Behavior of Localized Bottom Depression in Aboveground Oil Storage Tanks Under Liquid Pressure

2004 ◽  
Author(s):  
Shoichi Yoshida
Keyword(s):  
Finite Element Analysis ◽  
Deformation Analysis ◽  
Bottom Plate ◽  
Storage Tanks ◽  
Liquid Pressure ◽  
Element Analysis ◽  
Large Deformation Analysis ◽  
Oil Storage ◽  
Relationship Of ◽  
The Relationship

When constructing the bottom of aboveground oil storage tanks, the bottom plates are first laid out on the flat foundation, and they then are joined by welding the joints in sequence. As the foundation is difficult to be made completely homogeneous over the bottom area, the settlement of the bottom plates is not uniform under liquid pressure. The depressions of the bottom plates are sometimes found at the first internal inspection which is usually made about 10 years after the oil storage. This paper presents plane strain finite element analysis for the localized bottom depression in aboveground oil storage tanks. Load-incremental, elastic-plastic large deformation analysis is carried out considering contact with the foundation. The relationship of the stress at the depressed bottom plate to the liquid pressure is discussed together with the deformation of the depression.

Behavior of Localized Bottom Bulge in Aboveground Oil Storage Tanks Under Liquid Pressure

2001 ◽  
Vol 124 (1) ◽  
pp. 59-65
Author(s):  
Shoichi Yoshida
Keyword(s):  
Plastic Strain ◽  
Plate Thickness ◽  
Deformation Analysis ◽  
Bottom Plate ◽  
Storage Tanks ◽  
Liquid Pressure ◽  
Element Analysis ◽  
Oil Storage ◽  
Relationship Of ◽  
The Relationship

The bottom plate of aboveground oil storage tanks can bulge, separating from the foundation due to welding deformation. When such a bulge is subjected to liquid pressure, it deforms continuously to make contact with the foundation from the edge, and the remaining area of the bulge decreases with increasing liquid pressure. As a result, the deformation is extremely localized and plastic strain occurs at the bulge. This paper presents a plane strain finite element analysis for the evaluation of localized bottom bulges in aboveground oil storage tanks. Load-incremental, elastic-plastic large deformation analysis is carried out considering the bottom plate contact with the foundation. The relationship of the plastic strain at the bulged bottom plate to the liquid pressure is discussed together with the deformation of the bulge. As a result, the bottom plate thickness has a significant effect on the deformation, but the bulged height does not. After the bulged center makes contact with the foundation, the stress and strain do not increase with increasing liquid pressure. In addition, the permissible bulged profile specified by API Standard 653 elastically deforms to make contact with the foundation under low liquid pressure.

Buckling of Ring Stiffened Pontoons of Floating Roofs in Aboveground Oil Storage Tanks

2007 ◽  
Author(s):  
Shoichi Yoshida ◽  
Kazuhiro Kitamura
Keyword(s):  
Large Diameter ◽  
Bending Moment ◽  
Bottom Plate ◽  
Storage Tanks ◽  
Element Analysis ◽  
Linear Elastic ◽  
Structural Problems ◽  
Oil Storage ◽  
Bifurcation Buckling ◽  
Shell Finite Element

The 2003 Tokachi-Oki earthquake caused severe damage to oil storage tanks due to liquid sloshing. Six single-deck floating roofs had experienced structural problems as evidenced by sinking failure in large diameter tanks at the refinery in Tomakomai, Japan. The pontoon of floating roof might be buckled due to circumferential bending moment during the sloshing. The content in the tank was spilled on the floating roof from small failures which might be caused in the lap-welded joints or in the stress concentrated parts of the pontoon bottom plate by the buckling. Then the floating roof began to lose buoyancy and submerged into the content slowly. The failure of the roof expanded gradually in the sinking process. It is presumed that the initial small failures were caused by the elastic buckling of the pontoon due to circumferential bending moment. In this paper, the buckling strength of the pontoon is presented using axisymmetric shell finite element analysis. Linear elastic bifurcation buckling analyses are carried out and the buckling characteristics of ring stiffened pontoons are investigated.

