Probabilistic Assessment of Stiffened Panel Strength: An Interactive Tool Using PROBAN and PULS

2010 ◽  
Author(s):  
Hadi Amlashi ◽  
Torfinn Ho̸rte ◽  
Eivind Steen ◽  
Jon Kippenes
Keyword(s):  
Ultimate Strength ◽  
Probability Distributions ◽  
Ship Design ◽  
Probabilistic Methods ◽  
Computational Time ◽  
Stiffened Panel ◽  
Probabilistic Assessment ◽  
Limit States ◽  
Stiffened Panels ◽  
Safety Margins

To achieve an economic and reliable ship design, the ship structure has to be designed with adequate safety margins. This can be accomplished by a reliability-based limit states design approach, in which probabilistic methods are used to guide the development of the design criteria. A tool is developed to probabilistically assess the capacity distribution of the stiffened panels. A Monte Carlo simulation scheme, which samples a number of probability distributions, has been applied using PROBAN (DNV) which interactively utilizes PULS (DNV) as an efficient ultimate strength prediction tool for plated panels. It is demonstrated that this tool can successfully link the two internationally recognized programs, i.e. PROBAN and PULS for probabilistic assessment of stiffened panel’s ultimate strength. The results demonstrate that the suitability of the assumed distribution for the strength can be assessed with relatively little computational time, where the yield stress and imperfection sizes are treated as random variables. Such results are very informative and useful for further development of existing safety format ensuring a safe, economic and reliable ship design.

A Benchmark Study of ISO 18072-2 on the Stiffened Panel Ultimate Strength

2011 ◽  
Author(s):  
Paul A. Frieze ◽  
Martino Abbattista ◽  
Mirella Vallascas ◽  
Jeom K. Paik
Keyword(s):  
Ultimate Strength ◽  
Structural Reliability ◽  
Close Correlation ◽  
Stiffened Panel ◽  
Stiffened Panels ◽  
The Public ◽  
Benchmark Study ◽  
Wide Range ◽  
Non Linear ◽  
Complete Set

The paper presents a major benchmarking exercise to demonstrate the accuracy of the formulations for the ultimate strength of stiffened panels that had been proposed for inclusion in ISO TS 18072-2. The complete set of formulations addressed the ultimate strength of plates, hull girders and support members, in particular, transverse frames and webs. The stiffened panel strength formulations have been in the public domain for some time and represent the most comprehensive set yet published. Their potential application is to a wide range of structural forms, e.g. floating dock gates, caissons, bridge decks, FPSOs, etc, and as such have much to recommend for other than just ship structures. The benchmark study presents comparisons between two implementations of the formulations and the results of non-linear FEA. The structures analysed represent a range of different stiffened panels with varying overall dimensions, plate dimensions and stiffener shapes, in particular, flats, angles and Tees. Close correlation is generally realized but where differences arise, these are readily related to the approximations used in developing the strength formulations. The comparisons between the strength formulations and non-linear FEA results provides the basis for quantifying statistical uncertainties in the formulations which can be used in subsequent structural reliability analysis and partial resistance factor derivation.

Ultimate Strength of Stiffened Panels With Cracking Damage Under Axial Compression or Tension

2006 ◽  
Vol 50 (03) ◽  
pp. 231-238
Author(s):  
Jeom Kee Paik ◽  
Y. V. Satish Kumar
Keyword(s):  
Ultimate Strength ◽  
Limit State ◽  
Reliability Assessment ◽  
Nonlinear Finite Element ◽  
Stiffened Panel ◽  
Ultimate Limit State ◽  
Finite Element Analyses ◽  
Stiffened Panels ◽  
Aging Steel ◽  
Ultimate Limit

The aim of the present paper is to investigate the ultimate strength characteristics of a longitudinally stiffened panel with cracking damage and under axial compressive or tensile loads. A series of nonlinear finite element analyses are undertaken with varying the size and location of cracking damage. A relevant theoretical model for predicting the ultimate strength of the stiffened panel with cracking damage is studied. The insights and results developed from the present study will be very useful for the ultimate limit state-based risk or reliability assessment of aging steel plated structures with cracking damage.

scholarly journals Cohesive Zone Model Modification Techniques According to the Mesh Size in Finite Element Models of Stiffened Panels with Debonding

Computation ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 5
Author(s):  
Vasileios K. Mantzaroudis ◽  
Dimitrios G. Stamatelos
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Cohesive Zone ◽  
Cohesive Zone Modeling ◽  
Computational Time ◽  
Stiffened Panel ◽  
Zone Model ◽  
Fe Model ◽  
Stiffened Panels ◽  
Buckling Behavior

When catastrophic failure phenomena in aircraft structures, such as debonding, are numerically analyzed during their design process in the frame of “Damage Tolerance” philosophy, extreme requirements in terms of time and computational resources arise. Here, a decrease in these requirements is achieved by developing a numerical model that efficiently treats the debonding phenomena that occur due to the buckling behavior of composite stiffened panels under compressive loads. The Finite Element (FE) models developed in the ANSYS© software (Canonsburg, PA, USA) are calibrated and validated by using published experimental and numerical results of single-stringer compression specimens (SSCS). Different model features, such as the type of the element used (solid and solid shell) and Cohesive Zone Modeling (CZM) parameters are examined for their impact on the efficiency of the model regarding the accuracy versus computational cost. It is proved that a significant reduction in computational time is achieved, and the accuracy is not compromised when the proposed FE model is adopted. The outcome of the present work leads to guidelines for the development of FE models of stiffened panels, accurately predicting the buckling and post-buckling behavior leading to debonding phenomena, with minimized computational and time cost. The methodology is proved to be a tool for the generation of a universal parametric numerical model for the analysis of debonding phenomena of any stiffened panel configuration by modifying the corresponding geometric, material and damage properties.

