The Influence of Initial Geometric Imperfection on the Localized Buckling of Pressure Vessel Under Internal Pressure

2004 ◽  
Author(s):  
Li Wan ◽  
Wei-ming Tao ◽  
Xin-xin Wu ◽  
Shu-yan He
Keyword(s):  
Internal Pressure ◽  
Transition Region ◽  
Pressure Vessel ◽  
External Pressure ◽  
Pressure Vessels ◽  
Arc Length ◽  
Plastic Buckling ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection ◽  
Geometrical Imperfections

Pressure vessels are widely used in nuclear engineering and buckling is a common mechanical phenomenon in structure. The buckling problem of pressure vessels under external pressure has been researched for many years. This paper focuses on the influence of initial geometric imperfection on the localized elastic-plastic buckling of pressure vessel under internal pressure. The localized plastic buckling occurred in the transition region in the torispherical end closure of a pressure vessel is analyzed by FEM. By introducing two types of initial geometrical imperfections, the arc-length method of modified Riks/Ramm procedure is performed to simulate the buckling process during loading. The first type of imperfection is displacement, into the region where it is circumferentially compressed. The second type of imperfection is the irregular thickness of the vessel, also into the region where it is circumferentially compressed. The initial critical point is captured within the buckled region, and the corresponding initial buckling load is calculated. The results show that both artificial geometric imperfections can seduce the buckling. Furthermore, after the first buckling initiated, the succeeding loading will lead to more wrinkles within the compressive transition region. And then the case that with two distributed imperfections is also analyzed. It can be seen that the interaction between the imperfections is very weak before or even after the first buckling occurred, which means the buckling is fairly localized.

A Noncyclic Method for Determination of Accumulated Strain in Stainless Steel 304 Pressure Vessels

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Gongfeng Jiang ◽  
Gang Chen ◽  
Liang Sun ◽  
Yiliang Zhang ◽  
Xiaoliang Jia ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
Peak Stress ◽  
Pressure Vessels ◽  
Experimental Results ◽  
Elastic Domain ◽  
Ratcheting Strain ◽  
Stainless Steel 304 ◽  
Accumulated Strain

Experimental results of uniaxial ratcheting tests for stainless steel 304 (SS304) under stress-controlled condition at room temperature showed that the elastic domain defined in this paper expands with accumulation of plastic strain. Both ratcheting strain and viscoplastic strain rates reduce with the increase of elastic domain, and the total strain will be saturated finally. If the saturated strain and corresponded peak stress of different experimental results under the stress ratio R ≥ 0 are plotted, a curve demonstrating the material shakedown states of SS304 can be constituted. Using this curve, the accumulated strain in a pressure vessel subjected to cyclic internal pressure can be determined by only an elastic-plastic analysis, and without the cycle-by-cycle analysis. Meanwhile, a physical experiment of a thin-walled pressure vessel subjected to cyclic internal pressure has been carried out to verify the feasibility and effectiveness of this noncyclic method. By comparison, the accumulated strains evaluated by the noncyclic method agreed well with those obtained from the experiments. The noncyclic method is simpler and more practical than the cycle-by-cycle method for engineering design.

Analysis of Half-Pipe Heating Channels on Pressure Vessel Shells

1986 ◽  
Vol 108 (4) ◽  
pp. 526-529
Author(s):  
A. E. Blach
Keyword(s):  
Pressure Vessel ◽  
Analytical Method ◽  
External Pressure ◽  
Pressure Vessels ◽  
Numerical Examples ◽  
Asme Code

Half-pipe heating channels are used on the outside of pressure vessels such as agitators, mixers, reactors, etc., to avoid the high external pressure associated with heating jackets. No applicable method of analysis is contained in the ASME Code and proof tests are normally required for registration with governing authorities. An analytical method is presented which permits the evaluation of stresses in shell and half pipe; numerical examples are included.

