Analysis of the Creep Behaviour of Polypropylene

2005 ◽  
Vol 480-481 ◽  
pp. 175-180 ◽  
Author(s):  
José Reinas Dos Santos André ◽  
José Joaquim Cruz Pinto
Keyword(s):  
Experimental Data ◽  
Tensile Stress ◽  
Creep Behaviour ◽  
Retardation Time ◽  
Creep Data ◽  
Physical Mechanisms ◽  
Molecular Scale ◽  
Parameter Values ◽  
Different Levels ◽  
Good Agreement

In this work, creep data for a polypropylene (PP) were obtained at different levels of tensile stress and temperature, and were then analysed in the light of a model developed, which is based on physical mechanisms (at the molecular scale) responsible for the material’s behaviour, considering that a minimum retardation time does exist. The model yields very good agreement with the experimental data and physically meaningful theoretical parameter values.

scholarly journals CO2 Induced Foaming Behavior of Polystyrene near the Glass Transition

2017 ◽  
Vol 2017 ◽  
pp. 1-15
Author(s):  
Salah Al-Enezi
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Glass Transition ◽  
Dissolved Gas ◽  
Foaming Process ◽  
Foaming Behavior ◽  
Potential Applications ◽  
Model C ◽  
Parameter Values ◽  
Good Agreement

This paper examines the effect of high-pressure carbon dioxide on the foaming process in polystyrene near the glass transition temperature and the foaming was studied using cylindrical high-pressure view cell with two optical windows. This technique has potential applications in the shape foaming of polymers at lower temperatures, dye impregnation, and the foaming of polystyrene. Three sets of experiments were carried out at operating temperatures of 50, 70, and 100°C, each over a range of pressures from 24 to 120 bar. Foaming was not observed when the polymer was initially at conditions below Tg but was observed above Tg. The nucleation appeared to occur randomly leading to subsequent bubble growth from these sites, with maximum radius of 0.02–0.83 mm. Three models were applied on the foaming experimental data. Variable diffusivity and viscosity model (Model C) was applied to assess the experimental data with the WLF equation. The model shows very good agreement by using realistic parameter values. The expansion occurs by diffusion of a dissolved gas from the supersaturated polymer envelope into the bubble.

CFD Analysis of Gear Windage Losses: Validation and Parametric Aerodynamic Studies

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Matthew J. Hill ◽  
Robert F. Kunz ◽  
Richard B. Medvitz ◽  
Robert F. Handschuh ◽  
Lyle N. Long ◽  
...  
Keyword(s):  
Experimental Data ◽  
Spur Gear ◽  
Mitigation Strategies ◽  
Test Facility ◽  
Cfd Analysis ◽  
Physical Mechanisms ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Cfd Analyses ◽  
Good Agreement

A computational fluid dynamics (CFD) method has been applied to gear configurations with and without shrouding. The goals of this work have been to validate the numerical and modeling approaches used for these applications and to develop physical understanding of the aerodynamics of gear windage loss. Several spur gear geometries are considered, for which experimental data are available. Various canonical shrouding configurations and free spinning (no shroud) cases are studied. Comparisons are made with experimental data from open literature, and data recently obtained in the NASA Glenn Research Center Gear Windage Test Facility, Cleveland, OH. The results show good agreement with the experiment. The parametric shroud configuration studies carried out in the Glenn experiments and the CFD analyses elucidate the physical mechanisms of windage losses as well as mitigation strategies due to shrouding and newly proposed tooth contour modifications.

FRACTAL ANALYSIS OF GAS DIFFUSION IN POROUS NANOFIBERS

Fractals ◽  
2015 ◽  
Vol 23 (01) ◽  
pp. 1540011 ◽  
Author(s):  
BOQI XIAO ◽  
JINTU FAN ◽  
ZONGCHI WANG ◽  
XIN CAI ◽  
XIGE ZHAO
Keyword(s):  
Experimental Data ◽  
Fractal Dimension ◽  
Fractal Theory ◽  
Fractal Dimensions ◽  
Fractal Model ◽  
Gas Diffusion ◽  
Physical Mechanisms ◽  
Gas Diffusivity ◽  
Model Predictions ◽  
Good Agreement

