Pressure Re-Impulse Diagram of the FLNG Tanks Under Sloshing Loads

2018 ◽  
Vol Vol 160 (A2) ◽  
Author(s):  
S E Lee ◽  
J K Paik
Keyword(s):  
Finite Element ◽  
Structural Damage ◽  
Structural Response ◽  
Structural Mechanics ◽  
Liquefied Natural Gas ◽  
Nonlinear Finite Element ◽  
The Self ◽  
Impact Loads ◽  
Response Characteristics ◽  
Damage Tolerant

Sloshing impact loads can cause severe structural damage to cargo tanks in liquefied natural gas floating production storage offloading units (LNG-FPSOs or FLNGs). Studies of sloshing can be classified into two types, namely, hydrodynamics-related and structural mechanics-related studies. This study is a sequel to the authors’ previous studies (Paik et al. 2015; Lee et al. 2015), but is more related to issues of structural mechanics. In this study, a new method for probabilistic sloshing assessment, which has been previously developed by the authors, is briefly explained. The nonlinear impact structural response characteristics under sloshing impact loads are examined by a nonlinear finite element ANSYS/LS-DYNA method. An iso-damage curve, representing a pressure-impulse diagram, is derived for the self-supporting prismatic-shape IMO B type LNG cargo containment system of a hypothetical FLNG. The insights developed from this work can be useful for the damage-tolerant design of cargo tanks in FLNGs.

PRESSURE-IMPULSE DIAGRAM OF THE FLNG TANKS UNDER SLOSHING LOADS

2021 ◽  
Vol 160 (A2) ◽  
Author(s):  
S E Lee ◽  
J K Paik
Keyword(s):  
Structural Damage ◽  
Structural Response ◽  
Structural Mechanics ◽  
Liquefied Natural Gas ◽  
Nonlinear Finite Element ◽  
The Self ◽  
Impact Loads ◽  
Pressure Impulse ◽  
Response Characteristics ◽  
Damage Tolerant

Sloshing impact loads can cause severe structural damage to cargo tanks in liquefied natural gas floating production storage offloading units (LNG-FPSOs or FLNGs). Studies of sloshing can be classified into two types, namely, hydrodynamics-related and structural mechanics-related studies. This study is a sequel to the authors’ previous studies (Paik et al. 2015; Lee et al. 2015), but is more related to issues of structural mechanics. In this study, a new method for probabilistic sloshing assessment, which has been previously developed by the authors, is briefly explained. The nonlinear impact structural response characteristics under sloshing impact loads are examined by a nonlinear finite element ANSYS/LS-DYNA method. An iso-damage curve, representing a pressure-impulse diagram, is derived for the self-supporting prismatic-shape IMO B type LNG cargo containment system of a hypothetical FLNG. The insights developed from this work can be useful for the damage-tolerant design of cargo tanks in FLNGs.

Two-Dimensional Geometrically Nonlinear Finite Element Formulation for Analysis of Straight Pipes

2020 ◽  
Author(s):  
Saher Attia ◽  
Magdi Mohareb ◽  
Michael Martens ◽  
Nader Yoosef Ghodsi ◽  
Yong Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Virtual Work ◽  
Strain Tensor ◽  
Structural Response ◽  
Small Strain ◽  
Nonlinear Finite Element ◽  
Finite Element Formulation ◽  
Single Element ◽  
Element Formulation ◽  
Geometrically Nonlinear

Abstract The paper presents a new and simple geometrically nonlinear finite element formulation to simulate the structural response of straight pipes under in-plane loading and/or internal pressure. The formulation employs the Green-Lagrange strain tensor to capture finite deformation-small strain effects. Additionally, the First Piola-Kirchhoff stress tensor and Saint Venant-Kirchhoff constitutive model are adopted within the principle of virtual work framework in conjunction with a total Lagrangian approach. The formulation is applied for a cantilever beam under three loading conditions. Results are in good agreement with shell models in ABAQUS. Although the solution is based on a single element, the formulation provides reasonable displacement and stress predictions.

Corner loading and curling stress analysis for concrete pavements — an alternative approach

2002 ◽  
Vol 29 (4) ◽  
pp. 576-588 ◽  
Author(s):  
Ying-Haur Lee ◽  
Ying-Ming Lee ◽  
Shao-Tang Yen
Keyword(s):  
Finite Element ◽  
Stress Analysis ◽  
Projection Pursuit ◽  
Structural Response ◽  
Concrete Pavements ◽  
Finite Element Program ◽  
Response Characteristics ◽  
Wide Range ◽  
Bending Stresses ◽  
Wheel Loading

Since corner breaks are one of the major structural distresses in jointed concrete pavements, this research study mainly focuses on the determination of the critical bending stresses at the corner of the slab due to the individual and combination effects of wheel loading and thermal curling. A well-known slab-on-grade finite element program (ILLI-SLAB) was used for the analysis. The structural response characteristics of a slab corner were first investigated. Based on the principles of dimensional analysis, the dominating mechanistic variables were carefully identified and verified. A series of finite element factorial runs over a wide range of pavement designs was carefully selected and conducted. The resulting ILLI-SLAB corner stresses were compared with the theoretical Westergaard solutions, and adjustment factors were introduced to account for this discrepancy. Prediction equations for stress adjustments were developed using a modern regression technique (Projection Pursuit Regression). A simplified stress analysis procedure was proposed and implemented in a user-friendly computer program (ILLISTRS) to facilitate instant stress estimations and practical trial applications.Key words: concrete (rigid) pavements, corner breaks, loading, thermal curling, corner stress.

The Global Secant Relaxation-Based Accelerated Iteration Procedure for Solution of Nonlinear Finite Element Equation Systems of Offshore Structural Mechanics Problems

2011 ◽  
Author(s):  
Chang-New Chen
Keyword(s):  
Finite Element ◽  
Nonlinear Problems ◽  
Iterative Solution ◽  
Structural Mechanics ◽  
Iteration Scheme ◽  
Nonlinear Finite Element ◽  
Constant Stiffness ◽  
Iterative Computation ◽  
Newton Raphson ◽  
Quasi Newton

A global secant relaxation (GSR)-based accelerated iteration scheme can be used to carry out the incremental/iterative solution of various nonlinear finite element systems of offshore structural mechanics problems. This computation procedure can overcome the possible deficiency of numerical instability caused by local failure existing in the iterative computation. Moreover, this method can efficiently accelerate the convergency of the iterative computation. This incremental/iterative analysis can consistently be carried out to update the response history up to a near ultimate load stage, which is important for investigating the global failure behaviour of a structure under certain external cause, if the constant stiffness is used. Consequently, this method can widely be used to solve general nonlinear problems. Mathematical procedures of Newton-Raphson techniques in finite element methods for nonlinear finite element problems are summarized. These techniques are the Newton-Raphson method, quasi-Newton methods, modified Newton-Raphson methods and accelerated modified Newton-Raphson methods. Numerical results obtained by using various accelerated modified Newton-Raphson methods are used to study the convergency performances of these techniques for material nonlinearity problems and deformation nonlinearity problems, separately.

Structural mechanics characterization of steel intermeshed connection using nonlinear finite element analysis

2021 ◽  
Vol 238 ◽  
pp. 112264
Author(s):  
Mohammad E. Shemshadian ◽  
Arturo E. Schultz ◽  
Jia-Liang Le ◽  
Debra F. Laefer ◽  
Salam Al-Sabah ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Nonlinear Finite Element Analysis ◽  
Structural Mechanics ◽  
Nonlinear Finite Element ◽  
Element Analysis
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