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18 pages, 3787 KiB

Open AccessArticle

The Magnetoelastic Contribution to the Steel Internal Damping

by Antonietta Lo Conte

Materials 2023, 16(8), 3190; https://doi.org/10.3390/ma16083190 - 18 Apr 2023

Viewed by 655

In this paper, the steel internal damping due to both the thermoelastic and the magnetoelastic phenomena has been investigated through a formulation based on thermodynamical potential joints with a hysteretic damping model. With the aim of focusing on the temperature transient in the [...] Read more.

In this paper, the steel internal damping due to both the thermoelastic and the magnetoelastic phenomena has been investigated through a formulation based on thermodynamical potential joints with a hysteretic damping model. With the aim of focusing on the temperature transient in the solid, a first configuration has been considered, which is characterized by a steel rod with an imposed alternating pure shear strain in which only the thermoelastic contribution was studied. The magnetoelastic contribution was then introduced in a further configuration, in which a steel rod in free motion was subjected to torsion on its ends in the presence of a constant magnetic field. A quantitative assessment of the influence of the magnetoelastic dissipation in steel has been computed according to the Sablik-Jiles model by giving a comparison between the thermoelastic and the prevailing magnetoelastic damping coefficients. Full article

(This article belongs to the Special Issue Experimental Characterization and Numerical Modelling of Damping Capacity for Classical and Innovative Materials)

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21 pages, 9336 KiB

Open AccessArticle

Experimental Characterization, Modeling, and Numerical Evaluation of a Novel Friction Damper for the Seismic Upgrade of Existing Buildings

by Eleonora Bruschi, Luca Zoccolini, Sara Cattaneo and Virginio Quaglini

Materials 2023, 16(5), 1933; https://doi.org/10.3390/ma16051933 - 26 Feb 2023

Cited by 10 | Viewed by 1490

Abstract

The paper presents the experimental characterization, the formulation of a numerical model, and the evaluation, by means of non-linear analyses, of a new friction damper conceived for the seismic upgrade of existing building frames. The damper dissipates seismic energy through the friction force [...] Read more.

The paper presents the experimental characterization, the formulation of a numerical model, and the evaluation, by means of non-linear analyses, of a new friction damper conceived for the seismic upgrade of existing building frames. The damper dissipates seismic energy through the friction force triggered between a steel shaft and a lead core prestressed within a rigid steel chamber. The friction force is adjusted by controlling the prestress of the core, allowing the achievement of high forces with small dimensions, and reducing the architectural invasiveness of the device. The damper has no mechanical parts subjected to cyclic strain above their yield limit, thereby avoiding any risk of low-cycle fatigue. The constitutive behavior of the damper was assessed experimentally, demonstrating a rectangular hysteresis loop with an equivalent damping ratio of more than 55%, a stable behavior over repeated cycles, and a low dependency of the axial force on the rate of displacement. A numerical model of the damper was formulated in the OpenSees software by means of a rheological model comprising an in-parallel system of a non-linear spring element and a Maxwell element, and the model was calibrated on the experimental data. To assess the viability of the damper for the seismic rehabilitation of buildings, a numerical investigation was conducted by performing non-linear dynamic analyses on two case-study structures. The results highlight the benefits of the PS-LED in dissipating the largest part of seismic energy, limiting the lateral deformation of the frames, and controlling the increase in structural accelerations and internal forces at the same time. Full article

(This article belongs to the Special Issue Experimental Characterization and Numerical Modelling of Damping Capacity for Classical and Innovative Materials)

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18 pages, 5713 KiB

Open AccessArticle

Metaconcrete: An Experimental Study on the Impact of the Core-Coating Inclusions on Mechanical Vibration

by Meisam Ansari, Christin Zacharias and Carsten Koenke

Materials 2023, 16(5), 1836; https://doi.org/10.3390/ma16051836 - 23 Feb 2023

Cited by 3 | Viewed by 1394

Abstract

Resonance vibration of structures is an unpleasant incident that can be conventionally avoided by using a Tuned Mass Damper (TMD). The scope of this paper contains the utilization of engineered inclusions in concrete as damping aggregates to suppress resonance vibration similar to a [...] Read more.

