Full Scale Measurements of Fatigue and Extreme Loading Including Whipping on an 8600TEU Post Panamax Container Vessel in the Asia to Europe Trade

2011 ◽  
Author(s):  
Svein Erling Heggelund ◽  
Gaute Storhaug ◽  
Byong-Ki Choi
Keyword(s):  
Fatigue Cracks ◽  
Safety Margin ◽  
Fatigue Loading ◽  
Significant Degree ◽  
Full Scale ◽  
Environmental Data ◽  
Hull Girder ◽  
Bow Flare ◽  
Large Container ◽  
Side Shell

Large container vessels are known to vibrate heavily in head sea storms due to its flexible hull girder, pronounced bow flare and high vessel speeds. Strong vibrations are mainly excited by bow impacts causing transient vibrations referred to as whipping. This whipping response increases both fatigue and extreme loading. Further resonance vibration by springing response is also well known to contribute to increased fatigue loading. On these large container vessels it may however not be only the vertical vibration mode that is excited but also horizontal and torsional vibrations (coupled). The current paper describes the measurement system installed on a vessel operating between East Asia and Europe. Sensors for global loading, local loading and transverse hatch opening distortions are supplemented by navigational and environmental data. The system is an extended hull monitoring system analyzing data onboard and providing decision support onboard as well as providing statistical and time series of data to shore for further assessment. The measurements confirm that the fatigue loading of critical details are dominated by the vibrations, and that the fatigue loading level in deck in a storm is higher than ever measured before, also leading to high extreme loads above IACS rule values. The full scale measurements do to some degree confirm previous model tests of the same vessel, but the real vessel has been operated at reduced speeds. So far the fatigue loading on this route is at a comfortable level, partly due to reduced speeds, but also the encountered sea states may be less severe than the route specific scatter diagram. The loading may however increase if the vessel speed is increased, and the loading may become uncomfortable high if the vessel is put on a more harsh trade like North Pacific (or North Atlantic). Also torsional and horizontal vibrations are observed, but the transverse hatch opening distortions are moderate. Stern slamming is not measured to any significant degree, but bow flare slamming is measured in the storms. Side shell fatigue loading is at a comfortable level due to the CSA-2 notation involving direct hydrodynamic load calculations in the design introducing a sufficient safety margin against fatigue cracks. Vibration is however contributing significantly also in the side shell. Only a few storms have been encountered so far. The fatigue damage is concentrated amidships and the affect of warping in front of the superstructure does not increase the fatigue loading to a level of concern.

Effect of Whipping on Fatigue and Extreme Loading of a 13000TEU Container Vessel in Bow Quartering Seas Based on Model Tests

2011 ◽  
Author(s):  
Gaute Storhaug ◽  
Quentin Derbanne ◽  
Byung-Ki Choi ◽  
Torgeir Moan ◽  
Ole Andreas Hermundstad
Keyword(s):  
Cross Sections ◽  
Wave Energy ◽  
Safety Margin ◽  
Fatigue Loading ◽  
Operational Experience ◽  
Sea State ◽  
Hull Girder ◽  
Numerical Tools ◽  
Vertical Vibrations ◽  
Large Container

