scholarly journals Experimental Study on Dynamic Properties of a Recycled Composite Sleeper and Its Theoretical Model

Symmetry ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 17
Author(s):  
Zhenhang Zhao ◽  
Ying Gao ◽  
Chenghui Li
Keyword(s):  
Complex Modulus ◽  
Dynamic Properties ◽  
Low Frequency ◽  
Maxwell Model ◽  
Theoretical Models ◽  
Mechanical Analysis ◽  
Factors Affecting ◽  
Track System ◽  
Generalized Maxwell Model ◽  
Temperature Superposition

As a symmetrical structure in track system, the dynamic properties of recycled composite sleepers are important factors affecting the vibration characteristics of track structure. To study the viscoelastic dynamic properties of the composite sleeper, dynamic mechanical analysis (DMA) tests of a composite sleeper at −5 to 30 °C and 1–60 Hz were first carried out, and then the time-temperature superposition (TTS) and the Williams–Landel–Ferry (WLF) formula were used to predict the dynamic properties of a composite sleeper at a wider frequency range. Finally, the generalized Maxwell model was adopted to characterize the dynamic properties of the composite sleeper, which provides parameters and theoretical models for dynamic analysis. The research results show that the composite sleeper has obvious viscoelasticity. Its modulus is large at low temperature or high frequency. On the contrary, the modulus is small at high temperature or low frequency. Under the test conditions, its complex modulus ranges from 1500 to 2700 MPa. The loss factor is in the range of 0.08–0.13. Using the generalized Maxwell model (n = 4), which can better reflect the dynamic properties of the composite sleeper.

EXPERIMENTAL CHARACTERIZATION, MODELING AND PARAMETRIC IDENTIFICATION OF THE HYSTERETIC FRICTION BEHAVIOR OF VISCOELASTIC JOINTS

2013 ◽  
Vol 05 (02) ◽  
pp. 1350018 ◽  
Author(s):  
HANEN JRAD ◽  
FRANCK RENAUD ◽  
JEAN LUC DION ◽  
IMAD TAWFIQ ◽  
MOHAMED HADDAR
Keyword(s):  
Maxwell Model ◽  
Parametric Identification ◽  
Mechanical Analysis ◽  
Friction Model ◽  
Structural Vibrations ◽  
Friction Behavior ◽  
Proposed Model ◽  
Essential Components ◽  
Generalized Maxwell Model ◽  
Dahl Friction Model

Viscoelastic joints connecting solids are essential components of mechanical systems. Viscoelastic components have inherent damping in their structure. Moreover, energy losses in structural vibrations are strongly linked to the friction properties of joints. In this work, a new visco-tribological model was developed by coupling the rheological linear generalized Maxwell model and Dahl friction model. A method for parametric identification is proposed. Parameters of the model are identified from dynamic mechanical analysis (DMA) tests for different excitation frequencies. Comparison between measurements and simulations is performed and the validity of the proposed model is discussed.

scholarly journals Non-Linear Generalized Maxwell Model for Dynamic Characterization of Viscoelastic Components and Parametric Identification Techniques

2012 ◽  
Author(s):  
Hanen Jrad ◽  
Jean Luc Dion ◽  
Franck Renaud ◽  
Imad Tawfiq ◽  
Mohamed Haddar
Keyword(s):  
Dynamic Stiffness ◽  
Maxwell Model ◽  
Parametric Identification ◽  
Mechanical Analysis ◽  
Dynamical Behaviour ◽  
Static Displacement ◽  
Generalized Maxwell Model ◽  
Non Linear ◽  
Identification Techniques

Viscoelastic components are incorporated into automobile and aerospace structures system in order to damp mechanical vibrations. Viscoelastic components are a key element in designing desired dynamic behaviour of mechanical systems. Viscoelastic components dynamic characteristics are often very complex, due to the dependence of its response on several variables, such as frequency, amplitude, preload, and temperature. These dependencies can be critical in capturing the mechanical proprieties and so non linear dynamical behaviour may appear. Assuming that non linearities are due to non linear elasticity, the non linear Generalized Maxwell Model (GMM) is proposed to characterize dynamics of viscoelastic components. Parameters of GMM are identified from Dynamic Mechanical Analysis (DMA) tests for different excitation frequencies. A particular result from identification is that the non linear stiffness is dependent upon displacement amplitude and static displacement under static preload. The significance of this result is that the non linear dynamics of the viscoelastic component can be represented by a simple analytical model capable to produce accurate results. Comparison between measurements and simulations of dynamic stiffness of viscoelastic component has been carried on.

