Showing papers on "Internal pressure published in 2018"
TL;DR: In this paper, the effect of low velocity impact (LVI) response of carbon/glass hybrid filament wound composite pipes has been studied based on this motivation, and the effects of stacking sequence upon damage formation and damage progression under LVI loading have been evaluated based on the obtained data and microscopic analysis.
Abstract: Filament wound hybrid composite pipes can expose to impact loading from various causes during their service life which can cause an invisible level of damage. Thus, revealing the effect of impact damage gains great importance to design hybrid composite pipes with enhanced damage tolerance. Based on this motivation, the low velocity impact (LVI) response of carbon/glass hybrid filament wound composite pipes has been studied. Hybrid pipes were produced with the winding angle of ±55° by using glass and carbon fiber layers in various stacking sequences by filament winding method. The stacking sequence configurations were set as Carbon/Glass/Glass (CGG), Glass/Carbon/Glass (GCG) and Glass/Glass/Carbon (GGC). Before generating impact damage, an internal pressure of 32 bar was applied to the hybrid pipes in accordance with ANSI/AWWA C950 standard and pre-stress was generated in the pipes. Following, the hybrid pipes subjected to internal pressure were subjected to low velocity impact tests at energy levels of 5, 10, 15 and 20 J. The variation of contact force versus time, contact force versus displacement and energy versus time were obtained. After the testing, the effects of stacking sequence upon damage formation and damage progression under LVI loading have been evaluated based on the obtained data and microscopic analysis. It has been found that the damage formation such as matrix cracking on outer/inner surfaces, radial cracks, delamination, transfer cracks, splitting and leakage can take place. Moreover, the hybrid pipes with CGG stacking represents higher impact resistance while the GCG stacking has a better response of damage formation since this stacking does not show leakage damage.
108 citations
TL;DR: In this article, the main objective is to predict burst pressure of composite pressure vessels subjected to internal pressure taking into account manufacturing uncertainties, and a stochastic model is used to estimate burst pressure.
86 citations
TL;DR: In this paper, the authors predict the load bearing capacity of composite tubes subjected to hydrostatic internal pressure using progressive damage modeling, which consists of four distinct stages as model preparation, stress analysis, failure assessment and material degradation.
58 citations
TL;DR: In this paper, a full-scale experimental burst test was performed, and a nonlinear finite element method was used to compare the numerical and experimental results in this study, and the finite element numerical results are verified using the experimental measurement results.
43 citations
TL;DR: In this paper, an alternative drilling technology has been developed, in which ultra-high pressure jetting with in excess of 2500 bar jet pressure is combined with mechanical drilling techniques.
41 citations
TL;DR: In this paper, the authors investigate some very basic single and two-layered examples regarding identifiability, because these tests are the basis for more complex geometrical and physical nonlinear problems.
Abstract: Material parameter identification using constitutive models of elasticity, viscoelasticity, rate-independent plasticity and viscoplasticity has a long history with regard to homogeneous and inhomogeneous deformations. For example, uniaxial tensile tests, pure shear tests, torsion experiments of thin-walled tubes or biaxial tensile tests are used to obtain the material parameters by solving the inverse problem. Frequently, the parameters are determined by numerical optimization tools. In this paper, we investigate some very basic single- and two-layered examples regarding identifiability, because these tests are the basis for more complex geometrical and physical nonlinear problems. These simple examples are the uniaxial tensile/compression case, biaxial tensile tests of a cruciform specimen, torsion of a thin-walled tube, a thick-walled tube under internal pressure and the indentation test. For the thick-walled tube under internal and external pressure with an axial pre-strain with several layers, an analytical solution is provided directly suitable for programming. The aim is to get an understanding whether some problems lead to non-identifiable parameters.
40 citations
TL;DR: In this article, the effect of vent burst pressure on the whole explosion in a 2.5m stainless cylindrical vessel with the ethylene-air mixture is investigated as a function of the vent area and burst pressure, and it is shown that the dominant peak overpressure will change with different vent areas.
