Parameterization Process of the Maxwell Model to Describe the Transient Force Behavior of a Tire

2017 ◽  
Author(s):  
Andreas Hackl ◽  
Wolfgang Hirschberg ◽  
Cornelia Lex ◽  
Georg Rill
Keyword(s):  
Maxwell Model ◽  
Transient Force

The Effect of Nanoparticle Coating on the Thermal Conductivity of Nanofluids

2009 ◽  
Vol 1207 ◽  
Author(s):  
Michael John Fornasiero ◽  
Diana-Andra Borca-Tasciuc
Keyword(s):  
Thermal Conductivity ◽  
Iron Oxide ◽  
Effective Thermal Conductivity ◽  
Colloidal Suspensions ◽  
Maxwell Model ◽  
Carrier Fluid ◽  
Coated Nanoparticles ◽  
Transient Hot Wire Technique ◽  
Potential Applications ◽  
Iron Oxide Core

AbstractNanofluids are engineered colloidal suspensions of nanometer-sized particles in a carrier fluid and are receiving significant attention because of their potential applications in heat transfer area. Theoretical investigations have shown that the enhanced thermal conductivity observed in nanofluids is due to nanoparticle clustering and networking. This provides a low resistance path to the heat flowing through the fluid. However, the surface coating of the nanoparticles, which is often used to provide stable dispersion over the long term, may act as a thermal barrier, reducing the effective thermal conductivity of the nanofluid. Moreover, nanofluids with the same type of nanoparticles may exhibit different effective thermal conductivities, depending upon the thermal properties and thickness of the coating. In this context, thermal conductivity characterization of well dispersed iron oxide nanoparticles with two different surface coatings was carried out employing the transient hot wire technique. The diameter of the iron oxide core was 35 nm and the coatings used were aminosilane and carboxymethyl-dextran (CMX) of 7nm in thickness. Preliminary results suggest that effective thermal conductivity of CMX coated nanoparticle suspensions is slightly higher than that of aminosilane coated nanoparticles. In both cases, the effective thermal conductivity is higher than that predicted by the Maxwell model for composite media.

Study of Oscillating Flow of Viscoelastic Fluid With the Fractional Maxwell Model

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Jiu-hong Jia ◽  
Hong-xing Hua
Keyword(s):  
Exact Solution ◽  
Petroleum Chemistry ◽  
Viscoelastic Fluid ◽  
Maxwell Model ◽  
The Other ◽  
Oscillating Flow ◽  
Model Parameters ◽  
Series Approximation ◽  
Phase Lags ◽  
Annular Effect

The oscillating flow of the viscoelastic fluid in cylindrical pipes has been applied in many fields, such as industries of petroleum, chemistry, and bioengineering. It is studied using the fractional derivative Maxwell model in this paper. The exact solution is obtained utilizing a simpler and more reasonable technique. According to this velocity solution, the time-velocity profile of one kind of viscoelastic fluid is analyzed. From analysis, it is found that the flow behaves like the Newton fluid when the oscillating frequency is low, and the flow reversal occurs when the oscillating frequency is high. Moreover, two series approximations for the velocity are obtained and analyzed for different model parameters. In one series approximation, the velocity is parabolic in profile, while in the other series approximation, the velocity presents three characteristics: (1) it is independent of radius and at the centerline is smaller than that of steady Poiseuille flow, (2) the phase lags about 90deg with respect to the imposed pressure gradient, and (3) the Richardson annular effect is found near the wall.