Design and Testing of a Piezoelectrically Driven Airspike System on a .40 Cal Supersonic Projectile

2008 ◽  
Author(s):  
Robert W. Long
Keyword(s):  
Finite Element Analysis ◽  
Flight Control ◽  
Beam Theory ◽  
Pitching Moment ◽  
Piezoelectric Actuation ◽  
Element Analysis ◽  
Actuation System ◽  
Relationship Of ◽  
The Relationship ◽  
Design And Testing

This paper investigates the feasibility of using a piezoelectrically driven airspike system as a method of flight control on .40 caliber supersonic projectiles. The paper begins with a description of airspikes and a summary of their history in missiles and munitions. The paper then describes the piezoelectric actuation system and models its unloaded characteristics using bending beam theory. When the airspike is deflected, the axial force acting upon the airspike is shifted so that it no longer goes through the center of gravity and creates a pitching moment. This allows the bullet to create a pitching moment which can control the projectile. A basic aerodynamic analysis was done on the projectile, and subsequent wind tunnel tests through Mach 2.5 were done to prove this data. Bench top tests were also done on the system to determine the relationship of voltage to deflection of the airspike. The paper also includes considerations for setback, setforward and balloting. The paper includes a finite element analysis for the setback acceleration. The paper concludes with a system design of a beam rider projectile and simulates the trajectory of the projectile.

The Research on the Torque-Tension Relationship for Bolted Joints

2011 ◽  
Vol 486 ◽  
pp. 242-245 ◽  
Author(s):  
Jun Huang ◽  
Lian Shui Guo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bolted Joints ◽  
Fe Modeling ◽  
Bearing Surface ◽  
Element Analysis ◽  
Helical Geometry ◽  
Relationship Of ◽  
The Relationship

This paper has proposed an improved formula for the torque-tension relationship of bolted joints with consideration of all forces and moments acting on fasteners. Finite element analysis (FEA) is used to analyze and evaluate the relationship. An effective finite element (FE) modeling scheme which considers the helical geometry is developed. Effects of contact radii ratios of the nut bearing surface on the percentages of component torques are investigated. Percentages of component torques are calculated according to present and conventional formula, to compare with FEA results.

Finite Element Analysis and Design of Monolithic Multilayer Piezoelectric Micromanipulator

2008 ◽  
Vol 368-372 ◽  
pp. 218-220
Author(s):  
Xiang Cheng Chu ◽  
Jin Ding Huang ◽  
Long Tu Li ◽  
Zhi Lun Gui
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Single Layer ◽  
Analysis Method ◽  
Element Analysis ◽  
Analysis And Design ◽  
Distribution Of Stress ◽  
Relationship Of ◽  
The Relationship ◽  
Novel Model

A novel model of 3-DOF multilayer PZT micromanipulator is promoted and simulated with finite element analysis method. States under different applied voltages were discussed, including the motion along axis Z and the rotation along axis X and the bisector between X-Y. After analyzing the distribution of stress, we propose some method, which helps to improve the performance of the micromanipulator. We also do some quantificational analysis about the micromanipulator, discovering that the relationship between the displacements of the probe and applied voltages is almost perfectly linear. By comparing the constant D defining the relationship of the displacements of probe tip and applied voltages, the simulation is proved to be correct. Comparing the performance between the single-layer and multi-layer PZT, it shows that the multi-layer PZT can reduce input voltages, whereas can produce the same displacement. Ceramic sample is prepared for further experiment.

Buckling of Single-Deck Floating Roofs in Aboveground Oil Storage Tanks Due to Circumferential Bending Load

2006 ◽  
Author(s):  
Shoichi Yoshida ◽  
Kazuhiro Kitamura
Keyword(s):  
Large Diameter ◽  
Bending Moment ◽  
Bottom Plate ◽  
Storage Tanks ◽  
Element Analysis ◽  
Buckling Strength ◽  
Structural Problems ◽  
Oil Storage ◽  
Bending Load ◽  
Shell Finite Element

The 2003 Tokachi-Oki earthquake caused severe damage to oil storage tanks due to liquid sloshing. Six single-deck floating roofs had experienced structural problems as evidenced by sinking failure in large diameter tanks at the refinery at Tomakomai, Japan. The pontoon of floating roof might be buckled due to circumferential bending moment during the sloshing. The content in the tank was spilled on the floating roof from small failures which were caused in the rap welding joints of pontoon bottom plate by the buckling. Then the floating roof began to lose buoyancy and submerged into the content slowly. The failure of the roof expanded gradually in the sinking process. It is presumed that the initial small failures were caused by the elastic buckling of the pontoon due to circumferential bending moment. This paper presents the buckling strength of the pontoon using axisymmetric shell finite element analysis. Linear elastic bifurcation buckling analysis is carried out and the buckling characteristics of the pontoon are investigated. The result shows that the thickness of both pontoon roof and bottom plates have significantly affect the buckling strength.

