Part of the problem for fatigue and fatiguecrack propagation is that these behaviors are influenced by a wide range of parameters that include cyclic stress. The fatigue crack growth rates for al and ti are much more rapid than steel for a given. Cracks will not grow unless the initial size, ai, and stress range. On the other hand, we have also monitored crack growth in slowly rotating process equipment shafts that has taken many months and more than 10,000,000 cycles to fail. Dotfaaar0515 fatigue crack growth database for damage. The discussion focusses on an examination of whether crack growth data might provide an alternative means of predicting knockdown factors i. Crack growth simulations under accelerated and normal service conditions will thus be readily. Introduction there have been numerous research studies on the characterization of fatigue crack growth using fracture mechanics since the work of paris and colleagues 1 in the early 1960s. Fatigue analysis of the piston rod in a kaplan turbine based on crack propagation under unsteady hydraulic loads.
About this master class mc118 nuclear plants in the united states were originally licensed by the nuclear regulatory commission nrc. The fatigue crack growth analysis is an important part of the flaw acceptance. Recent advances in fatigue crack growth modeling 167 1. Paris law also known as the pariserdogan equation is a crack growth equation that gives the rate of growth of a fatigue crack. Safety and reliability assessment of fracture failure under the action of extreme loads sea ice, waves d. Reaching total fracture under cyclic loading involves both fatiguecrack initiation and propagation. Itis concluded that dynamic effects ofreactor coolant system primary loop pipe breaks need not be considered in the structural design basis of the turkey point units 3 and 4 nuclear power plants. Analyses of fatigue crack growth databases for use in a damage tolerance approach for aircraft propellers and rotorcraft. Finally, fatigue crack growth was shown not to be an issue for the primary loops. The structural integrity assessment includes fatigue crack growth analysis.
Evaluation of the testing and analysis methods in astm e276010 creep fatigue crack growth testing standard for a range of steels a. These cracks may not only affect the seismic response but also grow and break through causing loss of coolant. This approach to allowing and accounting for a safe level of crack growth during the operation of the system is referred to as damagetolerant design. Fundamentals of and applications to fatigue analysis on the web. The rates of fatiguecrack growth were determined as a function. Economic considerations have made it desirable to extend the 30 to 40 year operating life of power plants by another 10 to 20 years. However, fatigue crack growth analysis for nibase alloy is impossible since the fatigue crack growth rate curves in air and the bwr environment are not prescribed yet in the jsme ffs code. Analysis on crack fatigue growth calculation for nuclear power. However, when normalized by youngs modulus all metals exhibit. For some components the crack propagation life is neglected in design because stress levels are high, andor the critical flaw size small. Nuclear regulatory commission 400a office of nuclear regulatory research. To understand the influence of temperature on the rate of fatiguecrack growth in highstrength metal alloys, constantloadamplitude fatiguecrack grouth experiments were carried out using a iinchthick 6. Stripyield modeling uses analytical formulations for the stress intensity factors and crack opening profiles given different specimen configuration.
K \displaystyle k characterises the load around a crack tip and the rate of crack growth is experimentally shown to be a function of the range of stress intensity. Fatigue crack growth database for damage tolerance analysis august 2005 final report this document is available to the u. Stp415 fatigue crack propagation astm international. However, in most cases, flaws will becomecritical by growing from smaller flaws or from unflawed areas of stress concentration. A guideline for the assessment of uniaxial creep and creep. When defects are detected by inservice inspections of the nuclear power plants in japan, allowable flaws are evaluated according to the rules on fitnessforservice for nuclear power plants of japan society of mechanical engineers jsme maintenance rules. The analysis of fatigue crack growth relies on the concepts of fracture mechanics which are discussed on this page. The piping systems may have some defects caused by fatigue, stress corrosion cracking, etc. Analysis on crack fatigue growth calculation for nuclear power plant in service inspection. If you are not familiar with fracture mechanics, it is recommended that you read that page before proceeding. Fracture mechanics fatigue crack growth analysis is widely used in the engineering critical assessment of welded structures. Therefore, an evaluation method needs to be developed to predict crack growth behavior under seismic excitation.
Fatigue analysis of the piston rod in a kaplan turbine. Improvement and validation of the unigrow fatigue crack. Environmentally assisted fatigue analysis, monitoring and. Root cause failure analysis understanding mechanical. May 23, 20 fatigue crack growth simulation fraaz tahir. This fatigue crack can slowly work its way across a part until a fracture occurs. Part 1, summarized here, involved examining all high temperature creep fatigue crack growth codes being used today and from these, the task objective was to choose a methodology that is appropriate for possible implementation within nh. Fatigue crack growth rate model for metallic alloys r. This is analogous to the fatigue limit in traditional fatigue analysis. Pdf analysis of environmental fatigue crack growth behavior of. Investigation of cyclic crack growth transitional behavior. Nov 18, 2017 this project was created with explain everything interactive whiteboard for ipad. Characterization of creepfatigue crack growth in alloy 709. Paper to be presented at thetenth european conference on.