39 citations
TL;DR: In this paper, the burst pressure of commonly used ductile steel pipes in oil and gas industries, i.e., X52 and X60, is measured under internal pressure loading, and defect shapes and orientations are investigated in detail to study how they affect the failure behavior of interacting defects.
39 citations
TL;DR: In this paper, the main condensation regimes at sub-atmospheric pressure conditions were identified and a comparison was done between the condensation regime experimentally determined and those available in the literature, which were obtained at atmospheric pressure.
39 citations
TL;DR: In this paper, the thermal effect of process parameters on the average surface of selective laser melting (SLM) Ti-6Al-4V is discussed and mathematically characterized.
Abstract: Additive manufacturing is one of the promising production processes, which has the ability to manufacture final shape directly from computer-aided designs. In this research, the thermal effect of process parameters on the average surface of selective laser melting (SLM) Ti-6Al-4V is discussed and mathematically characterized. Based on Taguchi L25, the experiment was designed, and laser power, scan speed, hatch spacing, laser increment pattern angle, and heat treatment in five levels were selected as input parameters. Interfacial forces including surface tension, Marangoni’s effect, pressure in droplet, capillarity force, work adhesion, wetting, recoil pressure, drag forces (due to solid-liquid transition) and interaction of surface tension, hydrostatic and vapor pressures have been characterized mathematically to analyze their effect on surface quality. Results showed higher energy density and temperature cause lower surface tension and capillary force, generating unstable and lower surface quality. In addition, higher energy density and temperature increase droplet pressure, internal pressure, recoil pressure, and thermal stress and change the balance of forces on the surface of the melting pool and reduce surface quality.
29 citations
TL;DR: In this paper, an analytical solution of stresses and displacements in a long functionally graded (FGM) hollow cylinder subjected to uniform heat generation and internal pressure is presented, which reveals that stresses in FGM cylinder decrease considerably, compared to the homogenous one, for a particular interval of material parameters.
TL;DR: In this article, the authors investigated hydrogen embrittlement of steel pipelines originally designed for natural gas transportation is investigated based on solubility, permeation and diffusion phenomena of hydrogen molecules into the crystalline lattice structure of the pipeline material.
Abstract: Blending hydrogen into natural gas pipelines is a recent alternative adopted for hydrogen transportation as a mixture with natural gas. In this paper, hydrogen embrittlement of steel pipelines originally designed for natural gas transportation is investigated. Solubility, permeation and diffusion phenomena of hydrogen molecules into the crystalline lattice structure of the pipeline material are followed up based on transient evolution of internal pressure applied on the pipeline wall. The transient regime is created through changes of gas demand depending on daily consumptions. As a result, the pressure may reach excessive values that lead to the acceleration of hydrogen solubility and its diffusion through the pipeline wall. Furthermore, permeation is an important parameter to determine the diffusion amount of hydrogen inside the pipeline wall resulting in the embrittlement of the material. The numerical obtained results have shown that using pipelines designed for natural gas conduction to transport hydrogen is a risky choice. Actually, added to overpressure and great fluctuations during transients that may cause fatigue and damage the structure, also the latter pressure evolution is likely to induce the diffusion phenomena of hydrogen molecules into the lattice of the structure leading to brittle the pipe material. The numerical simulation reposes on solving partial differential equations describing transient gas flow in pipelines coupled with the diffusion equation for mass transfer. The model is built using the finite elements based software COMSOL Multiphysics considering different cases of pipe material; API X52 (base metal and nutrided) and API X80 steels. Obtained results allowed tracking the evolution with time of hydrogen concentration through the pipeline internal wall based on the pressure variation due to transient gas flow. Such observation permits to estimate the amount of hydrogen diffused in the metal to avoid leakage of this flammable gas. Thus, precautions may be taken to prevent explosive risks due to hydrogen embrittlement of steel pipelines, among other effects, that can lead to alter safe conditions of gas conduction.
TL;DR: In this paper, an experimental setup is developed, based on partial discharge detection in a vacuum system, to characterize the partial discharge inception voltage of three coaxial cable designs in an argon and nitrogen environment at controllable pressure.