An Approach to Derive Primary Bending Stress From Finite Element Analysis for Pressure Vessels and Applications in Structural Design

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Bingjun Gao ◽  
Xiaohui Chen ◽  
Xiaoping Shi ◽  
Junhua Dong
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessel ◽  
Engineering Application ◽  
Pressure Vessels ◽  
Bending Stress ◽  
Element Analysis ◽  
Lack Of Information ◽  
Relationship Of ◽  
The Relationship

An important issue in engineering application of the “design by analysis” approach in pressure vessel design is how to decompose an overall stress field obtained by finite element analysis into different stress categories defined in the ASME B&PV Codes III and VIII-2. In many pressure vessel structures, it is difficult to obtain PL+Pb due to the lack of information about primary bending stress. In this paper, a simple approach to derive the primary bending stress from the finite element analysis was proposed with application examples and verifications. According to the relationship of the bending stress and applied loads or the relationship of the bending stress and displacement agreement, it is possible to identify loads causing primary bending stress for typical pressure vessel structures. By applying the load inducing primary bending stress alone and necessary superposition, the primary bending stress and corresponding stress intensity PL+Pb can be determined for vessel design, especially for axisymmetric problems.

Eulerian Finite Element Formulation for Sloshing Response of Floating Roofs in Aboveground Storage Tanks

2008 ◽  
Author(s):  
Shoichi Yoshida ◽  
Kazuyoshi Sekine ◽  
Tsukasa Mitsuta
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Integrity ◽  
Dynamic Pressure ◽  
Oil Refining ◽  
Element Formulation ◽  
Storage Tanks ◽  
Element Analysis ◽  
Oil Storage ◽  
Hydrodynamic Coupling

The floating roofs are widely used to prevent evaporation of content in large aboveground oil storage tanks. The 2003 Tokachi-Oki earthquake caused severe damage to the floating roofs due to liquid sloshing. The structural integrity of the floating roofs for the sloshing is urgent issue to establish in petrochemical and oil refining industries. This paper presents the axisymmetric finite element analysis for the sloshing response of floating roofs in cylindrical storage tanks. The hydrodynamic coupling of fluid and floating roof under seismic excitation is taken into consideration in the analysis. It is assumed that the fluid is incompressible and inviscid, and the roof is linear elastic while the sidewall and the bottom are rigid. The theory for the finite element analysis in which the behavior of the fluid is formulated in terms of dynamic pressure as the Eulerian approach is developed. The basic vibration characteristics of the floating roof, such as natural periods and vibration modes, can be obtained from this analysis. These will give engineers important information on the floating roof design.

Dämpfungsschlitze in Kreissägeblättern*/Parametric FE analysis to identify the mode of action of damping slots in circular saw blades

2015 ◽  
Vol 105 (01-02) ◽  
pp. 41-46
Author(s):  
C. Birenbaum ◽  
U. Heisel ◽  
S. Weiland
Keyword(s):  
Finite Element Analysis ◽  
Thermal Expansion ◽  
Analytical Approach ◽  
Simulation Models ◽  
Fe Analysis ◽  
Element Analysis ◽  
Annular Plates ◽  
Circular Saw ◽  
Characteristic Modes ◽  
The Relationship

In Kreissägeblättern werden zur Verminderung von Schwingungen und zum Ausgleich thermischer Dehnungen sogenannte Dehnungs- und Dämpfungsschlitze eingebracht. Die Wirkungsweise der Schlitze auf die dynamischen Eigenschaften besteht einerseits in der Dämpfungswirkung sowie andererseits in der Modifikation der Schwingungseigenformen. Um Wirkmechanismen und Optimierungsmöglichkeiten zu identifizieren, werden in den hier vorgestellten Untersuchungen mithilfe der Finiten-Elemente-Methode (FEM) Analysen von Kreisscheiben mit einfachen Schlitzkonfigurationen durchgeführt. Hierdurch sollen Zusammenhänge einzelner Schlitzparameter mit den statischen und dynamischen Eigenschaften von Kreissägeblättern aufgezeigt werden. Zur Validierung des entwickelten Simulationsmodells dienen analytische Berechnungen.   To reduce vibrations and adjust for thermal expansion, so-called damping slots and expansion slots are applied to circular saw blades. The slots affect the dynamic behavior of the saw blades by damping the vibration and altering the characteristic modes and frequencies. An FE(Finite Element) analysis of annular plates with simple arrangements of damping and expansion slots is performed to identify the mechanisms and improvement opportunities. This allows determining the relationship between slot parameters and the static and dynamic qualities of circular saw blades. The developed simulation models are validated using an analytical approach.

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