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Articles de revues sur le sujet « Mastercurve »

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Auteur : Grafiati
Publié le 10 mars 2023

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1

Jacod, B., C. H. Venner et P. M. Lugt. « Extension of the Friction Mastercurve to Limiting Shear Stress Models ». Journal of Tribology 125, no 4 (25 septembre 2003) : 739–46. http://dx.doi.org/10.1115/1.1572513.

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A previous study of the behavior of friction in EHL contacts for the case of Eyring lubricant behavior resulted in a friction mastercurve. In this paper the same approach is applied to the case of limiting shear stress behavior. By means of numerical simulations the friction coefficient has been computed for a wide range of operating conditions and contact geometries. It is shown that the same two parameters that were found in the Eyring study, a characteristic shear stress, and a reduced coefficient of friction, also govern the behavior of the friction for the case of limiting shear stress models. When the calculated traction data is plotted as a function of these two parameters all results for different cases lie close to a single curve. Experimentally measured traction data is used to validate the observed behavior. Finally, the equations of the mastercurves for both types of rheological model are compared resulting in a relation between the Eyring stress τ0 and the limiting shear stress τL.
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2

Hohe, Jörg, Valérie Friedmann et Dieter Siegele. « Überprüfung des Mastercurve-Konzepts zur Sprödbruchbewertung ferritischer Stähle ». Materials Testing 48, no 5 (mai 2006) : 239–50. http://dx.doi.org/10.3139/120.100733.

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3

Schuster, Miriam. « Determination of the linear viscoelastic material behaviour of interlayers with semi-crystalline structures shown by the example of a semi-crystalline ionomer ». Glass Structures & ; Engineering 7, no 2 (août 2022) : 157–71. http://dx.doi.org/10.1007/s40940-022-00185-x.

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AbstractThe temperature dependent linear viscoelastic material behaviour of the most commonly used interlayer PVB is typically determined by means of Dynamic-Mechanical-Thermal-Analysis (DMTA). By horizontally shifting the isothermal modulus curves, a mastercurve is created at a certain reference temperature, which can then be mathematically approximated with a Prony series. A time–temperature superposition principle can be derived from the shift factors. In contrast to PVB, EVA and ionomer (or ionoplastic) interlayers have semi-crystalline structures that melt when the melting temperature is reached and form again when the sample is cooled below the crystallization temperature. The exact structure and number of crystallites depend e.g. on the cooling rate and the physical age (or thermal prehistory) of the sample. These factors must be taken into account in the experimental determination of the material parameters with DMTA. Using the example of SentryGlas®, this article shows that the stiffness of semi-crystalline interlayers is affected by the crystallinity. Mastercurves from DMTA with different temperature programs are created. The degrees of crystallization for the different temperature programs are determined with Differential Scanning Calorimetry (DSC). A time–temperature superposition principle, which applies to the purely amorphous material, and a time-crystallinity superposition principle are derived, which enable the determination of the material parameters for different temperatures and degrees of crystallization.
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4

Jung, YooSeok, Jae Hoon Lee, Nam Sik Mun et Yoon-Ho Cho. « Mastercurve-based image analysis method for curing compound quality control ». KSCE Journal of Civil Engineering 21, no 1 (4 mars 2016) : 253–57. http://dx.doi.org/10.1007/s12205-016-0277-z.

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5

Kutay, M. Emin, Karim Chatti et Ligang Lei. « Backcalculation of Dynamic Modulus Mastercurve from Falling Weight Deflectometer Surface Deflections ». Transportation Research Record : Journal of the Transportation Research Board 2227, no 1 (janvier 2011) : 87–96. http://dx.doi.org/10.3141/2227-10.

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6

Steen, M. « Tensile mastercurve of ceramic matrix composites : significance and implications for modelling ». Materials Science and Engineering : A 250, no 2 (juillet 1998) : 241–48. http://dx.doi.org/10.1016/s0921-5093(98)00597-8.

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7

Kassem, Hussein, Ghassan Chehab et Shadi Najjar. « Effect of Asphalt Mixture Components on the Uncertainty in Dynamic Modulus Mastercurves ». Transportation Research Record : Journal of the Transportation Research Board 2674, no 5 (9 avril 2020) : 135–48. http://dx.doi.org/10.1177/0361198120914292.

