Data Trend Monitoring and End Level Verification - Tools to Reduce Data Storage in Full-Scale Aircraft Fatigue Tests

2009 ◽  
pp. 49-49-13
Author(s):  
RL Hewitt ◽  
A Nelson
Keyword(s):  
Data Storage ◽  
Fatigue Tests ◽  
Full Scale ◽  
Trend Monitoring ◽  
Verification Tools

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.

A method of determining test load for full-scale wind turbine blade fatigue tests

2018 ◽  
Vol 32 (11) ◽  
pp. 5097-5104 ◽  
Author(s):  
Qiang Ma ◽  
Zong-Wen An ◽  
Jian-Xiong Gao ◽  
Hai-Xia Kou ◽  
Xue-Zong Bai
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Fatigue Tests ◽  
Full Scale ◽  
Wind Turbine Blade ◽  
Test Load

scholarly journals Analysis of Wear Debris from Full-Scale Bearing Fatigue Tests Using the Ferrograph

1981 ◽  
Vol 24 (3) ◽  
pp. 323-330 ◽  
Author(s):  
William R. Jones ◽  
Stuart H. Loewenthal
Keyword(s):  
Wear Debris ◽  
Fatigue Tests ◽  
Full Scale

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.

Crack Growth in Pipes Under Service Contortions

2009 ◽  
Author(s):  
Oddvin O¨rjasaeter ◽  
Richard Verley ◽  
Per Egil Kvaale ◽  
Tor Gunnar Eggen
Keyword(s):  
Crack Growth ◽  
Cathodic Protection ◽  
Growth Rates ◽  
Fatigue Cracks ◽  
High Growth ◽  
Potential Drop ◽  
Fatigue Tests ◽  
Full Scale ◽  
Small Scale ◽  
Loading Frequency

At the A˚sgard field a leak on a 10″, 13Cr production pipeline was discovered in December 2000 during pressure testing. The cause was a crack at an anode pad fillet weld (pads are connectors for the cathodic protection system). Later, a similar leak occurred on another A˚sgard flowline. During pigging inspection (AUT) several smaller crack indications were found at similar locations. Propagation of such cracks will depend on loading and environmental conditions. To investigate this further, a test programme was carried out using 13Cr pipe materials. Both small scale tests and full scale pipes were used. Specimens were prepared with small initial fatigue cracks at the pad weld. The propagation of the cracks was then recorded under various environmental and loading conditions. The loading was selected to cover a crack growth rate range of ∼10−6 to 10−3 mm/cycle for various crack depths and for two loading frequencies. Tests were conducted under cathodic protection (hydrogen in the material measured) and for temperatures up to 140°C and pressures up to 30bar. The crack growth was recorded by the potential drop method (ACPD). For the full scale pipe tests, specially developed equipment was used for simultaneous measuring at up to 24 individual locations. The results showed that low loading frequency (0.1 Hz) enhances the growth rates; elevated temperature gave equal or lower propagation rates than at 25°C and a pressure of 30bar did not influence the results. A few cracks were also initiated during the corrosion fatigue tests and exhibited high growth rates; possibly due to the so-called “small crack” effect and possibly in synergy with the influence of hydrogen.

scholarly journals Full-scale fatigue tests of CX-100 wind turbine blades. Part II: analysis

2012 ◽  
Author(s):  
Stuart G. Taylor ◽  
Hyomi Jeong ◽  
Jae Kyeong Jang ◽  
Gyuhae Park ◽  
Kevin M. Farinholt ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Turbine Blades ◽  
Fatigue Tests ◽  
Full Scale ◽  
Wind Turbine Blades

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.

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