Internal Pressure

This paper presents numerical results obtained using Finite Element Analysis (FEA) in studying large diameter welded neck steel flanges under different loading conditions. Obtained FEA results show the effect of the clamping pressure, internal pressure, axial end load, temperature effect, gasket elasticity modulus on the contact pressure between the gasket and the steel flange. As expected clamping pressure is a determinate factor for the sealing condition. Gasket material is another primary factor in designing flanged joints.

Ultrasonic investigations of molecular interactions of polymer blends of chitosan (Ch)/ polyvinyl pyrrolidone (PVP), in a buffer solution (0.1 M acetic acid + 0.2 M sodium acetate) have been reported within the temperature range 303.15 K-323.15 K. Several acoustic parameters such as acoustic impedance, isothermal compressibility, adiabatic compressibility, internal pressure have been determined. Various thermo-dynamical parameters viz; pseudo-Gruneisen parameter and surface tension have been evaluated. Some thermo-elastic parameters such as bulk modulus, shear modulus and Young's modulus are also computed. The non-ideal behaviour of the blend, in the buffer solution has been explained in terms of its composition and temperature variation of acoustical and thermo-dynamical parameters. The reliability model for polymer blends of chitosan (Ch)/ polyvinyl pyrrolidone (PVP) has also been proposed.

This paper discusses the stability of underground pipelines with preformed vertical bends buried in sandy soil. More specifically, the minimum cover height required to prevent the pipe from bowing under the action of forces due to temperature change and internal pressure is estimated. The variables considered include the pipe and soil materials, diameter, thickness, overburden height, bend radius, bend angle, internal pressure, fluid specific weight, and temperature variation. A comprehensive three-dimensional finite element analysis is carried out. The results are extracted from the output obtained. These results are put in a database which is used to develop general regression models to determine the relationships among the different variables. Different buckling modes are also considered. All of these results and models are entered into a computer software program for ready access.

Isotherms of experimental data of internal pressure of dense fluids versus molar volume, V m are shown to have each a maximum point at a V max below the critical molar volume. In this study, we investigated the role of attractive and repulsive intermolecular energies on this behavior using a molecular dynamics simulation technique. In the simulation, we choose the Lennard-Jones (LJ) intermolecular potential energy function. The LJ potential is known to be an effective potential representing a statistical average of the true pair and many-body interactions in simple molecular systems. The LJ potential function is divided into attractive and repulsive parts. MD calculations have produced internal energy, potential energy, transitional kinetic energy, and radial distribution function (RDF) for argon at 180 K and 450 K using LJ potential, LJ repulsive, and LJ attractive parts. It is shown that the LJ potential function is well capable of predicting the inflection point in the internal energy-molar volume curve as well as maximum point in the internal pressure-molar volume curve. It is also shown that at molar volumes higher than V max , the attractive forces have strong influence on determination of internal energy and internal pressure. At volumes lower than V max , neither repulsive nor attractive forces are dominating. Also, the coincidence between RDFs resulting from LJ potential and repulsive parts of LJ potential improves as molar volume approaches V max from high molar volumes. The coincidence becomes complete at Vmax >,= V.

Abstract Vibration analysis of a gossamer or inflated structure poses special problems, usually not encountered in a conventional metallic or composite structure. In an inflated structure, internal pressure is a major source of strength and rigidity. In the past, most of the studies conducted on the vibration analysis of gossamer structures used inaccurate or approximate theories in modelling the internal pressure. The inexactness in these theories arises due to (1) exclusion of the follower pressure loads, and (2) approximations in the geometric non-linearity. Taking cues from the earlier work done in this area and using line-of-curvature co-ordinates, we re-derive the governing equations for vibration analysis of a shell under pressure, and point out the shortcomings of the previous approximate theories. The same governing equations were derived earlier by Budiansky using tensors. Thereafter, a free-vibration analysis of an inflated torus with free boundary condition is performed using the accurate and the approximate shell theories. It can be seen that the natural frequencies and the mode shapes obtained from the approximate theories are significantly different from those obtained from the accurate shell theory. Since the boundary condition of the torus is free, the vibration analysis should yield six zero frequencies corresponding to the six rigid-body modes. It is shown here that while the accurate theory does give six zero frequencies, the approximate theories do not.

