scholarly journals Fatigue behaviour of threaded couplings – experimental research

2010 ◽  
Vol 1 (1) ◽  
pp. 50-57
Author(s):  
Bruno Meertens ◽  
Patrick De Baets ◽  
Wim De Waele ◽  
Jeroen Van Wittenberghe
Keyword(s):  
Fatigue Life ◽  
Experimental Research ◽  
Fatigue Behaviour ◽  
Bending Fatigue ◽  
Threaded Connection ◽  
Threaded Connections ◽  
Bending Fatigue Test ◽  
Dimensional Finite Element ◽  
Connection Design ◽  
Sn Curve

In this article the fatigue behaviour of threaded connections is studied, as used in oil country tubular goods (OCTG). Some manufacturers have designed their own couplings (so called „premium connections‟) and they claim having an improved fatigue life or better sealability. This study will compare different coupling designs with the standard API connection. The methods used to compare the different designs are based on two-dimensional finite element analyses. Experimental research is conducted to validate the results of the FEA. The experimental research consists of a 4-point bending fatigue test, which will result in a SN-curve for the threaded connection. Based on numerical and experimental results a performance factor is deduced for the particular connection design. This factor will be used to find the best design of threaded couplings. As eventual goal of this study, with the insights gained, a threadedconnection with optimized fatigue life and sealability will be designed.

Evaluation of the Effect of Different Mean Stress Levels on the Fatigue Resistance of OCTG Premium Threaded Connections

2017 ◽  
Author(s):  
Yoshinori Ando ◽  
Yosuke Oku ◽  
Masaaki Sugino ◽  
Carol Johnston
Keyword(s):  
Fatigue Life ◽  
Primary Root ◽  
Initiation Site ◽  
Mean Stress ◽  
Standard Material ◽  
Root Cause ◽  
Threaded Connection ◽  
Threaded Connections ◽  
Stress Levels ◽  
Scale Test

Identification of the effect of mean stress for fatigue performance of the premium threaded connection for the OCTG pipes, was conducted via full-scale test. API standard material [grade L80-1] was used for the test. The nominal pipe outside diameter and wall thickness were 244.48 mm (9-5/8 inch) and 11.99 mm (0.472 inch), respectively. The fatigue life of the specimens tested with no mean stress was longer than that of the specimens tested with a tensile mean stress. Through-wall cracks were found at the imperfect thread area of the male embodiment, but the crack initiation site depended on the mean stress. However, the primary root cause of the failure on both mean stress levels can be regarded as the fretting fatigue. Fatigue life was also able to be estimated using modified Goodman relation.

scholarly journals Study on Fatigue Test and Life Prediction of Polyurethane Cement Composite (PUC) under High or Low Temperature Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Hongshuai Gao ◽  
Quansheng Sun
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Asphalt Mixture ◽  
Cement Composite ◽  
Control Mode ◽  
Fatigue Properties ◽  
Coupling Condition ◽  
Bending Fatigue ◽  
Bending Fatigue Test ◽  
Steel Deck

There are many diseases in the deck pavement of long-span steel bridges under the action of vehicles, rainwater, and freezing. It is necessary to study a new type of pavement material with high waterproof property, light weight, and high bonding performance for steel deck pavement. Polyurethane cement composite (PUC) can be used for steel deck pavement. In order to find out the temperature effect on fatigue properties of PUC, the four-point bending fatigue test was carried out at different temperatures. In this paper, the optimum mix ratio of PUC was selected by compressive and flexural tests, and then the bending fatigue test was conducted under strain control mode. Under temperature and external force coupling condition, a method for predicting fatigue life of PUC is proposed by the combination of theoretical deduction and experimental research. The results show that the proposed formula can effectively describe the fatigue life and fatigue limit of PUC. Finally, compared with three different asphalt mixtures for steel deck pavement, it is found that the fatigue performance of polyurethane cement is better than that of asphalt mixture.

