A Study on the Dynamic Ultimate Strength of Global Hull Girder of Container Ships Subjected to Hogging Moment

2018 ◽  
Author(s):  
Yasuhira Yamada ◽  
Kyoko Kameya
Keyword(s):  
Finite Element ◽  
Strain Rate ◽  
Ultimate Strength ◽  
Large Scale ◽  
Plastic Material ◽  
Collapse Mechanism ◽  
Time Duration ◽  
Element Analysis ◽  
Hull Girder ◽  
Non Linear

The purpose of the present study is to investigate dynamic ultimate strength of global hull girder of container ships using large scale non-linear finite element analysis. A series of time domain non-linear FE-simulation is carried out using large scale FE models of a 8000 TEU container ship where a hogging moment is applied to the midship section. 5 types of finite element models (three full models, a half hold model, a 1 transverse model) are used. These models adopt elasto-plastic material model which includes strain rate effect. The hogging moment which is modeled by sinusoidal impulse is applied to these models, and collapse mechanism as well as dynamic hull girder ultimate strength is investigated by varying the load time duration. Moreover effects of load time duration, mass inertia, strain rate and analysis models are investigated in detail. It is found from the present study that ultimate strength as well as collapse mode are significantly dependent on load time duration of hogging moment.

Dynamic Collapse Mechanism of Global Hull Girder of Container Ships Subjected to Hogging Moment

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Yasuhira Yamada
Keyword(s):  
Finite Element ◽  
Strain Rate ◽  
Ultimate Strength ◽  
Large Scale ◽  
Nonlinear Finite Element ◽  
Elastoplastic Material ◽  
Collapse Mechanism ◽  
Time Duration ◽  
Element Analysis ◽  
Hull Girder

The purpose of the present study is to investigate dynamic ultimate strength of global hull girder of container ships using large-scale nonlinear finite element analysis (FEA). A series of time domain nonlinear finite element (FE)-simulation is carried out using large-scale FE models of a 8000 twenty-foot equivalent unit (TEU) container ship where a hogging moment is applied to the midship section. Five types of finite element models (three full models, a half hold model, a one transverse model) are used. These models adopt elastoplastic material model, which includes strain rate effect. The hogging moment, which is modeled by sinusoidal impulse, is applied to these models, and collapse mechanism as well as dynamic hull girder ultimate strength is investigated by varying the load time duration. Moreover, effects of load time duration, mass inertia, strain rate, and analysis models are investigated in detail. It is found from the present study that ultimate strength as well as collapse mode is significantly dependent on load time duration of hogging moment.

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.

Finite Element Analysis of Longitudinal Bending Collapse of Container Ship Considering Bottom Local Loads

2016 ◽  
Author(s):  
Akira Tatsumi ◽  
Masahiko Fujikubo
Keyword(s):  
Finite Element ◽  
Ultimate Strength ◽  
Container Ship ◽  
Element Analysis ◽  
Local Loads ◽  
Hull Girder ◽  
Longitudinal Bending ◽  
Collapse Behavior ◽  
Large Container ◽  
Collapse Region

The purpose of this research is to clarify the effect of bottom local loads on the hull girder collapse behavior of large container ship (8000TEU class) A 1/2+1+1/2 hold model of container ship is analyzed using implicit finite element method. The results reveal two major causes of reduction of hull girder ultimate strength due to local loads. One is biaxial compressive stresses induced at outer bottom. Thus, smaller hogging moment can induce a collapse of bottom panels. The other is a reduction of effectiveness of inner bottom that is on the tension side of local bending. As a result, the container ship attains hull girder ultimate strength with smaller spread of collapse region compared to that under pure bending.

