Biaxial Extension Studies Using Inflation of Sheets of Unimodal Model Networks

1990 ◽  
Vol 63 (2) ◽  
pp. 276-284 ◽  
Author(s):  
P. Xu ◽  
J. E. Mark
Keyword(s):  
Experimental Data ◽  
Uniaxial Extension ◽  
Specific Region ◽  
Rubber Elasticity ◽  
Experimental Results ◽  
Stress Strain ◽  
Biaxial Extension ◽  
Extension Ratio ◽  
Model Networks ◽  
Good Agreement

Abstract Measurements of uniaxial extension and compression were made on model poly(dimethylsiloxane) (PDMS) [−Si(CH3)2−O−]x networks to examine the molecular theories of rubber elasticity. The stress-strain isotherms showed that the Flory-Erman theory of rubber elasticity is in good agreement with experimental data from extension to compression (α−1: 0.3–13), while the Mooney-Rivlin relation is useful only in a specific region of extension ratio (α−1: 0.3–0.8). The experimental results strongly support the theory of Flory-Erman, rather than those of phantom and affine networks. It is thus evident that the Flory-Erman theory of rubber elasticity is the more nearly correct.

scholarly journals Assessing the Instantaneous Stiffness of Cracked Reinforced Concrete Beams Based on a Gradual Change in Strain Distributions

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Chunyu Fu ◽  
Dawei Tong ◽  
Yuyang Wang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Internal Force ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Gradual Change ◽  
Concrete Cracking ◽  
Good Agreement

Concrete cracking causes a gradual change in strain distributions along the cross section height of reinforced concrete beams, which will finally affect their instantaneous stiffness. A method for assessing the stiffness is proposed based on the gradual change, which is considered through modeling different strain distributions for key sections in cracked regions. Internal force equilibria are adopted to find a solution to top strains and neutral axes in the models, and then the inertias of the key sections are calculated to assess the beam stiffness. The proposed method has been validated using experimental results obtained from tests on five reinforced concrete beams. The predicted stiffness and displacements are shown to provide a good agreement with experimental data. The instantaneous stiffness is proven to greatly depend on the crack number and depth. This dependence can be exactly reflected by the proposed method through simulating the gradual change in concrete strain distributions.

Viscous Dissipation in Laminar Water Flows in Micro-Tubes

2007 ◽  
Author(s):  
In-Hwan Yang ◽  
Mohamed S. El-Genk
Keyword(s):  
Experimental Data ◽  
Viscous Dissipation ◽  
Temperature Rise ◽  
Experimental Results ◽  
Numerical Calculations ◽  
Analytical Expression ◽  
Water Flows ◽  
Good Agreement

Numerical calculations are performed to investigate the effect of viscous dissipation on the temperature rise and friction numbers for laminar water flows in micro-tubes. The calculated values are compared with those determined from reported experimental data for glass and diffused silica micro-tubes (D = 16 – 101 μm and L/D = 625 – 1479). The results confirm a definite slip at the wall with slip lengths of ∼ 0.7 μm and 1.0 μm, which decrease the friction number and the temperature rise in the micro-tubes, but their effect gradually diminishes as either D or L/D increases. The friction number decreases exponentially as D decreases and, to a lesser extent, as L/D increases. The effect of L/D on the friction number is insignificant for micro-tube diameters ≤ 20 μm. For D > 400 μm, the friction number approaches that of Hagen-Posieuille of 64 for macro-tubes when L/D > 1500, but approaches higher values at smaller L/D. The dimensionless analytical expression developed for calculating the friction number and the temperature rise for water flows in micro-tubes is in good agreement with both the numerical and experimental results.

Correlation Between Contact Start/Stop and Constant Speed Drag Testing in Magnetic Head-Disk Tribology

1993 ◽  
Vol 115 (3) ◽  
pp. 387-391 ◽  
Author(s):  
S. K. Ganapathi ◽  
F. E. Talke
Keyword(s):  
Experimental Data ◽  
Contact Force ◽  
Experimental Results ◽  
Constant Speed ◽  
Optical Profilometry ◽  
Magnetic Head ◽  
Good Agreement

A model to establish the correlation between wear in constant speed drag testing and contact start/stop testing is developed. The model is based on the Archard wear equation and uses the quasi-steady Kita-Kogure-Mitsuya model for the transition of a slider from sliding to flying to calculate the velocity dependent contact force between the slider and disk during start/stop. Experimental results for the wear of a zirconia overcoated disk are obtained for both start/stop and constant speed drag testing as a function of the number of repeated cycles using optical profilometry. The correlation between predictions and experimental data shows good agreement for up to at least 10,000 cycles of sliding.