A Study of the Conservatism in ASME BPVC Section VIII Division 2 Opening Design for External Pressure

2019 ◽  
Author(s):  
Barry Millet ◽  
Kaveh Ebrahimi ◽  
James Lu ◽  
Kenneth Kirkpatrick ◽  
Bryan Mosher
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
External Pressure ◽  
The Other ◽  
Finite Element Analyses ◽  
Division 1 ◽  
Section Viii ◽  
Allowable Compressive Stress ◽  
Division 2

Abstract In the ASME Boiler and Pressure Vessel Code, nozzle reinforcement rules for nozzles attached to shells under external pressure differ from the rules for internal pressure. ASME BPVC Section I, Section VIII Division 1 and Section VIII Division 2 (Pre-2007 Edition) reinforcement rules for external pressure are less stringent than those for internal pressure. The reinforcement rules for external pressure published since the 2007 Edition of ASME BPVC Section VIII Division 2 are more stringent than those for internal pressure. The previous rule only required reinforcement for external pressure to be one-half of the reinforcement required for internal pressure. In the current BPVC Code the required reinforcement is inversely proportional to the allowable compressive stress for the shell under external pressure. Therefore as the allowable drops, the required reinforcement increases. Understandably, the rules for external pressure differ in these two Divisions, but the amount of required reinforcement can be significantly larger. This paper will examine the possible conservatism in the current Division 2 rules as compared to the other Divisions of the BPVC Code and the EN 13445-3. The paper will review the background of each method and provide finite element analyses of several selected nozzles and geometries.

Study on the Stress Concentration at the Round Corners of Flat Heads in Pressure Vessels Subjected to Internal Pressure

1996 ◽  
Vol 118 (4) ◽  
pp. 429-433
Author(s):  
H. Chen ◽  
J. Jin ◽  
J. Yu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress Concentration ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Stress Index ◽  
Element Analysis ◽  
Approximate Formulas

Results from finite element analysis were used to show that the stress index kσ and the nondimensionalized highly stressed hub length kh of a flat head with a round corner in a pressure vessel subjected to internal pressure are functions of three dimensionless parameters: λ ≡ h/dt, η ≡ t/d, and ρ ≡ r/t. Approximate formulas for estimating kσ and kh from λ, η, and ρ p are given. The formulas can be used for determining a suitable fillet radius for a flat head in order to reduce the fabricating cost and to keep the stress intensity at the fillet under an acceptable limit.

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.

Elastic-Plastic Stress Analysis of Pressure Vessels

2012 ◽  
Author(s):  
Yang-chun Deng ◽  
Gang Chen
Keyword(s):  
Internal Pressure ◽  
Stress Analysis ◽  
Strain Hardening ◽  
Pressure Vessel ◽  
Plastic Instability ◽  
Pressure Vessels ◽  
Structural Deformation ◽  
Elastic Plastic ◽  
Thin Walled ◽  
Plastic Stress

To save material, the safety factor of pressure vessel design standards is gradually decreased from 5.0 to 2.4 in ASME Boiler and Pressure Vessel Codes. So the design methods of pressure vessel should be more rationalized. Considering effects of material strain hardening and non-linear structural deformation, the elastic-plastic stress analysis is the most suitable for pressure vessels design at present. This paper is based on elastic-plastic theory and considers material strain hardening and structural deformation effects. Elastic-plastic stress analyses of pressure vessels are summarized. Firstly, expressions of load and structural deformation relationship were introduced for thin-walled cylindrical and spherical vessels under internal pressure. Secondly, the plastic instability for thin-walled cylindrical and spherical vessels under internal pressure were analysed. Thirdly, to prevent pressure vessels from local failure, the ductile fracture strain of materials was discussed.

scholarly journals Buckling analysis of thin-walled metal liner of cylindrical composite overwrapped pressure vessels with depressions after autofrettage processing

2021 ◽  
Vol 28 (1) ◽  
pp. 540-554
Author(s):  
Guo Zhang ◽  
Haiyang Zhu ◽  
Qi Wang ◽  
Xiaowen Zhang ◽  
Mingfa Ren ◽  
...  
Keyword(s):  
Pressure Vessel ◽  
Local Buckling ◽  
Bending Moment ◽  
High Strength ◽  
External Pressure ◽  
Pressure Vessels ◽  
Buckling Analysis ◽  
Straight Section ◽  
Metal Liner ◽  
Autofrettage Pressure