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Practitioners and researchers in the paving industry have highlighted the importance of the adoption of reliability-based pavement design. The goal of developing reliable pavements with optimum performance over their design life has become a key factor to be considered during both pavement design and construction processes. This requires the adoption of statistical and probabilistic-based analyses for the formulation of the properties and behavior of pavement materials. Thus, many researchers worked on the quantification and modeling of the uncertainty caused by the inherent variability in pavement materials in general and that of asphalt concrete (AC) in particular. The dynamic modulus (| E*|), a fundamental property for mechanistic-empirical and purely mechanistic pavement designs, has been proven to have a significant level of uncertainty that is dependent on climatic and traffic loading conditions. The main objective of this study is to investigate the effect of the AC mixture properties and components on the uncertainty in the | E*| mastercurve. This objective is achieved by conducting an experimental program incorporating four different mixtures having the same material sources but different binder types and gradations. Monte Carlo simulations are used to model the uncertainty of | E*| for each of these mixtures. The paper shows that the uncertainty is dependent on mixture type, as the presence of larger nominal maximum aggregate size, modified binder, or additive can increase the uncertainty in the | E*| mastercurve, especially at high temperatures or slow loading rates. The uncertainty is proven to be material related and not imposed by the testing instrumentation.
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8

Yun, Tae Young, Sang Min Ham et Pyeong Jun Yoo. « Characteristics of Dynamic Shear Modulus Mastercurve of Aged or Unaged Asphalt Binders ». Journal of the Korean Society of Road Engineers 15, no 1 (15 février 2013) : 87–94. http://dx.doi.org/10.7855/ijhe.2013.15.1.087.

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9

Vogel, L., et W. Peukert. « Breakage behaviour of different materials—construction of a mastercurve for the breakage probability ». Powder Technology 129, no 1-3 (janvier 2003) : 101–10. http://dx.doi.org/10.1016/s0032-5910(02)00217-6.

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10

Pillot, Sylvain, et Pascal Pacqueau. « An attempt to define a Charpy V-notched mastercurve to fit transition of ferritic steels ». Engineering Fracture Mechanics 135 (février 2015) : 259–73. http://dx.doi.org/10.1016/j.engfracmech.2015.01.012.

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11

Berry, Nicholas K., John M. Fielke et Chris Saunders. « A Mastercurve to predict annual ryegrass (Lolium rigidum) seed devitalisation when exposed to multiple single sided impacts ». Biosystems Engineering 133 (mai 2015) : 56–63. http://dx.doi.org/10.1016/j.biosystemseng.2015.02.015.

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12

Pearson, Hamish, Brian Gabbitas et Sigurdur Ormarsson. « Tensile behaviour of radiata pine with different moisture contents at elevated temperatures ». Holzforschung 66, no 5 (1 juillet 2012) : 659–65. http://dx.doi.org/10.1515/hf-2011-0185.

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Abstract The aim of this study was to obtain tensile elastic modulus (EM) information for radiata pine (Pinus radiata D. Don) sapwood in tangential grain direction, over a temperature range of 70°C to 150°C for a wide range of moisture contents. Such information is scarce, probably because of difficulties with research equipment design and process control strategies to perform accurate tests. As expected, EM dramatically decreased with increasing temperature and moisture content. The results were modelled to yield a relationship between stress and strain. The results were also successfully transposed into a mastercurve based on temperature-moisture equivalence through a modified form of the Williams, Landel, and Ferry equation for amorphous polymers. This result is consistent with the view that wood is visco-plastic around the glass transition zone of the ligno-hemicellulosic matrix. It is demonstrated that moisture and temperature can play a significant role in reducing stress during drying, regardless of the drying time. Properties of wood, such as tensile elastic information at elevated temperatures, are important for mechanical design, distortion modelling and understanding the fundamental behaviour of wood in general.
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13

Jansen, K. M. B. « Effect of Resin Formulation on Thermoset Viscoelasticity ». Journal of Engineering Materials and Technology 128, no 4 (8 mai 2006) : 478–83. http://dx.doi.org/10.1115/1.2345437.

