Experimental Studies on the Full-Scale Fatigue Performance of X65 Marine Pipeline

2014 ◽  
Vol 1052 ◽  
pp. 555-560
Author(s):  
Yan Hua Hu ◽  
De Yu Tang ◽  
Zong Tao Fang ◽  
Hu Li Niu
Keyword(s):  
Fatigue Life ◽  
Experimental Studies ◽  
Fatigue Tests ◽  
Full Scale ◽  
Welding Residual Stress ◽  
Fatigue Performance ◽  
Four Point Bending ◽  
Inner Pressure ◽  
Quantitative Basis ◽  
Safety Operation

In this paper, the fatigue performance of X65 marine pipeline is domestically studied by means of full-scale fatigue tests (four-point bending + inner pressure), in which all the influencing factors, such as welding residual stress, stress concentration, initial defects, internal pressure shutdown and pressure fluctuation are taken into consideration comprehensively. Consequently, the fatigue cycles under different stress amplitude can be derived and applied to predicting the full-scale fatigue life of pipes quantitatively. Additionally, the test results are compared with the recommended data of international general standards, such as BS 7608 and DNV C203, by which the fatigue safety of pipes could be evaluated. Therefore, this study is not only beneficial to the accumulation of full-scale fatigue data of pipes, but also can provide quantitative basis for evaluating the fatigue life and ensuring the safety operation cycles of pipes.

scholarly journals Experimental study on fatigue performance of Q420qD high-performance steel cross joint in complex environment

2021 ◽  
Author(s):  
Haigen Cheng ◽  
Cong Hu ◽  
Yong Jiang
Keyword(s):  
Fatigue Life ◽  
High Performance ◽  
Steel Structure ◽  
Steel Structures ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Corrosive Media ◽  
Joint Connection ◽  
High Performance Steel ◽  
The Cross

AbstractThe steel structure under the action of alternating load for a long time is prone to fatigue failure and affects the safety of the engineering structure. For steel structures in complex environments such as corrosive media and fires, the remaining fatigue life is more difficult to predict theoretically. To this end, the article carried out fatigue tests on Q420qD high-performance steel cross joints under three different working conditions, established a 95% survival rate $$S{ - }N$$ S - N curves, and analyzed the effects of corrosive media and high fire temperatures on its fatigue performance. And refer to the current specifications to evaluate its fatigue performance. The results show that the fatigue performance of the cross joint connection is reduced under the influence of corrosive medium, and the fatigue performance of the cross joint connection is improved under the high temperature of fire. When the number of cycles is more than 200,000 times, the design curves of EN code, GBJ code, and GB code can better predict the fatigue life of cross joints without treatment, only corrosion treatment, and corrosion and fire treatment, and all have sufficient safety reserve.

A Hybrid Supervised Deep Learning and Nonlinear Finite Element Framework for Efficient Fatigue Life Predictions of Rotary Shouldered Threaded Connections

2020 ◽  
Author(s):  
Fei Song ◽  
Ke Li
Keyword(s):  
Finite Element ◽  
Deep Learning ◽  
Fatigue Life ◽  
Learning Algorithm ◽  
Fatigue Tests ◽  
Full Scale ◽  
Remaining Useful Life ◽  
Nonlinear Finite Element ◽  
Threaded Connections ◽  
Life Predictions

Abstract In this paper, a hybrid computational framework that combines the state-of-the art machine learning algorithm (i.e., deep neural network) and nonlinear finite element analysis for efficient and accurate fatigue life prediction of rotary shouldered threaded connections is presented. Specifically, a large set of simulation data from nonlinear FEA, along with a small set of experimental data from full-scale fatigue tests, constitutes the dataset required for training and testing of a fast-loop predictive model that could cover most commonly used rotary shouldered connections. Feature engineering was first performed to explore the compressed feature space to be used to represent the data. An ensemble deep learning algorithm was then developed to learn the underlying pattern, and hyperparameter tuning techniques were employed to select the learning model that provides the best mapping, between the features and the fatigue strength of the connections. The resulting fatigue life predictions were found to agree favorably well with the experimental results from full-scale bending fatigue tests and field operational data. This newly developed hybrid modeling framework paves a new way to realtime predicting the remaining useful life of rotary shouldered threaded connections for prognostic health management of the drilling equipment.

