Tensile Behavior of Local Members on Ship Hull Collapse

1994 ◽  
Vol 38 (03) ◽  
pp. 239-244
Author(s):  
Jeom Kee Paik
Keyword(s):  
Ductile Fracture ◽  
Fracture Behavior ◽  
Fracture Behaviour ◽  
Progressive Collapse ◽  
Tensile Behavior ◽  
Ship Hull ◽  
Simplified Model ◽  
Steel Members ◽  
Collapse Analysis ◽  
Collapse Behavior

A number of methods for hull collapse analysis have been developed, taking into account buckling and yielding, but the importance of necking and ductile-fracture behavior has been disregarded. In this paper, a simplified model for steel members is formulated for modeling necking and ductile-fracture behaviour. The model is incorporated into the previous ISUM units which have been developed, considering buckling and yielding. Application to analysis of the progressive collapse behavior for a 1/3-scale frigate test hull in the sagging condition is demonstrated, and tensile behavior of local members on hull collapse is discussed.

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.

A Guide for the Ultimate Longitudinal Strength Assessment of Ships

2004 ◽  
Vol 41 (03) ◽  
pp. 122-139
Author(s):  
Jeom Kee Paik
Keyword(s):  
Progressive Collapse ◽  
Limit State ◽  
Bending Moment ◽  
Ship Hull ◽  
Safety Measure ◽  
Ultimate Limit State ◽  
Ship Hulls ◽  
Collapse Analysis ◽  
Longitudinal Strength ◽  
Progressive Collapse Analysis

The aim of the present paper is to establish a practical guide for the ultimate longitudinal strength assessment of ships. The ultimate hull girder strength of a ship hull can be calculated using either the progressive collapse analysis method or closed-form design formulas. In the present paper, both the progressive collapse analysis method and the design formulas are presented. A comparison between the progressive collapse analysis results and the design formula solutions for merchant cargo ship hulls is undertaken. The total design (extreme) bending moment of a ship hull is estimated as the sum of the still-water and wave-induced bending moment components as usual. The safety measure of a ship hull is then defined as a ratio of the ultimate longitudinal strength to the total design bending moment. The developed guidelines are applied to safety measure calculations of merchant ship hulls with respect to hull girder collapse. It is concluded that the guidance and insights developed from the present study will be very useful for the ultimate limit state design of newly built ships as well as the safety measure calculations of existing ship hulls. The essence of the proposed guide shall form ISO code 18072-2: Ships and Marine Technology— Ship Structures—Part 2: Requirements of Their Ultimate Limit State Assessment.

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.

Evaluation of Dynamic Collapse Behavior of Steel Moment Frames Damaged by Blast

2011 ◽  
Vol 82 ◽  
pp. 404-409
Author(s):  
Kyung Koo Lee ◽  
Lan Chung ◽  
Sang Hyun Lee ◽  
Tae Won Park ◽  
Jieun Rho
Keyword(s):  
Progressive Collapse ◽  
Mitigation Strategies ◽  
Analysis Method ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Strain Rate Effects ◽  
Collapse Analysis ◽  
Alternate Path Method ◽  
Collapse Behavior ◽  
Progressive Collapse Analysis

Blast effects on structures and blast mitigation strategies have been vigorously studied in the world. The alternate path method, or common progressive collapse analysis method, of structures assumes the threat-independent removal of vertical load-carrying elements. However, in reality, a blast-induced column-missing event will produce the damage on adjacent structural elements and the rapid dynamic response of the structures. In this study, the strain rate effects on the dynamic collapse behavior of steel moment frames are investigated by performing the blast-induced sequential progressive collapse analysis. Then, the improvement of the progressive collapse analysis method is discussed based on the numerical results.

