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 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.

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 A new identification method of viscoelastic behavior: Application to the generalized Maxwell model

2011 ◽  
Vol 25 (3) ◽  
pp. 991-1010 ◽  
Author(s):  
Franck Renaud ◽  
Jean-Luc Dion ◽  
Gaël Chevallier ◽  
Imad Tawfiq ◽  
Rémi Lemaire
Keyword(s):  
Viscoelastic Behavior ◽  
Maxwell Model ◽  
Identification Method ◽  
Generalized Maxwell Model

scholarly journals Synthesis and characterization of biodegradable aliphatic copolyesters with hydrophilic soft segments

2004 ◽  
Vol 69 (12) ◽  
pp. 1013-1028 ◽  
Author(s):  
Danijela Jovanovic ◽  
Marija Nikolic ◽  
Jasna Djonlagic
Keyword(s):  
Mechanical Analysis ◽  
Transesterification Reaction ◽  
Degree Of Crystallinity ◽  
Solution Viscosity ◽  
Butylene Succinate ◽  
Dynamical Mechanical Analysis ◽  
Soft Segments ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

segmented poly(ester-ether)s based on poly(butylene succinate) and two different types of polyethers were investigated. The poly(ester-ether)s were synthesized by transesterification reaction of dimethyl succinate 1,4-butanediol and poly(ethylene oxide) (PEO, Mn = 1000 g/mol) in the first series, and poly(tetramethylene oxide) (PTMO,Mn = 1000 g/mol) in the second. The mass fraction of soft segments was varied between 10 and 50 mass. %. The effect of the introduction of two different polyether soft segments on the structure, thermal and rheological properties were investigated. The composition of the poly(ester-ether)s, determined from their 1H-NMR spectra showed that incorporation of soft polyether segments was successfully performed by the transesterification reaction in bulk. The molecular weight was estimated from solution viscosity measurements and complex dynamic viscosities. The thermal properties investigated by DSC indicated that the presence of soft segments lowers the melting and crystallization temperature of the hard phase, as well as the degree of crystallinity. Dynamical mechanical analysis was used to investigate the influence of composition on the rheological behavior of the segmented poly(ester-ether)s. The results obtained from an enzymatic degradation test performed on some of the synthesized polymers showed that the biodegradability is enhanced with increasing hydrophilicity.

Characterization of Mg AZ31 Alloy ECASD Processed Using Dynamical Mechanical Analysis (DMA)

2015 ◽  
Vol 1766 ◽  
pp. 109-114
Author(s):  
Daniel Peláez ◽  
Adriana Restrepo-Osorio ◽  
Emigdio Mendoza ◽  
Cesar Isaza ◽  
Patricia Fernandez-Morales
Keyword(s):  
Plastic Deformation ◽  
Magnesium Alloy ◽  
Room Temperature ◽  
Az31 Alloy ◽  
Mechanical Analysis ◽  
Metal Plate ◽  
Dynamical Mechanical Analysis ◽  
Dimensional Changes ◽  
Severe Plastic Deformation Technique

ABSTRACTIn the present work was used Dynamical Mechanical Analysis (DMA) to study the magnesium alloy Mg AZ31-B, in plate form with a thickness of 2.5 mm. The plates were processed using Equal Channel Angular Sheet Drawing (ECASD), which is a severe plastic deformation technique, which allows imposing strain without dimensional changes to a metal plate, at room temperature with an angle of 135°. The obtained results show dependence between the storage modulus (M’), temperature and frequency used on the tests. The greater M’ values were obtained at the lower temperatures and at the higher frequency used. However, at lower frequencies M’ response is not affected by the used frequencies. At the higher temperatures there is an M’ reduction, which promotes the material deformation.

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.

Light-cured dental composites characterization by Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 428-429
Author(s):  
B. M. Culbertson ◽  
M. L. Devinev ◽  
E. C. Kao
Keyword(s):  
Electron Microscopy ◽  
Mechanical Analysis ◽  
Service Performance ◽  
Dental Composite ◽  
Dental Composites ◽  
Neat Resin ◽  
Scanning Calorimetry ◽  
Research Meeting ◽  
Formulation Variables

The service performance of current dental composite materials, such as anterior and posterior restoratives and/or veneer cements, needs to be improved. As part of a comprehensive effort to find ways to improve such materials, we have launched a broad spectrum study of the physicochemical and mechanical properties of photopolymerizable or visible light cured (VLC) dental composites. The commercially available VLC materials being studied are shown in Table 1. A generic or neat resin VLC system is also being characterized by SEM and TEM, to more fully understand formulation variables and their effects on properties.At a recent dental research meeting, we reported on the differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) characterization of the materials in Table 1. It was shown by DSC and DMA that the materials are substantially undercured by commonly used VLC techniques. Post curing in an oral cavity or a dry environment at 37 to 50°C for 7 or more hours substantially enhances the cure of the materials.

scholarly journals Preparation and Characterization of Talc Filled Thermoplastic Polyurethane/Polypropylene Blends

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Emi Govorčin Bajsić ◽  
Vesna Rek ◽  
Ivana Ćosić
Keyword(s):  
Thermal Properties ◽  
Thermoplastic Polyurethane ◽  
Mechanical Analysis ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Polypropylene Blends ◽  
Pp Blends ◽  
The Degree Of Crystallinity ◽  
Better Than

The effect of the addition of talc on the morphology and thermal properties of blends of thermoplastic polyurethane (TPU) and polypropylene (PP) was investigated. The blends of TPU and PP are incompatible because of large differences in polarities between the nonpolar crystalline PP and polar TPU and high interfacial tensions. The interaction between TPU and PP can be improved by using talc as reinforcing filler. The morphology was observed by means of scanning electron microscopy (SEM). The thermal properties of the neat polymers and unfilled and talc filled TPU/PP blends were studied by using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The addition of talc in TPU/PP blends improved miscibility in all investigated TPU/T/PP blends. The DSC results for talc filled TPU/PP blends show that the degree of crystallinity increased, which is due to the nucleating effect induced by talc particles. The reason for the increased storage modulus of blends with the incorporation of talc is due to the improved interface between polymers and filler. According to TGA results, the addition of talc enhanced thermal stability. The homogeneity of the talc filled TPU/PP blends is better than unfilled TPU/PP blends.

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