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Viscoelastic relaxation curves of thermoset resins may change considerably for relatively small changes in properties of the initial monomer mixture or final conversion level. In order to be able to predict the effect of such changes, a model is proposed which relates the properties of the initial monomer mixture such as the functionality, mixing ratio, and conversion level to changes in the relaxation curves. It basically consists of two parts. Firstly, the crosslink density is calculated based on the exact composition of the monomer mixture and, secondly, the effect of this crosslink density on the position of the glass transition and the rubbery modulus was calculated. The model was tested with a series of Novolac epoxies in which the functionality, mixing ratio, and conversion level were varied systematically. It turned out that changes in the relaxation curves due to variations in conversion level could be predicted quite accurately from the shape and shift factor of the fully cured mastercurve. The agreement between relaxation curve predictions for the series with changing functionality and mixing ratio was only moderate, which was ascribed to errors in the prediction of correct values for the crosslink density.
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14

Nébouy, Matthias, Ameur Louhichi et Guilhem P. Baeza. « Volume fraction and width of ribbon-like crystallites control the rubbery modulus of segmented block copolymers ». Journal of Polymer Engineering 40, no 9 (25 octobre 2020) : 715–26. http://dx.doi.org/10.1515/polyeng-2019-0222.

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AbstractWe discuss the origin of the plateau modulus enhancement (χ) in semi-crystalline segmented block copolymers by increasing the concentration in hard segments within the chains (XHS). The message we deliver is that the plateau modulus of these thermoplastic elastomers is greatly dominated by the volume fraction (Φ) and the width (W) of crystallites according to χ–1 ~ ΦW in agreement with a recent topological model we have developed. We start by a quick review of literature with the aim to extract χ(Φ) for different chemical structures. As we suspected, we find that most of the data falls onto a mastercurve, in line with our predictions, confirming that the reinforcement in such materials is mainly dominated by the crystallite’s content. This important result is then supported by the investigation of copolymer mixtures in which Φ is fixed, providing a similar reinforcement, while the chains compositions is significantly different. Finally, we show that the reinforcement can be enhanced at constant Φ by increasing W for a given class of block copolymers. This can be done by changing the process route and is again in good agreement with our expectations.
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15

Tarefder, Rafiqul A., et Mekdim T. Weldegiorgis. « Maneuvering MEPDG Input Variables to Improve Level-3 and Level-2 Mastercurve Predictions to the Accuracy of Level-1 Input Hierarchy ». Journal of Testing and Evaluation 44, no 3 (26 décembre 2014) : 20140070. http://dx.doi.org/10.1520/jte20140070.

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16

Poh, Leslie, Esmaeil Narimissa et Manfred H. Wagner. « Universality of steady shear flow of Rouse melts ». Rheologica Acta 59, no 10 (29 août 2020) : 755–63. http://dx.doi.org/10.1007/s00397-020-01236-2.

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Abstract The data set of steady and transient shear data reported by Santangelo and Roland Journal of Rheology 45: 583–594, (2001) in the nonlinear range of shear rates of an unentangled polystyrene melt PS13K with a molar mass of 13.7 kDa is analysed by using the single integral constitutive equation approach developed by Narimissa and Wagner Journal of Rheology 64:129–140, (2020) for elongational and shear flow of Rouse melts. We compare model predictions with the steady-state, stress growth, and stress relaxation data after start-up shear flows. In characterising the linear-viscoelastic relaxation behaviour, we consider that in the vicinity of the glass transition temperature, Rouse modes and glassy modes are inseparable, and we model the terminal regime of PS13K by effective Rouse modes. Excellent agreement is achieved between model predictions and shear viscosity data, and good agreement with first normal stress coefficient data. In particular, the shear viscosity data of PS13K as well as of two polystyrene melts with M = 10.5 kDa and M = 9.8 kDa investigated by Stratton Macromolecules 5 (3): 304–310, (1972) agree quantitatively with the universal mastercurve predicted by Narimissa and Wagner for unentangled melts, and approach a scaling of Wi−1/2at sufficiently high Weissenberg numbers Wi. Some deviations between model predictions and data are seen for stress growth and stress relaxation of shear stress and first normal stress difference, which may be attributed to limitations of the experimental data, and may also indicate limitations of the model due to the complex interactions of Rouse modes and glassy modes in the vicinity of the glass transition temperature. Graphical abstract
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17

Honerkamp, J., et J. Weese. « A note on estimating mastercurves ». Rheologica Acta 32, no 1 (janvier 1993) : 57–64. http://dx.doi.org/10.1007/bf00396677.

