Stress Analyses and Parametric Study on Full-Scale Fatigue Tests of Rib-to-Deck Welded Joints in Steel Orthotropic Decks

This paper focus on fatigue problem of submarine pipelines, four points bending full scale fatigue experiment were conducted on X65 pipelines butt joints specimens, utilizing pipeline full scale fatigue test machine developed by CNPC. Meanwhile contrast test was also carried out on small specimens. The results show that the fatigue strength of full scale welded joints is lower than the small scale joints. Owing to having no regard for the influence of residual stress and size effect, the small test would provide dangerous results. The fatigue property of full scale welded joints only meets the requirement of DNV C203 W3 curve, and meets the needs of DNV C203 F3 curve basically while not meet BS 7608 F2 curve’s requirements which relatively demand higher. Weld toe and geometric discontinuous near weld root is the weak point for the whole welded joints.

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

Volume 12: Mechanics of Solids, Structures, and Fluids ◽

10.1115/imece2020-24047 ◽

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.

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

Journal of Mechanical Science and Technology ◽

10.1007/s12206-018-1006-y ◽

2018 ◽

Vol 32 (11) ◽

pp. 5097-5104 ◽

Cited By ~ 2

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

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Full-scale Fatigue Tests of Riveted Girders

Fatigue Life of Riveted Steel Bridges ◽

10.1201/b10429-7 ◽

2010 ◽

pp. 103-136

Keyword(s):

Fatigue Tests ◽

Full Scale

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Influence of backing materials towards the fatigue strength of butt-welded joints

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406211403570 ◽

2011 ◽

Vol 225 (8) ◽

pp. 1798-1807 ◽

Cited By ~ 3

Author(s):

M H Kim ◽

H J Kim ◽

J H Han ◽

J M Lee ◽

Y D Kim ◽

...

Keyword(s):

Finite Element ◽

Fatigue Strength ◽

Welded Joints ◽

Fatigue Tests ◽

Experimental Results ◽

Finite Element Analyses ◽

Cold Metal Transfer ◽

Notch Stress ◽

Effective Notch Stress ◽

Cold Metal

The purpose of this study is to investigate the fatigue strength of butt-welded joints with special attention paid to employing different kinds of backing plates. The effect of the under-matched weld was also considered. Four different cases of backing scenarios for butt-welded specimens such as steel backing, ceramic backing, CMT (no backing by cold metal transfer) and UM (under-matched welded specimen) were investigated. A series of fatigue tests was performed to compare the fatigue strength of butt-welded joints with respect to different backing scenarios. Effective notch stress was used for the interpretation of fatigue strength of butt-welded specimens with backing plates based on finite element analyses for calculating fatigue notch factors. When results were presented from the effective notch stress, all backing scenarios considered in this study exhibited the fatigue strengths corresponding to the FAT 225 curve. From the experimental results of this study, it was determined that the fatigue strengths of butt-welded joints were found to be in the order of CMT, ceramic backing, UM, and steel backing. No significant decrease in fatigue strength, however, was observed when backing plates were steel backing and ceramic backing types.

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Differences in Fatigue Strength Between Arc and Laser Hybrid Welded Joints

Journal of Ship Production ◽

10.5957/jsp.2008.24.3.139 ◽

2008 ◽

Vol 24 (03) ◽

pp. 139-146

Author(s):

H. Remes ◽

P. Varsta

Keyword(s):

Fatigue Strength ◽

Welded Joints ◽

Fatigue Tests ◽

Notch Depth ◽

Butt Joints ◽

Fatigue Design ◽

Notch Stress ◽

Notch Geometry ◽

Laser Hybrid ◽

Fatigue Endurance

This paper presents the results of fatigue tests, including tests of laser hybrid and arc welded butt joints, for two plate thicknesses, 6 and 12 mm. Pure laser welded joints were also tested. The S-N curves based on nominal stresses for the different welded joints are presented. The results were further analyzed using the notch stress approach, where the fatigue notch factors were determined from the measured geometries of the welded joints. Unexpected differences in the S-N curves based on the notch stresses were found between the laser hybrid and arc welded joints and between the laser hybrid and pure laser welded joints. The reasons for this difference were studied with the help of extensive measurements of weld notch geometries. Significant differences in the geometries were observed. Taking into account the notch geometry and the notch depth, the notch stress approach partially explains the differences between the fatigue endurance limits of the laser hybrid and arc welded joints. The applicability of the notch stress approach to the fatigue design of laser hybrid welded joints is also discussed.

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