Collapse Analysis of Ship Hull Girder Using Hydro-Elastoplastic Beam Model: Part 2

2020 ◽  
Author(s):  
Han Htoo Htoo Ko ◽  
Akira Tatsumi ◽  
Kazuhiro Iijima ◽  
Masahiko Fujikubo
Keyword(s):  
Cross Sections ◽  
Ship Hull ◽  
Average Stress ◽  
Beam Model ◽  
Fundamental Study ◽  
Hull Girder ◽  
Softening Behavior ◽  
Smith Method ◽  
Collapse Analysis ◽  
Elastoplastic Beam

Abstract In Part 1 study, a time-domain collapse analysis method of ship hull girder was developed and named FE-Smith method. Hull girder was treated as elastoplastic beam model and Smith’s method was used for collapse analysis of cross sections. A concept of average stress-average plastic strain relationship was introduced so that nonlinear collapse behavior of members can be treated as pseudo strain-hardening/softening behavior. Fluid-structure interaction effects were considered. Uniform cross-section beam was assumed as a most fundamental study. In this Part 2, a container ship is taken as subject model. Not only FE-Smith analysis but also non-linear FE analyses using shell model for collapse parts are performed for comparison purpose. Two types of average stress-average strain curves are considered for FE-Smith analysis, i.e. obtained by Gordo-Soares formulae and by shell FEM. Applicability of FE-Smith method is examined comparing with more precise but time-consuming methods. Some parametric studies are also performed. Wave response will be reported in the next papers.

Collapse Analysis of Ship Hull Girder Using Hydro-Elastoplastic Beam Model

2018 ◽  
Author(s):  
Han Htoo Htoo Ko ◽  
Akira Tatsumi ◽  
Kazuhiro Iijima ◽  
Masahiko Fujikubo
Keyword(s):  
Cross Sections ◽  
Progressive Collapse ◽  
Ship Hull ◽  
Average Stress ◽  
Beam Model ◽  
Structural Elements ◽  
Hull Girder ◽  
Collapse Analysis ◽  
Strain Relationship ◽  
Collapse Behavior

A method of time-domain collapse analysis of ship hull girder considering the interaction between elastoplastic deformation and hydrostatic/dynamic forces is developed. Ship hull girder is longitudinally divided by conventional beam elements, and progressive collapse behavior of cross sections is simulated by Smith method considering material yielding, buckling and post-buckling of structural elements. Average stress–average strain relationship of structural elements is transformed to average stress–average plastic strain relationship so that it can be treated as pseudo strain-hardening/softening effects. Strip method is used for the calculation of hydrodynamic forces on the hull girder. Hydrodynamic coefficients for cross-sections are calculated by 2D-BEM. In-house analysis code is developed and applied to the collapse analysis of a uniform hull-girder model under impulsive bending loads. The effects of load duration time on the dynamic collapse behavior of the hull girder are discussed.

Collapse Analysis of Ship Hull Girder Using Hydro-Elastoplastic Beam Model (Part 2)

2021 ◽  
Author(s):  
HanHtoo HtooKo ◽  
Akira Tatsumi ◽  
Kazuhiro Iijima ◽  
Masahiko Fujikubo
Keyword(s):  
Ship Hull ◽  
Beam Model ◽  
Hull Girder ◽  
Collapse Analysis ◽  
Elastoplastic Beam

Finite Element Analysis on the Hull Girder Ultimate Strength of Asymmetrically Damaged Ships

2016 ◽  
Author(s):  
Muhammad Zubair Muis Alie ◽  
Ganding Sitepu ◽  
Juswan Sade ◽  
Wahyuddin Mustafa ◽  
Andi Mursid Nugraha ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Ultimate Strength ◽  
Cross Sections ◽  
Progressive Collapse ◽  
Ship Hull ◽  
Strength Analysis ◽  
Functional Requirements ◽  
Element Analysis ◽  
Hull Girder

This paper discusses the influence of asymmetrically damaged ships on the ultimate hull girder strength. When such damages take place at the asymmetric location of cross sections, not only translation but also inclination of instantaneous neutral axis takes place during the process of the progressive collapse. To investigate this effect, the Finite Element Analysis (FEA) is employed and the damage is assumed in the middle hold. The collision damage is modeled by removing the plate and stiffener elements at the damage region assuming the complete loss of the capacity at the damage part. For the validation results obtained by Finite Element Analysis of the asymmetrically damaged ship hull girder, the simplified method is adopted. The Finite Element method of ultimate strength analysis of a damaged hull girder can be a practical tool for the ship hull girder after damages, which has become one of the functional requirements in IMO Goal Based Ship Construction Standard.