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18

Wagner, M. H., V. Schulze et A. Göttfert. « Rheotens-mastercurves and drawability of polymer melts ». Polymer Engineering & ; Science 36, no 7 (avril 1996) : 925–35. http://dx.doi.org/10.1002/pen.10480.

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19

Wagner, Manfred H., Bertrand Collignon et J�r�me Verbeke. « Rheotens-mastercurves and elongational viscosity of polymer melts ». Rheologica Acta 35, no 2 (1996) : 117–26. http://dx.doi.org/10.1007/bf00396038.

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20

Bernnat, A., M. H. Wagner et C. K. Chai. « Assessment of LDPE Melt Strength by Use of Rheotens Mastercurves ». International Polymer Processing 15, no 3 (septembre 2000) : 268–72. http://dx.doi.org/10.3139/217.1595.

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21

Rema, Aswathy, et Aravind Krishna Swamy. « Effect of Construction Methodology on Uncertainty in Asphalt Concrete Mastercurves ». Journal of Transportation Engineering, Part B : Pavements 145, no 3 (septembre 2019) : 04019021. http://dx.doi.org/10.1061/jpeodx.0000124.

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22

Andersons, J., R. Joffe, E. Spārniņš et O. Rubenis. « Progressive cracking mastercurves of the transverse ply in a laminate ». Polymer Composites 30, no 8 (août 2009) : 1175–82. http://dx.doi.org/10.1002/pc.20674.

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23

Bernnat, A., et M. H. Wagner. « Effect of Wall Slip on Rheotens Mastercurves for Linear PE Melts ». International Polymer Processing 14, no 4 (décembre 1999) : 336–41. http://dx.doi.org/10.3139/217.1559.

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24

Tamuzs, V., K. Dzelzitis et K. Reifsnider. « Fatigue of Woven Composite Laminates in Off-Axis Loading I. The Mastercurves ». Applied Composite Materials 11, no 5 (septembre 2004) : 259–79. http://dx.doi.org/10.1023/b:acma.0000037132.63191.3a.

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25

Zhong, Lei, et Ji Zhao Liang. « Extensional Rheology of LDPE from Melt Spinning Technique ». Materials Science Forum 675-677 (février 2011) : 499–502. http://dx.doi.org/10.4028/www.scientific.net/msf.675-677.499.

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The extensional rheology of low density polyethylene (LDPE) is studied bymelt spinning technique. Melt spinning mastercurves for LDPE are plotted for the measurement results of various temperatures and extrusion velocities. Linear relations between scaling factor b and T, Logb and Logv0 have been found. The analysis indicates that b can be regarded as a useful index of combination effects on the pre-orientation before extension, and on the unwrapping and orientation of macromolecular chains during extension. By using the values of b and the data from reference curve, extension viscosity curves of any setting temperature and extrusion velocity can be calculated, which will effectively enlarge the measurement range of melt spinning technique.
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26

Samal, S. K., S. Mohanty et S. K. Nayak. « Fabrication and Characterization of Polypropylene/Ethylene-Octene Copolymer Blend Nanocomposites ». Advanced Materials Research 29-30 (novembre 2007) : 267–70. http://dx.doi.org/10.4028/www.scientific.net/amr.29-30.267.