Abstract The cylindrical filament wound composite overwrapped pressure vessels (COPV) with metal liner has been widely used in spaceflight due to their high strength and low weight. After the autofrettage process, the plastic deformation of the metal liner is constrained by composite winding layers, which introduce depressions to the metal liner that causes local buckling. To predict the local buckling of the inner liner with depressions of the pressure vessel after the autofrettage process, a local buckling analysis method for the metal liner of COPV was developed in this article. The finite element method is used to calculate the overall stress distribution in the pressure vessel before and after the autofrettage process, and the influence of local depressions on the buckling is evaluated. The axial buckling of the pressure vessel under external pressure is analyzed. The control equation of the metal liner with depressions is developed, considering the changes in the pressure and the bending moment of the liner depressions and its vicinity during the loading and unloading process. Taking the cylindrical COPV (38 L) with aluminum alloy liner as an example, the effects of liner thickness, liner radius, the thickness-to-diameter ratio, autofrettage pressure, and the length of straight section on the autofrettage process are discussed. The results show that the thickness of the inner liner has the most significant influence on the buckling of the liner, followed by the length of the straight section and the radius of the inner liner, while the autofrettage pressure has the least influence.

Material Test and Analysis for Pressure Vessel Rupture Study Under Fire in Plant

2015 ◽  
Author(s):  
Yoshiyasu Itoh ◽  
Yoshiyuki Waki ◽  
Kazuyuki Kasuya
Keyword(s):  
Internal Pressure ◽  
Pressure Vessel ◽  
Oil And Gas ◽  
Pressure Vessels ◽  
Design Guidelines ◽  
Plant Design ◽  
Design Code ◽  
Safe Level ◽  
Fire Incident ◽  
Vessel Rupture

In case fire incident occurs in Oil and Gas plant, pressure vessels will be exposed to fire. Though entire system will be depressurized when the fire is detected, internal pressure may still remain in the pressure vessels. Therefore, pressure vessels, if leakage of its internal fluids will escalate the incident, shall be confirmed that they will withstand internal pressure without rupture at least until internal pressure is decreased down to safe level. For design for such critical pressure vessel, a pressure vessel rupture study is conducted in addition to design code calculations. As safer plant design is requested in recent projects, demands for the pressure vessel rupture study are also growing. In this research, material data at high temperature range, that are necessary to obtain reliable results by the pressure vessel rupture study, were measured for carbon steel and stainless steel type304 and type304L. In addition, pressure vessel rupture studies were performed for two sample pressure vessels by means of FEM analyses and calculation methods in published design guidelines.

Evaluation of collapse moment of pressurized 30°–180° bend pipes subjected to out-of-plane bending moment

2021 ◽  
pp. 095440622110614
Author(s):  
Manish Kumar ◽  
Pronab Roy ◽  
Kallol Khan
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Plastic Material ◽  
Bending Moment ◽  
Bend Angle ◽  
Pipe Bend ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection ◽  
Out Of Plane ◽  
Plane Bending

The present paper determines collapse moments of pressurized 30°–180° pipe bends incorporated with initial geometric imperfection under out-of-plane bending moment. Extensive finite element analyses are carried out considering material as well as geometric nonlinearity. The twice-elastic-slope method is used to determine collapse moment. The results show that initial imperfection produces significant change in collapse moment for unpressurized pipe bends and pipe bends applied to higher internal pressure. The application of internal pressure produces stiffening effect to pipe bends which increases collapse moment up to a certain limit and with further increase in pressure, collapse moment decreases. The bend angle effect on collapse moment reduces with the increase in internal pressure and bend radius. Based on finite element results, collapse moment equations are formed as a function of the pipe bend geometry parameters, initial geometric imperfection, bend angle, and internal pressure for elastic-perfectly plastic material models.

Localized Plastic Buckling of a Heavy Beam on a Contacting Surface

1986 ◽  
Vol 108 (2) ◽  
pp. 146-150 ◽  
Author(s):  
H. D. Yun ◽  
S. Kyriakides
Keyword(s):  
Axial Load ◽  
Large Deflection ◽  
Limit Load ◽  
Axial Loads ◽  
Plastic Buckling ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection ◽  
Beam Mode

The paper considers the uplifting of a long elastoplastic heavy beam on a rigid flat foundation caused by an axial load. The problem is studied through a large deflection formulation. The beam is considered to possess a localized initial geometric imperfection. It is found that the load-deflection response is characterized by a limit load. Plastic effects can precipitate the limit load and cause a more localized type of deformation with higher curvatures. The problem is presented as a model for the “beam mode buckling” of pipelines due to earthquake-caused axial loads.

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