Resonance vibration of structures is an unpleasant incident that can be conventionally avoided by using a Tuned Mass Damper (TMD). The scope of this paper contains the utilization of engineered inclusions in concrete as damping aggregates to suppress resonance vibration similar to a TMD. The inclusions are composed of a stainless-steel core with a spherical shape coated with silicone. This configuration has been the subject of several studies and it is best known as Metaconcrete. This paper presents the procedure of a free vibration test conducted with two small-scaled concrete beams. The beams exhibited a higher damping ratio after the core-coating element was secured to them. Subsequently, two meso-models of small-scaled beams were created: one representing conventional concrete and the other representing concrete with the core-coating inclusions. The frequency response curves of the models were obtained. The change in the response peak verified the ability of the inclusions to suppress the resonance vibration. This study concludes that the core-coating inclusions can be utilized in concrete as damping aggregates. Full article

(This article belongs to the Special Issue Experimental Characterization and Numerical Modelling of Damping Capacity for Classical and Innovative Materials)

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10 pages, 3351 KiB

Open AccessArticle

Magnetic Damping and Dzyaloshinskii–Moriya Interactions in Pt/Co₂FeAl/MgO Systems Grown on Si and MgO Substrates

by Nabil Challab, Yves Roussigné, Salim Mourad Chérif, Mihai Gabor and Mohamed Belmeguenai

Materials 2023, 16(4), 1388; https://doi.org/10.3390/ma16041388 - 7 Feb 2023

Cited by 1 | Viewed by 1019

Abstract

Spin-pumping-induced damping and interfacial Dzyaloshinskii–Moriya interaction (iDMI) have been studied in Pt/Co₂FeAl/MgO systems grown on Si or MgO substrates as a function of Pt and Co₂FeAl (CFA) thicknesses. For this, we combined vibrating sample magnetometry (VSM), microstrip ferromagnetic resonance [...] Read more.

Spin-pumping-induced damping and interfacial Dzyaloshinskii–Moriya interaction (iDMI) have been studied in Pt/Co₂FeAl/MgO systems grown on Si or MgO substrates as a function of Pt and Co₂FeAl (CFA) thicknesses. For this, we combined vibrating sample magnetometry (VSM), microstrip ferromagnetic resonance (MS-FMR), and Brillouin light scattering (BLS). VSM measurements of the magnetic moment at saturation per unit area revealed the absence of a magnetic dead layer in both systems, with a higher magnetization at saturation obtained for CFA grown on MgO. The key parameters governing the spin-dependent transport through the Pt/CFA interface, including the spin mixing conductance and the spin diffusion length, have been determined from the CFA and the Pt thickness dependence of the damping. BLS has been used to measure the spin wave non-reciprocity via the frequency mismatch between the Stokes and anti-Stokes lines. iDMI has been separated from the contribution of the interface perpendicular anisotropy difference between Pt/CFA and CFA/MgO. Our investigation revealed that both iDMI strength and spin pumping efficiency are higher for CFA-based systems grown on MgO due to its epitaxial growth confirmed by MS-FMR measurements of the in-plane magnetic anisotropy. This suggests that CFA grown on MgO could be a promising material candidate as a spin injection source via spin pumping and for other spintronic applications. Full article

(This article belongs to the Special Issue Experimental Characterization and Numerical Modelling of Damping Capacity for Classical and Innovative Materials)

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20 pages, 5210 KiB

Open AccessEditor’s ChoiceArticle

Damping Behaviour and Mechanical Properties of Restorative Materials for Primary Teeth

by Thomas Niem, Roland Frankenberger, Stefanie Amend, Bernd Wöstmann and Norbert Krämer

Materials 2022, 15(21), 7698; https://doi.org/10.3390/ma15217698 - 2 Nov 2022

Viewed by 1538

Abstract

The energy dissipation capacity and damping ability of restorative materials used to restore deciduous teeth were assessed compared to common mechanical properties. Mechanical properties (flexural strength, modulus of elasticity, modulus of toughness) for Compoglass F, Dyract eXtra, SDR flow, Tetric Evo Ceram, Tetric [...] Read more.