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PP/EOC thermoplastic blend nanocomposites were prepared by melt intercalation technique using an intermeshing co-rotating twin screw extruder. The organoclay (Na+ MMT, Cloisite 20A, Cloisite 30B) content was varied between 0-5wt. % whereas the blend composition was kept constant (70PP: 30EOC) as optimized in our previous work. The effects of clays on the mechanical and rheological properties have been studied. Mechanical studies of PP/EOC nanocomposites reveal a significant increase in the impact strength upto a clay content of 3%. X-ray diffraction (XRD) analysis showed a significant increase in the interlayer gallery space with increase in clay loading. The rheological characterization made employing parallel plate rheometer revealed a maximum increase in storage modulus (G’) and loss modulus (G”) in case of modified clay indicating higher stiffness of the nanocomposites as compared to unmodified nanocomposites. Time Temperature superposition (TTS) was employed to generate various viscoelastic mastercurves.
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27

Chung, M. H., et G. R. Hamed. « Bonding of Butyl and Nitrile Rubber by in situ Copolymer Formation ». Rubber Chemistry and Technology 62, no 2 (1 mai 1989) : 367–85. http://dx.doi.org/10.5254/1.3536251.

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Abstract We summarize and conclude the following: 1. The T-peel adhesion between uncrosslinked layers of IIR and NBR is rate and temperature dependent. Failure is interfacial at low rates; bulk cohesive tearing of the rubber occurs at intermediate rates, while interfacial failure returns at high rates. 2. Adhesion data could be reduced to mastercurves with experimentally determined shift factors which were in reasonable agreement with those calculated from the universal WLF equation with a Tg=−69°C. 3. At the lowest test rates, peel specimens containing in situ-formed copolymer had lower strength than those without the copolymer. This is probably due to the easy slippage of the segments of the low-molecular-weight copolymer in this regime. 4. At intermediate rates, in situ copolymer had no effect on peel strength; specimens failed by bulk cohesive tearing of rubber, whether or not the copolymer was present. 5. At high rates, peel specimens containing the copolymer exhibited improved strengths. The behavior is consistent with previous results on the autohesion of elastomers. Interdiffused chains of relatively low molecular weight are only capable of providing strong adhesion when the test speed is sufficiently rapid.
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Kassem, Hussein, Ghassan Chehab et Shadi Najjar. « Development of Probabilistic Viscoelastic Continuum Damage Model for Asphalt Concrete ». Transportation Research Record : Journal of the Transportation Research Board 2673, no 5 (2 avril 2019) : 285–98. http://dx.doi.org/10.1177/0361198119838980.

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The main objective of this paper is to develop a realistic probabilistic framework for characterization of different types of asphalt concrete using advanced material modeling. The adopted methodology builds on and enhances a viscoelastic continuum damage (VECD) material model by utilizing a suite of associated experimental testing protocols and incorporating the uncertainties associated with the different material properties. The modeled uncertainties address the variabilities and errors associated with the linear viscoelastic (LVE) functions achieved from the complex modulus test and damage characteristic curves obtained from constant crosshead rate testing. A probabilistic scheme using First Order approximations and Monte Carlo simulations is developed to characterize the inherent uncertainty of each of the LVE functions over the time domain of their mastercurves. For damage characteristic curves, the uncertainty in normalized pseudostiffness increases as the level of damage becomes larger. The uncertainties of LVE properties are propagated along with those of C versus stress curves to yield a probabilistic viscoelastic continuum damage model (P-VECD). The P-VECD not only predicts the average viscoelastic response to a given loading input, but it can also provide its distribution, which is essential for a reliability-based pavement design.
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29

Cho, P. L., et G. R. Hamed. « Green Strength of Carbon-Black-Filled Styrene—Butadiene Rubber ». Rubber Chemistry and Technology 65, no 2 (1 mai 1992) : 475–87. http://dx.doi.org/10.5254/1.3538625.

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Abstract The green strengths of a gum SBR and two black-filled samples, at twenty-three volume percent filler, have been determined at various strain rates and temperatures. At higher temperatures, all samples exhibit yielding, followed by strain-softening. The gum exhibits this type of behavior down to −20°C, whereas, filled specimens undergo strain hardening at this temperature. Yield strength increases with decreasing temperature or increasing rate, indicating that it is largely controlled by chain mobility. Yield strengths at various temperatures may be shifted along the rate axis to form mastercurves. The dependence of yield stress on reduced rate is similar for the gum and the composition filled with the large-sized thermal black (N990). Stiffening is reasonably well accounted for by strain and strain-rate amplification, using the well-known Guth—Gold amplification factor. At low reduced rates, the extent of stiffening is substantially greater for samples filled with the much finer furnace black, N110. Unlike with the N990, SBR filled with N110 forms a coherent bound-rubber gel. This provides a strong resistance to deformation (beyond simple strain or strain-rate amplification) and results in high yield strength. At low temperatures, perhaps when the magnitude of chain—chain and chain—filler internal friction is comparable, the effect of filler size is greatly diminished.
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Barraj, Firas, Jamal Khatib, Alberte Castro et Adel Elkordi. « Effect of Chemical Warm Mix Additive on the Properties and Mechanical Performance of Recycled Asphalt Mixtures ». Buildings 12, no 7 (21 juin 2022) : 874. http://dx.doi.org/10.3390/buildings12070874.

