Limit Pressures of Cylindrical and Spherical Shells

2000 ◽  
Vol 123 (3) ◽  
pp. 288-292 ◽  
Author(s):  
Arturs Kalnins ◽  
Dean P. Updike
Keyword(s):  
Geometric Parameter ◽  
Cylindrical Shells ◽  
Length Effect ◽  
Spherical Shells ◽  
Simply Supported ◽  
Limit Pressure ◽  
Section Viii ◽  
Division 2

Tresca limit pressures for long cylindrical shells and complete spherical shells subjected to arbitrary pressure, and several approximations to the exact limit pressures for limited pressure ranges, are derived. The results are compared with those in Section III-Subsection NB and in Section VIII-Division 2 of the ASME B&PV Code. It is found that in Section VIII-Division 2 the formulas agree with the derived limit pressures and their approximations, but that in Section III-Subsection NB the formula for spherical shells is different from the derived approximation to the limit pressure. The length effect on the limit pressure is investigated for cylindrical shells with simply supported ends. A geometric parameter that expresses the length effect is determined. A formula and its limit of validity are derived for an assessment of the length effect on the limit pressures.

Investigation of Reduction in Buckling Capacity of Cylindrical Shells Under External Pressure Due to Partially Cut Ring Stiffeners

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Snehankush Chikode ◽  
Nilesh Raykar
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Cylindrical Shells ◽  
External Pressure ◽  
Geometrical Parameters ◽  
Section Shape ◽  
Clear Guideline ◽  
Section Viii ◽  
Special Circumstances ◽  
Division 2

Circumferential ring stiffeners are commonly used to improve the buckling strength of cylindrical shells. Under special circumstances, stiffener ring needs to be partially cut in order to avoid interference with vessel attachments or surrounding structures. No clear guideline is available in rule-based method to deal with such case. This paper investigates the extent of reduction in buckling capacity for a range of cylindrical shell geometries with stiffener rings having different cross sections and different extents of circumferential cut. Finite-element (FE)-based analysis as per ASME Section VIII, Division 2, Part 5 has been employed to determine the permissible external pressure in each of the cases. Effects of ring cross section and extent of circumferential cut of stiffening ring on the maximum permissible external pressure have been presented. A total of 63 combinations of shell-stiffening ring configurations of different L/D, D/t ratios, cross section shape, and extent of cut have been investigated. Geometrical parameters for these combinations under study are so chosen that normal working range in industries is covered. The results obtained provide guidelines to design shells with partially cut stiffening rings.

Axially Compressed Cylindrical Shell Containing Axisymmetric Random Imperfections: Fourier Series Techniques and ASME Section VIII Division 2 Rules

2008 ◽  
Author(s):  
Gurinder Singh Brar ◽  
Yogeshwar Hari ◽  
Dennis K. Williams
Keyword(s):  
Cylindrical Shell ◽  
Fourier Series ◽  
Fourier Coefficients ◽  
Cylindrical Shells ◽  
Structural Features ◽  
Geometric Imperfections ◽  
Fourier Decomposition ◽  
Buckling Stress ◽  
Section Viii ◽  
Division 2

This paper presents the comparison of reliability technique that employ Fourier series representations of random axisymmetric imperfections in axially compressed cylindrical shells with evaluations prescribed by ASME Section VIII, Division 2. The ultimate goal of the reliability type technique is to predict the buckling load associated with the axially compressed cylindrical shell. The representation of initial geometrical imperfections in the cylindrical shell requires the determination of appropriate Fourier coefficients. The buckling of cylindrical shells in any type of loading is sensitive to the form and amplitude of geometric imperfections present in the structure. Initial geometric imperfections have significant effect on the load carrying capacity of axisymmetrical cylindrical shells. Many deterministic and probabilistic techniques are there to predict shell behavior during buckling. Fourier decomposition is used to interpret imperfections as structural features can be easily related to the different components of imperfections. The mean vector and the variance-covariance matrix of Fourier coefficients are calculated from the simulated shell profiles. Recommendations for further use of Fourier coefficients through simulation by Monte Carlo Method are laid down. Large number of shells thus created can be used to calculate buckling stress for each shell. The probability of the ultimate buckling stress exceeding a predefined threshold stress can be calculated.