Abstract: Design of cables for operation in a low pressure environment is challenging, when applications also demand lightweight and flexibility, and material choice is restricted. The operating pressures in combination with relevant distances, can be situated near gas breakdown and cause partial discharges, making long-term damage conceivable. An experimental setup is developed, based on partial discharge detection in a vacuum system, to characterize the partial discharge inception voltage of three coaxial cable designs in an argon and nitrogen environment at controllable pressure. In order to cope with outgassing behavior, a lumped element model is presented to simulate the internal pressure distribution along the cable as a function of settling time. Microscopic cross sections of the cables are analysed with electrostatic voltage simulations. Using scaled Paschen curves, expected partial discharge inception is determined and compared with measurements. Quantifying cable performance, in terms of minimum PD inception voltage and pressure, in relation to its design is feasible, but also deviations occur which are discussed.
TL;DR: In this paper, the relation between the volume of a balloon and its internal pressure was analyzed when the balloon is subjected to different voltages, and it was shown that when the applied voltage is small, the pressure vs. volume diagram of balloon can be represented by an N-like curve, which is similar to the conventional hyperelastic balloon only subjected internal pressure.
TL;DR: In this paper, a nonlinear finite element hose model is created with commercial software ABAQUS and validated to predict its structural behavior under internal pressure, which can predict hose failure pressure and provide guidance for reliable hose design in practice.
TL;DR: In this article, the analytical and numerical calculation of the critical internal load for a pressure vessel containing a longitudinal edge crack or cracks was performed using an extended finite element method (XFEM).
Abstract: This paper concentrates on the analytical and numerical calculation of the critical internal load for a pressure vessel containing a longitudinal edge crack or cracks. Initially, the vessel’s capacity is analyzed based on the theoretical fracture methods for seven material properties, different crack lengths, and vessel’s wall thickness. Theses analyses are conducted using an extended finite element method (XFEM) to observe its accuracy and applicability. In problems with complex configuration of crack, it’s difficult to use theoretical method for analyzing the structure. Therefore, after verifying the XFEM with excellent accuracy, several analyses are made for different cases. By employing the XFEM, the effects of having multiple cracks along the vessel’s circumference, crack width along the vessel’s wall, crack location on the internal or external edge of the vessel, and applying the FRP laminates to reinforce the vessel are investigated. Besides, the effect of mode II (sliding mode) on behavior of vessel and the elastic-plastic analysis are analytically studied. Results show that the critical internal pressure for a single cracked and a multiple cracked vessel are the same unless two cracks be very close to each other. Increasing the crack width decreases the critical pressure meaningfully. It is also shown that the vessel is more vulnerable to fail by external crack than an internal crack with similar length and width. Also, the cracked bodies are reinforced with FRP laminates which proves that laminates with higher modulus of elasticity have more effect on the critical internal pressure. Moreover, the elastic-plastic analysis does not have significant influence on critical pressure load due to small plastic zone.
TL;DR: In this article, a 90° back-to-back pipe bend structure subjected to cyclic inplane bending moment and steady internal pressures is analyzed by means of the Linear Matching Method (LMM) in order to create the limit, shakedown, and ratchet boundaries.
Abstract: A 90° back-to-back pipe bend structure subjected to cyclic in-plane bending moment and steady internal pressures is analysed by means of the Linear Matching Method ( LMM ) in order to create the limit, shakedown, and ratchet boundaries. The analyses performed in this work demonstrate that the cyclic moment has a more significant impact upon the structural integrity of the pipe bend than the constant pressure. Full cyclic incremental analyses are used to verify the structural responses either side of each boundary and confirm correct responses. In addition, the shakedown boundary produced by the LMM is compared to another shakedown boundary of an identical pipe bend computed by the simplified technique and it is shown that the LMM calculates results more accurately. Parametric studies involving a change of geometry of the pipe bends and loading type are carried out. From the studies of the geometry, two semi-empirical equations are derived from correlations of the reverse plasticity limit and the limit pressure with the bend characteristic. Finally, the results presented in this paper provide a comprehensive understanding of post-yield behaviours of the 90° back-to-back pipe structure under the combined loading as well as offering essential points to be concerned for the life assessment of the piping system.