Many large and ultra large container vessels have entered operation lately and more vessels will enter operation in the coming years. The operational experience is limited and one of the concerns is the additional effect of hull girder vibrations especially from whipping (bow impacts), but also from springing (resonance). Whipping contributes both to increased fatigue and extreme loading, while springing does mainly contribute to increased fatigue loading. MAIB recommended the industry to join forces to investigate the effect of whipping after MSC Napoli, a Post-Panamax container vessel, broke in two in January 2007. This has been followed up by a JIP initiated in 2008 with the following participants: HHI, DNV, BV, CeSOS and Marintek. In 2009 a new design 13000TEU vessel was tested in head seas and reported in [1]. The current paper deals with fatigue and extreme loading of the same vessel, but from realistic quartering sea conditions tested in 2010. Different headings and the effect of wave energy spreading have been investigated and compared to results from head seas. Further, the effect of the vibrations have been investigated on torsion and horizontal bending, as the model is also allowed to vibrate with realistic frequencies in other modes in addition to vertical bending. The findings suggest that changing the course is not effective to reduce the fatigue loading of critical fatigue sensitive details amidships. The effect of wave energy spreading did also not reduce the fatigue loading significantly. For the highest observed vertical bending moments in each sea state and for the three cross sections the wave energy spreading in average reduced the maxima, but for the highest sea state the effect of wave spreading did not consistently give reduced maxima. This is an important aspect when considering the available safety margin that may be reduced by whipping. The whipping gave also a considerable contribution to horizontal bending and torsion. This suggests that validation of numerical tools is urgent with respect to off head sea conditions and that these tools must incorporate the real structural behavior to confirm the importance of the response from torsional and horizontal as well as for vertical vibrations.

Analysis of Cracks and Stresses of Welded Attachments on Full-Scale Plate Girder under Fatigue Loading

2006 ◽  
Vol 324-325 ◽  
pp. 459-462 ◽  
Author(s):  
Myung Gu Lee ◽  
Seung Yong Lee ◽  
Cheol Woo Park
Keyword(s):  
Fatigue Damage ◽  
Fatigue Cracks ◽  
Steel Structure ◽  
Fatigue Loading ◽  
Design Criterion ◽  
Full Scale ◽  
Parent Metal ◽  
Girder Bridges ◽  
Fatigue Design ◽  
Plate Girder

In steel structure systems such as plate girder bridges and framed structures, fatigue damage used to occur at welded areas rather than primary structural members. These damages and behaviors of the welded attachments need to be extensively investigated so that the fatigue design criterion can effectively control the fatigue damage of steel structure systems. This study utilized a full-scale plate girder on which various welding attachments were mounted. The welded attachments investigated herein included flange gussets, web gussets, vertical stiffeners, and cover plates. The fatigue cracks initiated at the longitudinal end of joint area of the weld bead and the parent metal where stress was significantly concentrated. The initiated fatigue cracks developed along the weld path and then, propagated to the parent metal in the direction perpendicular to the principal stress. The fatigue cracks developed even under a compressive stress when a significant residual stress was experienced from the welding. The fatigue strengths of the each welded attachment were evaluated and compared with the current fatigue design specifications in AASHTO [1] and JSSC [2].

Full Scale Measurement of a Large Container Carrier on the Far East - Europe Route

2008 ◽  
Author(s):  
H. C. Yu ◽  
J. W. Choi ◽  
G. I. Park ◽  
S. Y. Han ◽  
S. C. Tai ◽  
...  
Keyword(s):  
Far East ◽  
Structural Response ◽  
Full Scale ◽  
Ship Motions ◽  
First Year ◽  
East Europe ◽  
Hull Girder ◽  
The Far East ◽  
Large Container

There is limited long term service experience with the modern generation of large container carriers and hence there is great interest in improving our understanding of the performance of these vessels. In an effort to assess the actual structural service performance of a large container carrier, a comprehensive full-scale measurement system was developed to measure the wave environment, ship motions and structural response. The system was installed on an 8063 TEU container carrier built in 2006, and the first year measurement campaign has successfully been completed. This paper presents a summary of noteworthy observations during the first year’s voyage records which includes ship motion, wind and wave conditions, and hull girder strains and derived hull girder bending and torsional moments. The observed vibratory responses of the hull girder are also presented.

Which Sea States Are Dimensioning for Container Vessels When Whipping Is Included?