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Newer technologies such as warm mix asphalt (WMA) and reclaimed asphalt pavement (RAP) have gained international approval and have been considered as appropriate solutions that support the sustainability goals of the highway sector. However, both technologies present some shortcomings. The lower mixing and compaction temperatures of WMA reduce the binder aging and the bond between the aggregates and the coating binder, thus resulting in less rutting resistance and higher moisture susceptibility. On the other hand, RAP mixes tend to be stiffer and more brittle than conventional hot mix asphalt (HMA) due to the effect of aged binder. This tends to increase the crack propagation distresses. In an attempt to overcome their individual shortcomings, this study investigated the new concept of a combined WMA-RAP technology. The chemical WMA additive Rediset LQ1102CE was utilized with mixtures incorporating low (15%), medium (25%), and high (45%) RAP contents. Dynamic modulus (DM) and flow number (FN) tests were conducted to investigate the effect of Rediset on the behavior of RAP mixtures. The dynamic modulus |E*| mastercurves were developed using the sigmoidal model and Franken model was used to fit the accumulated permanent deformation curve. The results of this study showed that Rediset addition improved the cracking resistance of RAP mixtures. However, the rutting resistance was reduced but kept within the acceptable range except for mixtures containing low RAP content.
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Costanzo, Salvatore, Rossana Pasquino, Jörg Läuger et Nino Grizzuti. « Milligram Size Rheology of Molten Polymers ». Fluids 4, no 1 (18 février 2019) : 28. http://dx.doi.org/10.3390/fluids4010028.

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During laboratory practice, it is often necessary to perform rheological measurements with small specimens, mainly due to the limited availability of the investigated systems. Such a restriction occurs, for example, because the laboratory synthesis of new materials is performed on small scales, or can concern biological samples that are notoriously difficult to be extracted from living organisms. A complete rheological characterization of a viscoelastic material involves both linear and nonlinear measurements. The latter are more challenging and generally require more mass, as flow instabilities often cause material losses during the experiments. In such situations, it is crucial to perform rheological tests carefully in order to avoid experimental artifacts caused by the use of small geometries. In this paper, we indicate the drawbacks of performing linear and nonlinear rheological measurements with very small amounts of samples, and by using a well-characterized linear polystyrene, we attempt to address the challenge of obtaining reliable measurements with sample masses of the order of a milligram, in both linear and nonlinear regimes. We demonstrate that, when suitable protocols and careful running conditions are chosen, linear viscoelastic mastercurves can be obtained with good accuracy and reproducibility, working with plates as small as 3 mm in diameter and sample thickness of less than 0.2 mm. This is equivalent to polymer masses of less than 2 mg. We show also that the nonlinear start-up shear fingerprint of polymer melts can be reliably obtained with samples as small as 10 mg.
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Saleh, Nooralhuda F., Douglas Mocelin, Farhad Yousefi Rad, Cassie Castorena, B. Shane Underwood et Y. Richard Kim. « Predictive Framework for Modeling Changes in Asphalt Mixture Moduli with Oxidative Aging ». Transportation Research Record : Journal of the Transportation Research Board 2674, no 10 (12 août 2020) : 79–93. http://dx.doi.org/10.1177/0361198120938775.

