Thermomechanical Creep Analysis of FGM Thick Cylindrical Pressure Vessels with Variable Thickness

2018 ◽  
Vol 10 (01) ◽  
pp. 1850008 ◽  
Author(s):  
Mosayeb Davoudi Kashkoli ◽  
Khosro Naderan Tahan ◽  
Mohammad Zamani Nejad
Keyword(s):  
Temperature Gradient ◽  
Differential Equations ◽  
Variable Thickness ◽  
Pressure Vessel ◽  
Shear Deformation Theory ◽  
Pressure Vessels ◽  
Mechanical And Thermal Properties ◽  
Creep Response ◽  
Cylindrical Pressure Vessel ◽  
Creep Analysis

In the present study, a theoretical solution for thermomechanical creep analysis of functionally graded (FG) thick cylindrical pressure vessel with variable thickness based on the first-order shear deformation theory (FSDT) and multilayer method (MLM) is presented. To the best of the researchers’ knowledge, in the literature, there is no study carried out into FSDT and MLM for creep response of cylindrical pressure vessels with variable thickness under thermal and mechanical loadings. The vessel is subjected to a temperature gradient and nonuniform internal pressure. All mechanical and thermal properties except Poisson’s ratio are assumed to vary along the thickness direction based on a power-law function. The thermomechanical creep response of the material is described by Norton’s law. The virtual work principle is applied to extract the nonhomogeneous differential equations system with variable coefficients. Using the MLM, this differential equations system is converted into a system of differential equations with constant coefficients. These set of differential equations are solved analytically by applying boundary and continuity conditions between the layers. In order to verify the results of this study, the finite element method (FEM) has been used and according to the results, good agreement has been achieved. It can be concluded that the temperature gradient has significant influence on the creep responses of FG thick cylindrical pressure vessel.

Time-Dependent Thermomechanical Creep Behavior of FGM Thick Hollow Cylindrical Shells Under Non-Uniform Internal Pressure

2017 ◽  
Vol 09 (06) ◽  
pp. 1750086 ◽  
Author(s):  
Mosayeb Davoudi Kashkoli ◽  
Khosro Naderan Tahan ◽  
Mohammad Zamani Nejad
Keyword(s):  
Internal Pressure ◽  
Shear Deformation Theory ◽  
Pressure Vessels ◽  
Functionally Graded ◽  
Time Dependent ◽  
Mechanical And Thermal Properties ◽  
Creep Analysis ◽  
Steady State Heat ◽  
Creep Constitutive Model ◽  
Walled Cylinder

In this paper, a theoretical solution for time-dependent thermo-elastic creep analysis of a functionally graded (FG) thick-walled cylinder based on the first-order shear deformation theory is presented. The cylinder is subjected to the non-uniform internal pressure and distributed temperature field due to steady-state heat conduction from inner to outer surface of the cylinder. Mechanical and thermal properties except Poisson’s ratio are assumed to vary along the thickness direction based on a power function. The creep constitutive model is on the basis of the Norton’s law. The effects of the temperature gradient and FG grading index on the creep stresses of the cylinder are investigated. A numerical solution using finite element method is also presented and good agreement was found. Although previous publications presented analytical solutions for creep analysis of thick-walled cylindrical pressure vessels under uniform pressure, to the best of the authors’ knowledge, so far, no analytical solution has been provided for time-dependent creep analysis of FG cylinder under non-uniform internal pressure. The results of this study are applicable for designing optimum FG thick-walled cylinder.

scholarly journals A Semi-Analytical Solution for Elastic Analysis of Rotating Thick Cylindrical Shells with Variable Thickness Using Disk Form Multilayers

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Mohammad Zamani Nejad ◽  
Mehdi Jabbari ◽  
Mehdi Ghannad
Keyword(s):  
Cylindrical Shell ◽  
Analytical Solution ◽  
Differential Equations ◽  
Variable Thickness ◽  
Deformation Theory ◽  
Shear Deformation Theory ◽  
First Order ◽  
Thick Cylinder ◽  
Good Agreement

Using disk form multilayers, a semi-analytical solution has been derived for determination of displacements and stresses in a rotating cylindrical shell with variable thickness under uniform pressure. The thick cylinder is divided into disk form layers form with their thickness corresponding to the thickness of the cylinder. Due to the existence of shear stress in the thick cylindrical shell with variable thickness, the equations governing disk layers are obtained based on first-order shear deformation theory (FSDT). These equations are in the form of a set of general differential equations. Given that the cylinder is divided intondisks,nsets of differential equations are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. A numerical solution using finite element method (FEM) is also presented and good agreement was found.

