, the one-dimensional transfer matrix method was used to develop [...] Read more.
Although grid network structures are often not necessarily intended to absorb sound, the gaps between the rods that make up the grid network are expected to have a sound absorption effect. In this study, the one-dimensional transfer matrix method was used to develop a simple mathematical model for accurately estimating the sound absorption coefficient of a grid network structure. The gaps in the grid network structure were approximated as the clearance between two parallel planes, and analysis units were derived to consider the exact geometry of the layers. The characteristic impedance and propagation constant were determined for the approximated gaps and treated as a one-dimensional transfer matrix. The transfer matrix obtained for each layer was used to calculate the sound absorption coefficient. The samples were fabricated from light-curing resin by using a Form2 3D printer from Formlabs. The measurement results showed that a sound absorption coefficient of 0.81 was obtained at the peak when seven layers were stacked. A sensitivity analysis was carried out to investigate the influence of the rod diameter and pitch. The simulated values tended to be close to the experimental values. The above results indicate that the mathematical model used to calculate the sound absorption coefficient is sufficiently accurate to predict the sound absorption coefficient for practical application. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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13 pages, 11367 KiB  
Article
Estimation of the Acoustic Properties of the Random Packing Structures of Granular Materials: Estimation of the Sound Absorption Coefficient Based on Micro-CT Scan Data
by Shuichi Sakamoto, Kyosuke Suzuki, Kentaro Toda and Shotaro Seino
Materials 2023, 16(1), 337; https://doi.org/10.3390/ma16010337 - 29 Dec 2022
Cited by 1 | Viewed by 1087
Abstract
In this study, the sound absorption properties of randomly packed granular materials were estimated. Generally, it is difficult to construct a general mathematical model for the arrangement of randomly packed granular materials. Therefore, in this study, an attempt was made to estimate the [...] Read more.
In this study, the sound absorption properties of randomly packed granular materials were estimated. Generally, it is difficult to construct a general mathematical model for the arrangement of randomly packed granular materials. Therefore, in this study, an attempt was made to estimate the sound absorption coefficient using a theoretical analysis by introducing data from computed tomography (CT) scans, as the tomographic images of CT scans correspond to the slicing and elemental division of packing structures. In the theoretical analysis, the propagation constants and characteristic impedances in the voids were obtained by approximating each tomographic image as a void between two parallel planes. The derived propagation constants and characteristic impedances were then treated as a one-dimensional transfer matrix in the propagation of sound waves, and the transfer matrix method was used to calculate the normal incident sound absorption coefficient. The theoretical value of the sound absorption coefficient was derived using the effective density to which the measured tortuosity was applied. As a result, for the theoretical values considering the tortuosity, in many cases, the theoretical values were close to the measured values. For the theoretical values, when both the surface area and tortuosity were considered, the peak sound absorption frequency moved to a lower frequency and was in general agreement with the measured values. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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14 pages, 3976 KiB  
Article
Mathematical Models and Experiments on the Acoustic Properties of Granular Packing Structures (Measurement of Tortuosity in Hexagonal Close-Packed and Face-Centered Cubic Lattices)
by Shuichi Sakamoto, Kyosuke Suzuki, Kentaro Toda and Shotaro Seino
Materials 2022, 15(20), 7393; https://doi.org/10.3390/ma15207393 - 21 Oct 2022
Cited by 2 | Viewed by 1155
Abstract
In this study, the sound absorption characteristics of hexagonal close-packed and face-centered cubic lattices were estimated by theoretical analysis. Propagation constants and characteristic impedances were obtained by dividing each structure into elements perpendicular to the incident direction of sound waves and by approximating [...] Read more.
In this study, the sound absorption characteristics of hexagonal close-packed and face-centered cubic lattices were estimated by theoretical analysis. Propagation constants and characteristic impedances were obtained by dividing each structure into elements perpendicular to the incident direction of sound waves and by approximating each element to a clearance between two parallel planes. Consequently, the propagation constant and the characteristic impedance were treated as a one-dimensional transfer matrix in the propagation of sound waves, and the normal incident sound absorption coefficient was calculated by the transfer matrix method. The theoretical value of the sound absorption coefficient was derived by using the effective density applied to the measured tortuosity. As a result, the theoretical value was becoming closer to the measured value. Therefore, the measured tortuosity is reasonable. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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20 pages, 9626 KiB  
Article
Optimal Design of Acoustic Metamaterial of Multiple Parallel Hexagonal Helmholtz Resonators by Combination of Finite Element Simulation and Cuckoo Search Algorithm
by Fei Yang, Enshuai Wang, Xinmin Shen, Xiaonan Zhang, Qin Yin, Xinqing Wang, Xiaocui Yang, Cheng Shen and Wenqiang Peng
Materials 2022, 15(18), 6450; https://doi.org/10.3390/ma15186450 - 16 Sep 2022
Cited by 15 | Viewed by 2013
Abstract
To achieve the broadband sound absorption at low frequencies within a limited space, an optimal design of joint simulation method incorporating the finite element simulation and cuckoo search algorithm was proposed. An acoustic metamaterial of multiple parallel hexagonal Helmholtz resonators with sub-wavelength dimensions [...] Read more.