A Quasi-Greens Function Method for the Bending Problem of Simply Supported Polygonal Shallow Spherical Shells on Pasternak Foundation

2013 ◽  
Vol 353-356 ◽  
pp. 3215-3219
Author(s):  
Shan Qing Li ◽  
Hong Yuan
Keyword(s):  
Function Method ◽  
Homogeneous Boundary Condition ◽  
Fredholm Integral Equations ◽  
Pasternak Foundation ◽  
Boundary Equation ◽  
Spherical Shells ◽  
Simply Supported ◽  
Suitable Form ◽  
Greens Function ◽  
Good Agreement

The quasi-Greens function method (QGFM) is applied to solve the bending problem of simply supported polygonal shallow spherical shells on Pasternak foundation. A quasi-Greens function is established by using the fundamental solution and the boundary equation of the problem. And the function satisfies the homogeneous boundary condition of the problem. Then the differential equation of the problem is reduced to two simultaneous Fredholm integral equations of the second kind by the Greens formula. The singularity of the kernel of the integral equation is overcome by choosing a suitable form of the normalized boundary equation. The comparison with the ANSYS finite element solution shows a good agreement, and it demonstrates the feasibility and efficiency of the proposed method.

Vibrations of rotating cylindrical shells with functionally graded material using wave propagation approach

2018 ◽  
Vol 232 (23) ◽  
pp. 4342-4356 ◽  
Author(s):  
Muzammal Hussain ◽  
M Nawaz Naeem ◽  
Aamir Shahzad ◽  
Mao-Gang He ◽  
Siddra Habib
Keyword(s):  
Wave Propagation ◽  
Natural Frequencies ◽  
Volume Fraction ◽  
Cylindrical Shells ◽  
Functionally Graded ◽  
Wave Number ◽  
Type I ◽  
Rotating Speed ◽  
Simply Supported ◽  
Fundamental Frequencies

Fundamental natural frequencies of rotating functionally graded cylindrical shells have been calculated through the improved wave propagation approach using three different volume fraction laws. The governing shell equations are obtained from Love’s shell approximations using improved rotating terms and the new equations are obtained in standard eigenvalue problem with wave propagation approach and volume fraction laws. The effects of circumferential wave number, rotating speed, length-to-radius, and thickness-to-radius ratios have been computed with various combinations of axial wave numbers and volume fraction law exponent on the fundamental natural frequencies of nonrotating and rotating functionally graded cylindrical shells using wave propagation approach and volume fraction laws with simply supported edge. In this work, variation of material properties of functionally graded materials is controlled by three volume fraction laws. This process creates a variation in the results of shell frequency. MATLAB programming has been used to determine shell frequencies for traveling mode (backward and forward) rotating motions. New estimations show that the rotating forward and backward simply supported fundamental natural frequencies increases with an increase in circumferential wave number, for Type I and Type II of functionally graded cylindrical shells. The presented results of backward and forward simply supported fundamental natural frequencies corresponding to Law I are higher than Laws II and III for Type I and reverse effects are found for Type II, depending on rotating speed. Our investigations show that the decreasing and increasing behaviors are noted for rotating simply supported fundamental natural frequencies with increasing length-to-radius and thickness-to-radius ratios, respectively. It is found that the fundamental frequencies of the forward waves decrease with the increase in the rotating speed, and the fundamental frequencies of the backward waves increase with the increase in the rotating speed. This investigation has been made with three different volume fraction laws of polynomial (Law I), exponential (Law II), and trigonometric (Law III). The presented numerical results of nonrotating isotropic and rotating functionally graded simply supported are in fair agreement with parts of other earlier numerical results.