The Effects of Mechanical Properties on Fatigue Behavior of ECAPed AA7075

2016 ◽  
Vol 35 (3) ◽  
pp. 225-234 ◽  
Author(s):  
Hasan Kaya ◽  
Mehmet Uçar
Keyword(s):  
Electron Microscope ◽  
Fatigue Life ◽  
Fatigue Behavior ◽  
Optical Microscope ◽  
Fatigue Tests ◽  
Angular Pressing ◽  
Four Point Bending ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Hardness Values

AbstractIn this study, the effects of equal channel angular pressing (ECAP) on high-cycle fatigue and fatigue surface morphology of AA7075 have been investigated at a constant temperature (483 K) and the “C” route for four passes at ECAP process. ECAPed and as-received specimens were tested by four-point bending fatigue device. Fatigue tests were carried out by using 100, 120 and 140 MPa strength values. ECAPed specimens were characterized for each pass with optical microscope (OM), scanning electron microscope (SEM), energy-dispersive spectroscope (EDS), transmission electron microscope (TEM), selected area electron diffraction (SAED) and hardness measurements. Fracture surfaces of the specimens were also characterized with SEM. The results show that the highest hardness values (137 HV) and the best fatigue life (5.4 × 107for 100 MPa) were measured in ECAPed four-pass sample. For this reason hardness values and fatigue life were increased with increasing number of severe plastic deformation (SPD) process.

The Effect of Asphalt Binder Aging on Fatigue Performance of Evotherm WMA

2012 ◽  
Vol 535-537 ◽  
pp. 1686-1692
Author(s):  
Yong Chun Qin ◽  
Sui Yuan Wang ◽  
Wei Zeng ◽  
Xiao Pei Shi ◽  
Jian Xu ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Warm Mix Asphalt ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Asphalt Binders ◽  
Different Temperatures ◽  
Binder Aging ◽  
Lower Production

One of the main benefits advertised with the use of warm mix asphalt (WMA) is the decreasing aging of the asphalt binder resulting from the lower production temperature compared to conventional hot mix asphalt (HMA). Some tests were performed to determine the asphalt binder aging properties from WMA and HMA. Asphalt binders were recovered by extraction and distillation from asphalt mixtures premixed at different temperatures (140°C, 160°C, 180°C for HMA, 100°C and 120°C for WMA) in the mixing plant. Penetration@25°C, softening point (R&B) and rotational Brookfield viscosity tests were carried out. Results show that the aging of asphalt binder increases as the mixing temperature is elevated, and remarkably accelerates at the temperatures higher than 150°C. Warm mix asphalt (for example, mixing temperature at 100°Cor 120°C) can greatly reduce the aging of asphalt. Aging of the asphalt binder is one of the factors that would affect the mixture’s fatigue life. Four-point beam fatigue test samples were mixed and compacted at 140°C for HMA and 120°C for WMA, and fatigue tests with a frequency of 10 Hz and three constant strain levels (150 micro-strain, 300 micro-strain, 450 micro-strain, respectively) were performed. Results show that WMA’s fatigue life was higher than the control HMA, which indicates that it may reduce aging of asphalt binder and improve fatigue performance of asphalt mixture at lower production temperatures.

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 Testing of Out-of-Plane Bending Mechanism of Chain Links

2006 ◽  
Author(s):  
Lucile Rampi ◽  
Pedro Vargas
Keyword(s):  
Fatigue Testing ◽  
Empirical Relationship ◽  
Fatigue Tests ◽  
Full Scale ◽  
Fatigue Performance ◽  
Special Focus ◽  
Out Of Plane ◽  
Plane Bending ◽  
Chain Links ◽  
Mooring Chain