2014 ◽  
Author(s):  
Gaute Storhaug
Keyword(s):  
Model Tests ◽  
Main Concern ◽  
Container Ship ◽  
Sea State ◽  
Hull Girder ◽  
Severe Accidents ◽  
Wave Heights ◽  
Bow Flare ◽  
Large Container ◽  
Flare Model

Four container vessels have broken in two during the last four decades. There may not be one single cause explaining these severe accidents. They all broke in moderate storms, but they did not break in extreme storms in terms of extreme wave heights. How could this happen? This paper addresses one possible contributing effect to all of these accidents, i.e. whipping, and how whipping contribute in different sea states. Whipping, as a sudden hull girder vibration caused by bow flare impacts, can contribute significantly to increase the vertical hull girder bending moments of container vessels, which have high design speeds and pronounced bow flare. Model tests have been carried out based on modern container ship designs covering one Panamax vessel, one Post Panamax vessel and one Ultra Large Container Ship. The tests have been carried out primarily in head seas. The whipping contribution depends on the vessel speed, and the tests have been carried out using realistic speed in each sea state. Lower sea states are more frequent than higher sea states, and lower sea states are associated with higher speeds. Does this speed dependence give other dimensioning sea states when whipping is considered? For all three vessel designs, it is not the highest sea states, which define the dimensioning wave moments when whipping is included. Actually, realistic encountered storms can produce the dimensioning wave bending with whipping. These sea states differ considerably from the sea states, which produce the maximum wave moment without whipping. It is also demonstrated how different trades affect the dimensioning wave bending with whipping. The industry seems most concerned about the effect of whipping for the largest vessels. These model tests demonstrate that the dimensioning moment with whipping for the largest vessel is not the main concern. The tests suggest that the bow flare angle is most important, and these may be high for Post Panamax vessels. The speed is well known to be important, while size in terms of length is not particularly important from these tests.

The 1st International Project Competition for Structural Health Monitoring (IPC-SHM, 2020): A summary and benchmark problem

2021 ◽  
pp. 147592172110064
Author(s):  
Yuequan Bao ◽  
Jian Li ◽  
Tomonori Nagayama ◽  
Yang Xu ◽  
Billie F Spencer ◽  
...  
Keyword(s):  
Structural Health Monitoring ◽  
Undergraduate Students ◽  
Health Monitoring ◽  
Fatigue Cracks ◽  
Full Scale ◽  
Asia Pacific ◽  
International Project ◽  
Full Time ◽  
Structural Health ◽  
Institute Of Technology

To promote the development of structural health monitoring around the world, the 1st International Project Competition for Structural Health Monitoring (IPC-SHM, 2020) was initiated and organized in 2020 by the Asia-Pacific Network of Centers for Research in Smart Structures Technology, Harbin Institute of Technology, the University of Illinois at Urbana-Champaign, and four leading companies in the application of structural health monitoring technology. The goal of this competition was to attract more young scholars to engage in the study of structural health monitoring, encouraging them to provide creative and effective solutions for full-scale applications. Recognizing the recent advent and importance of artificial intelligence in structural health monitoring, three competition projects were set up with the data from full-scale bridges: (1) image-based identification of fatigue cracks in bridge girders, (2) data anomaly detection for structural health monitoring, and (3) condition assessment of stay cables using cable tension data. Three corresponding data sets were released at http://www.schm.org.cn and http://sstl.cee.illinois.edu/ipc-shm2020 . Participants were required to be full-time undergraduate students, M.S. students, Ph.D. students, or young scholars within 3 years after obtaining their Ph.D. Both individual and teams (each team had no more than five individuals) could compete. Submissions for the competition included a 10- to 15-page technical paper, a 10-min presentation video with PowerPoint slides, and commented code. The organizing committee then conducted the validation, review, and evaluation. A total of 330 participants in 112 teams from 70 universities and institutions in 12 countries registered for the competition, resulting in 75 papers from 56 teams from 57 different affiliations finally being submitted. Of those submitted, 31, 30, and 14 papers were for Projects 1, 2, and 3, respectively. After completion of the review by the organization committee and awards committee, the top 10, 10, and 5 teams were selected as the prize winners for the three competition projects.