A Fundamental Study on the Dynamic Response of Hull Girder of Container Ships due to Slamming Load

2017 ◽  
Author(s):  
Yasuhira Yamada ◽  
Kyoko Kameya
Keyword(s):  
Plastic Material ◽  
Bending Moment ◽  
Beam Model ◽  
Time Duration ◽  
Fundamental Study ◽  
Natural Period ◽  
Hull Girder ◽  
Slamming Load ◽  
Explicit Analysis ◽  
Vertical Bending Moment

The purpose of the present study is to fundamentally investigate dynamic hull girder response due to slamming load. A series of time domain FE-simulation is carried out using a non-uniform finite element beam model of a 8000 TEU container ship where slamming load is applied at the bottom of the bow. The ship is modeled by elaso-plastic material with equivalent ultimate strength and strain rate effect is considered. Hull-girder vertical bending moment as well as deformation modes, bending stress are investigated by varying the time duration of the slamming load which is modeled by sinusoidal impulse. In order to obtain post vibration after the first slamming load explicit analysis is adopted instead of implicit analysis with considering gravity and buoyancy. Buoyancy is modeled by inelastic spring elements. It is found from the present study hull girder vertical bending moment is dependent on time duration of slamming load. Especially if time duration is smaller than natural period response bending moment may become smaller than applied bending moment. Moreover effect of inertia at fore and aft is also investigated in detail.

Collapse Analysis of Ship Hull Girder in Waves Using Idealized Structural Unit Method

2016 ◽  
Author(s):  
Masahiko Fujikubo ◽  
Kazuhiro Iijima ◽  
Zhiyong Pei ◽  
Han Htoo Htoo Ko
Keyword(s):  
Simple Procedure ◽  
Progressive Collapse ◽  
Ship Hull ◽  
Element Formulation ◽  
Total System ◽  
Plate Element ◽  
Hull Girder ◽  
Hull Structure ◽  
Collapse Analysis ◽  
Progressive Collapse Analysis

Recent progress in the development and application of the ISUM plate element is highlighted with a particular focus on its application to the progressive collapse analysis of a ship hull structure. The plate element is characterized by idealized shape functions for defection based on buckling collapse mode and a simple procedure for element formulation similar to that for standard displacement-based finite elements. The formulation of the plate element under in-plane loads is presented, and then the plate element and the plate-stiffener combination model are applied to the progressive collapse analysis of a hull-girder cross section and double bottom structure. The development of a total system for motion/collapse analysis of a whole ship in waves is also presented. The effectiveness of these ISUM models is demonstrated.

Study on the Standardized Nonlinear Finite Element Analysis of the Ultimate Strength of Ship Hull Girder

2009 ◽  
Author(s):  
Guoqing Feng ◽  
Huilong Ren ◽  
Baoqiang Bai ◽  
Chenfeng Li ◽  
Xiaobo Liu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Ultimate Strength ◽  
Nonlinear Finite Element Analysis ◽  
Ship Hull ◽  
Nonlinear Finite Element ◽  
Welding Residual Stress ◽  
Element Analysis ◽  
Hull Girder ◽  
Smith Method

The ultimate strength of ship hull girder has been a study hot spot in ship mechanics. Caldwell method, Smith method, idealized structural unit method and nonlinear finite element method are usually used to predict the ultimate strength of ship hull girder. In the paper, a standardized procedure on the nonlinear finite element analysis of the ultimate strength of ship hull girder is presented. Firstly, the finite element modeling for the ultimate strength of ship hull girder is studied, which include material property, element type, mesh size, model length and boundary conditions. Then, the influence of welding residual stress and initial deflection are studied. For the validation of the method in this paper, a MST-3 model from the test of Nishihara is used as an example. Finally, the results from the nonlinear finite element analysis and Smith method are compared for the ultimate strength analysis of a container ship. The study shows the standardized procedure on the nonlinear finite element analysis of the ultimate strength of ship hull girder is satisfactory and suitable for engineering application.

