Fatigue Life Extension of Riveted Connections

1975 ◽  
Vol 101 (12) ◽  
pp. 2591-2608 ◽  
Author(s):  
Harold S. Reemsnyder
Keyword(s):  
Fatigue Life ◽  
Life Extension

scholarly journals Correction: Wang et al. Generalized SCF Formula of Out-Of-Plane Gusset Welded Joints and Assessment of Fatigue Life Extension by Additional Weld. Materials 2021, 14, 1249

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2331
Author(s):  
Yixun Wang ◽  
Yuxiao Luo ◽  
Yuki Kotani ◽  
Seiichiro Tsutsumi
Keyword(s):  
Fatigue Life ◽  
Welded Joints ◽  
Life Extension ◽  
Out Of Plane

The authors wish to revise in the text of Appendix A, pages 19–21 [...]

scholarly journals Generalized SCF Formula of Out-Of-Plane Gusset Welded Joints and Assessment of Fatigue Life Extension by Additional Weld

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1249
Author(s):  
Yixun Wang ◽  
Yuxiao Luo ◽  
Yuki Kotani ◽  
Seiichiro Tsutsumi
Keyword(s):  
Fatigue Life ◽  
Fatigue Resistance ◽  
Welded Joints ◽  
Life Extension ◽  
Leg Length ◽  
Notch Stress ◽  
Out Of Plane ◽  
Weld Toe ◽  
Effective Notch Stress ◽  
Geometric Effects

The existing S-N curves by effective notch stress to assess the fatigue life of gusset welded joints can result in reduced accuracy due to the oversimplification of bead geometries. The present work proposes the parametric formulae of stress concentration factor (SCF) for as-welded gusset joints based on the spline model, by which the effective notch stress can be accurately calculated for fatigue resistance assessment. The spline model is also modified to make it applicable to the additional weld. The fatigue resistance of as-welded and additional-welded specimens is assessed considering the geometric effects and weld profiles. The results show that the error of SCFs by the proposed formulae is proven to be smaller than 5%. The additional weld can increase the fatigue life by as great as 9.4 times, mainly because the increasing weld toe radius and weld leg length lead to the smaller SCF. The proposed series of S-N curves, considering different SCFs, can be used to assess the welded joints with various geometric parameters and weld profiles.

A comparison of the turbine tower damping effects of a series of back twisted active pitch-to-stall blades for a spar and a semi-submersible FOWT

2021 ◽  
pp. 1-21
Author(s):  
Dawn Ward ◽  
Maurizio Collu ◽  
Joy Sumner
Keyword(s):  
Fatigue Life ◽  
Twist Angle ◽  
Offshore Wind ◽  
Life Extension ◽  
Variable Speed ◽  
Initiation Point ◽  
Variable Pitch ◽  
Floating Offshore Wind Turbines ◽  
The Impact ◽  
Axial Fatigue

Abstract Floating offshore wind turbines are subjected to higher tower fatigue loads than their fixed-to-seabed counterparts, which could lead to reductions in turbine life. The worst increases are generally seen in the tower axial fatigue, associated with the tower fore-aft bending moment. For a spar type platform this has been shown to increase by up to x2.5 and, for a semi-submersible platform, by up to x1.8. Reducing these loads would be beneficial, as the alternative of strengthening the towers leads to increases in cost. Here, two offshore floating wind turbine systems, of the spar type, are analysed and selected responses and tower fatigue compared: one incorporates a variable speed, variable pitch-to-stall blade control system and a back twisted blade, and the other a conventional pitch-to-feather control. The results are then compared to those obtained in an earlier study, where the same turbine configurations were coupled to a semi-submersible platform. A weighted wind frequency analysis at three mean turbulent wind speeds highlights that the impact of the back twist angle magnitude and initiation point on tower axial fatigue life extension was the same for both platform types. Compared to their respective feather base models, an increase in the tower axial fatigue life of 18.8% was seen with a spar platform and 10.2% with a semi-submersible platform, when a back twist angle to the tip of −6° was imposed along with the variable speed, variable pitch-to-stall control.

Local Shape Optimization of Notches in Airframe for Fatigue-Life Extension

2008 ◽  
Vol 32 (12) ◽  
pp. 1132-1139 ◽  
Author(s):  
Jun-Ho Won ◽  
Joo-Ho Choi ◽  
Jin-Hyuk Gang ◽  
Da-Wn An ◽  
Gi-Jun Yoon
Keyword(s):  
Fatigue Life ◽  
Shape Optimization ◽  
Life Extension ◽  
Local Shape

scholarly journals Numerical and Experimental Study on Fatigue Life Extension of U-rib Steel Structure by Hammer Peening

2017 ◽  
Vol 35 (2) ◽  
pp. 169s-172s ◽  
Author(s):  
Seiichiro Tsutsumi ◽  
Ryota Nagao ◽  
Riccardo Fincato ◽  
Toshiyuki Ishikawa ◽  
Risa Matsumoto
Keyword(s):  
Experimental Study ◽  
Fatigue Life ◽  
Steel Structure ◽  
Life Extension ◽  
Hammer Peening

Life Extending Minimum-Time Path Planning for a Hexapod Robot

2010 ◽  
Author(s):  
Xin Wu ◽  
Yaoyu Li ◽  
Thomas R. Consi
Keyword(s):  
Fatigue Life ◽  
Path Planning ◽  
Radial Force ◽  
Minimum Time ◽  
Life Extension ◽  
Euler Formula ◽  
Time Path ◽  
Degradation Rates ◽  
Planning Algorithm ◽  
Path Planning Algorithm

This paper presents a life extending minimum-time path planning algorithm for legged robots, with application for a six-legged walking robot (hexapod). The leg joint fatigue life can be extended by reducing the constraint on the dynamic radial force. The dynamic model of the hexapod is built with the Newton Euler Formula. In the normal condition, the minimum-time path planning algorithm is developed through the bisecting-plane (BP) algorithm with the constraints of maximum joint angular velocity and acceleration. According to the fatigue life model for ball bearing, its fatigue life increases while the dynamic radial force on the bearing decreases. The minimum-time path planning algorithm is thus revised by reinforcing the constraint of maximum radial force based on the expectation of life extension. A symmetric hexapod with 18 degree-of-freedom is used for simulation study. As a simplified treatment, the magnitudes of dynamic radial force on proximal joints at the pair of supporting legs are set identical to achieve similar degradation rates on each joint bearing and obtain the dynamic radial force on each joint. The simulation results validate the effectiveness of the proposed idea. This scheme can extend the operating life of robot (joint bearing fatigue life) by modifying the joint path only without affecting the primary task specifications.

scholarly journals Fatigue life extension of epoxy materials using ultrafast epoxy-SbF5 healing system introduced by manual infiltration

2015 ◽  
Vol 9 (3) ◽  
pp. 177-184 ◽  
Author(s):  
X. J. Ye ◽  
Y. Zhu ◽  
Y. C. Yuan ◽  
Y. X. Song ◽  
G. C. Yang ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Life Extension ◽  
Healing System
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