European Fitness-for-Service Network (FITNET): Fatigue Module Development

2005 ◽  
Author(s):  
Jean-Jacques Janosch ◽  
Michel Huther ◽  
Nigel Taylor ◽  
Steve Maddox ◽  
Mustafa Kocak
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Critical Issue ◽  
Service Network ◽  
Metallic Structures ◽  
Ship Structure ◽  
Load Carrying ◽  
Module Development

FITNET is a four-year European thematic network with the objective of developing and extending the use of fitness-for-service (FFS) procedures for welded and non-welded metallic structures throughout Europe. It is partly funded by the European Commission within the fifth framework program and it was launched in February 2002. The network currently consists of about 50 organisations from 17 European countries and supported by institutions from USA, Japan and Korea. Further information can be found in the FITNET TN website: http://www.eurofitnet.org. The FITNET FFS Procedure is built up in four major analysis modules namely fracture, fatigue, creep and corrosion. The first official draft is available in early 2006 in the form of an official CEN document. Industrial components are as a rule exposed to fluctuating loads and hence consideration of fatigue damages accumulation or of fatigue crack growth is a critical issue. The aim of this paper is to present the features and the main analysis routes of the FITNET FFE Fatigue Module of the FITNET FFS Procedure to assess the fatigue life of the load carrying metallic components manufactured with and without welds. The paper includes an industrial case from ship structure for the application of two fatigue assessment routes.

scholarly journals OBSERVATIONS ON FATIGUE CRACK GROWTH AND FATIGUE LIFE OF RIVETED LAP JOINTS

2012 ◽  
Vol 31 (3) ◽  
pp. 108
Author(s):  
Andrzej SKORUPA ◽  
Małgorzata SKORUPA ◽  
Tomasz MACHNIEWICZ ◽  
Andrzej KORBEL
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Lap Joints ◽  
Riveted Lap Joints

scholarly journals Influence of Pre-Stress Magnitude on Fatigue Crack Growth Behavior of Al-Alloy

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1267
Author(s):  
Chunguo Zhang ◽  
Weizhen Song ◽  
Qitao Wang ◽  
Wen Liu
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Shot Peening ◽  
Fatigue Property ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Al Alloy ◽  
Fatigue Crack Growth Behavior

From tensile overload to shot peening, there have been many attempts to extend the fatigue properties of metals. A key challenge with the cold work processes is that it is hard to avoid generation of harmful effects (e.g., the increase of surface roughness caused by shot peening). Pre-stress has a positive effect on improving the fatigue property of metals, and it is expected to strength Al-alloy without introducing adverse factors. Four pre-stresses ranged from 120 to 183 MPa were incorporated in four cracked extended-compact tension specimens by application of different load based on the measured stress–strain curve. Fatigue crack growth behavior and fractured characteristic of the pre-stressed specimens were investigated systematically and were compared with those of an as-received specimen. The results show that the pre-stress ranged from 120 to 183 MPa significantly improved the fatigue resistance of Al-alloy by comparison with that of the as-received specimen. With increasing pre-stress, the fatigue life first increases, then decrease, and the specimen with pre-stress of 158 MPa has the longest fatigue life. For the manner of pre-stress, no adverse factor was observed for increasing fatigue property, and the induced pre-stress reduced gradually till to disappear during subsequent fatigue cycling.

A Flaw Tolerance Concept for Plant Maintenance Using Virtual Fatigue Crack Growth Curve

2013 ◽  
Author(s):  
Masayuki Kamaya ◽  
Takao Nakamura
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Curve ◽  
Growth Behavior ◽  
Plant Design ◽  
Flaw Tolerance ◽  
Plant Maintenance ◽  
Crack Growth Curve

Incorporation of the flaw tolerance concept in plant design and maintenance is discussed in order to consider the reduction in fatigue life due to the high-temperature water environment of class 1 components of NPPs. The flaw tolerance concept has been included in Section XI of the ASME BPVC. The structural factor (safety factor) for the flaw evaluation is considered in the stress, whereas it was considered in the design fatigue curve in Section III of the ASME BPVC. In order to apply the flaw tolerance concept to plant design and maintenance, it is necessary to assume the crack initiation and growth behavior. In this study, first, crack initiation and growth behavior during fatigue tests was reviewed and a relationship between the crack growth and fatigue life was quantified. Then, the safety factor was considered in the crack growth curve. It was shown that the crack size could be correlated to the usage factor and the flaw tolerance concept was reasonably considered in the plant maintenance by using the proposed virtual fatigue crack growth curve.