TL;DR: In this paper, the effect of shape imperfections on the buckling of a large-scale thin-walled ellipsoidal head subjected to internal pressure is investigated, and an equation was proposed to quantitatively characterize bulging of weld in the knuckle.
Abstract: Buckling is a failure mode of a large-scale thin-walled ellipsoidal head for a cylindrical steel containment vessel, which is widely used in nuclear power plants such as AP1000 and CAP1400. Manufacturing processes always induce shape imperfections in large-scale thin-walled ellipsoidal heads. However, the study on the effect of shape imperfections on the buckling of a large-scale thin-walled ellipsoidal head subjected to internal pressure is still lacking. In this work, we first used a 3D laser scanner to measure the overall shape of the ellipsoidal head which has a diameter of 5000 mm, a radius-to-height ratio of 2.0 and a thickness of 5.5 mm. On the basis of the measured overall shape, shape imperfections were determined, and an equation was proposed to quantitatively characterize bulging of weld in the knuckle. Secondly, the measured overall shape and the equation were used to develop FEA models with shape imperfections. Buckling pressures were predicted by using nonlinear FEA. Good agreement between the predictions of the FEA models with shape imperfections indicates that bulging of weld has a considerable effect on buckling pressure. Thirdly, a buckling experiment was performed on the ellipsoidal head and buckling behavior was obtained. The experimental results show that all the buckles occurred at the bulgings of welds. The agreement between the experimental results and the predictions based on the models with shape imperfections is good. At last, FEA models, including different bulging heights of welds characterized by the equation, were established to perform an imperfection sensitivity analysis. Thin-walled ellipsoidal heads subjected to internal pressure demonstrate a significant sensitivity to the bulging height of weld in the knuckle.
TL;DR: In this article, an elasto-plastic analysis of a thick-walled cylinder made of functionally graded materials (FGMs) subjected to constant internal pressure and cyclic temperature gradient loading is carried out using MATLAB.
TL;DR: In this article, the significance of internal pressure pulsation characteristics between prototype and model pump devices, monitoring of computational fluid dynamics and dynamic measurement of a model were studied, in order to study the relationship between pump internal pressure and model parameters.
Abstract: To study the significance of internal pressure pulsation characteristics between prototype and model pump devices, monitoring of computational fluid dynamics and dynamic measurement of a model were...
TL;DR: In this paper, an analytical approach for predicting the free vibration and elastic critical load of functionally graded material (FGM) thin cylindrical shells filled with internal pressured fluid is presented.
Abstract: An analytical approach for predicting the free vibration and elastic critical load of functionally graded material (FGM) thin cylindrical shells filled with internal pressured fluid is presented in...
TL;DR: In this article, the authors analyzed the capacity of the Prestressed Concrete Containment Vessel (PCCV) to provide technical support for development of severe accident management guidelines (SAMG) in nuclear power plants.
TL;DR: In this article, an experimental study of high strength steel pipe with local wall thinning (gouge) under internal pressure has been carried out through experimental procedure and numerical analysis and the results show that the analytical relations estimate greater lateral resistance than numerical results.
01 Apr 2018
TL;DR: In this article, the problem of strength and stability of shells under torsion and internal pressure was solved and it was found out the influence of the internal pressure, ellipticity and nonlinearity of deformation on the critical buckling load of the shell.
Abstract: The problem of strength and stability of shells under torsion and internal pressure was solved. It was found out the influence of the internal pressure, ellipticity and nonlinearity of deformation on the critical buckling load of the shell.
TL;DR: In this article, the effect of pulsating pressure on the hot tube gas bulging process has been investigated by experimental and numerical methods, where an oscillating heating mechanism was used to provide a uniform temperature distribution along the tube.