scholarly journals Study on the Generalized Formulations with the Aim to Reproduce the Viscoelastic Dynamic Behavior of Polymers

2020 ◽  
Vol 10 (7) ◽  
pp. 2321
Author(s):  
Andrea Genovese ◽  
Francesco Carputo ◽  
Antonio Maiorano ◽  
Francesco Timpone ◽  
Flavio Farroni ◽  
...  
Keyword(s):  
Experimental Data ◽  
Low Frequency ◽  
Maxwell Model ◽  
Wide Frequency Range ◽  
Material Behavior ◽  
Viscoelastic Materials ◽  
Optimum Parameters ◽  
Generalized Maxwell Model ◽  
Minimum Number ◽  
Real Behavior

Appropriate modelling of the real behavior of viscoelastic materials is of fundamental importance for correct studies and analyses of structures and components where such materials are employed. In this paper, the potential to employ a generalized Maxwell model and the relative fraction derivative model is studied with the aim to reproduce the experimental behavior of viscoelastic materials. For both models, the advantage of using the pole-zero formulation is demonstrated and a specifically constrained identification procedure to obtain the optimum parameters set is illustrated. Particular emphasis is given on the ability of the models to adequately fit the experimental data with a minimum number of parameters, addressing the possible computational issues. The question arises about the minimum number of experimental data necessary to estimate the material behavior in a wide frequency range, demonstrating that accurate results can be obtained by knowing only the data of the upper and low frequency plateaus plus the ones at the loss tangent peak.

Generalized Maxwell model for the viscoelastic behavior of a soda-lime-silica glass under low frequency shear loading

1997 ◽  
Vol 36 (2) ◽  
pp. 173-186
Author(s):  
Lucas Duffrène *, † , Ren&#x ◽  
Hélène Burlet ◽  
Roland Piques ◽  
Annelise Faivre ◽  
Anas Sekkat ◽  
...  
Keyword(s):  
Silica Glass ◽  
Low Frequency ◽  
Viscoelastic Behavior ◽  
Maxwell Model ◽  
Soda Lime ◽  
Shear Loading ◽  
Generalized Maxwell Model ◽  
Soda Lime Silica Glass

Generalized Maxwell model for the viscoelastic behavior of a soda-lime-silica glass under low frequency shear loading

1997 ◽  
Vol 36 (2) ◽  
pp. 173-186 ◽  
Author(s):  
Lucas Duffr�ne ◽  
Ren� Gy ◽  
H�l�ne Burlet ◽  
Roland Piques ◽  
Annelise Faivre ◽  
...  
Keyword(s):  
Silica Glass ◽  
Low Frequency ◽  
Viscoelastic Behavior ◽  
Maxwell Model ◽  
Soda Lime ◽  
Shear Loading ◽  
Generalized Maxwell Model ◽  
Soda Lime Silica Glass

Viscoelasticity Measurement and Identification of Viscoelastic Parametric Models

2011 ◽  
Author(s):  
Franck Renaud ◽  
Gael Chevallier ◽  
Jean-Luc Dion ◽  
Re´mi Lemaire
Keyword(s):  
Complex Function ◽  
Shear Stiffness ◽  
Maxwell Model ◽  
Mechanical Analysis ◽  
Parametric Models ◽  
Dynamical Mechanical Analysis ◽  
Identification Method ◽  
Generalized Maxwell Model ◽  
Classical Models

Generally speaking, the behaviour of viscoelastic material is more complicated than the behaviour proposed by classical models as Voigt, Maxwell or Zener. The stiffness of such materials is a frequency dependent complex function. Above 1000Hz, classical measurements techniques are unable to achieve accurate measurements of the stiffness. In this paper, a new Dynamical Mechanical Analysis (DMA) tester is presented. It allows the characterization of the shear stiffness of preloaded viscoelastic materials between 200 and 3500Hz and without using frequency-temperature equivalences. Then the Generalized Maxwell model is used to describe behaviours measured with the DMA tester. A new iterative identification method of the parameter of the Generalized Maxwell model is described. This identification method is based on the asymptotes of the model.