Pipe Resonant Bending Fatigue Test Setup With Optical Measurement System

2010 ◽  
Author(s):  
Jeroen Van Wittenberghe ◽  
Patrick De Baets ◽  
Wim De Waele ◽  
Wouter Ost ◽  
Matthias Verstraete ◽  
...  
Keyword(s):  
Optical Measurement ◽  
Fatigue Cracks ◽  
Pressure Gauge ◽  
Preliminary Test ◽  
Fatigue Behaviour ◽  
Measuring System ◽  
Wave Form ◽  
Bending Fatigue ◽  
Bending Fatigue Test ◽  
Dynamic Measuring

Pipes and tubular members are used in offshore applications as structural elements such as columns or in transport pipelines, risers etc. When subjected to dynamic loads, weld defects or geometrical stress raisers can initiate fatigue cracks causing the columns or pipelines to fail prematurely. In order to investigate the fatigue behaviour of pipe joints, a resonant bending fatigue setup was designed, suitable for testing pipes within a diameter range from 6″ to 20″. In this setup the pipe, filled with water, is subjected to a dynamic excitation force with a frequency close to the natural frequency of the filled pipe. The force is applied using a unique drive unit with excentric masses. The pipe is supported in the nodes of its natural wave-form, so that no dynamic forces are transmitted to the setup. The deformation of the pipe is measured at discrete locations using an optical 3D dynamic measuring system. Through thickness fatigue cracks can be detected by pressurizing the water in the pipe and applying a pressure gauge. In this paper some unique aspects of the design of the resonant bending fatigue setup are discussed by presenting the results of a semi-analytical model used for calculating the deformation and bending stress in the excitated pipe and by comparing these results to the deformation measurements made by the dynamic measuring system. The working principles of the setup are illustrated by showing the preliminary test results for a 12″ diameter X65 steel pipe with a wall thickness of 12.7mm. It is demonstrated that the model predicts the behaviour of the pipe in the setup very accurately.

Investigation of Fatigue Behaviour and Notch Sensitivity of Ti-6Al-4V

2011 ◽  
Vol 80-81 ◽  
pp. 7-12 ◽  
Author(s):  
Shabnam Hosseini ◽  
Mohammad Bagher Limooei
Keyword(s):  
Biomedical Application ◽  
Low Cycle Fatigue ◽  
Fatigue Behaviour ◽  
Notch Sensitivity ◽  
Cycle Fatigue ◽  
Bending Fatigue ◽  
Notched Specimens ◽  
Bending Fatigue Test ◽  
Sensitivity Data ◽  
Low Sensitivity

In this research, fatigue behaviour of Ti-6Al-4V alloy was investigated for smooth and notched specimens with stress concentration factor(Kt) 3.6 and 4.1.This investigation was conducted for various diameter bars having different ultimate strength.Rotating bending fatigue test at R= -1 was emploied for this research. Notch sensitivity data was compared with those of steels. The result indicated that the presence of notch in this alloy has a different amount of sensitivity when the notch specimens were subjected to high cycle fatigue (HCF) and low cycle fatigue(LCF) tests.The notch sensitivity of this alloy was shown generally to be much lower than steel alloys with similar ultimate strength values. Therefore,considering the low sensitivity to notch of this alloy, can be recommended for applications with the presence of notch such as biomedical application

Comparison of Two Axisymmetric Finite Element Models of Threaded Connections

1999 ◽  
Author(s):  
Mark Hommel
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Tensile Load ◽  
Bending Moment ◽  
Element Analysis ◽  
Axisymmetric Loading ◽  
Axisymmetric Model ◽  
Threaded Connection ◽  
Threaded Connections ◽  
Run Time

Abstract Predicting the fatigue life of threaded connections using finite element analysis generally requires a 2-D axisymmetric model capable of handling non-axisymmetric loading in order to simulate an applied bending moment. This is desirable from the standpoint of computer run time, as compared with the alternative approach, namely, developing a full 3-D model. Unfortunately, due to their esoteric nature, the 2-D axisymmetric elements with non-axisymmetric loading capability are not supported by the software vendors as well as the other elements, hence pre- and post-processing are more challenging. In addition, due to the Fourier representation of the non-axisymmetric load, computer run time and storage is increased significantly over that of a strictly 2-D axisymmetric model. In view of this, common practice has been to use instead the conventional axisymmetric model with an equivalent applied axial tensile stress equal to the mean bending stress through the wall thickness in order to simulate the bending moment and thereby avoid the necessity for non-axisymmetric loading. The question therefore arises as to how well the results from the strictly axisymmetric model agree with the results from the axisymmetric model with non-axisymmetric loading capability. The purpose of this paper is to compare the results of the two models. A 5-1/2 F.H. threaded connection is modeled by means of a commercial finite element code. First, the axisymmetric model with non-axisymmetric loading capability is treated and results are obtained. Second, the axisymmetric model with applied equivalent tensile load is examined and its results are compared with the former model. It is found that the value of the primary variable of interest for quantification of fatigue life, namely, alternating stress, agrees between the two models within 4%. Thus, it is concluded that the simplified model provides a viable alternative for modeling fatigue life of threaded connections.