Remaining Life Assessment of an External Pressure Vessel in Creep Range and Inspection Findings

2017 ◽  
Author(s):  
Yoichi Ishizaki ◽  
Futoshi Yonekawa ◽  
Takeaki Yumoto ◽  
Teppei Suzuki ◽  
Shuji Hijikawa
Keyword(s):  
Pressure Vessel ◽  
Creep Damage ◽  
External Pressure ◽  
Pressure Vessels ◽  
Life Assessment ◽  
Remaining Life ◽  
Assessment Technique ◽  
Creep Cavity ◽  
Creep Analysis ◽  
Remaining Life Assessment

As widely recognized in the industry, it is important to evaluate the creep damage of an elevated temperature vessel so that the mechanical integrity of the vessel can be achieved through the adequate repair and replacement planning. This is quite straight forward procedure for internal pressure vessels. For an external pressure vessel, it is not easy to assess the creep damage due to the complexity of the creep buckling analysis. Eventually, creep cavity evaluation technique without identifying the correct stress distribution has been used so often. However, due to the uncertainty of the technique itself plus conservative mindset of the inspectors, it tends to leads to an excessive maintenance most of the cases. In order to conduct a reasonable remaining life assessment, it is desirable to use the creep cavity inspection in conjunction with another assessment technique such as FEM creep analysis as stated in API 579-1/ASME FFS-1 10.5.7. In this paper, comprehensive approach with FEM and field inspection such as creep cavity evaluation to reinforce the uncertainty of each method will be demonstrated.

Verifying Structural Integrity of Repaired Cylindrical Pressure Vessels by Partitioning Method

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Husain J. Al-Gahtani ◽  
Mahmoud Naffa'a
Keyword(s):  
Pressure Vessel ◽  
Structural Integrity ◽  
Welded Joint ◽  
Test Validity ◽  
Pressure Vessels ◽  
Testing Method ◽  
State Of Stress ◽  
Cylindrical Pressure Vessel ◽  
Pressure Test ◽  
Alternative Test

Pressure vessels that undergo repairs are normally pressure tested to verify their structural integrity before returning into service. Conventionally, the entire vessel is pressure tested, according to the relevant construction code. In this paper, partitioning the pressure vessel is suggested as an equivalent alternative test arrangement, where pressure testing is limited to the zone where a repair has been performed. Use of such an arrangement would alleviate potential concerns associated with the conventional testing method. Procedures are provided to specify the position of the partition relative to the repair location, in order to maintain the state-of-stress to that achieved in a conventional pressure test. Validity of this approach has been demonstrated for a repaired full-circumferential welded joint in the wall of a cylindrical pressure vessel.

scholarly journals Numerical Analysis of Filament Wound Cylindrical Composite Pressure Vessels Accounting for Variable Dome Contour

2021 ◽  
Vol 5 (2) ◽  
pp. 56
Author(s):  
Kumar C. Jois ◽  
Marcus Welsh ◽  
Thomas Gries ◽  
Johannes Sackmann
Keyword(s):  
Stress Distribution ◽  
Pressure Vessel ◽  
Single Layer ◽  
Pressure Vessels ◽  
Filament Wound ◽  
Cylindrical Pressure Vessel ◽  
Composite Pressure Vessel ◽  
Polymer Liner ◽  
Specific Distance ◽  
Composite Pressure Vessels

