On the Determination of the Propagation Pressure of Long Circular Tubes

1984 ◽  
Vol 106 (2) ◽  
pp. 150-159 ◽  
Author(s):  
S. Kyriakides ◽  
M.-K. Yeh ◽  
D. Roach
Keyword(s):  
Large Deflection ◽  
External Pressure ◽  
Circular Ring ◽  
Experimental Results ◽  
Circular Tubes ◽  
Inelastic Analysis ◽  
State Propagation ◽  
Characteristic Pressure ◽  
Good Agreement

A propagating buckle can be initiated in tubes under external pressure from localized imperfections. Once initiated a buckle will propagate with the result of flattening the tube behind it. The lowest pressure at which it can propagate is known as the propagation pressure, and it represents a characteristic pressure of the tube. The paper attempts to model quasistatic steady-state propagation through a plane strain large deflection, inelastic analysis of the collapse of a circular ring. An energy balance type of argument is used to obtain a lower-bound estimate of the propagation pressure from the ring response. The results are compared with experimental results obtained from stainless steel and aluminum tubes having diameter-to-thickness ratios ranging between 100 and 10. It was found that for these two materials the estimated value for the propagation pressure was in good agreement with experimental results for D/t > 20.

Theoretical Determination of Absorption With an Emphasis on High Temperatures and a Specific Application to Carbon Monoxide

1973 ◽  
Vol 95 (4) ◽  
pp. 535-538 ◽  
Author(s):  
J. C. Lin ◽  
R. Greif
Keyword(s):  
Carbon Monoxide ◽  
High Temperatures ◽  
Rotational Band ◽  
Experimental Results ◽  
Theoretical Determination ◽  
Hot Band ◽  
Good Agreement

The absorption of a vibrational-rotational band has been studied and the contribution from the first hot band has been included. A specific application has been made to carbon monoxide and good agreement with experimental results has been obtained.

Determination of the limits of stable combustion at high supersonic flow velocities in a channel

2010 ◽  
Vol 3 (2) ◽  
pp. 47-60
Author(s):  
Alexey V. Starov
Keyword(s):  
Paper Analysis ◽  
Measurement Methods ◽  
Experimental Results ◽  
Physical Parameters ◽  
Supersonic Speed ◽  
Combustion Limits ◽  
Criterial Description ◽  
Selection Of ◽  
Good Agreement

In this paper, analysis of existing methods application of criterial description of ignition conditions and combustion break-out for summarizing of experimental results is carried out. Experimental results are obtained at investigations of hydrogen combustion in combustor with high supersonic speed of airflow. For these conditions selection of several criterions was substantiated and they have a good agreement with new experimental results. At the same time complexity of determination of experimental physical parameters, which are included in criterions, do not allow confidently to apply them for prediction of steady-state combustion limits. Therefore further accumulation of experimental data and development of measurement methods are necessary for accurate criterions obtaining.

Measurement of the Isothermal Volume Dilation Accompanying the Unilateral Extension of Rubber

1959 ◽  
Vol 32 (2) ◽  
pp. 428-433
Author(s):  
Fred G. Hewitt ◽  
Robert L. Anthony
Keyword(s):  
Molecular Weight ◽  
Young’S Modulus ◽  
Experimental Results ◽  
Molecular Weights ◽  
Rubber Specimen ◽  
A Value ◽  
Fractional Increase ◽  
Internal Agreement ◽  
Good Agreement

Abstract The fractional increase in volume accompanying the isothermal extension of soft gum rubber was measured for four rubber samples at mean extensions of 14, 33, and 51%. The chain molecular weights Mc of the four samples were 5500, 5100, 4400, and 3000, with an estimated uncertainty of about 10% in each value of Mc. The observed fractional increase in volume ranged from 3.2×10−5 to 142×10−5, the latter value being observed for the sample of lowest chain molecular weight and at the extension of 51%. The experimental results for each sample have been represented by theoretical curves based on Gee's expression for the fractional increase in volume as a function of the sample extension. The theoretical curves exhibit good agreement with those of Gee, Stern, and Treloar. The process of fitting the theoretical curves to the experimental points constituted a determination of Young's modulus E for each rubber specimen. As a check on the experimental results, and also on the theory employed, determinations of E were also made by two additional methods, namely, from rough stess-strain curves, and from the relation E=3γρRT/Mc. With one exception, the internal agreement between the three determinations of E for the four different samples was satisfactory. The exception noted can probably be ascribed to the use of too small a value of Mc for the sample of lowest chain molecular weight.

Explicit formulation for the axial collapse of a pipe during drilling

2010 ◽  
Vol 224 (8) ◽  
pp. 1547-1549
Author(s):  
A Almasi
Keyword(s):  
Closed Form ◽  
Plastic Hinge ◽  
Variable Length ◽  
Experimental Results ◽  
Displacement Curve ◽  
Explicit Formulation ◽  
Theoretical Predictions ◽  
Hinge Zone ◽  
Good Agreement

New closed-form expressions are introduced for ax-symmetric progressive axial collapse of pipes that use a plastic folding mechanism based on variable length of an active plastic hinge zone. A procedure for determination of a load—displacement curve of axial pipe collapse is presented. Theoretical predictions give a good agreement with the experimental results owing to the influence of presented new refinements.