Collision–induced absorption in gaseous methane at low temperatures

1986 ◽  
Vol 64 (7) ◽  
pp. 763-767 ◽  
Author(s):  
I. R. Dagg ◽  
A. Anderson ◽  
S. Yan ◽  
W. Smith ◽  
C. G. Joslin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Low Temperatures ◽  
Low Frequency ◽  
Frequency Region ◽  
Experimental Results ◽  
Published Data ◽  
Frequency Range ◽  
Simple Method ◽  
Induced Absorption ◽  
Good Agreement

A recently developed theory for collision-induced absorption in methane is compared with experimental results over a wider spectral range and at lower temperatures than previously reported. The present experimental results covering the frequency range below 400 cm−1 exhibit good agreement with other recently published data. The theory shows excellent agreement with experiment in the low-frequency region below approximately 200 cm−1 but underestimates the experimental data somewhat at higher frequencies. Possible theoretical reasons for this discrepancy are given. The theory represents a simple method of obtaining a good estimate of the collision-induced absorption spectra of methane in this frequency region and for extrapolating to lower temperatures for which experimentation is not feasible. In addition, the moments α1 and γ1are compared with earlier determinations and indicate good agreement with the previously obtained values for the octupole and hexadecapole moments of methane.

Influences of Process Conditions on Stretching Characteristics of Crystalline Polymer Film

2014 ◽  
Vol 939 ◽  
pp. 342-348
Author(s):  
Liang Yu Chen ◽  
Chung Cheng Su ◽  
Ren Haw Chen
Keyword(s):  
Process Analysis ◽  
Annealing Treatment ◽  
Experimental Results ◽  
Process Conditions ◽  
Extension Rate ◽  
Uniform Size ◽  
Super Structure ◽  
Biaxial Extension ◽  
Extension Ratio ◽  
Extension Process

Developing the interior structures of polymer films is essential for creating novel functions of such films. This study investigates the effects of extension parameters and processing procedures on the super-structure of a polypropylene (PP) film. An biaxial extension device is also designed and fabricated to analyze the effects of annealing, extension temperature, extension rate and other parameters on the super-structures of PP films. Based on super-structure analyses, the relationships between extension parameters and film structures are determined, and an extension process that involves a second time stretching procedure is suggested. Experimental results indicate that void structures can be generated by biaxial extension at the interface between the crystalline and amorphous regions in a film. The mechanical strength of the film is also affected by stretching and become highly oriented. Although a low extension temperature can increase the number of void structures generated at a low extension ratio, structure sizes are dispersed. Additionally, voids with uniform size can be obtained when the film is stretched at a high temperature; however, it needs a high extension ratio to promote the formation of void structures. As for annealing treatment, when the annealing temperature increased, the size and quantity of the spherulites that were formed in films by annealing also increased, but these films tend to have similar sizes and numbers of void structures. Based on the experimental results, this study also describes how parameters influence the void structures of a PP film created during the extension process. Analysis results further demonstrate how extension parameters and processing procedures can be adjusted to improve the fabrication of PP films.

A New Slip Theory of Plasticity

1974 ◽  
Vol 41 (3) ◽  
pp. 587-592 ◽  
Author(s):  
T. H. Lin ◽  
Y. M. Ito ◽  
C. L. Yu
Keyword(s):  
Experimental Data ◽  
Equilibrium Condition ◽  
Numerical Calculations ◽  
Thin Wall ◽  
Face Centered Cubic ◽  
Stress Strain ◽  
Elastic Range ◽  
Theory Of Plasticity ◽  
Face Centered ◽  
Good Agreement

A slip theory is presented for the calculation of the incremental stress-strain relations of a face-centered cubic polycrystal such as aluminum and its alloys, from its experimental uniaxial curves. This theory satisfies the conditions of equilibrium, condition of continuity of displacement as well as the slip characteristics of the component crystals. Numerical calculations based on this theory give results which are in good agreement with known experimental data on thin wall cylinders subject to different ratios of incremental axial and torsional loadings after being compressed beyond the elastic range.