: An elastically deformable pressure vessel is used as an actuator. The internal pressure is controlled hydraulically via force applied to an external bellows. The resulting elongation of the vessel is a linear function of the input force, and depends on the physical properties of the vessel, fluid, and bellows. The design includes an orifice through which fluid flows, adding damping to the actuator. Mathematical models of the actuator are developed which relate performance of the actuator to its geometry and material properties. A static analysis yields the linear relationship between the commanded input force and the resulting elongation of the vessel. A model of the passive (no input force) response of the actuator indicates it will act as a passive damper. The active response (application of a dynamic input force yielding a dynamic elongation) is limited in frequency by the orifice damping. Strategies for optimizing the actuator size and material properties are developed from th...

"Ultrasonic velocities, Densities and Viscosities are measured for ternary liquid mixture of formic acid and tri-ethylamine (TEA) with ethanol. From this experimental data freelength, excess freelength, internal pressure and excess internal pressure have been calculated. The behaviour of mixture has been investigated at 303K, 308K and 313K for frequency 2Mz. These parameters have been discussed to throw light on intermolecular interactions between the components of ternary mixture. P J Thakare | J B Thakare | N G Belsare""Study of Intermolecular Interactions through Freelength, and Internal Pressure of Ternary Liquid Mixture of Alcohol, Formic Acid and Tri-Ethyl Amines"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-1 | Issue-5 , August 2017, URL: http://www.ijtsrd.com/papers/ijtsrd2352.pdf
Article URL: http://www.ijtsrd.com/physics/acoustics/2352/study-of-intermolecular-interactions-through-freelength-and-internal-pressure-of-ternary-liquid-mixture-of-alcohol-formic-acid-and-tri-ethyl-amines/p-j-thakare"

A computational fluid dynamics solution of the Navier-Stokes equations has been applied to the internal and external flow of inert solid-fuel ramjet projectiles. Computational modeling reveals internal flowfield details not attainable by flight or wind tunnel measurements, thus contributing to the current investigation into the flight performance of solid-fuel ramjet projectiles. The present code employs numerical algorithms termed total variational diminishing (TVD). Computational solutions indicate the importance of several special features of the code including the zonal grid framework, the TVD scheme, and a recently developed backflow turbulence model. The solutions are compared with results of internal surface pressure measurements. As demonstrated by these comparisons, the use of a backflow turbulence model distinguishes between satisfactory and poor flowfield predictions.

Most of the industrial applications of ester-based synthetic lubricants are performed at medium and high pressures, but in the case of viscosity and density, the existing studies are carried out mainly at atmospheric pressure. Lubricants are normally composed by several ...

This paper discusses the stability of underground pipelines with preformed vertical bends buried in sandy soil. More specifically, the minimum cover height required to prevent the pipe from bowing under the action of forces due to temperature change and internal pressure is estimated. The variables considered include the pipe and soil materials, diameter, thickness, overburden height, bend radius, bend angle, internal pressure, fluid specific weight, and temperature variation. A comprehensive three-dimensional finite element analysis is carried out. The results are extracted from the output obtained. These results are put in a database which is used to develop general regression models to determine the relationships among the different variables. Different buckling modes are also considered. All of these results and models are entered into a computer software program for ready access.

Some ultrasonic investigations in binary mixtures of molten salts with a common ion and reciprocal salt pair mixtures have been carried out. Prissiajnyi et al had reported data on ultrasonic velocity and adiabatic compressibilities for four molten salt pairs with a common ion. They calculated isothermal compressibility, molar ultrasonic velocity, excess molar volume and excess isothermal compressibility in such systems on the basis of a hole theory. In the present investigation, several acoustical and thermodynamically parameters of CdBr2 + KBr, CdCl2 + KCl, LiBr + LiCl and LiBr +KBr have been studied. While the first two systems are investigated at 973 K and the other two systems are studied at 1023 K. The ultrasonic velocities and adiabatic compressibilities data for these systems have been taken from the literature for these studies. The interactions prevailing in these binary mixtures have been interpreted from the obtained results.