High-Speed Melt Spinning of Sheath-Core Bicomponent Polyester Fibers: High and Low Molecular Weight Poly(ethylene Terephthalate) Systems

1997 ◽  
Vol 67 (9) ◽  
pp. 684-694 ◽  
Author(s):  
J. Radhakrishnan ◽  
Takeshi Kikutani ◽  
Norimasa Okui
Keyword(s):  
Molecular Weight ◽  
High Speed ◽  
Melt Spinning ◽  
Ethylene Terephthalate ◽  
Maxwell Model ◽  
Low Molecular Weight ◽  
Structural Development ◽  
Solidification Temperature ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene

Sheath-core bicomponent spinning of high molecular weight poly (ethylene terephthalate) (hmpet, IV = 1.02 dl/g) and low molecular weight pet (lmpet, IV = 0.65 dl/g) is done at a take-up velocity range of 1 to 7 km/min. The structures of the individual components in the as-spun bicomponent fibers are characterized. Orientation and orientation-induced crystallization of the hmpet component are enhanced, while those of the lmpet component are suppressed in comparison to corresponding single component spinning. Numerical simulation with the Newtonian model shows that elongational stress in the hmpet component is enhanced and that of the lmpet decreases during high-speed bicomponent spinning. The difference in elongational viscosity is the main factor influencing the mutual interaction between hmpet and lmpet, which in turn affect spinline dynamics, solidification temperature, and structural development in high-speed bicomponent spinning. Simulation with an upper-convected Maxwell model shows that considerable stress relaxation can occur in the lmpet component if the hmpet component solidifies before lmpet. A mechanism for structural development is also proposed, based on the simulation results and structural characterization data.

Simulation of the Film Blowing Process Using a Continuum Model for Crystallization in Polymers

2000 ◽  
Author(s):  
I. J. Rao
Keyword(s):  
Viscoelastic Fluid ◽  
Crystalline Phase ◽  
Elastic Solid ◽  
Second Law Of Thermodynamics ◽  
Maxwell Model ◽  
Polymer Processing ◽  
Solid Polymer ◽  
Crystalline Solid ◽  
Film Blowing ◽  
Anisotropic Elastic

Abstract In this paper we simulate the film blowing process using a model developed to study crystallization in polymers (see Rao (1999), Rao and Rajagopal (2000b)). The framework was developed to generate mathematical models in a consistent manner that are capable of simulating the crystallization process in polymers. During crystallization the polymer transitions from a fluid like state to a solid like state. This transformation usually takes place while the polymer undergoes simultaneous cooling and deformation, as in film blowing. Specific models are generated by choosing forms for the internal energy, entropy and the rate of dissipation. The second law of thermodynamics along with the assumption of maximization of dissipation is used to determine constitutive forms for the stress tensor and the rate of crystallization. The polymer melt is modeled as a rate type viscoelastic fluid and the crystalline solid polymer is modeled as an anisotropic elastic solid. The mixture region, where in the material transitions from a melt to a semi-crystalline solid, is modeled as a mixture of a viscoelastic fluid and an elastic solid. The anisotropy of the crystalline phase and consequently that of the final solid depends on the deformation in the melt during crystallization, a fact that has been known for a long time and has been exploited in polymer processing. The film blowing process is simulated using a generalized Maxwell model for the melt and an anisotropic elastic solid for the crystalline phase. The results of the simulation agree qualitatively with experimental observations and the methodology described provides a framework in which the film blowing problem can be analyzed.

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.

Onset of Triply Diffusive Convection in a Maxwell Fluid Saturated Porous Layer

2013 ◽  
Vol 353-356 ◽  
pp. 2580-2585 ◽  
Author(s):  
Mo Li Zhao ◽  
Shao Wei Wang ◽  
Qiang Yong Zhang
Keyword(s):  
Porous Layer ◽  
Normal Mode Analysis ◽  
Lewis Number ◽  
Maxwell Fluid ◽  
Maxwell Model ◽  
Mode Analysis ◽  
Analysis Model ◽  
Diffusive Convection ◽  
Saturated Porous Layer ◽  
Triply Diffusive Convection

The linear stability of triply diffusive convection in a binary Maxwell fluid saturated porous layer is investigated. Applying normal mode analysis , the criterion for the onset of stationary and oscillatory convection is obtained. The modified Darcy-Maxwell model is used as the analysis model. This allows us to make a thorough investigation of the processes of viscoelasticity and diffusions that causes the convection to set in through oscillatory rather than stationary. The effects of the parameters of Vadasz number, normalized porosity parameter, relaxation parameter, Lewis number and solute Rayleigh number are presented.

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