A Study on the Method to Estimate Ship Hull Girder Ultimate Strength Considering Biaxial Compression in Bottom Stiffened Plates

2017 ◽  
Author(s):  
Yoshiaki Naruse ◽  
Yasumi Kawamura ◽  
Tetsuo Okada
Keyword(s):  
Ultimate Strength ◽  
Compressive Load ◽  
Ship Hull ◽  
Biaxial Compression ◽  
Stiffened Plates ◽  
Effective Width ◽  
Element Analysis ◽  
Hull Girder ◽  
Smith Method ◽  
New Formula

In this study, ship hull girder ultimate strength considering biaxial compression in bottom stiffened plates is investigated. Firstly, elasto-plastic finite element analysis is carried out for the stiffened plates under biaxial compression by using the commercial FEM software, LS-DYNA. From the observation of collapse behavior of the stiffened plates, it is found that the decrease of the effective width of the stiffened plate under biaxial compression is more rapid compared with the formula in the Common Structure Rules (CSR). This is because the buckling in one half-wave mode occurs when the transverse compressive load becomes larger, while the buckling with multi half-waves mode usually occurs in longitudinal direction when only longitudinal compressive load is applied. Based on the observation, a new formula to estimate ultimate strength of stiffened plates considering biaxial compression is proposed in which three new parameters are introduced which can represent the decrease of the effective width. Next, a method to estimate ultimate strength of hull girder considering the biaxial compression of ship bottom is developed based on the conventional Smith method provided in the CSR, by introducing the above new formula to estimate the ultimate strength of stiffened plates, and by improving the conventional formula of the hard corner element in the Smith method. Finally, the hull girder strength of a container ship under biaxial compression estimated by the proposed method is compared with the result of FEM analysis to show validity of the method.

Assessment of Residual Ultimate Strength of VLCC According to Damage Extents and Average Compressive Strength of Stiffened Panel

2014 ◽  
Author(s):  
Ji-Myung Nam ◽  
Joonmo Choung ◽  
Se-Yung Park ◽  
Sung-Won Yoon
Keyword(s):  
Compressive Strength ◽  
Ultimate Strength ◽  
Probabilistic Approach ◽  
Stiffened Panel ◽  
Moment Capacity ◽  
Hull Girder ◽  
Damage Area ◽  
Damage Indices ◽  
Smith Method ◽  
Average Compressive Strength

This paper presents the prediction of residual ultimate strength of a very large crude oil carrier considering damage extents due to collision and grounding accidents. In order to determine extents of damage, two types of probabilistic approaches are employed: deterministic approach based on regulations based on ABS [1], DNV [2], and MARPOL [3] and probabilistic approach based on IMO probability density functions (PDFs) (IMO guidelines [4]). Hull girder ultimate strength is calculated using Smith method which is dependent on how much average compressive strength of stiffened panel is accurate. For this reason, this paper uses two different methods to predict average compressive strength of stiffened panel composing hull girder section: CSR formulas and nonlinear FEA. Calculated average compressive strength curves using CSR formulas (IACS [5, 6]) and nonlinear FEA are imported by an in-house software UMADS. Residual ultimate moment capacities are presented for various heeling angles from 0° (sagging) to 180° (hogging) by 15° increments considering possible flooding scenarios. Three regulations and IMO guidelines yield minimum of reduction ratios of hull girder moment capacity (minimum of damage indices) approximately at heeling angles 90° (angle of horizontal moment) and 180° (angle of hogging moment), respectively, because damage area is located farthest from neutral axis.

scholarly journals Application of the Generalized Nonlinear Constitutive Law in 2D Shear Flexible Beam Structures

2021 ◽  
Author(s):  
Damian Mrówczyński ◽  
Tomasz Gajewski ◽  
Tomasz Garbowski
Keyword(s):  
Finite Element ◽  
Cross Sections ◽  
Reference Model ◽  
Constitutive Models ◽  
Constitutive Law ◽  
Flexible Beam ◽  
Beam Model ◽  
Beam Structures ◽  
Nodal Displacements ◽  
Nonlinear Constitutive Law

The paper presents a modified finite element method for nonlinear analysis of 2D beam structures. To take into account the influence of the shear flexibility, a Timoshenko beam element was adopted. The algorithm proposed enables using complex material laws without the need of implementing advanced constitutive models in finite element routines. The method is easy to implement in commonly available CAE software for linear analysis of beam structures. It allows to extend the functionality of these programs with material nonlinearities. By using the structure deformations, computed from the nodal displacements, and the presented here generalized nonlinear constitutive law, it is possible to iteratively reduce the bending, tensile and shear stiffnesses of the structures. By applying a beam model with a multi layered cross-section and generalized stresses and strains to obtain a representative constitutive law, it is easy to model not only the complex multi-material cross-sections, but also the advanced nonlinear constitutive laws (e.g. material softening in tension). The proposed method was implemented in the MATLAB environment, its performance was shown on the several numerical examples. The cross-sections such us a steel I-beam and a steel I-beam with a concrete encasement for different slenderness ratios were considered here. To verify the accuracy of the computations, all results are compared with the ones received from a commercial CAE software. The comparison reveals a good correlation between the reference model and the method proposed.

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