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Guedes C Soares - One of the best experts on this subject based on the ideXlab platform.
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system reliability analysis of a Stiffened Panel under combined uniaxial compression and lateral pressure loads
Structural Safety, 2012Co-Authors: B Gaspar, Bernt J. Leira, Arvid Naess, Guedes C SoaresAbstract:A system reliability analysis of an oil tanker bottom component which consists of a Stiffened Panel under combined uniaxial compression and lateral sea pressure loads is presented in this paper. The Stiffened Panel is idealized as a structural system composed by several stiffeners with attached plating in parallel. The structural capacity of each stiffener with attached plating or system component is described by a nonlinear finite element model, considering as failure criterion the buckling collapse under the combined uniaxial compression and lateral sea pressure loads. These load components are defined considering a typical seagoing operational condition of the oil tanker in ballast load. The uncertainty in the relevant design basic variables is quantified using stochastic models proposed in the literature. To efficiently solve the structural system reliability problem a Monte Carlo based reliability estimation method recently proposed is combined with a response surface method. The combination of these two methods has been shown to be an efficient technique to solve structural system reliability problems that involve computationally demanding numerical models to describe the structural capacity of the system components. Annual probabilities of buckling collapse failure of the Stiffened Panel are estimated using this solution technique. The effect of corrosion on the Stiffened Panel reliability is quantified. The importance of considering the lateral sea pressure and correlation between the local and global wave-induced loads in the reliability problem are evaluated.
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influence of model geometry and boundary conditions on the ultimate strength of Stiffened Panels under uniaxial compressive loading
ASME 2012 31st International Conference on Ocean Offshore and Arctic Engineering, 2012Co-Authors: Mingcai Xu, Masahiko Fujikubo, Guedes C SoaresAbstract:The aim of this paper is to find out an appropriate configuration of boundary conditions and geometric model to calculate the ultimate strength of a continuous Stiffened Panel under uniaxial compressive loading in FE analysis. The 1+1 bays model with periodical symmetric boundary conditions is proposed to be used in FE analysis, whose results are compared with 1/2+1+1/2 bays model with periodical symmetric and symmetric boundary conditions, and 1/2+1+1+1/2 bays model with symmetric boundary conditions. The effects of the continuity of the Stiffened Panel with different geometric models and boundary conditions on its collapse mode are investigated. A beam tension test has been used to define the true stress-strain relationship.Copyright © 2012 by ASME
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fatigue reliability of a Stiffened Panel subjected to correlated crack growth
Structural Safety, 2012Co-Authors: G.q. Feng, Yordan Garbatov, Guedes C SoaresAbstract:The objective of this work is to analyze the fatigue reliability of a Stiffened Panel subjected to the growth of correlated cracks. A probabilistic crack growth model is applied, allowing for the existence of multiple cracks both in the stiffener and in the plate, accounting for the correlation between them. The geometry functions of the correlated cracks in the plate and in the stiffener are defined from calculations of stress intensity factors applying the finite element method. Monte Carlo simulations are used to define the statistical descriptions of crack growth. The failure probability assessment is performed based on a First Order Reliability method (FORM), in which the residual strength of the plate and stiffener in the Stiffened Panel are formulated in terms of the crack tip opening displacement. The formulation is extended to account for inspections, updating the probability of failure with its outcomes. Various parameters related to the quality of manufacture, inspections, time interval between inspection, load level and target reliability acceptance are studied.
Bernt J. Leira - One of the best experts on this subject based on the ideXlab platform.
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a response comparison of a Stiffened Panel subjected to rule based and measured ice loads
ASME 2014 33rd International Conference on Ocean Offshore and Arctic Engineering, 2014Co-Authors: Boris Erceg, Rocky Taylor, Soren Ehlers, Bernt J. LeiraAbstract:Ships operating in ice-covered waters are exposed to intense loads from ice features. Thus, their structures have to be designed to resist these ice loads. To achieve compliance with classification societies’ rules, analysis of these ice loads is achieved through the introduction of a uniform pressure patch applied to the hull surface. This uniform pressure approach does not account for the high degree of spatial and temporal variations observed in ice load measurements, which are inherent to the ice failure process. Thus, this paper will compare the response of a Stiffened Panel to ice loading by applying a rule-based uniform pressure patch as well as instantaneous non-uniform pressures based on measured spatial distributions of loads from field tests in order to investigate the effect of spatially localized loads due to high pressure zones on local plastic deformation of the hull.Copyright © 2014 by ASME
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system reliability analysis of a Stiffened Panel under combined uniaxial compression and lateral pressure loads
Structural Safety, 2012Co-Authors: B Gaspar, Bernt J. Leira, Arvid Naess, Guedes C SoaresAbstract:A system reliability analysis of an oil tanker bottom component which consists of a Stiffened Panel under combined uniaxial compression and lateral sea pressure loads is presented in this paper. The Stiffened Panel is idealized as a structural system composed by several stiffeners with attached plating in parallel. The structural capacity of each stiffener with attached plating or system component is described by a nonlinear finite element model, considering as failure criterion the buckling collapse under the combined uniaxial compression and lateral sea pressure loads. These load components are defined considering a typical seagoing operational condition of the oil tanker in ballast load. The uncertainty in the relevant design basic variables is quantified using stochastic models proposed in the literature. To efficiently solve the structural system reliability problem a Monte Carlo based reliability estimation method recently proposed is combined with a response surface method. The combination of these two methods has been shown to be an efficient technique to solve structural system reliability problems that involve computationally demanding numerical models to describe the structural capacity of the system components. Annual probabilities of buckling collapse failure of the Stiffened Panel are estimated using this solution technique. The effect of corrosion on the Stiffened Panel reliability is quantified. The importance of considering the lateral sea pressure and correlation between the local and global wave-induced loads in the reliability problem are evaluated.