To achieve the broadband sound absorption at low frequencies within a limited space, an optimal design of joint simulation method incorporating the finite element simulation and cuckoo search algorithm was proposed. An acoustic metamaterial of multiple parallel hexagonal Helmholtz resonators with sub-wavelength dimensions was designed and optimized in this research. First, the initial geometric parameters of the investigated acoustic metamaterials were confirmed according to the actual noise reduction requirements to reduce the optimization burden and improve the optimization efficiency. Then, the acoustic metamaterial with the various depths of the necks was optimized by the joint simulation method, which combined the finite element simulation and the cuckoo search algorithm. The experimental sample was prepared using the 3D printer according to the obtained optimal parameters. The simulation results and experimental results exhibited excellent consistency. Compared with the derived sound absorption coefficients by theoretical modeling, those achieved in the finite element simulation were closer to the experimental results, which also verified the accuracy of this optimal design method. The results proved that the optimal design method was applicable to the achievement of broadband sound absorption with different low frequency ranges, which provided a novel method for the development and application of acoustic metamaterials. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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14 pages, 1039 KiB  
Article
Experimental Studies on Adaptive-Passive Symmetrical Granular Damper Operation
by Mateusz Żurawski and Robert Zalewski
Materials 2022, 15(17), 6170; https://doi.org/10.3390/ma15176170 - 05 Sep 2022
Viewed by 1257
Abstract
This paper presents experimental studies on a controllable granular damper, whose dissipative properties are provided by the friction phenomenon occuring between loose granular material. In addition, in order to adjust to the current trends in vibration suppression, we built a semi-active device, controlled [...] Read more.
This paper presents experimental studies on a controllable granular damper, whose dissipative properties are provided by the friction phenomenon occuring between loose granular material. In addition, in order to adjust to the current trends in vibration suppression, we built a semi-active device, controlled by a single parameter—underpressure. Such granular structures subjected to underpressure are called Vacuum-Packed Particles. The first section presents the state of the art. A brief description of the most often used intelligent and smart materials for the manufacture of dampers is presented. The main advantages of the proposed device are a simple structure, low construction cost, symmetrical principle of operation, and the ability to change the characteristics of the damper by quickly and suddenly changing the negative pressure inside the granular core. The second section provides a detailed description of the construction and operation principles of the original symmetrical granular damper. A description of its application in the laboratory research test stand is also provided. The third section presents the results of the experimental studies including the recorded damping characteristics of the investigated damper. The effectiveness of the ethylene–propylene–diene grains’ application is presented. The two parameters of underpressure and frequency of excitation were considered during the empirical tests. The influence of the system parameters on its global dissipative behavior is discussed in detail. The damper operation characteristics are close to linear, which is positive information from the point of view of the potential adaptive-passive control process. Brief conclusions and the prospective application of vacuum-packed particle dampers are presented in the final section. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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14 pages, 3145 KiB  
Article
Addition of Two Substantial Side-Branch Silencers to the Interference Silencer by Incorporating a Zero-Mass Metamaterial
by Shuichi Sakamoto, Juung Shin, Shota Abe and Kentaro Toda
Materials 2022, 15(15), 5140; https://doi.org/10.3390/ma15155140 - 24 Jul 2022
Cited by 1 | Viewed by 1557
Abstract
Zero-mass metamaterials comprise an orifice and a thin film. The resonance between the film and the air mass of the orifice hole is caused by sound waves, which significantly decreases the transmission loss at a specific frequency. The study novelly incorporates acoustic metamaterials [...] Read more.
