Low Cycle Fatigue of T-Tubular Joints With Out-of-Plane Bending Loading

2007 ◽  
Author(s):  
Fro̸ydis Boge ◽  
Torgeir K. Helland ◽  
Stig Berge
Keyword(s):  
Low Cycle Fatigue ◽  
Hot Spot ◽  
Fatigue Loading ◽  
Published Data ◽  
Hot Spot Stress ◽  
Tubular Joints ◽  
R Ratio ◽  
Out Of Plane ◽  
Plane Bending ◽  
Bending Loading

Tubular T-joints were fatigue tested with out-of-plane bending loading. Six models were tested, three models with R-ratio of 0 and three with R = −1. Hot spot stress was measured for the brace and for the chord using the ECSC linear extrapolation procedure. Fatigue loading was applied in load control, to obtain through thickness cracking at a number of cycles in the range 4 000–200 000 cycles. The data were analysed and compared with published data and with current fatigue design criteria for tubular joints.

Low Cycle Fatigue of T-Tubular Joints With In-Plane Bending Loading

2005 ◽  
Author(s):  
Jo̸rn Waalen ◽  
Stig Berge
Keyword(s):  
Low Cycle Fatigue ◽  
Hot Spot ◽  
Fatigue Loading ◽  
Hot Spot Stress ◽  
Tubular Joints ◽  
Fatigue Design ◽  
R Ratio ◽  
Plane Bending ◽  
Number Of Cycles ◽  
Bending Loading

Tubular T-joints were fatigue tested with in-plane bending loading. Six models were tested, three models with R-ratio of 0 and three with R = −1. Hot spot stress was measured for the brace and for the chord using the ECSC linear extrapolation procedure. Fatigue loading was applied in load control, to obtain through thickness cracking at a number of cycles in the range 3 000–64 000 cycles. The data were analysed and compared with the current fatigue design criteria for tubular joints.

A Comparative Study on the Fatigue Evaluation for Weldments under Out-of Plane Bending Load Using Structural Stress and Hot Spot Stress

2006 ◽  
Vol 326-328 ◽  
pp. 995-998
Author(s):  
Myung Hyun Kim ◽  
Chung In Ha ◽  
Sung Won Kang ◽  
Jeong Hwan Kim ◽  
Jae Myung Lee
Keyword(s):  
Fatigue Strength ◽  
Hot Spot ◽  
Mesh Size ◽  
Structural Stress ◽  
Hot Spot Stress ◽  
Strength Assessment ◽  
Bending Load ◽  
Load Carrying ◽  
Out Of Plane ◽  
Plane Bending

Fatigue strength assessments with two types of load carrying fillet weldment under out-of-plane bending load have been carried out by using both hot spot stress and structural stress methods. Basis for the derivation of structural stress method is discussed in detail. Finite element analyses using shell elements models have been performed for the fatigue strength assessment of weldments. As a result of the fatigue strength evaluation for load carrying transverse fillet weldment, hot spot stress method is found to be consistent with structural stress method as well as measurement. Hot spot stress, however, estimated for the load carrying longitudinal fillet weldment exhibit large variation with respect to mesh size and element type while the calculated structural stress for the longitudinal fillet weldment is relatively independent of mesh size. The fatigue life estimation according to structural stress has been introduced with the master S-N curve.

Hot-spot stress caused by out-of-plane bending moments of three-planar tubular Y-joints

2020 ◽  
Vol 100 ◽  
pp. 102179
Author(s):  
Shiliu Bao ◽  
Wenhua Wang ◽  
Xin Li ◽  
Haisheng Zhao
Keyword(s):  
Hot Spot ◽  
Bending Moments ◽  
Hot Spot Stress ◽  
Out Of Plane ◽  
Plane Bending

A model technique for bending strength of tubular joints

1992 ◽  
Vol 27 (4) ◽  
pp. 197-210 ◽  
Author(s):  
H Fessler ◽  
W Hassell ◽  
T H Hyde
Keyword(s):  
Bending Strength ◽  
Strength Reduction ◽  
Lead Alloy ◽  
Bending Moments ◽  
Tubular Joints ◽  
Die Cast ◽  
Out Of Plane ◽  
Plane Bending ◽  
Bending Loading ◽  
Model Technique

One shape of ‘Y—T’ joint has been die-cast in a tin-lead alloy. Twenty-one models have been tested in in-plane or out-of-plane bending, loading one or both braces. The results are presented non-dimensionally as Ultimate Strength Reduction Ratios (USRR) i.e., as fractions of (simply calculated) bending moments which would have ensured failure of the brace remote from the joint. The results from the tin-lead models agreed with relevant results from steel models. Parametric equations derived mainly from ‘T’ joint data predict the failure of 90 degree braces well, but underestimate the strength of 45 degree braces in in-plane and out-of-plane bending. Plastic collapse occurs on the compressed side of the braces before tearing on the tension side.