Creep Buckling of Ovalized Tubes Under External Pressure

1996 ◽  
Vol 118 (4) ◽  
pp. 460-463 ◽  
Author(s):  
V. Koundy ◽  
T. Forgeron ◽  
J. Hivroz
Keyword(s):  
Analytical Approach ◽  
External Pressure ◽  
The Finite Element Method ◽  
Creep Tests ◽  
Circular Tubes ◽  
Geometrical Characteristics ◽  
Calculation Results ◽  
Numerical Program ◽  
Good Agreement

In order to get a better understanding of the role of various parameters on the creep collapse phenomenon of long circular tubes, an experimental and numerical program has been undertaken. It mainly aims at studying the influence of the behavior of the material composing the circular tubes and their geometrical characteristics on the flattening time. This paper presents the results of numerical simulations performed with a specific computer program using an analytical approach. They have been compared with the data obtained from creep tests performed in various conditions on preovalized tubes as well as with the solutions obtained from the finite element method. It is shown that a good agreement is achieved between experimental results and calculation results.

The Elastic Instability of a Complete Spherical Shell

1962 ◽  
Vol 13 (2) ◽  
pp. 189-201 ◽  
Author(s):  
J.M.T. Thompson
Keyword(s):  
Spherical Shell ◽  
High Speed ◽  
Large Deflection ◽  
Elastic Shell ◽  
External Pressure ◽  
Maximum Pressure ◽  
Elastic Instability ◽  
Rotationally Symmetric ◽  
Post Buckling ◽  
Good Agreement

SummaryThe elastic instability of a complete spherical shell under uniform external pressure is studied experimentally and theoretically. The premature snapping of a thin elastic shell, made of polyvinyl chloride, is seen to be classical in nature. The experimental maximum pressure and pre-snapping bending deformation are correlated with the theoretical behaviour of an initially imperfect shell. The large deflection behaviour of a perfect shell is assessed experimentally, and the stable post-buckling states are observed to be rotationally symmetric. A fairly precise theoretical analysis of these states is performed, the use of a high-speed digital computer allowing a considerable advance over previous treatments. The experimental and theoretical post-buckling curves are in good agreement, yielding the first detailed correlation of post-snapping equilibrium states in the field of shell instability.

Electrothermally Actuated Microbeams With Varying Stiffness

2017 ◽  
Author(s):  
Sherif Tella ◽  
Nouha Alcheikh ◽  
Mohammad I. Younis
Keyword(s):  
Resonance Frequency ◽  
Considerable Increase ◽  
Large Deflection ◽  
Variable Stiffness ◽  
Experimental Results ◽  
Mechanical Stiffness ◽  
Frequency Tunability ◽  
End Conditions ◽  
Variable Stiffness Actuation ◽  
Good Agreement

We present axially loaded clamped-guided microbeams that can be used as resonators and actuators of variable stiffness, actuation, and anchor conditions. The applied axial load is implemented by U-shaped electrothermal actuators stacked at one of the beams edges. These can be configured and wired in various ways, which serve as mechanical stiffness elements that control the operating resonance frequency of the structures and their static displacement. The experimental results have shown considerable increase in the resonance frequency and mid-point deflection of the microbeam upon changing the end conditions of the beam. These results can be promising for applications requiring large deflection and high frequency tunability, such as filters, memory devices, and switches. The experimental results are compared to multi-physics finite-element simulations showing good agreement among them.

scholarly journals Use of the corrected plane wave model for the determination of the reflection coefficient during horizontal plate swell interaction

2019 ◽  
Vol 286 ◽  
pp. 09001
Author(s):  
M. Amimi ◽  
S. Naasse ◽  
C. Chahine
Keyword(s):  
Reflection Coefficient ◽  
Plane Wave ◽  
Relative Length ◽  
Wave Model ◽  
Experimental Results ◽  
Regular Wave ◽  
Horizontal Plate ◽  
Submerged Horizontal Plate ◽  
Good Agreement

The main objective of this work, is to calculate variations of the reflection coefficient of the regular wave by a submerged horizontal plate, using the corrected plane wave model, by choosing appropriately the immersion and the relative length of the plate. It is shown that with this correction the reflection coefficient has a good agreement with the experimental results (Brossard et al., Liu C.R).

The Determination of Forced-Convection Surface-Boiling Heat Transfer

1964 ◽  
Vol 86 (3) ◽  
pp. 365-372 ◽  
Author(s):  
A. E. Bergles ◽  
W. M. Rohsenow
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Experimental Results ◽  
Boiling Curve ◽  
Wall Superheat ◽  
Good Agreement

The characteristics of the boiling curve for forced-convection surface boiling are examined in detail. In the region of low wall superheat, the heat transfer can be predicted by available correlations for forced convection. An analysis is presented for the inception of first significant boiling. Experimental results are in good agreement with analytical predictions. Pool-boiling data were taken under saturated and subcooled conditions for surfaces similar to those used in forced-convection surface boiling. These data indicate that the curves for forced-convection surface boiling cannot be based on data for saturated pool boiling but must rather be based on actual forced-convection data.

Experimental Determination of Friction Factors for Straight and Curved Microchannels

2010 ◽  
Vol 5 (3) ◽  
pp. 63-70
Author(s):  
Vladimir М. Aniskin ◽  
Kseniya V. Adamenko ◽  
Anatoliy A. Maslov
Keyword(s):  
Friction Factor ◽  
Software Package ◽  
Reference Value ◽  
Reynolds Numbers ◽  
Experimental Results ◽  
Friction Factors ◽  
Inner Diameter ◽  
Curved Section ◽  
Good Agreement

This article presents experimental results of determining the friction factors for two microchannels with circular crosssection: rectilinear and curvilinear. The inner diameter of channels in both cases was 100 microns. The Reynolds numbers ranged from 110 to 2216. Pressure measurement was carried out simultaneously in four locations along the channel. Friction factor for the straight microchannel was in good agreement with the theoretical value for the round smooth tubes. For the curved microchannel, the value of friction factor of the curved section was 17 percent less than the reference value for smoothly curved tubes. The experimental results are compared with calculations which were made using the software package Fluent

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