Optimization of lightweight sub-stiffened panels with buckling analysis and imperfection sensitivity analysis

2019 ◽  
Vol 233 (15) ◽  
pp. 5507-5521 ◽  
Author(s):  
Hao Chen ◽  
Yuanming Xu ◽  
Junhao Hu ◽  
Xi Wang
Keyword(s):  
Sensitivity Analysis ◽  
Ultimate Strength ◽  
Multidisciplinary Optimization ◽  
Uniaxial Loading ◽  
Stiffened Panel ◽  
Imperfection Sensitivity ◽  
Engineering Structures ◽  
Buckling Loads ◽  
Stiffened Panels ◽  
Post Buckling

On the purpose of improving the structural efficiency of stiffened panels, which is widely used in engineering, three promising layouts of sub-stiffened thin-walled structures were optimized in view of structure's initial buckling and further analyzed through post-buckling and imperfection-sensitivity analysis. The optimization tasks were carried out using an integrated framework, which is based on the multidisciplinary optimization platform Model Center and finite element method software ABAQUS. The particle swarm optimization algorithm was applied to optimize layout parameters. Three optimal sub-stiffened panels were then evaluated based on their performance on critical buckling loads and post-buckling ultimate strength under uniaxial loading. Imperfection-sensitivity analysis was also conducted to investigate the stability behavior of the proposed panels with defect. The results indicate that the introduction of sub-stiffeners into the traditional stiffened panel can achieve significant improvements on the panel's buckling loads and ultimate strength under uniaxial loading, which are favorable to expand design space for engineering structures under requirements of lightweight with high bending stiffness and bucking resistance.

A Simple Design Formula to Estimate the Ultimate Strength of Stiffened Panels Under Bi-Axial Compression Mainly in Transverse Direction

2018 ◽  
Author(s):  
Yusuke Komoriyama ◽  
Daisuke Yanagihara
Keyword(s):  
Ultimate Strength ◽  
Axial Compression ◽  
Transverse Direction ◽  
Yield Condition ◽  
Stiffened Panel ◽  
Simple Design ◽  
Buckling Mode ◽  
Stiffened Panels ◽  
Design Formula ◽  
Collapse Behavior

Most of stiffened panels subjected to bi-axial compression mainly in transverse direction collapse with the buckling deformation of one times one half-wave in a local panel between longitudinal stiffeners and transverse frames. The authors defined this collapse mode as “local panel buckling mode”. In this study, the collapse behavior of the stiffened panel with local panel buckling mode is investigated in detail. Then, a simple design formula to estimate ultimate strength of a stiffened panel with local panel buckling mode is derived based on the collapse behavior. This formula is composed of a formula to predict the ultimate strength of a rectangular unstiffened panel subjected to uniaxial transverse compression, and the effects of stiffeners, bi-axial compression and von Mises yield condition are added to the formula. The ultimate strength calculated by the proposed formula is in good agreement with FEA results. Finally, the proposed formula is compared with an existing method and formulae used in the CSR-OT, CSR-BC and H-CSR. As a result, it is confirmed that the proposed formula has sufficient accuracy and high availability.

Influence of Model Geometry and Boundary Conditions on the Ultimate Strength of Stiffened Panels Under Uniaxial Compressive Loading

2012 ◽  
Author(s):  
Mingcai Xu ◽  
Masahiko Fujikubo ◽  
C. Guedes Soares
Keyword(s):  
Boundary Conditions ◽  
Ultimate Strength ◽  
Geometric Model ◽  
Compressive Loading ◽  
Fe Analysis ◽  
Stiffened Panel ◽  
Stiffened Panels ◽  
Collapse Mode ◽  
Strain Relationship ◽  
Model Geometry

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.

Ultimate Strength of Stiffened Plates Subjected to Longitudinal Compression and Lateral Pressure

2014 ◽  
Author(s):  
Karan Doshi ◽  
Suhas Vhanmane
Keyword(s):  
Finite Element ◽  
Ultimate Strength ◽  
Lateral Pressure ◽  
Stiffened Plates ◽  
Stiffened Panel ◽  
Element Analysis ◽  
Stiffened Panels ◽  
Linear Finite Element ◽  
Non Linear ◽  
Compressive Loads

This paper presents a non-linear finite element analysis (FEA) and subsequent formula development for ultimate strength of stiffened panels of ship structures. A review of studies on ultimate strength of ship plating subjected to lateral pressure was carried out. The present work takes into account, the influence due to the lateral pressure on the ultimate strength of stiffened plates with initial imperfections subject to longitudinal compressive loads. ANSYS non-linear FE software was used for non linear finite element analyses of stiffened panels (864 cases) considering VLCC hull. Based on regression analysis, a set of semi-analytical formulae were proposed and described. It is observed that depending upon the failure mode, scantlings of the stiffened panel and magnitude of lateral pressure, ultimate strength of the stiffened panels in compression is affected.