Zero-mass metamaterials comprise an orifice and a thin film. The resonance between the film and the air mass of the orifice hole is caused by sound waves, which significantly decreases the transmission loss at a specific frequency. The study novelly incorporates acoustic metamaterials in the delay tube of an interference silencer. In this case, it is determined that an interference silencer and a “side-branch silencer with two different branch pipe lengths” can be realized in a single silencer. At certain frequencies, the acoustic mass of the acoustic metamaterial approaches zero, which results in an interference silencer with the full length of the delay tube applied. At other frequencies, the acoustic metamaterial acts as a rigid wall with high transmission loss, thereby reflecting sound waves at the zero-mass metamaterial location. In this case, it is a side-branch silencer with two different tube lengths, corresponding to the tube lengths from the entrance and exit of the delay tube to the zero-mass metamaterial, respectively. The incorporation of zero-mass metamaterial into an interference-type silencer can introduce the silencing effect of a side-branch silencer with two different branch tube lengths without increasing the volume of the interference-type silencer. Theoretical values were obtained using the transfer matrix. Consequently, the theoretical and experimental values were close, enabling us to predict the transmission loss of the proposed silencer. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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11 pages, 3007 KiB  
Article
Effect of Sheet Vibration on the Theoretical Analysis and Experimentation of Nonwoven Fabric Sheet with Back Air Space
by Shuichi Sakamoto, Ryo Iizuka and Takumi Nozawa
Materials 2022, 15(11), 3840; https://doi.org/10.3390/ma15113840 - 27 May 2022
Cited by 2 | Viewed by 1140
Abstract
The purpose of this study was to improve the accuracy of the theoretical analysis of sound absorption mechanisms when a back air space is used in nonwoven fabrics. In the case of a nonwoven sheet with a back air space, it can be [...] Read more.
The purpose of this study was to improve the accuracy of the theoretical analysis of sound absorption mechanisms when a back air space is used in nonwoven fabrics. In the case of a nonwoven sheet with a back air space, it can be shown that there is a difference between the experimental results and theoretical analysis results obtained using the Miki model when the area of the nonwoven sheet is large. Therefore, in this study, the accuracy of the theoretical values was improved using the plate vibration model in conjunction with the Miki model. The experimental results showed that when the vibration of the nonwoven sheet was suppressed, the sound absorption coefficient was higher than that of the vibration-prone nonwoven sheet alone. The sound absorption coefficient at the peak frequency was increased by >0.2, especially for 3501BD. Using the support frame, the sound absorption coefficient at the peak frequencies of 3A01A and 3701B was increased to 0.99. In the theoretical analysis of a large-area, vibration-prone nonwoven fabric, in which the vibration of the nonwoven fabric was taken into account, the theoretical values were in agreement with the experimental values, and the accuracy of the theoretical values was improved. Comparing the theoretical values for nonwoven fabrics without high ventilation resistance, the sound absorption coefficient was greater when vibration was not considered. Therefore, it was suggested that the vibration of the nonwoven fabric hinders sound absorption. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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17 pages, 26871 KiB  
Article
A New Efficient Approach to Simulate Material Damping in Metals by Modeling Thermoelastic Coupling
by Christin Zacharias, Carsten Könke and Christian Guist
Materials 2022, 15(5), 1706; https://doi.org/10.3390/ma15051706 - 24 Feb 2022
Cited by 1 | Viewed by 1387
Abstract
The realistic prediction of material damping is crucial in the design and dynamic simulation of many components in mechanical engineering. Material damping in metals occurs mainly due to the thermoelastic effect. This paper presents a new approach for implementing thermoelastic damping into finite [...] Read more.
The realistic prediction of material damping is crucial in the design and dynamic simulation of many components in mechanical engineering. Material damping in metals occurs mainly due to the thermoelastic effect. This paper presents a new approach for implementing thermoelastic damping into finite element simulations, which provides an alternative to computationally intensive, fully coupled thermoelastic simulations. A significantly better agreement between simulation results and experimental data was achieved, when compared with the empirical damping values found in the literature. The method is based on the calculation of the generated heat within a vibration cycle. The temperature distribution is determined by the mechanical eigenmodes and the energy converted into heat, and thus dissipated, is calculated. This algorithm leads to modal damping coefficients that can then be used in subsequent analyses of dynamically excited oscillations. The results were validated with experimental data obtained from vibration tests. In order to measure material damping only, a test setup excluding friction and environmental influences was developed. Furthermore, comparisons with fully coupled thermoelastic simulations were performed. It was clear that the new approach achieved results comparable to those of a computationally expensive, coupled simulation with regard to the loss factors and frequency response analyses. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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14 pages, 1664 KiB  
Article
Natural Frequencies Optimization of Thin-Walled Circular Cylindrical Shells Using Axially Functionally Graded Materials
by Nabeel Taiseer Alshabatat
Materials 2022, 15(3), 698; https://doi.org/10.3390/ma15030698 - 18 Jan 2022
Cited by 9 | Viewed by 1829
Abstract
One method to avoid vibration resonance is shifting natural frequencies far away from excitation frequencies. This study investigates optimizing the natural frequencies of circular cylindrical shells using axially functionally graded materials. The constituents of functionally graded materials (FGMs) vary continuously in the longitudinal [...] Read more.