In this study, with the consideration of pore size distribution and tortuosity of capillaries, the analytical model for gas diffusivity of porous nanofibers is derived based on fractal theory. The proposed fractal model for the normalized gas diffusivity (De/D0) is found to be a function of the porosity, the area fractal dimensions of pore and the fractal dimension of tortuous capillaries. It is found that the normalized gas diffusivity decreases with increasing of the tortuosity fractal dimension. However, the normalized gas diffusivity is positively correlated with the porosity. The prediction of the proposed fractal model for porous nanofibers with porosity less than 0.75 is highly consistent with the experimental and analytical results found in the literature. The model predictions are compared with the previously reported experimental data, and are in good agreement between the model predictions and experimental data is found. The validity of the present model is thus verified. Every parameter of the proposed formula of calculating the normalized gas diffusivity has clear physical meaning. The proposed fractal model can reveal the physical mechanisms of gas diffusion in porous nanofibers.

Direct Simulation of Double-Diffusive Layered Convection

1995 ◽  
Vol 117 (2) ◽  
pp. 334-339 ◽  
Author(s):  
M. T. Hyun ◽  
T. L. Bergman
Keyword(s):  
Experimental Data ◽  
Rayleigh Number ◽  
Mixing Time ◽  
Direct Simulation ◽  
Lateral Heating ◽  
Physical Mechanisms ◽  
Heating And Cooling ◽  
Buoyancy Ratio ◽  
Double Diffusive ◽  
Good Agreement

A two-layer, salt-stratified system destabilized and mixed by lateral heating and cooling is simulated numerically using a spectral methodology. As noted in previous studies, the mixing time is delayed as the stabilizing buoyancy ratio increases, and as the Rayleigh number decreases. Depending on the regime of operation, however, distinct physical mechanisms are responsible for interface erosion and system mixing. At low Ra, erosion is gradual with overlying (underlying) fluid sheared from the interface and mixed into the adjacent thermally convecting layer. At high Ra, an intermittent mechanism is predicted to occur with solutally distinct plumes bombarding the interface and ejecting fluid into the convecting layers. Predictions obtained with the spectral method are in relatively good agreement with experimental data.

Energy Levels and Electromagnetic Transition of 90-94mo Nuclei Using Ibm-1

2020 ◽  
pp. 149-152
Keyword(s):  
Experimental Data ◽  
Transition Probability ◽  
Energy Levels ◽  
Dynamical Symmetry ◽  
Interacting Boson Model ◽  
Excitation Energies ◽  
Electromagnetic Transition ◽  
Boson Model ◽  
Energy States ◽  
Good Agreement

The energy states for the J , b , ɤ bands and electromagnetic transitions B (E2) values for even – even molybdenum 90 – 94 Mo nuclei are calculated in the present work of "the interacting boson model (IBM-1)" . The parameters of the equation of IBM-1 Hamiltonian are determined which yield the best excellent suit the experimental energy states . The positive parity of energy states are obtained by using IBS1. for program for even 90 – 94 Mo isotopes with bosons number 5 , 4 and 5 respectively. The" reduced transition probability B(E2)" of these neuclei are calculated and compared with the experimental data . The ratio of the excitation energies of the 41+ to 21+ states ( R4/2) are also calculated . The calculated and experimental (R4/2) values showed that the 90 – 94 Mo nuclei have the vibrational dynamical symmetry U(5). Good agreement was found from comparison between the calculated energy states and electric quadruple probabilities B(E2) transition of the 90–94Mo isotopes with the experimental data .

Predicting the Effect of Tire Tread Pattern Design on Thick Film Wet Traction

1977 ◽  
Vol 5 (1) ◽  
pp. 6-28 ◽  
Author(s):  
A. L. Browne
Keyword(s):  
Experimental Data ◽  
Network Design ◽  
Thick Film ◽  
Digital Computer ◽  
Analytical Tool ◽  
Design Practice ◽  
Pattern Design ◽  
Performance Results ◽  
Good Agreement

Abstract An analytical tool is presented for the prediction of the effects of changes in tread pattern design on thick film wet traction performance. Results are reported for studies in which the analysis, implemented on a digital computer, was used to determine the effect of different tread geometry features, among these being the number, width, and lateral spacing of longitudinal grooves and the angle of zigzags in longitudinal grooves, on thick film wet traction. These results are shown to be in good agreement with experimental data appearing in the literature and are used to formulate guidelines for tread groove network design practice.