scholarly journals The challenging SED of AP Librae

2011 ◽  
Vol 7 (S284) ◽  
pp. 411-413 ◽  
Author(s):  
David Sanchez ◽  
Berrie Giebels ◽  
Pascal Fortin ◽  
Keyword(s):  
Spectral Energy Distribution ◽  
Broad Band ◽  
Low Frequency ◽  
Theoretical Models ◽  
Intermediate Frequency ◽  
High Energy ◽  
Spectral Energy ◽  
Broad Band Emission ◽  
Band Emission ◽  
Bl Lac

AbstractMatching the broad-band emission of active galaxies with the predictions of theoretical models can be used to derive constraints on the properties of the emitting region and to probe the physical processes involved. AP Librae is the third low frequency peaked BL Lac (LBL) detected at very high energy (VHE, E>100GeV) by an Atmospheric Cherenkov Telescope; most VHE BL Lacs (34 out of 39) belong to the high-frequency and intermediate-frequency BL Lac classes (HBL and IBL). LBL objects tend to have a higher luminosity with lower peak frequencies than HBLs or IBLs. The characterization of their time-averaged spectral energy distribution is challenging for emission models such as synchrotron self-Compton (SSC) models.

Mechanical Analysis of Warm Extrusion Precision Forming on 42CrMo Steel Cutting Pick

2012 ◽  
Vol 538-541 ◽  
pp. 1061-1066 ◽  
Author(s):  
Chun Jian Su ◽  
Quan Lan Li ◽  
Lin Jing Xiao ◽  
Su Min Guo
Keyword(s):  
New Technology ◽  
Mechanical Analysis ◽  
Extrusion Force ◽  
Factors Affecting ◽  
42Crmo Steel ◽  
Pick Body ◽  
Mining Tool ◽  
Main Factors ◽  
The Cost ◽  
Warm Extrusion

Cutting pick is a kind of widely-used consumptive mining tool. The traditional producing technics of cutting pick body is foundry, or machining after roughly forging, or machining directly from metal bar. By former technics, the property of products is poor, and by latter, the material availability is low and the cost is high. The patent technology for cutting pick body warm extrusion introduced in this paper can overcome all the disadvantages mentioned above. In this paper, by analyzing the characteristic of cutting pick body warm extrusion, adopting the principle of power balance to solve the approximate solution of strain forces, the approximate calculating formulas of extruding power are deduced. The main factors affecting on extrusion force are determined theoretically. This research can be used as basis to design tooling and choose proper equipment for this new technology.

EXPERIMENTAL RESEARCH ON VISCOELASTICITY PROPERTY OF DIFFERENT LAYERS PERIODONTAL LIGAMENT UNDER COMPRESSION

2021 ◽  
pp. 2150050
Author(s):  
JINLAI ZHOU ◽  
YANG SONG ◽  
CHENGUANG XU ◽  
CHUNQIU ZHANG ◽  
XUE SHI
Keyword(s):  
Elastic Modulus ◽  
Periodontal Ligament ◽  
Creep Compliance ◽  
Relaxation Modulus ◽  
Maxwell Model ◽  
Kelvin Model ◽  
Generalized Maxwell Model ◽  
Relaxation Stress ◽  
Generalized Kelvin Model ◽  
Fitting Accuracy

The periodontal ligament (PDL) exhibits different material mechanical properties along the long axis of the teeth. To explore the creep and the relaxation effects of dissimilar layers of PDL, this paper took the central incisors of porcine mandibular as experimental subjects and divided them perpendicular to the teeth axis into five layers. Creep experiments and relaxation experiments on five layers were conducted to obtain the creep compliance and relaxation modulus at different layers. Linear elastic model, generalized Kelvin model, and generalized Maxwell model were used to describe the major characteristics of the PDL: Instantaneous elasticity, creep and relaxation. Fitting accuracy of three-parameter, five-parameter, and seven-parameter of the model was compared, and the constitutive equations of different layers were established by the least square method. The results presented that the creep strain and the relaxation stress of PDL were exponentially correlated with time under different loading conditions. Different layers showed a significant effect on the creep strain and relaxation stress of PDL. Along the long axis of the teeth, the changing rule of the creep compliance and relaxation modulus of each layer showed quite the contrary, and the instantaneous elastic modulus first decreased to the minimum, then increased to the maximum. Higher instantaneous elastic modulus led to lower creep compliance and higher relaxation modulus. The generalized Kelvin model and the generalized Maxwell model well characterized the creep and relaxation properties of PDL. Fitting accuracy increased with the number of model parameters. The relaxation time of PDL was about one order of magnitude shorter than the creep retardation time, which indicated that the relaxation effect lasted shorter than the creep effect.

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