Change of Steel’s Yield Stress Over Ship’s Service Life and its Effect on the First Yield Hull Girder Bending Moment - Technical Note

2013 ◽  
Vol 155 (A3) ◽  
Keyword(s):  
Service Life ◽  
Tensile Stress ◽  
Laboratory Test ◽  
Yield Stress ◽  
Bending Moment ◽  
Probability Of Failure ◽  
Technical Note ◽  
Bulk Carrier ◽  
Shipbuilding Steel ◽  
Hull Girder

The publication deals with the decrease of the yield and tensile stress of high tensile shipbuilding steel AH-32 over ship's service life and its effect on the first yield bending moment as a representative of the hull girder capacity. An example is given for a sample 25K DWT (25 thousand tons deadweight) bulk carrier. The probability of failure is calculated as the probability of the total hull girder bending moment exceeding the first yield bending moment. The probabilistic distributions of yield and tensile stress are obtained from laboratory test of the specimen of AH-32 steel (corroded plates of a 20 year old ship). It is found that although the decrease of yield stress may not be great, the increase of the probability of failure (i.e., the probability that the total hull girder bending moment will exceed the first yield bending moment) could be substantial.

CHANGE OF STEEL’S YIELD STRESS OVER SHIP’S SERVICE LIFE AND ITS EFFECT ON THE FIRST YIELD HULL GIRDER BENDING MOMENT

2021 ◽  
Vol 155 (A3) ◽  
Author(s):  
Lyuben D Ivanov
Keyword(s):  
Service Life ◽  
Tensile Stress ◽  
Laboratory Test ◽  
Yield Stress ◽  
Bending Moment ◽  
Probability Of Failure ◽  
Bulk Carrier ◽  
Shipbuilding Steel ◽  
Hull Girder

The publication deals with the decrease of the yield and tensile stress of high tensile shipbuilding steel AH-32 over ship’s service life and its effect on the first yield bending moment as a representative of the hull girder capacity. An example is given for a sample 25K DWT (25 thousand tons deadweight) bulk carrier. The probability of failure is calculated as the probability of the total hull girder bending moment exceeding the first yield bending moment. The probabilistic distributions of yield and tensile stress are obtained from laboratory test of the specimen of AH-32 steel (corroded plates of a 20 year old ship). It is found that although the decrease of yield stress may not be great, the increase of the probability of failure (i.e., the probability yield bending moment) could be substantial.

scholarly journals Analysis on the Hull Girder Ultimate Strength of a Bulk Carrier Using Simplified Method Based on an Incremental–Iterative Approach

2006 ◽  
Author(s):  
O. Ozguc ◽  
P. K. Das ◽  
N. D. P. Barltrop
Keyword(s):  
Ultimate Strength ◽  
Interaction Design ◽  
Curvature Vector ◽  
Structural Response ◽  
Bending Moment ◽  
Iterative Approach ◽  
Bulk Carrier ◽  
Hull Girder ◽  
Simplified Method ◽  
The Moment

The hull girder ultimate strength of a typical bulk carrier is analyzed using simplified method based on an incremental–iterative approach. First, vertical bending moment is examined by seven different methods. The moment versus curvature curves and the values of the ultimate longitudinal moments at collapse states are determined for both hogging and sagging cases. Secondly, the ultimate strength under coupled vertical and horizontal bending moment is accounted. An interaction curve is obtained corresponding to the results of series of calculation for the ship hull subject to bending conditions with different angles of curvature. It is found that the interaction curve is asymmetrical because the hull cross-section is not symmetrical with respect to horizontal axis and the structural response of the elements under compression is different from that under tension due to nonlinearity caused by buckling. The angles of the resultant bending moment vector and that of the curvature vector are different in investigated cases. The interaction design equations proposed by other researches are also addressed to discuss the results presented by this study.

scholarly journals Analysis on the Hull Girder Ultimate Strength of a Bulk Carrier Using Simplified Method Based on an Incremental-Iterative Approach

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Özgür Özgüç ◽  
N. D. P. Barltrop
Keyword(s):  
Ultimate Strength ◽  
Interaction Design ◽  
Curvature Vector ◽  
Structural Response ◽  
Bending Moment ◽  
Iterative Approach ◽  
Bulk Carrier ◽  
Hull Girder ◽  
Simplified Method ◽  
The Moment

The hull girder ultimate strength of a typical bulk carrier is analyzed using a simplified method based on an incremental—iterative approach. First, vertical bending moment is examined by seven different methods. The moment versus curvature curves and the values of the ultimate longitudinal moments at collapse states are determined for both hogging and sagging cases. Second, the ultimate strength under coupled vertical and horizontal bending moment is accounted. An interaction curve is obtained, which corresponds to the results of series of calculation for the ship hull subject to bending conditions with different angles of curvature. It is found that the interaction curve is asymmetrical because the hull cross section is not symmetrical with respect to the horizontal axis and the structural response of the elements under compression is different from that under tension due to nonlinearity caused by buckling. The angles of the resultant bending moment vector and that of the curvature vector are different in investigated cases. The interaction design equations proposed by other researches are also addressed to discuss the results presented by this study.

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.