Efficient Fatigue Testing of Tubular Joints

2015 ◽  
Author(s):  
P. Thibaux ◽  
J. Van Wittenberghe ◽  
E. Van Pottelberg ◽  
M. Van Poucke ◽  
P. De Baets ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Testing ◽  
Fatigue Loading ◽  
Tubular Joints ◽  
Testing Method ◽  
Out Of Plane ◽  
Resonance Principle ◽  
Tubular Joint ◽  
The Cost ◽  
Good Agreement

Tubular joints are intensively used in off-shore structures for shallow waters. Depending on the sea conditions and the type of structure, the design can be fatigue driven. This is particularly the case for off-shore wind turbines, where turbulences are generating a fatigue loading. Any improvement of the fatigue performance of the tubular joint would be beneficial to reduce the weight and the cost of the structure. To assess efficiently the fatigue resistance of the tubular joint, a testing method has been developed based on the resonance principle. The complete circumference of the welded joint can be loaded, successively in the in-plane and out-of-plane modes at a frequency close to 20Hz. Finite element computations were used to investigate the feasibility of the concept. Then, an X-node was made and successfully tested to investigate the stress distribution along the weld. The experimental results were compared with finite element computations, giving a good agreement.

Chain Out of Plane Bending (OPB) Fatigue Joint Industry Project (JIP) Static Test Program and OPB Interlink Stiffness

2016 ◽  
Author(s):  
Lucile Rampi ◽  
Fata Dewi ◽  
Michel Francois ◽  
Arnaud Gerthoffert ◽  
Pedro Vargas
Keyword(s):  
Fatigue Loading ◽  
Time Frame ◽  
Small Time ◽  
Static Test ◽  
Fatigue Design ◽  
Out Of Plane ◽  
Bending Stresses ◽  
Plane Bending ◽  
Mooring Chain ◽  
Fatigue Mechanism

In 2002, several mooring chains of a deepwater offloading buoy failed prematurely within a very small time frame. These chains were designed according to conventional offshore fatigue assessment using API recommendations. With this first deepwater buoy application, a new mooring chain fatigue mechanism was discovered. High pretension levels combined with significant mooring chain motions caused interlink rotations that generated significant Out of Plane Bending (OPB) fatigue loading. Traditionally, interlink rotations are relatively harmless and generate low bending stresses in the chain links. The intimate mating contact that occurs due to the plastic deformation during the proof loading and the high pretension of the more contemporary mooring designs have been identified as aggravating factors for this phenomenon. A Joint Industry Project (JIP), gathering 26 different companies, was started in 2007 to better understand the Out of Plane Bending (OPB) mooring chain fatigue mechanism and to propose mooring chain fatigue design recommendations. This paper summarizes the quasi static OPB stiffness measurement campaign and the post processing work to derive the OPB interlink stiffness.

scholarly journals Fatigue Strength Curve for Tubular Joints of Offshore Structures under Dynamic Loading

Dynamics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 125-133
Author(s):  
Sudath C. Siriwardane ◽  
Nirosha D. Adasooriya ◽  
Dimitrios Pavlou
Keyword(s):  
Fatigue Strength ◽  
Hot Spot ◽  
Offshore Structures ◽  
Hot Spot Stress ◽  
Tubular Joints ◽  
Jacket Structures ◽  
Strength Curve ◽  
Tubular Joint ◽  
Stress Concentration Factors

Offshore structures are subjected to dynamic environmental loads (wave and wind loads). A stress-life fatigue strength curve is proposed for tubular joints which are in the splash zone area of offshore jacket structures. The Det Norske Veritas (DNV) offshore structures standards given design T-curve in the air is modified with the environment-dependent parameters to obtain this fatigue strength curve. Validity of the curve is done by comparing fatigue lives given by the proposed curve with experimental fatigue lives of tubular joints tested in seawater under different loading conditions. The fatigue assessment of a case study tubular joint is performed using the proposed curve. Nominal stress ranges of the members, which are connected to the joint, are obtained by dynamic analysis of the jacket structure. Stress concentration factors are utilized with the nominal stresses to obtain the hot spot stress ranges. Fatigue lives are calculated and compared with the conventional approach. Hence the applicability and significance of the proposed fatigue strength curve are discussed.

Sign in / Sign up

Export Citation Format

Share Document