Influence of Model Geometry and Boundary Conditions on the Ultimate Strength of Stiffened Panels Under Uniaxial Compressive Loading

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Ming Cai Xu ◽  
Masahiko Fujikubo ◽  
C. Guedes Soares
Keyword(s):  
Boundary Conditions ◽  
Ultimate Strength ◽  
Geometric Model ◽  
Compressive Loading ◽  
Fe Analysis ◽  
Stiffened Panel ◽  
Stiffened Panels ◽  
Symmetric Boundary Condition ◽  
Strain Relationship ◽  
Model Geometry

The aim of this paper is to determine an appropriate configuration of the boundary conditions and geometric model to calculate the ultimate strength of a continuous stiffened panel under compressive loading in the finite element (FE) analysis. The 1 + 1 spans model with periodical symmetric boundary conditions is proposed to be used in the FE analysis, whose results are compared with the 1/2 + 1 + 1/2 span model with periodical symmetric and symmetric boundary condition, and the 1/2 + 1 + 1 + 1/2 span 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 in the FE analysis. The two-span model, either 1 + 1 or 1/2 + 1 + 1/2, with periodical symmetric conditions give a reasonable FE modeling, which can consider both odd and even number half waves and, thus, have the smallest model uncertainty.

Ultimate Strength of Damaged Stiffened Panels Subjected to Uniaxial Compressive Loads Accounting for Impact Induced Residual Stress and Deformation

2015 ◽  
Author(s):  
Jie Cai ◽  
Xiaoli Jiang ◽  
Gabriel Lodewijks
Keyword(s):  
Residual Stress ◽  
Ultimate Strength ◽  
Carrying Capacity ◽  
Stiffened Panel ◽  
Load Carrying Capacity ◽  
Stiffened Panels ◽  
Load Carrying ◽  
Stress And Deformation ◽  
The Impact ◽  
Residual Stress And Deformation

In case of ship accidents, the ship’s hull will inevitably suffer from damages such as holes, cracks, dent etc., which will threaten the structural safety of ship. It is essential to study the ultimate strength of damaged ships in order to facilitate the decision-making process of ship salvage. There are considerable publications on the subject, however, the impact of the induced residual stress and deformation are normally excluded in those studies. This paper therefore aims at investigating the effect of the impact induced residual stress and deformation on the ultimate strength of a stiffened panel through application of a nonlinear Finite Element Analysis (FEA) method. Firstly, a literature review on ultimate strength of damaged ships is presented. Secondly, a nonlinear numerical simulation is adopted to investigate the ultimate strength of stiffened panels accounting for residual stress and deformation. this procedure consists of two stages: the impact stage and the static stage. The results of the numerical simulation of both stages are validated through the results of experiments and simulations available in literature. Afterwards, a series of case studies are performed deploying the validated numerical method. Finally, a closed form expression to predict the ultimate strength accounting for impact induced residual stress and deformation is proposed based on direct simulation. Results show that the combined effect of impact induced residual stress and deformation can significantly reduce structures’ load carrying capacity. The maximum reduction ratio reaches 37% in local stiffened panel. The method of removal of all the plastic deformation area is generally too conservative to predict the ultimate strength of a damaged local stiffened panel, which will underestimate the residual load carrying capacity of ships considerably.

Effects of Cumulative Buckling Deformation Formed by Cyclic Loading on Ultimate Strength of Stiffened Panel

2018 ◽  
Author(s):  
Yusuke Komoriyama ◽  
Yoshiteru Tanaka ◽  
Takahiro Ando ◽  
Yutaka Hashizume ◽  
Akira Tatsumi ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Ultimate Strength ◽  
The Other ◽  
Stiffened Panel ◽  
Test Cases ◽  
Stiffened Panels ◽  
Cyclic Compression ◽  
Loading System ◽  
Number Of Cycles

In this study, for the stiffened panels subjected to the in-plane cyclic compression loads, the two followings are clarified. One is a generating process of the cumulative buckling deformation at panel parts of stiffened panels. The other is the effect of the cumulative buckling deformation on the ultimate strength of stiffened panels. To clarify them, the cyclic compression loading experiments were carried out with two stiffened panel specimens by using Multi Axis Loading System in National Maritime Research Institute (NMRI) in Japan. For one stiffened panel specimen, the thirty-one sets of compression test cases were conducted with different strokes and for each case. The number of cycles in each set was 100. While, for the other, it was subjected to the cyclic compression loads until it collapsed. In addition, Finite Element Method (FEM) analyses for stiffened panels subjected cyclic compression loads are carried out with the same condition as the experiments by using commercial FEM software, LS-DYNA.

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