Venkata M K Akula - One of the best experts on this subject based on the ideXlab platform.
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multiscale reliability analysis of a composite Stiffened Panel
Composite Structures, 2014Co-Authors: Venkata M K AkulaAbstract:Abstract A method for performing reliability analysis of a composite Stiffened Panel subjected to axial compression using the finite element method is discussed. Three-dimensional shell and brick element models are utilized for baseline response prediction, and comparison with experimental results. Owing to the multiscale nature of composite materials, microscale and macroscale design parameters are identified for the Panel. The microscale parameters consist of fiber ⧹ matrix properties and the volume fraction. The macroscale parameters consist of structural dimensions, layup definition, and an imperfection scale factor. The fiber and matrix properties are estimated utilizing a micromechanics model in conjunction with an optimization method. Thereafter, parameterized finite element models are used to generate an approximation model. Utilizing the Monte Carlo method, design parameters were subject to variation and the variation in response was predicted using the approximation model along with the probability of failure measured against experimental results and baseline finite element responses.
B Gaspar - One of the best experts on this subject based on the ideXlab platform.
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system reliability analysis of a Stiffened Panel under combined uniaxial compression and lateral pressure loads
Structural Safety, 2012Co-Authors: B Gaspar, Bernt J. Leira, Arvid Naess, Guedes C SoaresAbstract:A system reliability analysis of an oil tanker bottom component which consists of a Stiffened Panel under combined uniaxial compression and lateral sea pressure loads is presented in this paper. The Stiffened Panel is idealized as a structural system composed by several stiffeners with attached plating in parallel. The structural capacity of each stiffener with attached plating or system component is described by a nonlinear finite element model, considering as failure criterion the buckling collapse under the combined uniaxial compression and lateral sea pressure loads. These load components are defined considering a typical seagoing operational condition of the oil tanker in ballast load. The uncertainty in the relevant design basic variables is quantified using stochastic models proposed in the literature. To efficiently solve the structural system reliability problem a Monte Carlo based reliability estimation method recently proposed is combined with a response surface method. The combination of these two methods has been shown to be an efficient technique to solve structural system reliability problems that involve computationally demanding numerical models to describe the structural capacity of the system components. Annual probabilities of buckling collapse failure of the Stiffened Panel are estimated using this solution technique. The effect of corrosion on the Stiffened Panel reliability is quantified. The importance of considering the lateral sea pressure and correlation between the local and global wave-induced loads in the reliability problem are evaluated.
J Loughlan - One of the best experts on this subject based on the ideXlab platform.
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the buckling performance of composite Stiffened Panel structures subjected to combined in plane compression and shear loading
Composite Structures, 1994Co-Authors: J LoughlanAbstract:In this paper a study is made of the buckling behaviour of some composite Stiffened Panel structures subjected to in-plane compression and shear load combinations. The finite strip method, a computer aided engineering analysis procedure, is employed to determine the buckling solutions. Since the prediction of structural performance is quickly and accurately determined through computer simulation, the analysis capabilities of the finite strip method promotes the examination of many design alternatives. The designer is encouraged and indeed readily aided to make the most efficient use of materials and thus the development of highly reliable structural components, which are able to operate at optimised performance levels, can be achieved. A basic strip formulation for composite material construction is presented which is able to predict the complex buckling modes associated with in-plane load combinations. The buckling displacement fields are represented by algebraic polynomials across the strip and trigonometric functions along the strip length. The inclusion of sufficient harmonics in the appropriate displacement representations provides the required flexibility of the strip formulation to accommodate the more elaborate buckling modes associated with the presence of in-plane shear loading. The results presented in the paper are those pertaining to the buckling capabilities of Stiffened Panels manufactured from high strength carbon-epoxy composite material. The results illustrate, graphically, the effect on buckling performance of changes in stiffener geometry. Interaction curves are presented in the paper which detail the limiting boundaries for critical load combinations of specific structural configurations.
