scholarly journals Model fatigue test result of welded structural element and proposal for fatigue design procedure

1991 ◽  
Vol 1991 (170) ◽  
pp. 723-735
Author(s):  
Ryuichi Nagamoto ◽  
Masaaki Matoba ◽  
Tetsuro Kawasaki ◽  
Katsuaki Inoue ◽  
Tohru Hori ◽  
...  
Keyword(s):  
Fatigue Test ◽  
Design Procedure ◽  
Structural Element ◽  
Fatigue Design ◽  
Test Result

Characteristic S-N Curves for Fatigue Design of Titanium Risers

2002 ◽  
Author(s):  
Knut O. Ronold ◽  
Stig Wa¨stberg
Keyword(s):  
Fatigue Test ◽  
Test Data ◽  
Base Material ◽  
Offshore Structures ◽  
Defect Size ◽  
Statistical Analyses ◽  
Stress Range ◽  
Fatigue Design ◽  
Range Interval ◽  
Lower Tolerance

A recommended practice for design of titanium risers is currently being developed as part of Det Norske Veritas’ series of standards and recommended practices for offshore structures. A recommendation is given herein for characteristic S-N curves for use in design of titanium risers against fatigue failure. As a basis for this recommendation, a set of statistical analyses of available fatigue test data have been carried out. Separate analyses have been carried out for base material and welds. The analysis results have been interpreted with respect to mean S-N curves as well as 97.7% lower tolerance bounds with 95% confidence. Characteristic S-N curves for base material and welds, which are not non-conservative with respect to these tolerance bounds, have been proposed. The paper presents the assumptions, the test data, the statistical analyses and their results, and the proposed characteristic S-N curves. The areas of application of the proposed curves are discussed with a particular view to stress range interval, material grade, weld position, temperature, and defect size.

Assessment of Fatigue Damage of Floating Fish Cages Due to Wave Induced Response

2009 ◽  
Author(s):  
Paul E. Thomassen ◽  
Bernt J. Leira
Keyword(s):  
Structural Analysis ◽  
Fatigue Damage ◽  
Design Procedure ◽  
Irregular Waves ◽  
Induced Response ◽  
Fish Farms ◽  
Analysis And Design ◽  
Drag Forces ◽  
Fatigue Design ◽  
Fish Cages

Floating fish cages provide the main production utilities for salmon farming. However, despite their pivotal role in production safety as well as in protection of the environment, there is still much room for improvement in relation to verified structural design procedures and computerized tools for structural analysis. To a large extent they can be regarded as not being in accordance with the state-of-the-art of structural analysis and design for more traditional types of marine structures. In this paper a study of fatigue design for floating fish farms is presented. The study is based on a structure which is being applied by the Norwegian fish farming industry today. The floater is made of steel cylinders which are configured as a square. The formulation for the wave loading is based on a combination of potential theory and horizontal drag forces on the floater. Horizontal and vertical drag forces on the netpen are also accounted for. A fatigue design procedure for floating fish farms in steel is suggested. The procedure is based on a time domain analysis of the structure in irregular waves. For each seastate half an hour (real time) analysis is performed and the stress history for an assumed critical location is computed. Based on the stress histories, the fatigue damage is estimated by application of rain flow counting and a given SN curve. The scatter diagram for the seastates at a given location is generated from the associated wind speed distribution.

Design Curves for High-Cycle Fatigue Loaded Structural Elements

2013 ◽  
Vol 752 ◽  
pp. 135-144 ◽  
Author(s):  
Zsuzsanna Koncsik ◽  
János Lukács
Keyword(s):  
High Cycle Fatigue ◽  
Empirical Method ◽  
Fatigue Tests ◽  
Structural Elements ◽  
Cycle Fatigue ◽  
Structural Element ◽  
Fatigue Design ◽  
Structural Details ◽  
Important Design

Frequently, the cause of the failure of different structures or structural elements is the cyclic loading. Both fatigue design curves and methods for determination of these curves can be found in the literature. Even so, there are structural details whereabouts executing of examinations is necessary. The aims of the study are as follows: to give a short summary of important design curves can be found in different standards or specifications; and to demonstrate of own high cycle fatigue tests on a soldered structural element and the comparing of our results and the results of an empirical method.