Applicability of Design Rules for Openings in Shells, ASME B&PV Code, Section VIII, Division 2 - A Case Study

2021 ◽  
Author(s):  
Gurumurthy Kagita ◽  
Krishnakant V. Pudipeddi ◽  
Subramanyam V. R. Sripada
Keyword(s):  
Stress Analysis ◽  
Failure Modes ◽  
Element Analysis ◽  
Design Rules ◽  
Area Method ◽  
Replacement Method ◽  
Local Stresses ◽  
Pressure Area ◽  
Section Viii ◽  
Division 2

Abstract The Pressure-Area method is recently introduced in the ASME Boiler and Pressure Vessel (B&PV) Code, Section VIII, Division 2 to reduce the excessive conservatism of the traditional area-replacement method. The Pressure-Area method is based on ensuring that the resistive internal force provided by the material is greater than or equal to the reactive load from the applied internal pressure. A comparative study is undertaken to study the applicability of design rules for certain nozzles in shells using finite element analysis (FEA). From the results of linear elastic FEA, it is found that in some cases the local stresses at the nozzle to shell junctions exceed the allowable stress limits even though the code requirements of Pressure-Area method are met. It is also found that there is reduction in local stresses when the requirement of nozzle to shell thickness ratio is maintained as per EN 13445 Part 3. The study also suggests that the reinforcement of nozzles satisfy the requirements of elastic-plastic stress analysis procedures even though it fails to satisfy the requirements of elastic stress analysis procedures. However, the reinforcement should be chosen judiciously to reduce the local stresses at the nozzle to shell junction and to satisfy other governing failure modes such as fatigue.

Free vibration analysis of porous laminated rotating circular cylindrical shells

2019 ◽  
Vol 25 (18) ◽  
pp. 2494-2508 ◽  
Author(s):  
Ahmad Reza Ghasemi ◽  
Mohammad Meskini
Keyword(s):  
Free Vibration ◽  
Boundary Conditions ◽  
Cylindrical Shells ◽  
Free Vibration Analysis ◽  
Equilibrium Equations ◽  
Rotating Speed ◽  
Simply Supported ◽  
Numerical Result ◽  
Love’S Shell Theory ◽  
Circular Cylindrical Shells

In this research, investigations are presented of the free vibration of porous laminated rotating circular cylindrical shells based on Love’s shell theory with simply supported boundary conditions. The equilibrium equations for circular cylindrical shells are obtained using Hamilton’s principle. Also, Navier’s solution is used to solve the equations of the cylindrical shell due to the simply supported boundary conditions. The results are compared with previous results of other researchers. The numerical result of this study indicates that with increase of the porosity coefficient the nondimensional backward and forward frequency decreased. Then the results of the free vibration of rotating cylindrical shells are presented in terms of the effects of porous coefficients, porous type, length to radius ratio, rotating speed, and axial and circumferential wave numbers.

Section VIII: Division 2–Alternative Rules

2020 ◽  
Author(s):  
David A. Osage ◽  
Clay D. Rodery ◽  
Thomas P. Pastor ◽  
Robert G. Brown ◽  
Philip A. Henry ◽  
...  
Keyword(s):  
Section Viii ◽  
Division 2

Design, Manufacture and Safety Aspects of Forged Vessels for High-Pressure Services

1980 ◽  
Vol 102 (1) ◽  
pp. 98-106 ◽  
Author(s):  
G. J. Mraz ◽  
E. G. Nisbett
Keyword(s):  
High Pressure ◽  
Pressure Vessel ◽  
Low Alloy Steels ◽  
Nickel Chromium ◽  
Molybdenum Alloys ◽  
Tension Tests ◽  
Alloy Steels ◽  
Section Viii ◽  
Division 2

Steels at present included in Sections III and VIII of the ASME Boiler and Pressure Vessel Code severely limit its application for high-pressure design. An extension of the well-known AISI 4300 series low alloy steels has long been known as “Gun Steel.” These alloys, which are generally superior to AISI 4340, offer good harden-ability and toughness and have been widely used under proprietary names for pressure vessel application. The ASTM Specification A-723 was developed to cover these nickel-chromium-molybdenum alloys for pressure vessel use, and is being adopted by Section II of the ASME Boiler and Pressure Vessel Code for use in Section VIII, Division 2, and in Section III in Part NF for component supports. The rationale of the specification is discussed, and examples of the mechanical properties obtained from forgings manufactured to the specification are given. These include the results of both room and elevated temperature tension tests and Charpy V notch impact tests. New areas of applicability of the Code to forged vessels for high-pressure service using these materials are discussed. Problems of safety in operation of monobloc vessels are mentioned. Procedures for in-service inspection and determination of inspection intervals based on fracture mechanics are suggested.

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