Numerical Study on the Residual Ultimate Strength of Hull Girder of a Bulk Carrier After Ship-Ship Collision

2014 ◽  
Author(s):  
Yasuhira Yamada
Keyword(s):  
Large Scale ◽  
Numerical Study ◽  
Bending Moment ◽  
Second Step ◽  
Collapse Mechanism ◽  
Bulk Carrier ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
Hull Girder ◽  
Ship Collision

The purpose of the present study is to investigate residual Ultimate Longitudinal Strength (ULS) of bulk carriers after ship-ship collision. A series of a large-scale explicit finite element analysis (FEA) as well as simplified analysis (SA) are carried out using a cape size bulk carrier. In order to accurately investigate collapse mechanism of “damaged ships” under vertical bending moment nonlinear FEA are carried out where two steps analysis is adopted. First step is ship-ship collision analysis; Second step is ULS analysis of the damaged ship. Ship-ship collision analysis is carried out assuming the right angle collision at the midship region of the struck ship, and damage extent of the struck ship is estimated with varying collision speed of 3kt, 6kt, 9kt and 12kt. In the second step of analysis, residual ULS analysis is carried out taking into account residual stress and deformation of the struck ship caused by ship-ship collision. Collapse mechanism of the bulk carrier in damaged condition due to sagging moment as well as combination of longitudinal and horizontal bending moment is investigated and discussed in detail. ULS of hull girder of the bulk carrier in intact condition is also estimated and compared with that in damaged condition. The effect of damaged condition on the reduction of ULS is discussed in detail. Finally some of numerical methodologies are summarized in assessing residual ULS of hull girder after collision.

Study on Numerical Methodologies for Assessing Ultimate Bending Moment of Ship Hull Girder

2016 ◽  
Author(s):  
Ming Cai Xu ◽  
Zhao Jun Song
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Ultimate Strength ◽  
Bending Moment ◽  
Finite Element Models ◽  
Element Analysis ◽  
Hull Girder ◽  
Computer Resource ◽  
Explicit Dynamic ◽  
Convergence Of Solution

Nonlinear finite element analysis is usually used to assess the ultimate strength of hull girder, which includes implicit analysis and explicit dynamic analysis. So far, most of researchers use the implicit analysis to assess the ultimate strength of various vessels or stiffened plates. Comparing with the implicit analysis, the explicit dynamic analysis may be more stable since this method doesn’t need to consider the convergence of solution, and can consider the transient influence of time. However, the accuracy of solution results and time in the explicit dynamic method is very important. This depends on modelling configurations, such as the loading time, geometric ranges of finite element models, element types and applying methods of loading. The purpose of the present paper is to investigate the influences of these factors, and then to figure out a reliable numerical method which meets permitted accuracy and consumes acceptable computer resource in explicit dynamic analysis.

Finite Element Analysis for Prediction of Permanent Growth of Rotating Disc of Aero Engine During Over-Speed and Burst-Speed Conditions and Validation of Results Through Experiment

2013 ◽  
Author(s):  
M. Rudra Goud ◽  
C. Manjunatha ◽  
M. Venkateshwarlu ◽  
B. V. A. Patnaik
Keyword(s):  
Finite Element ◽  
Plastic Material ◽  
Strain Curve ◽  
Element Model ◽  
Rotating Disc ◽  
Stress Strain ◽  
Element Analysis ◽  
Non Linear ◽  
Strain Relationship ◽  
Elastic Plastic Material

The service life of critical aerospace components is governed by the modes of degradation and failure such as: yielding, fatigue, fracture, creep, corrosion, wear, etc. A single disc is used for over-speed and burst-speed tests to know the growths (plastic deformation). In this paper, a cyclic symmetry sector of disc model with non linear elastic-plastic material is considered. A non-linear finite element method is utilized to determine the stress and strain state of the disc under over-speed and burst-speed conditions using material stress strain curves. Permanent growths and strains obtained from the over-speed analysis are incorporated in the burst-speed Finite element Model. The original stress strain curve used in over-speed analysis is modified with plastic strain and used in burst-speed analysis of same disc. Elastic strains obtained from the over-speed and burst-speed analysis are utilized in stress strain relationship equations to calculate the permanent growths at critical locations of disc. Growths predicted from Analysis are comparable with the experimental results of disc where a maximum variation of 11% at bore and rim of disc is observed.

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.

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