scholarly journals Short fatigue crack growth in welded joints described by the effective cyclic J-integral

2018 ◽  
Vol 165 ◽  
pp. 09002
Author(s):  
Désiré Tchoffo Ngoula ◽  
Michael Vormwald
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Residual Stresses ◽  
Crack Growth ◽  
Welded Joints ◽  
Driving Force ◽  
J Integral ◽  
Crack Driving Force ◽  
Short Fatigue Crack

The purpose of the present contribution is to predict the fatigue life of welded joints by using the effective cyclic J-integral as crack driving force. The plasticity induced crack closure effects and the effects of welding residual stresses are taken into consideration. Here, the fatigue life is regarded as period of short fatigue crack growth. The node release technique is used to perform finite element based crack growth analyses. For fatigue lives calculations, the effective cyclic J-integral is employed in a relation similar to the Paris (crack growth) equation. For this purpose, a specific code was written for the determination of the effective cyclic J-integral for various lifetime relevant crack lengths. The effects of welding residual stresses on the crack driving force and the calculated fatigue lives are investigated. Results reveal that the influence of residual stresses can be neglected only for large load amplitudes. Finally, the predicted fatigue lives are compared with experimental data: a good accordance between both results is achieved.

Fatigue Damage Analysis on Crack Growth and Fatigue Life of Welded Bridge Members with Initial Crack

2006 ◽  
Vol 324-325 ◽  
pp. 251-254 ◽  
Author(s):  
Tai Quan Zhou ◽  
Tommy Hung Tin Chan ◽  
Yuan Hua
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Fatigue Damage ◽  
Initial Crack ◽  
Traffic Loading

The behavior of crack growth with a view to fatigue damage accumulation on the tip of cracks is discussed. Fatigue life of welded components with initial crack in bridges under traffic loading is investigated. The study is presented in two parts. Firstly, a new model of fatigue crack growth for welded bridge member under traffic loading is presented. And the calculate method of the stress intensity factor necessary for evaluation of the fatigue life of welded bridge members with cracks is discussed. Based on the concept of continuum damage accumulated on the tip of fatigue cracks, the fatigue damage law suitable for steel bridge member under traffic loading is modified to consider the crack growth. The proposed fatigue crack growth can describe the relationship between the cracking count rate and the effective stress intensity factor. The proposed fatigue crack growth model is then applied to calculate the crack growth and the fatigue life of two types of welded components with fatigue experimental results. The stress intensity factors are modified by the factor of geometric shape for the welded components in order to reflect the influence of the welding type and geometry on the stress intensity factor. The calculated and measured fatigue lives are generally in good agreement, at some of the initial conditions of cracking, for a welded component widely used in steel bridges.

scholarly journals Prediction of Corrosive Fatigue Life of Submarine Pipelines of API 5L X56 Steel Materials

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1031 ◽  
Author(s):  
Xudong Gao ◽  
Yongbo Shao ◽  
Liyuan Xie ◽  
Yamin Wang ◽  
Dongping Yang
Keyword(s):  
Growth Rate ◽  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Shape Factor ◽  
Bohai Sea ◽  
Paris Law

Corrosive fatigue failure of submarine pipelines is very common because the pipeline is immersed in a sea environment. In Bohai sea, many old pipelines are made of API 5L X56 steel materials, and it is necessary to provide an accurate method for predicting the residual life of these pipelines. As Paris law has been proven to be reliable in predicting the fatigue crack growth in metal materials, the two constants in Paris law for API 5L X56 steel materials are obtained by using a new proposed shape factor based on the analysis of experimental data measured from fatigue tests on compact tension specimens immersed in the water of Bohai sea. The results of the newly proposed shape factor show that, for a given stress intensity factor range (ΔK), the fatigue crack growth rate (da/dN) in seawater is 1.6 times of that that in air. With the increase of fatigue crack growth rate, the influence of seawater on corrosive fatigue decreases gradually. Thereafter, a finite element model for analyzing the stress intensity factor of fatigue crack in pipelines is built, and the corrosive fatigue life of a submarine pipeline is then predicted according to the Paris law. To verify the presented method, the fatigue crack growth (FCG) behavior of an API 5L X56 pipeline with an initial crack under cyclic load is tested. Comparison between the prediction and the tested result indicates that the presented method is effective in evaluating the corrosive fatigue life of API 5L X56 pipelines.

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