Three years ago, several mooring chains of an off-loading buoy failed after only 8 months of service. These chains were designed according to conventional fatigue assessment using API RP 2SK T-N curves to a fatigue life or 20 years with a factor of safety equal to 3 on life. Of particular interest is that the mooring chain failure underwent significant mooring chain motions that caused interlink rotations. Although traditionally neglected, these interlink rotations, when combined with significant chain tensions can cause bending stresses in the chain links (See Figure 1). This recently identified phenomena, Out-of-Plane Bending (OPB), explains the extensive fatigue damage causing the mooring chains of the off-loading buoy to fail [3][4][5]. References [3] and [4] document full scale tests of the OPB mechanism using a full scale test frame with the ability of applying inter-link rotation to a pre-tensioned chain. This testing confirmed that interlink rotations with a constant tension load can result in significantly high stresses. OPB stresses were measured on four different chain sizes of various grades: 1) 81 mm Studded Grade R3S, 2) 107 mm Stud-less Grade RQ3, 3) 124 mm Stud-less Grade R4, and 4) 146 mm Stud-less Grade RQ4, Grade R3 in [3] and [4], but no actual fatigue tests were performed. References [3] and [5] document analytical and computational efforts to explain and quantify the OPB stresses. In this paper, special focus is placed on obtaining actual fatigue failures of chains from OPB loading. Smaller chain sizes (40 mm) are used to accommodate the load limits of the testing frame. To mimic the actual loading as close as possible, sub size models of actual chainhawses were used in the testing. Two chainhawses were used: 1) the chainhawse has internal curvature where a link rests on the intrados, similar to offloading buoy that failed in eight months, and 2) a straight chainhase, a design that is in use today with demonstrated improved fatigue performance over the curved chainhawse. OPB stresses are measured and reported. Fatigue loading in the OPB mode was applied for several configurations. The two chainhawse exhibit very different stress levels and fatigue performance. An empirical relationship previously reported in [3][4][5] is compared to the measured OPB stresses with mixed results. Although limited in number, the fatigue tests indicate that overall the chain fatigue performance is at or above the B1 DnV curve. The BS B1 curve is also compared.

Fatigue of Zirconia - Bioglass Dental Ceramics

2008 ◽  
Vol 591-593 ◽  
pp. 628-633 ◽  
Author(s):  
Luiz A. Bicalho ◽  
R.C. Souza ◽  
Claudinei dos Santos ◽  
M.J.R. Barboza ◽  
Carlos Antonio Reis Pereira Baptista
Keyword(s):  
Fracture Toughness ◽  
Fatigue Life ◽  
Bending Strength ◽  
Cyclic Fatigue ◽  
Fatigue Tests ◽  
Modulus Of Rupture ◽  
Dental Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Four Point Bending

In this work the cyclic fatigue life of 3mol.%Y2O3-stabilized zirconia polycrystalline ceramics, doped with 5%wt 3CaO.P2O5,-SiO2-MgO, has been investigated. Samples with 5 and 10%wt were cold uniaxial pressed (80MPa) and sintered in air at 1200 and 1300oC for 120 minutes. Sintered samples were characterized by X-Ray diffraction and Scanning Electronic Microscopy. Hardness and fracture toughness were determined using Vicker’s indentation method, and Modulus of Rupture was determined by four-point bending testing. Furthermore, the cyclic fatigue tests were also realized by four-point bending tests, under frequency of 25 Hz and stress ratio, R, of 0.1, for the best condition. In this condition, highly dense samples were obtained and presented values of hardness, fracture toughness and bending strength of 11.3 ±0.1GPa, 6.1±0.4MPa.m1/2 and 320±55MPa, respectively. The increasing of stress level leads to decreasing of the number of cycles and the number of run-out specimens. The stress induced tetragonal-monoclinic (t-m)-ZrO2 transformation, observed by X-Ray diffraction, contributes to the increasing of the fatigue life. Samples 3Y-TZP presents clearly a range of loading conditions where cyclic fatigue can be detected.