Fatigue Life Prediction of Cold Rolled Rotary Shouldered Threaded Connections

2018 ◽  
Author(s):  
Fei Song ◽  
Michael Du ◽  
Ke Li
Keyword(s):  
Fatigue Life ◽  
Cold Rolling ◽  
Fatigue Resistance ◽  
Element Model ◽  
Drill String ◽  
Directional Drilling ◽  
Drilling Tool ◽  
Threaded Connection ◽  
Threaded Connections ◽  
Cold Rolled

The bottom hole assembly (BHA) of a modern drill string for directional drilling mainly comprises a drill bit, a rotary steerable system, and a measurement while drilling tool. The tools and subs used on a BHA are screwed together through rotary shouldered threaded connections. Each connection is made up with a pin and a box. These connections are the weakest links when the BHA undergoes a large number of revolutions in a curved well section. When the fatigue life of a connection is consumed during a drilling job, a twist-off would occur, which could result in an enormous amount of non-productive time and possibly loss of the bottom BHA section in the hole. Cold rolling has proven to be able to improve fatigue resistance of a threaded connection by pressing a rolling wheel against the thread root and generating a layer of compressive residual stress at the root. Understanding how cold rolling improves fatigue resistance of a threaded connection is important for optimization of the rolling parameters and prediction of the BHA service life in a given drilling condition. In this paper, a predictive method is presented for fatigue life of a cold rolled threaded connection. A finite element model was developed to simulate the cold rolling process. The resulting deformation and stress states at the root were carried over through makeup of the pin and the box as well as through cyclic bending of the connection. The fatigue life predictions were found to be in favorable agreement with the experimental measurements from full-scale fatigue tests at different bending moment levels applied.

Evaluation of Fatigue Life of Automotive Bevel Gear

2006 ◽  
Vol 324-325 ◽  
pp. 839-842
Author(s):  
Jae Hoon Kim ◽  
Duck Hoi Kim ◽  
Young Shin Lee ◽  
Gi Gwang Kim
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Fatigue Loading ◽  
Analytical Investigation ◽  
Bevel Gear ◽  
Cold Forging ◽  
Experimental Investigations ◽  
Bending Fatigue ◽  
Bending Fatigue Test ◽  
Random Fatigue

This paper presented the results for experimental investigations and numerical analysis performed with the aim of studying on fatigue life of hobbed and cold forged bevel gears used in automobiles. To evaluate the bending fatigue strength improvement by cold forging process, fatigue test and analysis were performed. For the monotonic fatigue loading, bending fatigue test and analysis were carried out. To simulate the real driving condition, random fatigue loading was defined here, and the random fatigue analysis was also performed. It was concluded that fatigue life and crack initiation sites of automotive bevel gear were well agreed with the test results. Fatigue lives for hobbed and cold forged bevel gear from experimental and analytical investigation were also presented and compared.

scholarly journals Three-Point Bending Fatigue Test of TiAl6V4 Titanium Alloy at Room Temperature

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Juraj Belan ◽  
Lenka Kuchariková ◽  
Eva Tillová ◽  
Mária Chalupová
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Room Temperature ◽  
Fatigue Tests ◽  
Dynamic Force ◽  
Bending Fatigue ◽  
Three Point Bending ◽  
Bending Fatigue Test ◽  
Number Of Cycles ◽  
Test Loading

A polycrystalline alpha-beta TiAl6V4 alloy in the annealed condition was used for the three-point bending fatigue test at frequency f∼100 Hz. The static preload Fstat. = −15 kN and variable dynamic force Fdyn. = −7 kN to −13.5 kN were set as fatigue test loading parameters. The fatigue life S-N curve presented the stress amplitude σa as a function of a number of cycles to fracture Nf. A limiting number of cycles to run out of 2.0 × 107 cycles were chosen for the 3-point fatigue tests of rectangular specimens. In addition, the Smith diagram was used to predict the fatigue life. The alpha lamellae width has a significant influence on fatigue life. It is assumed that the increasing width of alpha lamellae decreases fatigue life. A comparison of fatigue results with given alpha lamellae width in our material to the results of other researchers was performed. The SEM fractography was performed with an accent to reveal the initiation sites of crack at low and high load stresses and mechanism of crack propagation for the fatigue part of fracture.

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