The energy dissipation capacity and damping ability of restorative materials used to restore deciduous teeth were assessed compared to common mechanical properties. Mechanical properties (flexural strength, modulus of elasticity, modulus of toughness) for Compoglass F, Dyract eXtra, SDR flow, Tetric Evo Ceram, Tetric Evo Ceram Bulk Fill, and Venus Diamond were determined using a 4-point bending test. Vickers hardness and Martens hardness, together with its plastic index (η_ITdis), were recorded using instrumented indentation testing. Leeb hardness (HLD) and its deduced energy dissipation data (HLD_dis) were likewise determined. The reliability of materials was assessed using Weibull analysis. For common mechanical properties, Venus Diamond always exhibited the significantly highest results and SDR flow the lowest, except for flexural strength. Independently determined damping parameters (modulus of toughness, HLD_dis, η_ITdis) invariably disclosed the highest values for SDR flow. Composite materials, including SDR flow, showed markedly higher reliabilities (Weibull modulus) than Compoglass F and Dyract eXtra. SDR flow showed pronounced energy dissipation and damping characteristics, making it the most promising material for a biomimetic restoration of viscoelastic dentin structures in deciduous teeth. Future developments in composite technology should implement improved resin structures that facilitate damping effects in artificial restorative materials. Full article

(This article belongs to the Special Issue Experimental Characterization and Numerical Modelling of Damping Capacity for Classical and Innovative Materials)

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23 pages, 10293 KiB

Open AccessArticle

Identification of Vibration Modes and Wave Propagation of Operational Rails by Multipoint Hammering and Reciprocity Theorem

by Kodai Matsuoka, Kazuhiro Kajihara and Hirofumi Tanaka

Materials 2022, 15(3), 811; https://doi.org/10.3390/ma15030811 - 21 Jan 2022

Cited by 7 | Viewed by 1968

Abstract

Vertical bending vibration modes and rail wave propagation, including the damping characteristics, are the factors that cause rail corrugation. However, the ability to identify actual railways has been limited because of the huge number of sensors required for field tests. In this study, [...] Read more.

Vertical bending vibration modes and rail wave propagation, including the damping characteristics, are the factors that cause rail corrugation. However, the ability to identify actual railways has been limited because of the huge number of sensors required for field tests. In this study, a novel and field-applicable method for identifying rail vibration modes and wave propagation characteristics is developed by multipoint hammering and the reciprocity theorem instead of multipoint measuring. Additionally, the proposed method is applied to an actual rail with a direct fastening track system on a bridge that has corrugation with a wavelength of approximately 0.04 m. As a result, the wavelength (wavenumber)-, group velocity-, and distance damping (attenuation) frequency relationship of the wave propagation is clarified in addition to the rail frequencies and mode shapes up to approximately 1500 Hz, including the pinned-pinned mode. Finally, the identified wavelength-frequency relationships and the measured rail irregularity can empirically demonstrate that the generated corrugation on the rail is produced by wave interference on the two axles in the bogie. Full article

(This article belongs to the Special Issue Experimental Characterization and Numerical Modelling of Damping Capacity for Classical and Innovative Materials)

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18 pages, 3387 KiB

Open AccessArticle

Testing and Modelling of Elastomeric Element for an Embedded Rail System

by Qianqian Li, Roberto Corradi, Egidio Di Gialleonardo, Stefano Bionda and Andrea Collina

Materials 2021, 14(22), 6968; https://doi.org/10.3390/ma14226968 - 18 Nov 2021

Cited by 6 | Viewed by 1857

Abstract

Modelling of elastomeric elements of railway components, able to represent stiffness and damping characteristics in a wide frequency range, is fundamental for simulating the train–track dynamic interaction, covering issues such as rail deflection as well as transmitted forces and higher frequency phenomena such [...] Read more.