Time-Variant Redundancy of Ship Structures

2011 ◽  
Vol 55 (03) ◽  
pp. 208-219 ◽  
Author(s):  
Alberto Decó ◽  
Dan M. Fragopol ◽  
Nader M. Okasha
Keyword(s):  
Bending Strength ◽  
Progressive Collapse ◽  
Probability Of Failure ◽  
Optimization Approach ◽  
Ship Structures ◽  
Hull Girder ◽  
Reliability Method ◽  
Ultimate Bending Strength ◽  
Ultimate Failure ◽  
Bending Failure

An efficient procedure for the computation of the redundancy of ship structures is presented. The changes in the redundancy due to corrosion section loss over time are also studied. Moreover, uncertainties associated with structural geometry, material properties, and loading, are accounted for. In order to calculate the redundancy index, the probability of failure of the first component and the probability of ultimate failure of the whole hull girder must be evaluated. The probability of failure is computed using a hybrid Latin Hypercube - second-order reliability method (SORM) technique. The deterministic analyses during the simulations are conducted using an optimization approach for computing the ultimate bending strength of the whole hull girder and the progressive collapse method for computing the first bending failure.

Study on the Design of SMA Mixture on Expressway

2014 ◽  
Vol 496-500 ◽  
pp. 2582-2585
Author(s):  
Jian Ping Xu ◽  
Fu Ming Liu
Keyword(s):  
Service Life ◽  
Laboratory Test ◽  
Material Properties ◽  
Road Traffic ◽  
Jiangxi Province ◽  
Skid Resistance ◽  
Maintenance Costs ◽  
Modified Asphalt ◽  
Superior Surface ◽  
Structure Strength

The rapid growth of road traffic brings some requirements on driving comfort and safety, which include good smoothness, skid resistance and reduced noise of the pavement. SMA has adequate structure strength to reduce rutting and provide superior surface function of skid resistance. Modified asphalt as mixture binder, has considerable durability to ensure the service life with less maintenance costs. Associated with laboratory test and trial section, some suggestion and requirements are brought forward in this paper for the material properties and mixture design of SMA on the FuZhou-JiAn expressway in Jiangxi Province.

scholarly journals DESIGN OF UNDIRECT GUY WIRE TENSION METER BASED ON STRAIN GAUGE

2019 ◽  
Vol 13 (2) ◽  
pp. 111-120
Author(s):  
Agus Sasmito ◽  
Yudi Irawadi
Keyword(s):  
Tensile Stress ◽  
Design Process ◽  
Mathematical Analysis ◽  
Strain Gauge ◽  
Bending Moment ◽  
Load Cell ◽  
Wire Tension ◽  
Main Component ◽  
Design Result ◽  
Data Result

The safety of the tower is depend the tension of guy wire, where it must have the same tensile stress at all positions. To meet this requirement, the load cell guy wire is designed based on strain gauge. Load cell guy wire  is designed portable and it can detect stress of the guy wire indirectly. The main component of load cell is a beam, two hooks and a cylinder to form a bending moment force in the beam, the value of the bending moment on the beam will be directly proportional to the increase or decrease in force drag on guy wire. Design process of load cell doone using mathematical analysis, and then the load cell is calibrated by standard load cell, based on the data result of calibration is known that the stress at the guy wire load cell is close and under the yield stress of the load cell material, it is proved that load guy wire cell’s design result is safe to use.

On the Effect of Hull Girder Flexibility on the Vertical Wave Bending Moment for Ultra Large Container Vessels

2012 ◽  
Author(s):  
Ingrid Marie Vincent Andersen ◽  
Jørgen Juncher Jensen
Keyword(s):  
Bending Moment ◽  
Main Concern ◽  
Hull Girder ◽  
Numerical Predictions ◽  
Strip Theory ◽  
Reliability Method ◽  
Non Linear ◽  
Large Container ◽  
The Waves ◽  
Good Agreement

Currently, a number of very large container ships are being built and more are on order, and some concerns have been expressed about the importance of the reduced hull girder stiffness to the wave-induced loads. The main concern is related to the fatigue life, but also a possible increase in the global hull girder loads as consequence of the increased hull flexibility must be considered. This is especially so as the rules of the classification societies do not explicitly account for the effect of hull flexibility on the global loads. In the present paper an analysis has been carried out for the 9,400 TEU container ship used as case-ship in the EU project TULCS (Tools for Ultra Large Container Ships). A non-linear time-domain strip theory is used for the hydrodynamic analysis of the vertical bending moment amidships in sagging and hogging conditions for a flexible and a rigid modelling of the ship. The theory takes into account non-linear radiation forces (memory effects) through the use of a set of higher order differential equations. The non-linear hydrostatic restoring forces and non-linear Froude-Krylov forces are determined accurately at the instantaneous position of the ship in the waves. Slamming forces are determined by a standard momentum formulation. The hull flexibility is modelled as a non-prismatic Timoshenko beam. Generally, good agreement with experimental results and more accurate numerical predictions has previously been obtained in a number of studies. The statistical analysis is done using the First Order Reliability Method (FORM) supplemented with Monte Carlo simulations. Furthermore, strip-theory calculations are compared to model tests in regular waves of different wave lengths using a segmented, flexible model of the case-ship and good agreement is obtained for the longest of the waves. For the shorter waves the agreement is less good. The discrepancy in the amplitudes of the bending moment can most probably be explained by an underestimation on the effect of momentum slamming in the strip-theory applied.

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