Relaxation of Residual Stresses in and around Mechanical Fasteners Due to Fatigue Loading

2006 ◽  
Vol 524-525 ◽  
pp. 153-158 ◽  
Author(s):  
Matthew E. Fox ◽  
Philip J. Withers
Keyword(s):  
Residual Stresses ◽  
Hoop Stress ◽  
Fatigue Cracks ◽  
Fatigue Loading ◽  
Far Field ◽  
Synchrotron Diffraction ◽  
Fastener Hole ◽  
Single Plate ◽  
Mechanical Fasteners ◽  
Hoop Stresses

The residual stresses around clearance-fit mechanical fasteners have been found to be similar to those around cold expanded holes where compressive hoop stresses close to the fastener hole are balanced by far-field tensile stresses. This compressive zone has been shown to prolong fatigue lifetimes around fastener holes. Constant amplitude fatigue loading was applied to single plate rivet specimens for varying numbers of cycles to investigate the redistribution of these stresses after fatiguing. Synchrotron diffraction was used to map the evolution of the residual stresses around the rivets. Little change in the hoop stress local to the rivets occurred until visible fatigue cracks were observed suggesting that relaxation of these stresses is due to the cracks rather than their cause.

Learnings From Strain Measurements on an In-Field Conductor and Wellhead System

2018 ◽  
Author(s):  
Rohit Shankaran ◽  
Alexander Rimmer ◽  
Alan Haig
Keyword(s):  
Fatigue Damage ◽  
Strain Gauge ◽  
Transfer Functions ◽  
Fatigue Loading ◽  
Accurate Method ◽  
Environmental Data ◽  
Analytical Methodology ◽  
Data Set ◽  
Soil Model ◽  
Drilling Operations

In recent years due to use of drilling risers with larger and heavier BOP/LMRP stacks, fatigue loading on subsea wellheads has increased, which poses potential restrictions on the duration of drilling operations. In order to track wellhead and conductor fatigue capacity consumption to support safe drilling operations a range of methods have been applied: • Analytical riser model and measured environmental data; • BOP motion measurement and transfer functions; • Strain gauge data. Strain gauge monitoring is considered the most accurate method for measuring fatigue capacity consumption. To compare the three approaches and establish recommendations for an optimal approach and method to establish fatigue accumulation of the wellhead, a monitoring data set is obtained on a well offshore West of Shetland. This paper presents an analysis of measured strain, motions and analytical predictions with the objective of better understanding the accuracy, limitations, or conservatism in each of the three methods defined above. Of the various parameters that affect the accuracy of the fatigue damage estimates, the paper identifies that the selection of analytical conductor-soil model is critical to narrowing the gap between fatigue life predictions from the different approaches. The work presented here presents the influence of alternative approaches to model conductor-soil interaction than the traditionally used API soil model. Overall, the paper presents the monitoring equipment and analytical methodology to advance the accuracy of wellhead fatigue damage measurements.

First Ocean Going Ships With Springing and Whipping Included in the Ship Design

2011 ◽  
Author(s):  
Gaute Storhaug ◽  
Erlend Moe ◽  
Ricardo Barreto Portella ◽  
Tomazo Garzia Neto ◽  
Nelson Luiz Coelho Alves ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
Current Model ◽  
Life Time ◽  
Model Tests ◽  
Full Scale ◽  
Development Projects ◽  
Transient Vibration ◽  
Hull Girder ◽  
Fatigue Evaluation ◽  
Wave Induced