One method to avoid vibration resonance is shifting natural frequencies far away from excitation frequencies. This study investigates optimizing the natural frequencies of circular cylindrical shells using axially functionally graded materials. The constituents of functionally graded materials (FGMs) vary continuously in the longitudinal direction based on a trigonometric law or using interpolation of volume fractions at control points. The spatial change of material properties alters structural stiffness and mass, which then affects the structure’s natural frequencies. The local material properties at any place in the structure are obtained using Voigt model. First-order shear deformation theory and finite element method are used for estimating natural frequencies, and a genetic algorithm is used for optimizing material volume fractions. To demonstrate the proposed method, two optimization problems are presented. The goal of the first one is to maximize the fundamental frequency of an FGM cylindrical shell by optimizing the material volume fractions. In the second problem, we attempt to find the optimal material distribution that maximizes the distance between two adjoining natural frequencies. The optimization examples show that building cylindrical shells using axially FGM is a useful technique for optimizing their natural frequencies. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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10 pages, 3055 KiB  
Article
Effect of Conditioning on PU Foam Matrix Materials Properties
by Lubomír Lapčík, Martin Vašina, Barbora Lapčíková and Yousef Murtaja
Materials 2022, 15(1), 195; https://doi.org/10.3390/ma15010195 - 28 Dec 2021
Cited by 3 | Viewed by 3190
Abstract
This article deals with the characterization of the thermal-induced aging of soft polyurethane (PU) foams. There are studied thermal and mechanical properties by means of thermal analysis, tensile, compression and dynamic mechanical vibration testing. It was found in this study, that the increasing [...] Read more.
This article deals with the characterization of the thermal-induced aging of soft polyurethane (PU) foams. There are studied thermal and mechanical properties by means of thermal analysis, tensile, compression and dynamic mechanical vibration testing. It was found in this study, that the increasing relative humidity of the surrounding atmosphere leads to the initiation of the degradation processes. This is reflected in the observed decreased mechanical stiffness. It is attributed to the plasticization of the PU foams wall material. It is in agreement with the observed increase of the permanent deformation accompanied simultaneously with the decrease of Young’s modulus of elasticity. The latter phenomenon is studied by the novel non-destructive forced oscillations vibration-damping testing, which is confirmed by observed lower mechanical stiffness thus indicating the loss of the elasticity induced by samples conditioning. In parallel, observed decreasing of the matrix hardness is confirming the loss of elastic mechanical performance as well. The effect of conditioning leads to the significant loss of the PU foam’s thermal stability. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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18 pages, 2724 KiB  
Article
Study of the Mechanical, Sound Absorption and Thermal Properties of Cellular Rubber Composites Filled with a Silica Nanofiller
by Marek Pöschl and Martin Vašina
Materials 2021, 14(23), 7450; https://doi.org/10.3390/ma14237450 - 04 Dec 2021
Cited by 4 | Viewed by 3302
Abstract
This paper deals with the study of cellular rubbers, which were filled with silica nanofiller in order to optimize the rubber properties for given purposes. The rubber composites were produced with different concentrations of silica nanofiller at the same blowing agent concentration. The [...] Read more.
This paper deals with the study of cellular rubbers, which were filled with silica nanofiller in order to optimize the rubber properties for given purposes. The rubber composites were produced with different concentrations of silica nanofiller at the same blowing agent concentration. The mechanical, sound absorption and thermal properties of the investigated rubber composites were evaluated. It was found that the concentration of silica filler had a significant effect on the above-mentioned properties. It was detected that a higher concentration of silica nanofiller generally led to an increase in mechanical stiffness and thermal conductivity. Conversely, sound absorption and thermal degradation of the investigated rubber composites decreased with an increase in the filler concentration. It can be also concluded that the rubber composites containing higher concentrations of silica filler showed a higher stiffness to weight ratio, which is one of the great advantages of these materials. Based on the experimental data, it was possible to find a correlation between mechanical stiffness of the tested rubber specimens evaluated using conventional and vibroacoustic measurement techniques. In addition, this paper presents a new methodology to optimize the blowing and vulcanization processes of rubber samples during their production. Full article
(This article belongs to the Special Issue Advanced Materials Structures for Sound and Vibration Damping)
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