Modelling of elastomeric elements of railway components, able to represent stiffness and damping characteristics in a wide frequency range, is fundamental for simulating the train–track dynamic interaction, covering issues such as rail deflection as well as transmitted forces and higher frequency phenomena such as short pitch corrugation. In this paper, a modified non-linear Zener model is adopted to represent the dependences of stiffness and damping of the rail fastening, made of elastomeric material, of a reference Embedded Rail System (ERS) on the static preload and frequency of its deformation. In order to obtain a reliable model, a proper laboratory test set-up is built, considering sensitivity and frequency response issues. The equivalent stiffness and damping of the elastomeric element are experimentally characterised with force-controlled mono-harmonic tests at different frequencies and under various static preloads. The parameters of the non-linear Zener model are identified by the experimental equivalent stiffness and damping. The identified model correctly reproduces the frequency- and preload-dependent dynamic properties of the elastomeric material. The model is verified to be able to predict the dynamic behaviour of the elastomeric element through the comparison between the numerically simulated and the experimentally measured reaction force to a given deformation time history. Time domain simulations with the model of the reference ERS demonstrate that the modelled frequency- and preload-dependent stiffness and damping of the elastomeric material make a clear difference in the transient and steady-state response of the system when distant frequency contributions are involved. Full article

(This article belongs to the Special Issue Experimental Characterization and Numerical Modelling of Damping Capacity for Classical and Innovative Materials)

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20 pages, 6387 KiB

Open AccessArticle

Study on Possible Application of Rubber Granulate from the Recycled Tires as an Elastic Cover of Prototype Rail Dampers, with a Focus on Their Operational Durability

by Cezary Kraśkiewicz, Bogumiła Chmielewska, Artur Zbiciak and Anna Al Sabouni-Zawadzka

Materials 2021, 14(19), 5711; https://doi.org/10.3390/ma14195711 - 30 Sep 2021

Cited by 8 | Viewed by 1837

Abstract

This study is an attempt to investigate possible applications of rubber granulate SBR (styrene-butadiene rubber) produced from recycled waste tires as an elastic cover for prototype rail dampers, which are aimed at reducing the level of railway noise emitted in the environment. The [...] Read more.

This study is an attempt to investigate possible applications of rubber granulate SBR (styrene-butadiene rubber) produced from recycled waste tires as an elastic cover for prototype rail dampers, which are aimed at reducing the level of railway noise emitted in the environment. The authors present laboratory procedures and discuss the results of several experimental tests performed on seven different SBR materials with the following densities: 1100, 1050, 1000, 850, 750, 700 and 650 kg/m³. It is proven that rubber granulate SBR produced from recycled waste tires, can be used as an elastic cover in steel inserts in rail dampers, provided that the material density is not lower than 1000 kg/m³. In the conducted tests, samples of the materials with high densities exhibited good static and dynamic elastic characteristics and had sufficient operational durability. Full article

(This article belongs to the Special Issue Experimental Characterization and Numerical Modelling of Damping Capacity for Classical and Innovative Materials)

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16 pages, 5516 KiB

Open AccessArticle

Analysis of the Influence of Fatigue Strength of Prototype Under Ballast Mats (UBMs) on the Effectiveness of Protection against Vibration Caused by Railway Traffic

by Cezary Kraśkiewicz, Artur Zbiciak, Anna Al Sabouni-Zawadzka and Michał Marczak

Materials 2021, 14(9), 2125; https://doi.org/10.3390/ma14092125 - 22 Apr 2021

Cited by 12 | Viewed by 2048

Abstract

The present paper focuses on laboratory tests of fatigue strength of prototype under ballast mats (UBMs), carried out according to the procedure described in the new European standard EN 17282, which was released in October 2020. The mineral wool-based mat revealed significant differences [...] Read more.