Physico-chemical properties like ultrasonic velocity, density, viscosity and refractive index have been measured for the following four ternary systems: 1. n-hexane + p-dioxane + methanol 2. n-hexane + p-dioxane + ethyl acetate 3. Carbon tetrachloride + Pyridine + ethyl acetate 4. Carbontetrachloride + Pyridine + methanol The dielectric constant and dipole moment measurements are also made for a ternary mixture: n-hexane + p-dioxane + ethyl acetate at 30.5, 35.5 and 40.5 degrees Celsius. Using the experimentally obtained data a large number of acoustical and thermodynamical parameters e.g. adiabatic compressibility, Rao's parameter, intermolecular free length, Wada's parameter, acoustic impedance and Relative association have been studied. Free volume and internal pressure values for the systems have also been calculated. The trends of variation of these parameters have been explained in terms of the interactions present among the molecules of the constituent liquids. Using measured viscosity data, interaction energies have been found and the strength of interactions between constituents of the mixtures are also reported. The validity of the Eykman relation is checked in the case of ternary liquid systems for the first time. Auerback relation is used to predict the surface tension values for the systems under investigation. An analysis of the results obtained indicates that the response of a ternary system does not depend significantly on the aromatic or aliphatic nature of the liquids. It depends primarily on the polarity and molecular radius of the each component.

The purpose of this study is to determine limit loads for pipe elbows subjected to inplane bending moments that tend to open the elbow (i.e., increase its radius of curvature), and the influence of internal pressure on the value of the limit load. Load-deflection curves were obtained, and from these curves plastic collapse and instability loads at various values of internal pressure were determined. This was done for different pipe bend factors (h = Rt/r2) using the nonlinear finite element analysis code (ABAQUS) with its special elbow element. A set of limit curves was generated from the results. These curves show the variation of collapse and instability loads with internal pressure for different elbows. Collapse loads were found to increase and then decrease with increasing pressure for all the elbow geometries studied. Instability loads were difficult to reach because of the large stiffening effect of the elbow cross-sectional deformation, and they were generally found to decrea...

Abstract : This report documents an exact closed-form solution to the problem of a two-layer viscoelastic solid infinite cylinder that is immersed in an infinite ideal inviscid fluid and contains an infinite ideal inviscid fluid within its diameter. The viscoelasticity is modeled with structural damping, which is incorporated by the use of a complex modulus of elasticity. The composite system is subject to forced harmonic vibration at the outer solid/fluid interface. The response to both nonaxisymmetric (described in terms of circumferential order number n) and axisymmetric excitations is derived. The problem is resolved with a three-dimensional dynamic elasticity solution. Simulations of the transfer surfaces for the interior pressure field are performed for radial excitation P0 and longitudinal excitation Px applied to a single-layer cylinder for n = 0, 1, and 2. The circumferential excitation P theta is applied to the single-layer cylinder for interior pressure simulation with n = 1 and 2. Simulations of the circumferential strain are performed for excitations P0 and Px applied to a two-layer cylinder for n = 0. Additionally, the P0 excitation is applied to the two-layer cylinder for n = 0, 1, and 2, resulting in simulations for the pressure field in the inner fluid. Simulations are displayed as response transfer surfaces in the longitudinal wavenumber-frequency plane. Comparisons are made between the elasticity models derived in this report and the membrane and bending shell models from previous work. The nulls occurring in the interior pressure field at higher frequencies are explored as well as the resonances relating to the thickness of the cylinder.

This paper proposes a method for determining endurance limits to leakage for fiberglass pipes under internal pressure using acoustic emission signals and static pressure tests. Results are presented from a series of cyclic internal pressure tests performed on fiberglass pipes fabricated according to ASME RTP-1 (1989) recommendations. The specimens were 8in.(20.32cm) internal diameter and 5ft(1.525m) long. The construction layup consisted of an internal corrosion barrier followed by several layers of continuous filament wound glass. A state of pure hoop stress was imposed via an internal pressure system that allowed free axial movement of the pipe. The purpose of the tests was to evaluate current design procedures and to assess the capabilities of acoustic emission (AE) monitoring to detect damage and to predict the leakage pressure for the pipes. Twenty-four specimens were tested to failure with AE monitoring. The results of these tests are presented, including data on the measured ...