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This paper presents a predictive framework for asphalt mixture moduli as a function of aging time with two levels of sophistication. This work is built on the method currently implemented in Pavement mechanistic-empirical (ME) that uses an effective time/frequency concept based on time-aging superposition to model the effect of aging on a mixture’s modulus. Time-aging superposition implies that an asphalt mixture’s modulus mastercurves, corresponding to different aging levels, coincide when they are shifted horizontally on the log-frequency axis. This study improves the accuracy of the existing model by decoupling the time-temperature and time-aging shifts. The new framework also uses the binder dynamic shear modulus | G*| as an aging index instead of the viscosity, which is used in Pavement ME. The | G*| aging index is used to calculate an effective frequency at short-term aging (STA), which is then used in the asphalt mixture sigmoidal model to calculate the corresponding asphalt mixture modulus with aging. The pavement aging model introduced by NCHRP 09-54 predicts log | G*| at 64°C and 10 rad/s for a specific field-aged condition and pavement depth. The proposed framework can use the predicted log | G*| to predict the mixture’s corresponding dynamic modulus (| E*|) at that aging level and pavement depth. Level 1 of this framework requires characterizing the | G*| at STA and calibrating the NCHRP 09-54 pavement aging model as well as measuring the mixture | E*| at STA. Level 2 does not require any binder testing, providing relatively less accurate predictions but relieving some testing requirements.
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33

Hamed, G. R., et P. S. Wu. « Relationship between the Cohesive Strength and Tack of Elastomers : Part IV, Carbon Black Filled Styrene-Butadiene Rubber ». Rubber Chemistry and Technology 68, no 2 (1 mai 1995) : 248–58. http://dx.doi.org/10.5254/1.3538739.

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Abstract The autohesion and cohesion of uncrosslinked SBR (gum and black-filled) have been determined over a broad range of test temperatures and rates using a T-peel geometry. Peeling energies can be time-temperature superposed to form mastercurves using shift factors in accord with the WLF form. Universal constants are appropriate for the gum. While experimental constants were obtained for the black composition. Cohesion for the gum and filled SBR increase continuously with increasing test speed or reduced temperature. On the other hand, autohesion for the gum shows an abrupt transition by decreasing at a critical reduced rate, while autohesion of the filled SBR does not exhibit the transition. The transition is associated with a viscous-to-elastic response change with increasing RaT; filled SBR has reduced elasticity relative to the gum and hence the transition is not present. By examining relative autohesion, it is seen that the gum undergoes an interfacial-cohesive-interfacial transition response with increasing RaT. This is quite different than the behavior found when peeling apart elastomer/hard substrate bonds, such as the SBR/polyester bonds of Gent and Petrich; here, there is simply a cohesive-interfacial transition with increasing RaT. For elastomer-elastomer junctions there is interpenetration and chain mobility in the interphase formed. At sufficiently low RaT, interdiffused chains simply slide by one another giving interfacial failure. With increasing RaT entanglement couplings in the interphase become effective in preventing facile flow, and, at this point, failure becomes cohesive; finally, at even higher RaT, with a sufficiently elastic response, stresses apparently become concentrated at the interface and failure proceeds there. When an elastomer is bonded to a hard, immobile material, the mechanism of bonding is restricted to surface site adsorption. This reduces elastomeric chain mobility and produces more “glassy” dispersive interactions which resist separation relative to the chains which are held together by “rubbery” dispersive forces. Again at sufficiently high RaT, with increased elasticity, failure becomes interfacial.
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34

Stacer, R. G., et F. N. Kelley. « Criteria for Unstable Tearing of Elastomers ». Rubber Chemistry and Technology 58, no 5 (1 novembre 1985) : 924–38. http://dx.doi.org/10.5254/1.3536104.