The present paper focuses on laboratory tests of fatigue strength of prototype under ballast mats (UBMs), carried out according to the procedure described in the new European standard EN 17282, which was released in October 2020. The mineral wool-based mat revealed significant differences in the values of static and dynamic characteristics, measured before and after the fatigue tests. The elastomeric mats based on recycled materials (SBR granulate and fibers) turned out to have had sufficient durability and effectiveness of protection against vibration caused by railway traffic. The values of static and dynamic bedding moduli, determined before and after the fatigue tests, were used to develop a viscoelastic rheological model of the vibration isolator with the use of fractional derivatives. Using this original model of the ballasted track system with four degrees of freedom, a significant influence of cyclic loading on the level of vibration suppression (insertion loss factor) was demonstrated. The analytical model confirmed that the mats with variations of bedding moduli exceeding 10% should not be used as resilient elements. Full article

(This article belongs to the Special Issue Experimental Characterization and Numerical Modelling of Damping Capacity for Classical and Innovative Materials)

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18 pages, 4042 KiB

Open AccessArticle

Laboratory Tests and Analyses of the Level of Vibration Suppression of Prototype under Ballast Mats (UBM) in the Ballasted Track Systems

by Cezary Kraśkiewicz, Artur Zbiciak, Kacper Wasilewski and Anna Al Sabouni-Zawadzka

Materials 2021, 14(2), 313; https://doi.org/10.3390/ma14020313 - 9 Jan 2021

Cited by 10 | Viewed by 2400

Abstract

The present paper is aimed at the analysis of under ballast mats (UBM) which are used in ballasted track structures as vibration isolators and to protect the ballast layer against fast degradation. The mats were tested in the laboratory and afterwards a novel [...] Read more.

The present paper is aimed at the analysis of under ballast mats (UBM) which are used in ballasted track structures as vibration isolators and to protect the ballast layer against fast degradation. The mats were tested in the laboratory and afterwards a novel 4-DoF mechanical model of the track structure with UBM was developed. The novelty of this study consists in the comparison of two testing procedures: a procedure based on the popular German standard DIN 45673-5 and a new European standard EN 17282, released in October 2020. Major discrepancies were demonstrated in the determined values of the static and dynamic characteristics using both approaches—especially in reference to the mats with higher stiffness. Full article

(This article belongs to the Special Issue Experimental Characterization and Numerical Modelling of Damping Capacity for Classical and Innovative Materials)

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14 pages, 3399 KiB

Open AccessArticle

A Novel Approach to the Analysis of Under Sleeper Pads (USP) Applied in the Ballasted Track Structures

by Artur Zbiciak, Cezary Kraśkiewicz, Anna Al Sabouni-Zawadzka, Jan Pełczyński and Sławomir Dudziak

Materials 2020, 13(11), 2438; https://doi.org/10.3390/ma13112438 - 26 May 2020

Cited by 23 | Viewed by 2894

Abstract

The present paper is dedicated to the analysis of under sleeper pads (USP), which are resilient elements used in ballasted track systems as vibration isolators. Four types of USP are considered. The authors present the results of laboratory tests, which are then used [...] Read more.

The present paper is dedicated to the analysis of under sleeper pads (USP), which are resilient elements used in ballasted track systems as vibration isolators. Four types of USP are considered. The authors present the results of laboratory tests, which are then used as input values for the finite element (FE) and mechanical model of the structure. A special focus is put on the description of an original four-degree-of-freedom (4DoF) mechanical model of the system that includes a fractional rheological model of USP. Using the proposed approaches, the dynamic characteristics of under sleeper pads are determined, and conclusions on vibration isolation effectiveness are drawn. Full article

(This article belongs to the Special Issue Experimental Characterization and Numerical Modelling of Damping Capacity for Classical and Innovative Materials)

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