Fatigue Test on Integral Joint of the Main Truss of the Baling River Bridge

2009 ◽  
Vol 417-418 ◽  
pp. 481-484 ◽  
Author(s):  
Gao Liu ◽  
Wen Ming Wu ◽  
Liang Tang ◽  
Tian Liang Wang
Keyword(s):  
Fatigue Test ◽  
Fatigue Resistance ◽  
Suspension Bridge ◽  
Scale Model ◽  
Fatigue Reliability ◽  
Truss Bridges ◽  
Long Span ◽  
Load Spectra ◽  
Main Girder ◽  
Test Result

The Baling River Bridge is a single-span simply-supported suspension bridge with a main span of 1088 m. The steel stiffening truss is employed as its main girder and comprises the integral joints connecting the chord members. The integral joint is a key structure and determines the safety of the bridge, but it is very complex in detail and has an undefined fatigue resistance. In order to investigate its mechanical behavior and fatigue reliability, a fatigue test was performed on a 1:1.4 scale model of the integral joint of the main truss of the Bridge. With an assumption of the load spectra represented by the standard fatigue vehicle in BS 5400, the test fatigue load was derived accounting for the multiple vehicle effect and the model scale. The test result shows that no cracks were detected in the model when subjected to two million stress range cycles, and the structure has an reliable fatigue resistance satisfying the design requirement. This type of integral joint is an alternative for long-span truss bridges.

Fatigue Performance of Grade R4 and R5 Mooring Chains in Seawater

2014 ◽  
Author(s):  
Jonathan Fernández ◽  
Walther Storesund ◽  
Jesús Navas
Keyword(s):  
Fatigue Test ◽  
Fatigue Damage ◽  
Fatigue Tests ◽  
Design Methods ◽  
Full Scale ◽  
Fatigue Performance ◽  
Test Program ◽  
Gas Industry ◽  
Fatigue Design ◽  
Cumulative Fatigue Damage

With more than 50.000 tons in service to date, the Oil&Gas Industry has the need to understand the tension fatigue performance of grade R5 chains in straight tension, and corroborate the validity of the existing design methods. The chain fatigue design curves in API and DNV are based on fatigue tests obtained in the nineties and early two thousands. However the tests were performed on lower grades such as ORQ, R3 and R4, and small chains, 76 mm diameter being the largest studless chain tested. The industry has moved towards the use of large studless chains, especially in permanent units, where chain diameters above 150 mm are not unusual. This paper gathers information from a full scale fatigue test program on grade R4 and R5 studless chains, performed in seawater and with diameters between 70 mm and 171 mm. The chains being tested are actual production chains supplied for different drilling units and large permanently moored production floating units. The paper analyses the data and determines tension-tension fatigue curves based on API and DNV methods for computation of cumulative fatigue damage, regardless of other damaging mechanisms. Improved fatigue capacity is obtained with respect to the above recommended design methods.

Fatigue Under Wide Band Random Stresses Using the Rain-Flow Method

1977 ◽  
Vol 99 (3) ◽  
pp. 205-211 ◽  
Author(s):  
P. H. Wirsching ◽  
A. Mohsen Shehata
Keyword(s):  
Fatigue Behavior ◽  
Design Procedure ◽  
Random Variable ◽  
Wide Band ◽  
Stress Process ◽  
Structural Elements ◽  
Constant Amplitude ◽  
Design Algorithm ◽  
Flow Method ◽  
Fatigue Design

A fatigue design procedure is proposed for the structural elements subjected to a stress process, modeled as stationary wide-band gaussian. This procedure, restricted to high cycle fatigue design, uses available constant amplitude material fatigue data and a modified, probability based, Palmgren-Miner (PM) rule. Statistical uncertainty in fatigue behavior and nonstatistical uncertainty in the PM rule are implicitly accounted for by treating the PM index at failure as a random variable. The rain flow method of counting stress cycles is used. The fatigue design algorithm requires only that the RMS and irregularity factor of the stress process be specified in addition to the constant amplitude S-N curve for the material.

Assessment of Design S-N Curve for Umbilical Tubes

2009 ◽  
Author(s):  
Inge Lotsberg ◽  
Stein Fredheim
Keyword(s):  
Fatigue Test ◽  
Test Data ◽  
Design Methodology ◽  
Fatigue Analysis ◽  
Analysis Procedure ◽  
Fatigue Design ◽  
Reliable Design

A reliable design methodology for fatigue design of umbilical tubes is required by the industry. A documented design S-N curve is part of such a fatigue analysis procedure. During the last years a number of new fatigue test data have been derived for umbilical tubes. A design S-N curve for as welded and strained tubes during reeling has been debated. The present paper presents an overview of data presented in the literature. In addition it presents a significant number of fatigue test data of umbilical tubes performed at DNV test laboratories in Oslo. In addition it includes an assessment of recommended design S-N curve based on relevant available fatigue test data for umbilical tubes.

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