Assessment of the Size Effect in Fatigue Analysis of Butt Welds and Cruciform Joints

2014 ◽  
Author(s):  
Inge Lotsberg
Keyword(s):  
Size Effect ◽  
Fatigue Test ◽  
Test Data ◽  
Hot Spot ◽  
Plate Thickness ◽  
Fatigue Analysis ◽  
Analysis Model ◽  
Design Standards ◽  
Cruciform Joints ◽  
Fatigue Design

Reduced fatigue capacity of welded structures for larger thicknesses was introduced in design standards approximately 30 years ago. A significant amount of research on this topic was performed during the following years. In general the presence of a size effect was agreed upon. The size effect is considered to be dependent on the plate thickness at the considered hot spot in addition to size of attachment plate and type of dynamic loading. Only simplified recommendations on the size effect are included in most fatigue design standards. One reason for this is normal scatter in fatigue test data and also somewhat different recommendations based on these data in the literature. This has made it difficult to arrive at full agreement on recommended fatigue analysis procedures. In this paper a review of literature and design standards are presented together with a calibration of analysis method with fatigue test data. The effect of different parameters contributing to the size effect is illustrated. An attempt has been made to use the calibrated analysis model to also quantify the size effect based on crack growth analyses. Finally some recommendations on size effect to be used in fatigue design standards are presented.

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.

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.

scholarly journals Evaluating the Impact of Conservatism in Industrial Fatigue Analysis of Life-Limited Components

2018 ◽  
Vol 165 ◽  
pp. 10017 ◽  
Author(s):  
Joshua Hoole ◽  
Pia Sartor ◽  
Julian Booker ◽  
Jonathan Cooper ◽  
Xenofon V. Gogouvitis ◽  
...  
Keyword(s):  
Industrial Sector ◽  
Fatigue Analysis ◽  
Design Standards ◽  
Safe Life ◽  
Industrial Sectors ◽  
Fatigue Design ◽  
4340 Steel ◽  
The Impact

This paper presents a review of the conservatism approaches applied by different industrial sectors to the stress-life (S-N) analysis of ‘life-limited’ or ‘safe-life’ components. A comparison of the fatigue design standards for 6 industrial sectors identified that the conservatism approaches are highly inconsistent when comparing the areas of variability and uncertainty accounted for along with the conservatism magnitude and method of application. Through the use of a case-study based on the SAE keyhole benchmark and 4340 steel S-N data, the industrial sector which introduces the greatest reduction of a component life-limit was identified as the nuclear sector. The results of the case-study also highlighted that conservatism applied to account for scatter in S-N data currently provides the greatest contribution to the reduction of component life-limits.

Fatigue Analysis of a Thin Cover Plate Structure in a Light Craft

2015 ◽  
Author(s):  
Till Köder ◽  
Berend Bohlmann
Keyword(s):  
Hot Spot ◽  
Gas Metal Arc Welding ◽  
Plate Thickness ◽  
Fatigue Analysis ◽  
Fatigue Tests ◽  
Cover Plate ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Notch Stress ◽  
Metal Arc Welding

Experimental fatigue analysis of a fillet-welded cover plate detail (‘floating frame’) of small and light craft was carried out at Kiel University of Applied Sciences. The structural detail is an intersection of longitudinal deck stiffener and transverse web frame with a plate thickness of 3.5mm and a doubling length of 100mm. Manual gas metal arc welding was used for the production of the 46mm long transverse fillet welds. The load-controlled constant amplitude fatigue tests at stress ratio R = 0 were supported by 3D finite-element analysis based on laser scans of the weld seams. Structural hot-spot stress, stress linearisation and Xiao and Yamada’s 1mm geometrical stress approaches were applied to the specimens as well as the notch stress concept with reference radii rref = 0.05mm and 1.00mm.

scholarly journals Experimental Data Assessment and Fatigue Design Recommendation for Stainless-Steel Welded Joints