A Theory of Sharp-Edged Orifices

1937 ◽  
Vol 4 (2) ◽  
pp. A53-A54
Author(s):  
W. E. Howland
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Discharge Coefficient ◽  
Reynolds Numbers ◽  
Experimental Results ◽  
Low Reynolds Numbers ◽  
Circular Orifice ◽  
Coefficient Of Discharge ◽  
Theoretical Considerations ◽  
Good Agreement

Abstract The author presents a figure in which the coefficient of discharge Cd, velocity Cv, and contraction Cc determined by several investigators are plotted logarithmically as points against Reynolds’ numbers. Curves for the coefficients drawn by the author, based on theoretical considerations, show good agreement with the experimental data, thus throwing some light upon the basic phenomena of the discharge of sharp-edged orifices. The variation of the coefficient of discharge of a circular orifice as a function of the Reynolds number is explained as a purely viscous phenomenon for low Reynolds numbers, and by means of a momentum analysis for higher speeds. The analysis presented by the author leads to the development of several formulas for the discharge coefficient, which formulas are in fair agreement with experimental results.

The bursting of a charged cylindrical film

1972 ◽  
Vol 328 (1575) ◽  
pp. 529-539 ◽  
Keyword(s):  
Experimental Data ◽  
Finite Length ◽  
Experimental Results ◽  
Exact Calculation ◽  
Conducting Film ◽  
Half Wavelength ◽  
Theoretical Predictions ◽  
Long Cylinder ◽  
Good Agreement

This paper is a sequel to Sir Geoffrey Taylor’s study of the bursting of an electrified cylindrical conducting film. Taylor described experiments in which the voltages, at which the film becomes statically unstable, were observed for various lengths of film. These results were compared with the theoretical predictions for disturbances on an infinitely long cylinder having a wavelength equal to the length of film used. It is shown here that a transition in the mode of bursting from an axisymmetric whole wavelength mode to a lateral half wavelength mode is to be expected and that the experimental data conform with this transition. An exact calculation of the modes for a film of finite length is also given here and the resulting theoretical predictions of instability and bursting voltages are in very good agreement with the experimental results.

A Simple Analytical Model to Simulate Oblique Ballistic Impact onto Fabric

2011 ◽  
Vol 110-116 ◽  
pp. 3453-3458
Author(s):  
Mohamad Ali Akbari ◽  
Golam Hosein Liaghat ◽  
Hadi Sabouri
Keyword(s):  
Experimental Data ◽  
Analytical Model ◽  
Ballistic Impact ◽  
Experimental Results ◽  
Simple Analytical Model ◽  
Good Agreement

A simple analytical model for oblique ballistic impact of projectiles into fabrics are presented. This model is extension of Chocron-Benloulo penetration model. Results are compared with experimental data. There is good agreement between analytical and experimental results.

Two-Phase Flow-Induced Forces on Bends in Small Scale Tubes

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
M. F. Cargnelutti ◽  
S. P. C. Belfroid ◽  
W. Schiferli
Keyword(s):  
Experimental Data ◽  
Structural Integrity ◽  
Two Phase Flow ◽  
Experimental Results ◽  
Small Scale ◽  
Phase Flow ◽  
Momentum Exchange ◽  
Two Phase ◽  
Worst Case ◽  
Good Agreement

Two-phase flow occurs in many situations in industry. Under certain circumstances, it can be a source of flow-induced vibrations. The forces generated can be sufficiently large to affect the performance or efficiency of an industrial device. In the worst-case scenario, the mechanical forces that arise may endanger structural integrity. Thus, it is important to take these forces into account in designing industrial machinery to avoid problems during operation. Although the occurrence of such forces is well known, not much is known about their magnitudes because, unfortunately, the amount of experimental data available in literature are rather limited. This paper describes the experiments performed to measure forces in 6 mm diameter tubing containing a bend. Experiments are performed on bends of different radii, with the bend positioned horizontally or vertically. The experimental results are analyzed based on flow regime and bend configuration. A comparison with available experimental results for bigger internal pipe diameter shows a general good agreement. To improve future predictions, a simple model based on momentum exchange is proposed to estimate the forces generated by multiphase flow. The proposed model shows a good agreement with the experimental data.

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