It is well known that ships vibrate due to waves. The wave induced vibrations of the hull girder are referred to as springing (resonance) and whipping (transient vibration from impacts). These vibrations contribute to the fatigue damage of fatigue sensitive details. An Ore Carrier of 400 000 dwt is currently being built by DSME, and at time of delivery, it will be the world’s largest bulk (ore) carrier. The scantlings of large ships must be carefully designed with respect to global loading, and when extending the design beyond experience, it is also wise to consider all aspects that may affect operation and the life time costs. The vessel will also enter a long term contract and is therefore to be evaluated for 30 year Brazil-China operation. In order to minimize the risk of fatigue damage, the vessel is designed according to DNV’s class notation CSA-2 requiring direct calculations of the loading and strength. Further it has been requested to include the effect of springing and whipping in the design. Reliable numerical tools for assessing the additional fatigue effect of vibrations are non-existing. DNV has, however, developed an empirical guidance on how the additional effect may be taken into account based on previous development projects related to the effect of vibrations on large ore carriers Due to the size and route of operation of the new design, it has, however, been required by the owner to carry out model tests in both ballast and cargo condition in order to quantify the contribution from vibration. The results from this project have been used for verification and further calibration of DNV’s existing empirical guidance. A test program has been designed for the purpose of evaluating the consequence in head seas for the Brazil to China trade. Full scale measurements from previous development projects of ore carriers and model tests have been utilized to convert the current model tests results into estimated full scale results for the 400 000 dwt vessels. It is further important to carefully consider how the vibrations are to be included in the design verification, and to develop a procedure for taking into account the vibrations which results in reasonable scantlings based on in-service experience with similar designs and trades. This procedure has been developed, and a structural verification has been carried out for the design. The final outcome of the model test was in line with previous experience and in overall agreement with DNV’s empirical guidance, showing a significant contribution from vibrations to the fatigue damage. The springing/whipping vibrations more than doubled the fatigue damage compared to fatigue evaluation of the isolated wave induced loading. The cargo condition vibrated relatively more than experienced on smaller vessels. Various sources to establish the wave conditions for the Brazil to China ore trade were used, and the different sources resulted in significant differences in the predicted fatigue life of the design.

The Effect of Bow Shape on the Springing/Whipping Response of a Large Ocean-Going Vessel: Investigated by an Experimental Method

2007 ◽  
Author(s):  
Gaute Storhaug ◽  
Torgeir Moan
Keyword(s):  
Fatigue Damage ◽  
Transfer Functions ◽  
Vertical Vibration ◽  
Full Scale ◽  
Relative Importance ◽  
High Frequency Response ◽  
Bow Flare ◽  
Excitation Mechanisms ◽  
The Difference ◽  
Wave Induced

Wave induced vibrations often referred to as springing and/or whipping increase the fatigue and extreme loading in ship hull girders. Both effects are disregarded in current ship rules. Various numerical codes exist for predicting the wave induced vibrations, but so far they are not considered reliable. Another means to investigate the importance of the high frequency response, although more resource demanding, is to carry out full scale measurements and/or model tests. Recently, full scale measurements of blunt ships have been carried out by DNV, and in this paper one of these ships was considered and tested in a towing tank to evaluate the additional fatigue damage due to the wave induced vibrations. Different excitation sources may excite the 2-node vertical vibration mode depending on ship design, and it is not straight forward to determine which is more important. The relative importance of the excitation mechanisms are investigated by two approaches in this paper. The first approach separates the whipping from springing to illustrate their relative importance based on basic theory in combination with model test results. The linear and second order transfer functions are utilized in this procedure. The second approach deals with the effect of the bow design on the additional fatigue damage. Three different bows were tested. The first bow design is identical to the real ship. The second bow design is a simplified version of the first one, by removing the bulb and flare. The third bow is fundamentally different from the two former blunt bows. Bow three is sharp pointed with a vertical sharp stem and vertical ship sides. The results indicate that the importance of whipping depends on the sea state, but that it is of similar importance as springing for the sea states that contributes most to the fatigue damage. Moreover, the difference in the additional fatigue damage due to wave induced vibrations for different bow shapes is moderate. This indicates that vessels with pointed bows and without pronounced bow flare, such as LNG vessels, may have a similar contribution from wave induced vibrations. Modern container vessels, which are more slender, but with pronounced bow flares should be further investigated.

Sign in / Sign up

Export Citation Format

Share Document