Fatigue behavior and life predictions of notched specimens made of QT and forged microalloyed steels

2004 ◽  
Vol 26 (6) ◽  
pp. 663-672 ◽  
Author(s):  
A Fatemi
Author(s):  
Gustavo Dória Lima ◽  
Brenno Lima Nascimento ◽  
Isau de Souza Alves Júnior ◽  
Matheus Porto Trindade ◽  
Sandro Griza

Author(s):  
Mario A. Polanco-Loria ◽  
Håvar Ilstad

This work presents a numerical-experimental methodology to study the fatigue behavior of dented pipes under internal pressure. A full-scale experimental program on dented pipes containing gouges were achieved. Two types of defects were studied: metal loss (plain dent) and sharp notch. Both defects acting independently reduce the fatigue life performance but their combination is highly detrimental and must be avoided. We did not find a severity threshold (e.g. dent depth or crack depth) where these defects could coexist. In addition, based on numerical analyses we proposed a new expression for stress concentration factor (SCF) in line with transversal indentation. This information was successfully integrated into a simple fatigue model where the fatigue life predictions were practically inside the window of experimental results.


Author(s):  
Adam J. Rinehart ◽  
Peter B. Keating

A full scale experimental study has demonstrated that long, unrestrained pipeline dents typically experience fatigue cracking in the dent contact region and have significantly shorter fatigue lives compared to other dent types studied. Furthermore, these dents often fully reround under normal pipeline operating pressures, making them difficult to reliably detect and assess using existing depth-based approaches. Several conditions unique to the dent contact region accelerate fatigue damage accumulation and are considered in a case-specific long dent fatigue life prediction method. First, the contact region develops significant bending stresses that contribute to a higher rate of fatigue crack growth. Second, history dependent, thru-thickness residual bending stresses that may have a significant influence on fatigue behavior are present in the contact region as a result of plastic deformation associated with dent formation and subsequent rebounding. A method for predicting the fatigue life of long dents that accounts for these factors is presented here and is used to analyze specific cases for which laboratory data is available. Nonlinear finite element modelling of the dent life cycle, including the indentation and rebounding phases, is used to determine local stress range behaviors and residual stress distributions. The application of appropriate fracture mechanics based models of fatigue is discussed and demonstrated. Fatigue life predictions are made on a case by case basis for situations studied in the laboratory so that the validity and accuracy of the approach presented here may be studied.


Author(s):  
Paulina Leiva-Padilla ◽  
Juliette Blanc ◽  
Aitor Salgado ◽  
Ferhat Hammoum ◽  
Pierre Hornych

Truck platooning for the transportation of loads is a strategy recently proposed by the automotive sector to cope with traffic congestion, fuel consumption, and operational costs. This new way of configuring trucks changes the typical pressures pavements structures experience. For this reason, the research efforts of the pavement sector should be aligned with the automotive sector to propose road-friendly platoon configurations. This is one of the objectives of the European project ENSEMBLE. ENSEMBLE, as indicated by its acronym, works on ENabling SafE Multi-Brand pLatooning for Europe. In this context, the present study presents a real scale test done in the Applus IDIADA facilities to evaluate the fatigue behavior of a pavement structure subjected to individual and platoon truck configurations. The effects of parameters such as traffic distribution through the year and by time of day, percentage of platoons, truck loads, number of trucks in platoon configuration, lateral wandering, and inter-truck distances were evaluated. The study’s findings revealed that the reduced rest times between trucks in the platoon configuration reduce the recovery time of the asphalt layers, increasing the fatigue damage to the pavement at high temperature conditions. This underlines the need for further research to allow the proper implementation of truck platoons. For example, research is needed to define strategies to make truck platoon configurations more pavement-friendly and analyze the costs associated with the changes in the required road maintenance/rehabilitation treatments, among others.


1995 ◽  
Author(s):  
E. Troiano ◽  
J. H. Underwood ◽  
D. Crayon ◽  
R. T. Abbott

2020 ◽  
Vol 50 ◽  
pp. 204-214 ◽  
Author(s):  
Zhihong Wu ◽  
Hongchao Kou ◽  
Nana Chen ◽  
Mengqi Zhang ◽  
Ke Hua ◽  
...  

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