Abstract: Hot metal gas forming is a modern metal forming process which is generally utilized to manufacture automotive parts with complex shape and light-weight materials such as aluminum-magnesium alloys. One of the critical parameters in this approach is controlling the internal pressure of the tube during the hot forming process. The improvement of formability in tube hydroforming by utilizing pulsating pressure paths has been confirmed in the last few years. In this paper, the effect of the pulsating pressure on the hot tube gas bulging process has been investigated by experimental and numerical methods. In addition, an oscillating heating mechanism was used to provide a uniform temperature distribution along the tube. A novel, simple pneumatic system was designed and used to provide pressure paths. Moreover, the finite element simulation of hot tube gas bulging was carried out to investigate the effect of different parameters of pulsating pressure on tube formability and thickness distribution. The simulation and experimental results showed that the proposed pulsating pressure path improved formability and thickness distribution along the tube in the hot metal tube gas bulging process. It was also concluded that the axial feeding intensifies the effect of pulsating pressure on formability and it should be applied right after the start of the plastic deformation of the tube.
TL;DR: In this paper, an automatic system for pressure control and load simulation of inflatable membrane structure, including a pressure control subsystem and a load simulation subsystem, is presented, which is considerably automatic, accurate, efficient and reliable for pressure and load simulations.
TL;DR: In this article, the effect of dome geometrical shape (hemispherical, torispherical and ellipsoidal domes) on mechanical deformation and crack length of laminated woven reinforced polymer (GRP) composite pressure vessels under low-velocity impact (LVI) or combination of LVI and internal pressure (case two).
TL;DR: In this article, a finite element based framework was proposed to capture the coupled effect of elastic strain energy and surface tension on the cavitation phenomenon in an infinite elastic media and cavitation rheology technique.
Abstract: Unbounded growth of cavity in soft solids subjected to internal pressure is a commonly observed phenomenon. Such phenomenon has been harnessed by developing cavitation rheology technique (CR) to investigate the local mechanical properties of many complex soft materials. The elasticity of the material, surface energy, and geometric factors in combination can dictate the cavitation behavior in a complex manner. We report a finite element based framework capturing the coupled effect of elastic strain energy and surface tension on the cavitation phenomenon. We show results for a spherical cavity in an infinite elastic media and for the CR geometry. The surface tension is shown to increase the critical pressure for cavitation. The energy release rate also depends on the surface tension. In CR geometry, by varying the distance between the needle and the immovable sample boundaries, we have captured the conditions leading to confinement. Our results provide new understanding regarding the effects of geometry and surface tension on the cavitation phenomenon in soft solids.
TL;DR: In this paper, a multiscale approach to model thick-walled laminate cylinder with internal pressure is presented, where the Lekhnitskii formalism is used to obtain the elastic solution of the stress and strain distributions and failure is analyzed employing the Tsai-Wu criterion.
Abstract: This paper deals with a multiscale approach to model thick-walled laminate cylinder with internal pressure. Micromechanics defines material homogenization considering two steps: determination of equivalent properties of each lamina from matrix and fiber properties according to the Mori-Tanaka model for elastic properties and to the Bridging model for strengths; and determination of anisotropic homogeneous properties of the laminate built with a set of laminae using asymptotic homogenization. On the other hand, macromechanics determines stress and failure analysis. Lekhnitskii formalism is used to obtain the elastic solution of the stress and strain distributions and failure is analyzed employing the Tsai-Wu criterion. Three different pressure vessel configurations are analyzed according to end conditions: restrained-ends, open-ends and closed-ends. Angle-ply laminates made of carbon fibers and epoxy matrix are considered to evaluate the influence of lay-up angle, fiber volume fraction, wall thickness and end-conditions. The optimum angles as well as the maximum internal pressure are obtained and a parametric analysis is presented. The main results indicate that the optimum angle is almost constant for restrained and closed-ends. On the other hand, for open-end, angle varies in a significant way. Besides, results show that the increase the fiber volume fraction is more effective to increase vessel strength than the increase of the number of layers.
TL;DR: Failure and stress analyses were carried out for composite pipes adhesively joined with sleeves subjected to internal pressure in this article, where the composite pipes and sleeves were E glass fiber/epox...
Abstract: Failure and stress analyses were carried out for composite pipes adhesively joined with sleeves subjected to internal pressure. In the study, the composite pipes and sleeves were E glass fiber/epox...