In this work, the stress distribution along cylindrical composite pressure vessels with different dome geometries is investigated. The dome contours are generated through an integral method based on shell stresses. Here, the influence of each dome contour on the stress distribution at the interface of the dome-cylinder is evaluated. At first, the integral formulation for dome curve generation is presented and solved for the different dome contours. An analytical approach for the calculation of the secondary stresses in a cylindrical pressure vessel is introduced. For the analysis, three different cases were investigated: (i) a polymer liner; (ii) a single layer of carbon-epoxy composite wrapped on a polymer liner; and (iii) multilayer carbon-epoxy pressure vessel. Accounting for nonlinear geometry is seen to have an effect on the stress distribution on the pressure vessel, also on the isotropic liner. Significant secondary stresses were observed at the dome-cylinder interface and they reach a maximum at a specific distance from the interface. A discussion on the trend in these stresses is presented. The numerical results are compared with the experimental results of the multilayer pressure vessel. It is observed that the secondary stresses present in the vicinity of the dome-cylinder interface has a significant effect on the failure mechanism, especially for thick walled cylindrical composite pressure vessel. It is critical that these secondary stresses are directly accounted for in the initial design phase.

Stress Analysis and Optimization Design of Pressure Vessel of Underwater Gamma Spectrometer

2014 ◽  
Vol 518 ◽  
pp. 275-278
Author(s):  
Feng Gao ◽  
Jian Guo Zhang ◽  
Fang Fang Yang
Keyword(s):  
Photon Energy ◽  
Pressure Vessel ◽  
Optimization Design ◽  
Detection Efficiency ◽  
Side Wall ◽  
Pressure Vessels ◽  
Monte Carlo Code ◽  
Gamma Spectrometer ◽  
Cylindrical Pressure Vessel ◽  
The Impact

Pressure vessel makes the underwater gamma spectrometer can operation in underwater environment. In this paper, a kind of cylindrical pressure vessel has been simulated and analyzed using CAD software named Solidworks. Analysis results show the end covers are much thicker than the side wall to satisfy the same design safety factor and the centers of the end covers are the stress concentration areas. Further more, a 2× 2 LaBr3: Ce scintillation detector and a series of pressure vessels with various design safety factors and same inner space have been simulated by Monte Carlo code MCNP. Calculation indicates that the thicker the shell, the lower the detection efficiency. Further more, calculation shows the impact of the pressure vessel on detection efficiency of underwater gamma spectrometer varies with the photon energy. The law is that the higher the photon energy, the lower the influence on the detection efficiency.

Time-Dependent Creep Analysis for Life Assessment of Cylindrical Vessels Using First Order Shear Deformation Theory

2017 ◽  
Vol 33 (4) ◽  
pp. 461-474 ◽  
Author(s):  
M. D. Kashkoli ◽  
Kh. N. Tahan ◽  
M. Z. Nejad
Keyword(s):  
Analytical Solution ◽  
Shear Deformation ◽  
Deformation Theory ◽  
Shear Deformation Theory ◽  
Pressure Vessels ◽  
Life Assessment ◽  
Time Dependent ◽  
Creep Life ◽  
Creep Response ◽  
First Order

AbstractIn the present study, assuming that the thermo-elastic creep response of the material is governed by Norton's law, an analytical solution has been developed for the purpose of time-dependent creep response for isotropic thick-walled cylindrical pressure vessels. To study the creep response, the first-order shear deformation theory (FSDT) is applied. To the best of the researchers’ knowledge, in the literature, there is no study carried out into FSDT for time-dependent creep response of cylindrical pressure vessels. The novelty of the present work is that it seeks to investigate creep life of the vessels made of 304L austenitic stainless steel (304L SS) using Larson-Miller Parameter (LMP) based on FSDT. Using this analytical solution, stress rates are calculated followed by an iterative method using initial thermo-elastic stresses at zero time. When the stress rates are known, the stresses at any time are obtained and then using LMP, creep life of the vessels are investigated. The Problem is also solved, using the finite element method (FEM), the result of which are compared with those of the analytical solution and good agreement was found. It is found that the temperature gradient distribution has significant influence on the creep life of the cylinder, so that the maximum creep life is located at the outer surface of the cylinder where the minimum value of temperature is located.