Comparisons of design methods for beam string structure based on reliability and progressive collapse analysis

Structures ◽  
2021 ◽  
Vol 33 ◽  
pp. 2166-2176
Author(s):  
Hao Zhou ◽  
Youbao Jiang ◽  
Sondipon Adhikari ◽  
Qianqian Yin ◽  
Jianguo Cai
Keyword(s):  
Progressive Collapse ◽  
Design Methods ◽  
Collapse Analysis ◽  
String Structure ◽  
Progressive Collapse Analysis

Macroscopic Fracture Behaviour of CrN Hard Coatings Evaluated by X-Ray Diffraction Coupled with Four-Point Bending

2013 ◽  
Vol 768-769 ◽  
pp. 272-279
Author(s):  
Mario Stefenelli ◽  
Angelika Riedl ◽  
Juraj Todt ◽  
Matthias Bartosik ◽  
Rostislav Daniel ◽  
...  
Keyword(s):  
Fracture Stress ◽  
Fracture Behavior ◽  
Fracture Behaviour ◽  
Hard Coatings ◽  
Relevant Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Four Point Bending ◽  
Macroscopic Fracture ◽  
Crn Coatings

Fracture behavior of hard nanocrystalline coatings decisively influences the lifetime and performance of coated tools. In this work, residual stresses in as-deposited and annealed CrN coatings deposited at 350 °C using bias voltages of −40 V and −120 V were evaluated using synchrotron X-ray diffraction coupled with four-point bending. The stress development during the bending experiments was used to analyse fracture properties of the coatings. The results indicate that an annealing at 550 °C does not deteriorate the fracture behavior of the coatings prepared using −40 V bias. In the case of −120 V bias coatings, the residual stress relaxation after the thermal treatment is accompanied by a fracture strain decrease and a fracture stress increase. The as-deposited and annealed CrN coatings deposited using −120 V bias exhibit significantly large fracture strains in comparison with −40 V samples. Finally the results document that the fracture stress may not be the only relevant parameter when comparing different coating systems. Also the strain at fracture can be considered as significant indicator of the coating fracture response. Methodologically, the results indicate that in-situ X-ray diffraction coupled with four point bending can be effectively used to evaluate macroscopic fracture behaviour of hard coatings.

Effect of Flaw Dimensions on Ductile Fracture Behavior of Non-Aligned Multiple Flaws in a Plate

2011 ◽  
Author(s):  
Katsumasa Miyazaki ◽  
Kunio Hasegawa ◽  
Koichi Saito
Keyword(s):  
Ductile Fracture ◽  
Flat Plate ◽  
Fracture Behavior ◽  
Maximum Load ◽  
Surface Flaws ◽  
Fracture Tests ◽  
The Difference ◽  
Almost All ◽  
Maximum Minimum

The fitness-for-service codes require the characterization of non-aligned multiple flaws for flaw evaluation, which is performed using a flaw proximity rule. Worldwide, almost all such codes provide their own proximity rule, often with unclear technical bases of the application of proximity rule to ductile or fully plastic fracture. In particular, the effect of flaw dimensions of multiple surface flaws on fully plastic fracture of non-aligned multiple flaws had not been clear. To clarify the effect of the difference of part through-wall and through-wall flaws on the behavior of fully plastic fracture, the fracture tests of flat plate specimens with non-aligned multiple part through-wall flaws were conducted. When the flaw depth a was shallow with 0.4 in ratio of a to thickness t, the maximum load Pmax occurred at penetration of multiple flaws and the effect of vertical distance of non-aligned multiple flaws H on Pmax was not so significant. However, when flaw depth was deep with 0.8 in a/t, Pmax occurred after penetration of flaws and the effect of H on Pmax could be seen clearly. It was judged that the through-wall flaw tests were appropriate for discussion of the effect of H on Pmax and the alignment rule of multiple flaws. In addition, in order to clarify the appropriate length parameter to estimate Pmax of test specimens with dissimilar non-aligned through-wall multiple flaws, the fracture tests of plate specimens were also conducted. The effect of different flaw length on Pmax was discussed with maximum, minimum and averages of dissimilar non-aligned multiple flaw lengths. Experimental results showed that the maximum length lmax would be an appropriate length parameter to estimate Pmax, when the non-aligned multiple through-wall flaws were dissimilar.

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