Influences of Inner Pressure and Overload on Low Cycle Fatigue Behaviors of Elbow Pipes With Local Wall Thinning

2010 ◽  
Author(s):  
Kyohei Sato ◽  
Koji Takahashi ◽  
Kanako Ogino ◽  
Yoshio Urabe ◽  
Kotoji Ando
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Growth Direction ◽  
Fatigue Tests ◽  
Metal Loss ◽  
Cycle Fatigue ◽  
Crack Penetration ◽  
Inner Pressure ◽  
Wall Thinning ◽  
Local Wall Thinning

Low cycle fatigue tests were conducted using 100A elbow pipe specimens with or without local wall thinning. Local wall thinning of 50% of the nominal pipe wall thickness was machined on the inside of the test elbows to simulate metal loss due to flow-accelerated corrosion. The local wall thinning area was machined at the extrados, which has been reported to be the section most likely to suffer local wall thinning. Low cycle fatigue tests were carried out under displacement control using pipe with local wall thinning at the extrados to investigate the influences of an inner pressure of 0∼12 MPa. To simulate seismic events, low cycle fatigue tests were also carried out on pipe with or without wall thinning to investigate the influences of cyclic overloads. No differences in fatigue life were caused by an inner pressure of 3 MPa. However, degradation of fatigue life was caused as inner pressure increased from 6 MPa to 12 MPa. The fatigue lives of overloaded pipes were similar to those of non-overloaded pipes. In addition, three-dimensional elastic-plastic analyses were carried out using the finite element method. The crack penetration area and the crack growth direction were successfully predicted by the analyses.

Effect of Aggregate Gradation on Fatigue Life of Asphalt Concrete Mixes

1998 ◽  
Vol 1630 (1) ◽  
pp. 62-68 ◽  
Author(s):  
Jorge B. Sousa ◽  
Jorge C. Pais ◽  
Manuel Prates ◽  
Rui Barros ◽  
Pierre Langlois ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Asphalt Concrete ◽  
Laboratory Tests ◽  
Fatigue Tests ◽  
Test Protocol ◽  
Predictive Equations ◽  
Aggregate Gradation ◽  
Bending Fatigue ◽  
Four Point Bending ◽  
Highway Research

Four-point bending fatigue tests following the Strategic Highway Research Program (SHRP) M009 test protocol were executed to investigate to what extent gradation has an effect on fatigue performance of asphalt aggregate mixes. Gradations and mixes were selected that would satisfy all volumetric Superpave designs passing below the restricted zone. Other mixes were prepared with gradations passing through and above the restricted zone. The measured fatigue lives of 130 actual laboratory tests were compared with predictions by the Shell, Asphalt Institute, and SHRP-A003A fatigue-predictive equations.

Study of Fatigue Tests on the Structural Details of Welding Joints of Integral Bridge Deck and Main Girder Gusset Plates

2011 ◽  
Vol 243-249 ◽  
pp. 1638-1645
Author(s):  
Cai Ping Huang ◽  
Zhong Xian Zhang ◽  
Ji Zhang ◽  
Jin Zhou Chen
Keyword(s):  
Fatigue Life ◽  
Bridge Deck ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Scale Model ◽  
Gusset Plates ◽  
Integral Bridge ◽  
Structural Details ◽  
Tensile Forces ◽  
Welding Joints

Under the action of both dead and live loads, the welding joints of the integral bridge deck and the main truss gusset plates of a steel truss bridge in the transverse and longitudinal directions are all subjected to tensile force, the fatigue performance of which greatly influence the safety and durability of the bridge during operation. Fatigue tests were carried out on a full-scale model designed and made in accordance with the structural details of the welding joints of the integral bridge deck and the main truss gusset plates of Dashengguan Changjiang River Bridge. On the basis of the results of the fatigue tests, the stress distribution of the welding joints was analyzed, the fatigue life of the welding joints under load cycles with constant amplitude was discussed and the fatigue performance of the welding joints under the condition of two-way tensile forces was studied. It is concluded that under the effect of fatigue loading with given amplitude, the fatigue life of the welding joints is more than 200 million numbers of load cycles, the structural details of welding joints have ample fatigue resistant ability under the condition of two-way tensile forces, and the maximum main stress value of the fatigue tests is lower than the allowable fatigue stress value given in various codes and relevant references and the fatigue strength meets requirement.

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