Fourier Series Analysis of Cylindrical Pressure Vessel Subjected to External Pressure

2009 ◽  
Author(s):  
Gurinder Singh Brar ◽  
Yogeshwar Hari ◽  
Dennis K. Williams
Keyword(s):  
Fourier Series ◽  
Pressure Vessel ◽  
Large Diameter ◽  
External Pressure ◽  
Pressure Vessels ◽  
Buckling Load ◽  
Critical Buckling Load ◽  
Cylindrical Pressure Vessel ◽  
Section Viii ◽  
Division 2

This paper presents the comparison of a reliability technique that employs a Fourier series representation of random asymmetric imperfections in a cylindrical pressure vessel subjected to external pressure. Comparison with evaluations prescribed by the ASME Boiler and Pressure Vessel Code, Section VIII, Division 2 Rules for the same shell geometries are also conducted. The ultimate goal of the reliability type technique is to predict the critical buckling load associated with the chosen cylindrical pressure vessel. Initial geometric imperfections are shown to have a significant effect on the load carrying capacity of the example cylindrical pressure vessel. Fourier decomposition is employed to interpret imperfections as structural features that can be easily related to various other types of defined imperfections. The initial functional description of the imperfections consists of an axisymmetric portion and a deviant portion, which are availed in the form of a double Fourier series. Fifty simulated shells generated by the Monte Carlo technique are employed in the final prediction of the critical buckling load. The representation of initial geometrical imperfections in the cylindrical pressure vessel requires the determination of appropriate Fourier coefficients. Multi-mode analyses are expanded to evaluate a large number of potential buckling modes for both predefined geometries and associated asymmetric imperfections as a function of position within a given cylindrical shell. The probability of the ultimate buckling stress that may exceed a predefined threshold stress is also calculated. The method and results described herein are in stark contrast to the “knockdown factor” approach as applied to compressive stress evaluations currently utilized in industry. Recommendations for further study of imperfect cylindrical pressure vessels are also outlined in an effort to improve on the current design rules regarding column buckling of large diameter pressure vessels designed in accordance with ASME Boiler and Pressure Vessel Code, Section VIII, Division 2 and ASME STS-1.

A Study of Integrity Changes in Structures During Exploitation

2002 ◽  
Author(s):  
Slavko Sebastijanovic ◽  
Milan Opalic ◽  
Nebojsa Sebastijanovic
Keyword(s):  
Stress State ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Element Analysis ◽  
Critical Crack ◽  
Cylindrical Pressure Vessel ◽  
Before And After ◽  
Useful Life ◽  
Vessel Integrity ◽  
Main Components

Spherical and cylindrical pressure vessels are manufactured as welded structures, where cracks could be initiated/propagated during fabrication, pre-service hydro-test, service itself, service welding repair, or during the service hydro-test. In this case, fracture mechanics approach is necessary. This paper analyzes the stress state around cracks in the bottom head which is one of the main components in a cylindrical pressure vessel (radius of 1056 mm, wall thickness of 92 mm, pressure of 15.5 MPa and temperature of 454°C). Sizes of several detected cracks at the inner surface are determined by the NDE methods. Finite element analysis is performed to determine the stress zones in the vicinity of the most critical crack. Such analysis is done before and after the hydro-test. It will show the influence of the hydro-test on propagation of the existing cracks and fracture behavior of repaired cracks through the stress state analysis. Changes in material properties were analyzed. Results will be used to assess the pressure vessel integrity and estimate its useful life.

Detail Investigation of Omega Method for Creep Analysis of Pressure Vessel Components

2013 ◽  
Author(s):  
Francesco Vivio ◽  
Luca Gaetani ◽  
Michele Ferracci ◽  
Alessandro Masia
Keyword(s):  
Pressure Vessel ◽  
Plastic Material ◽  
Material Model ◽  
Pressure Vessels ◽  
Operating Conditions ◽  
Material Behavior ◽  
Austenitic Steels ◽  
Omega Method ◽  
Creep Analysis ◽  
Pressure Stress

A comprehensive creep material model for evaluation of high temperature applications of ferritic, martensitic and austenitic steels is available in API 579-1/ASME FFS and in ASME VIII Div 2 CC-2605-1 codes based on MPC Project Omega. Although the model can be used directly to analyze pressure vessels components behavior in a non-linear finite element creep analysis, several numerical and theoretical limits are to be taken into account in the implementation of the FE user-subroutine of the material model. In this context, a deep parametric analysis, both theoretical and numerical, based on different possible operating conditions and material behavior (temperature, pressure, stress field, elastic-plastic material properties and plastic flow rules) has been performed to review the model results on a high pressure vessel component. Based on results of these analyses, a theoretical critical review of the method is presented.

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