Neural Network Model to Calculate the Creep Data Using Size

2017 ◽  
Vol 7 (8) ◽  
pp. 257
Author(s):  
Seetharam .K ◽  
Sharana Basava Gowda ◽  
. Varadaraj
Keyword(s):  
Neural Network ◽  
Risk Factors ◽  
Software Engineering ◽  
Network Model ◽  
Neural Network Model ◽  
Software Metrics ◽  
Creep Data ◽  
Engineering Software ◽  
Function Points ◽  
Different Levels

In Software engineering software metrics play wide and deeper scope. Many projects fail because of risks in software engineering development[1]t. Among various risk factors creeping is also one factor. The paper discusses approximate volume of creeping requirements that occur after the completion of the nominal requirements phase. This is using software size measured in function points at four different levels. The major risk factors are depending both directly and indirectly associated with software size of development. Hence It is possible to predict risk due to creeping cause using size.

A New Condition of Formation and Stablity of All Crystalline Systems in a Good Agreement with Experimental Data

2015 ◽  
Vol 11 (3) ◽  
pp. 3224-3228
Author(s):  
Tarek El-Ashram
Keyword(s):  
Experimental Data ◽  
Brillouin Zone ◽  
Electron Concentration ◽  
Free Electron ◽  
Lattice Point ◽  
Valence Electron ◽  
Fermi Gas ◽  
Valence Electron Concentration ◽  
Fermi Sphere ◽  
Good Agreement

In this paper we derived a new condition of formation and stability of all crystalline systems and we checked its validity andit is found to be in a good agreement with experimental data. This condition is derived directly from the quantum conditionson the free electron Fermi gas inside the crystal. The new condition relates both the volume of Fermi sphere VF andvolume of Brillouin zone VB by the valence electron concentration VEC as ;𝑽𝑭𝑽𝑩= 𝒏𝑽𝑬𝑪𝟐for all crystalline systems (wheren is the number of atoms per lattice point).

Virus Removal by Filtration

1982 ◽  
Vol 14 (4-5) ◽  
pp. 253-256
Author(s):  
N Sriramula ◽  
M Chaudhuri
Keyword(s):  
Experimental Data ◽  
Escherichia Coli ◽  
Cationic Polyelectrolyte ◽  
Electrokinetic Phenomena ◽  
Virus Removal ◽  
Bacterial Virus ◽  
Gravity Settling ◽  
And Diffusion ◽  
Model Virus ◽  
Good Agreement

An investigation was undertaken on the removal of a model virus, bacterial virus MS2 against Escherichia coli, by sand filtration using untreated, and alum or cationic polyelectrolyte treated media, and uncoagulated as well as alum coagulated influent. Data on discrete virus removal were satisfactorily accounted for by electrokinetic phenomena and diffusion. For virus in association with turbidity, filter coefficients computed from experimental data were in good agreement with those predicted by mechanical straining and gravity settling which were the dominant mechanisms for removal of the turbidity particles to which the viruses attached.

Diffusion model for deposition of epitaxial GaAs layers prepared by the MOCVD method

1991 ◽  
Vol 56 (10) ◽  
pp. 2020-2029
Author(s):  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma ◽  
Rudolf Hladina
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Kinetic Model ◽  
Gas Phase ◽  
Substrate Surface ◽  
Deposition Process ◽  
Hydrogen Atmosphere ◽  
Epitaxial Gaas ◽  
Kinetics Of ◽  
Good Agreement

The authors proposed and treated quantitatively a kinetic model for deposition of epitaxial GaAs layers prepared by reaction of trimethylgallium with arsine in hydrogen atmosphere. The transport of gallium to the surface of the substrate is considered as the controlling process. The influence of the rate of chemical reactions in the gas phase and on the substrate surface on the kinetics of the deposition process is neglected. The calculated dependence of the growth rate of the layers on the conditions of the deposition is in a good agreement with experimental data in the temperature range from 600 to 800°C.

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