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Abstract 1. Unstable, or stick-slip, tearing has been evaluated in a series of unfilled elastomers. It was found that unstable tearing in these materials occurs only in well defined regions of temperature and rate. The behavior of the material in these regions follows a definite time-dependent pattern, suggesting the existence of simple time-temperature correspondence. This has been demonstrated by showing that the same shift factors that superpose other viscoelastic functions also describe the time-dependent nature of unstable tearing. Previous work showed that the magnitude of unstable tearing could be controlled by test-specimen geometry. It is concluded in this work that the mechanistic origin of unstable tearing can be traced to viscoelastic processes of the rubbery network. The combined results of these 2 studies show that unstable tearing is a characteristic feature of the polymer network which may be controlled or eliminated by test-specimen design. 2. For the amorphous elastomers investigated, it has been shown that the boundaries between regions of stable and unstable tearing can be explained in terms of simple extension properties and characteristic viscoelastic transitions of the elastomer. Specifically, the long-time (or high-temperature) boundary between conditions of stable and unstable tearing has been associated with a critical extension ratio, λc, which corresponds to an upturn in tensile stress-strain curves. If temperature and rate conditions are such that the deforming material at the tear tip does not extend beyond λc, unstable tearing does not occur. This is consistent with an anisotropic tear-tip reinforcement model of unstable tearing which has been discussed in detail. The short-time (or low-temperature) boundary between stable and unstable tearing conditions has been related to a characteristic time, ttr, associated with the onset of the rubber-to-glass transition. This characteristic time also corresponds to a change in the simple extension response of the elastomer. At times shorter than ttr, a distinct yield point was observed in constant rate stress-strain curves. It is therefore surmised that unstable tearing does not occur in this region due to the plastic yielding of the material, which interrupts the formation of the anisotropically reinforced structure at the tear tip. 3. Time-dependent tear-energy master curves of elastomers over broad time scales all display the same general features. Near the glassy region, the elastomers were found to approach a glassy tear energy of approximately 60 kJ/m2. At much longer times, in the terminal regions of the mastercurves, the tear energy dropped rapidly. In between these two extremes, a plateau was observed for all the elastomers, with NR displaying the lowest plateau slope.
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35

Kannan, Sriraman, et Paul Lemaire. « Reliability Assessment of Optical Fibers and Fiber Gratings ». MRS Proceedings 531 (1998). http://dx.doi.org/10.1557/proc-531-403.

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AbstractThe topic of reliability of UV-induced fiber gratings is reviewed. Approaches to assess and predict changes in optical properties of fiber gratings due to thermal decay of refractive index modulation are presented and compared. The mastercurve/demarcation energy diagram approach is shown to be a powerful and general method for the purpose. The process of thermal stabilization to obtain gratings with superior stability is delineated. It is shown that the mastercurve approach could be used to analyze other reliability problems such as in predicting hydrogen-induced losses in fibers.
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36

Hasan, Md Amanul, et Rafiqul A. Tarefder. « New Mechanistic Procedure to Predict the Critical Cracking Temperature of Asphalt Concrete from Bending Beam Rheometer and Indirect Tension Test Data ». Transportation Research Record : Journal of the Transportation Research Board, 19 juillet 2021, 036119812110237. http://dx.doi.org/10.1177/03611981211023764.

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This study presents a new mechanistic procedure for determining the critical cracking temperature of asphalt concrete (AC) using data from bending beam rheometer (BBR) test of asphalt binder and indirect tension (IDT) test of AC. This new procedure uses BBR creep data to generate the mixture relaxation modulus mastercurve by utilizing the Hirsch model, time-temperature superposition principle, and Prony series-based interconversion method. The Hirsch model parameters are calibrated by comparing creep data from BBR and IDT creep tests performed at the same temperature. Boltzmann hereditary integral and second-order heat equation are then used to calculate thermal stress from the developed relaxation modulus mastercurve. IDT strength data is transferred from test strain rate to thermal strain rate using the viscoelastic continuum damage model. Since a strain gauge is not attached for traditional laboratory IDT strength testing, this study derived an analytical equation based on the Hondros solution to compute the horizontal strain rate from the applied vertical displacement rate. Finally, the critical cracking temperature is determined by coupling the thermal stress and strength profiles. Using the procedure presented in this paper, the critical cracking temperatures of four AC mixtures were predicted from BBR and IDT data. Their actual critical cracking temperatures were measured using thermal stress restrained specimen test performed in the laboratory to validate the method. The predicted critical cracking temperatures are found to be very close to the laboratory measured values. The developed procedure has substantial practical and technical importance in predicting the critical cracking temperature of AC because it utilizes widely available BBR and IDT tests.
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37

Rema, Aswathy, et Aravind Krishna Swamy. « A comprehensive approach to evaluate presence and propagation of uncertainty in asphalt binder mastercurves ». International Journal of Pavement Engineering, 5 août 2019, 1–16. http://dx.doi.org/10.1080/10298436.2019.1648812.

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