scholarly journals Fatigue Life Prediction of Steam Generator Tubes by Tube Specimens with Circular Holes

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 322 ◽  
Author(s):  
Qiwei Wang ◽  
Junfeng Chen ◽  
Xiao Chen ◽  
Zengliang Gao ◽  
Yuebing Li
Keyword(s):  
Finite Element Analysis ◽  
Fatigue Life ◽  
Life Prediction ◽  
Local Stress ◽  
Fatigue Life Prediction ◽  
Stress And Strain ◽  
Element Analysis ◽  
Transfer Tube ◽  
Inconel 690 ◽  
Circular Holes

Heat exchangers manufactured from Inconel 690 tubes are widely used for steam generators in nuclear power plants. Inconel 690 tubes have suffered failures of fatigue fracture due to flow induced vibration. It is difficult to obtain the fatigue life of the tube directly since the conventional fatigue test would potentially cause end fatigue failure due to the stress concentration at the clamp end. In this study, a thin-walled Inconel 690 tube with circular hole is designed to deduce the fatigue life of smooth tube based on the notch fatigue life prediction technology. Firstly, the local stress and strain distributions around the hole based on the finite element analysis are discussed. Local stress-strain is calculated and compared with Neuber’s ruler. Meanwhile, fatigue life tests using tube specimens with circular holes are carried out. Finally, based on the best-fitted fatigue life curve of Inconel 690 alloy, the fatigue life of tube specimen is estimated from the local strain according to Neuber’s ruler. The results show that the local stress and strain estimated by Neuber’s ruler are basically consistent with those obtained by finite element analysis. Compared with the average fatigue life of nickel-based alloy, the new predicted equivalent fatigue life of heat Inconel 690 transfer tube with a hole is higher. The Inconel 690 heat transfer tube has better fatigue performance.

TTK Chitra tilting disc heart valve model TC2: An assessment of fatigue life and durability

2017 ◽  
Vol 231 (8) ◽  
pp. 758-765 ◽  
Author(s):  
NN Subhash ◽  
Adathala Rajeev ◽  
Sreedharan Sujesh ◽  
CV Muraleedharan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Heart Valve ◽  
Life Prediction ◽  
Heart Valves ◽  
Failure Modes ◽  
Fatigue Life Prediction ◽  
Element Analysis ◽  
Valve Model

Average age group of heart valve replacement in India and most of the Third World countries is below 30 years. Hence, the valve for such patients need to be designed to have a service life of 50 years or more which corresponds to 2000 million cycles of operation. The purpose of this study was to assess the structural performance of the TTK Chitra tilting disc heart valve model TC2 and thereby address its durability. The TC2 model tilting disc heart valves were assessed to evaluate the risks connected with potential structural failure modes. To be more specific, the studies covered the finite element analysis–based fatigue life prediction and accelerated durability testing of the tilting disc heart valves for nine different valve sizes. First, finite element analysis–based fatigue life prediction showed that all nine valve sizes were in the infinite life region. Second, accelerated durability test showed that all nine valve sizes remained functional for 400 million cycles under experimental conditions. The study ensures the continued function of TC2 model tilting disc heart valves over duration in excess of 50 years. The results imply that the TC2 model valve designs are structurally safe, reliable and durable.

scholarly journals Design and finite element analysis of a fatigue life prediction for safe and economical machine shaft

2019 ◽  
Vol 8 (1) ◽  
pp. 105-111 ◽  
Author(s):  
Samuel O. Afolabi ◽  
Bankole I. Oladapo ◽  
Christianah O. Ijagbemi ◽  
Adeyinka O.M. Adeoye ◽  
Joseph F. Kayode
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Element Analysis

scholarly journals Influence of Weld Toe Radii on Fatigue Life Prediction

2018 ◽  
Vol 165 ◽  
pp. 22025 ◽  
Author(s):  
Kin Shun Tsang ◽  
John H. L. Pang ◽  
Hsin Jen Hoh
Keyword(s):  
Fatigue Life ◽  
Stress Intensity ◽  
Life Prediction ◽  
Crack Depth ◽  
Local Stress ◽  
Fatigue Life Prediction ◽  
Element Analysis ◽  
Weld Toe ◽  
Point Bend ◽  
Welded Pipe

A study was carried out to investigate the influence of the weld toe radii on the fatigue strength of butt welded joints loaded in bending and tension. Fatigue analysis starting from weld toe cracks in marine and offshore welded pipe specimens were conducted using cut-out four-point bend fatigue test specimens. Fatigue life can be enhanced by reducing the local stress concentration generated by weld toe radius effects. This study investigated the effect of different weld toe radii on the stress intensity factor at the region of the weld toe through Finite Element Analysis (FEA). FEA was used to model a butt welded steel plate extracted from a pipe subject to tension and four-point bend loading. Semi-elliptical surface (SESC) cracks were modeled at the weld toe region with different SESC crack depth and surface crack length. Four weld toe radii and two modes of loading were investigated. The stress intensity factors, weald toe magnification factors, or Mkc and Mka are reported and used for fatigue life prediction.

Sign in / Sign up

Export Citation Format

Share Document