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 723 ◽  
Author(s):  
Peng ◽  
Chen ◽  
Dong
Keyword(s):  
Stainless Steel ◽  
Fatigue Strength ◽  
Structural Steel ◽  
Fatigue Test ◽  
Test Data ◽  
Welded Joints ◽  
Steel Structures ◽  
Design Codes ◽  
Inverse Slope ◽  
Fatigue Design

Stainless steel possesses outstanding advantages such as good corrosion resistance and long service life. Stainless steel is one of the primary materials used for sustainable structures, and welding is one of the main connection modes of stainless-steel bridges and other structures. Therefore, fatigue damage at welded joints deserves attention. The existing fatigue design codes of stainless-steel structures mainly adopt the design philosophy of structural steel. In order to comprehensively review the published fatigue test data of welded joints in stainless steel, in this paper, the fatigue test data of representative welded joints of stainless steel were summarized comprehensively and the S–N curves of six representative stainless-steel welded joints were obtained by statistical evaluation. The comparison of the fatigue strength from existing design codes and fatigue test data was performed, and the results showed that the fatigue strength of welded joints of stainless steel was higher than that of structural-steel welded joints. The flexibility of regression analysis with and without a fixed negative inverse slope was discussed based on the scatter index. It was found that the fatigue test data of stainless-steel welded joints are more consistent with the S–N curve regressed by a free negative inverse slope. In this paper, a design proposal for the fatigue strength of representative welded joints of stainless steel is presented based on the S–N curve regressed by the free negative inverse slope.

An Approach for Reliability-Based Fatigue Design of Welded Joints on Aluminum High-Speed Vessels

2006 ◽  
Vol 50 (01) ◽  
pp. 85-98
Author(s):  
Matthew Collette ◽  
Atilla Incecik
Keyword(s):  
High Speed ◽  
Hot Spot ◽  
Fatigue Cracks ◽  
Limit State ◽  
Design Standards ◽  
State Equations ◽  
Fatigue Design ◽  
Highly Nonlinear ◽  
Input Variables ◽  
Fatigue Limit State

Fatigue cracks are an ongoing problem for aluminum high-speed vessels, and preventing fatigue cracks caused by wave loading is expected to be a significant challenge for future aluminum high-speed ferries and military vessels. To aid in this effort, a hot-spot fatigue design approach using first-order reliability methods (FORM) is constructed. Two different limit state functions are investigated, and the accuracy and consistency of the FORM method for the highly nonlinear fatigue limit state equations are evaluated through a comparison with Monte Carlo simulation results. The sensitivity of the resulting safety index to changes in the input variables, and their uncertainties, are presented graphically. The method is compared to existing design standards for four simple structural details.

Analysis of Recent Fatigue Data Using the Structural Stress Procedure in ASME Div. 2 Rewrite

2005 ◽  
Author(s):  
P. Dong ◽  
J. K. Hong ◽  
A. M. P. De Jesus
Keyword(s):  
Fatigue Test ◽  
Test Data ◽  
Hot Spot ◽  
Comparative Assessment ◽  
Structural Stress ◽  
Hot Spot Stress ◽  
Classification Approach ◽  
Fatigue Data ◽  
Fatigue Evaluation ◽  
Assessment Procedures

In support of the ASME Div 2 Rewrite, a master S-N curve approach has been developed using a mesh-insensitive structural stress procedure for fatigue evaluation of welded components. The effectiveness of the master S-N curve approach has been demonstrated in a number of earlier publications for many joint types and loading conditions for pipe and vessel components as well as plate joints. To further validate the structural stress method, a series of recent test data (small weld details and a full scale vessel) published by De Jesus et al (2004) were analyzed in this paper. A comparative assessment of various existing procedures and their effectiveness in correlating the fatigue test data by De Jesus et al (2004) is also presented. These assessment procedures include current ASME Sec. VIII Div 2, weld classification approach in PD 5500, and the surface extrapolation-based hot spot stress approach in recently approved European EN 13445 Standards.

Sign in / Sign up

Export Citation Format

Share Document