Crack growth due to cyclic loading is called fatigue crack growth and is the focus of this page. Fatigue crack growth rates for nickel base alloys in air. To make life estimations for fatigue crack growth and damage tolerant design, the following information are often needed. Dotfaaar0749 analyses of fatigue crack growth databases. Research result shows that creep phenomenon is responsible for maximum crack growth. Nevertheless, in its previous form the unigrow model had several serious limitations.
Fracture mechanics and fatigue crack growth analysis software. The data also showed that the fatiguecrack growth per cycle accelerated for all the steels, and that this transition from the above relationships to increased rates occurred when the crackopeningdisplacement range, which is a measure of the strain range. This paper presents an overview of hightemperature. Utilization of nondestructive methods for monitoring fatigue. Region iii is characterized by rapid, unstable crack growth. In order to study the mechanism of creep fatigue crack growth of g115, and to research the change of creep damage and fatigue damage and the interaction between the two factors during the crack growth process, the method of finite element analysis was used though the commercial software abaqus. Typically, a cracked test specimen is subjected to a constant amplitude cyclic load with a remote stress range given by. Fatigue crack growth studies on power plant piping materials under corrosive environment. This package developed and distributed by esa consists of various analysis tools used to generate load and stress spectra, perform fracture mechanics analysis, generate stress intensity factor solutions and to perform fatigue analysis. This project was created with explain everything interactive whiteboard for ipad. In this study, the fatigue crack growth behavior of type 347 stainless steel ss used in pressurizer surge line in korea standard nuclear power plant was. Conventional fatigue analysis with sn curve method.
K region i, crack propagation is difficult to predict since it depends on microstructure and flow properties of the material here, the growth may even come to an arrest crack growth rate is sensitive to the size of the grains. The conclusion is that the crack growth rate according to the similarity concept must be a function of k min and k max of the load cycle. Nlregcr6674 pnnl227 fatigue analysis of components for 60year plant life pacific northwest national laboratory u. A practical, case studybased training program led by. Apr 17, 20 the esacrack package is the structural analysis software utilized by esa for damage tolerance evaluation of spaceflight structures.
Creep crack growth in power plant materials springerlink. At high stress intensities, crack growth rates are extremely high and little fatigue life is involved. Fatigue analysis of the piston rod in a kaplan turbine based. These fluctuating loads are called fatigue loads, and when the fatigue strength is exceeded, a crack can develop. Following this work, in the early 1970s, elber 23 pioneered the concept of premature. Referenced papers involve the extended finite element method, aerospace structures and fatigue crack growth, or any combination thereof. Specimen geometrys used in fatigue crack closure research. On the finite element analysis of fatigue crack closure. Nasgrofracture mechanics and fatigue crack growth analysis software 2010.
Nikbin 41 characterizations of creep fatigue crack initiation and growth life for p92 using circular notched round bar specimen. In this case, fatigue crack growth analysis is key to safe operation of the system. Xfem based analysis of fatigue crack growth in damaged. A crack growth equation is used for calculating the size of a fatigue crack growing from cyclic loads. Fatigue crack growth studies on power plant piping materials. Introduction the degradation of mechanical properties of a reactor pressure vessel material, which determine. Typical constant amplitude crack growth data are shown in figure 1. Xfem based analysis of fatigue crack growth in damaged wingfuselage attachment lug. Creep crack growth in power plant materials indian academy of. Analysis of fatiguecreep crack growth in the superheater. Crack growth at elevated temperatures is an important consideration in estimating the remaining life, determining operating conditions and deciding inspection criteria and intervals for power plant materials. Department of transportation federal aviation administration. Fatigue creep crack growth was achieved using crack growth rules and the remaining lifetime was obtained.
Creepfatigue crack growth behavior of g115 steel at 650 c. Application of a double linear damage rule to cumulative fatigue. Significance of fatigue cracks in microrange and macrorange. A crack growth equation can be used to ensure safety, both in the design phase and during operation, by predicting the size of cracks. As indicated in these equations, the fatiguecrackgrowth rates were higher for martensitic steels than for ferritepearlite steels. Good practices for assessment deterministic evaluation for the integrity of reactor pressure vessel. Environmentally assisted fatigue analysis, monitoring and management of nuclear plant components. Stochastic fatigue crack growth analysis for space system reliability. Safety and reliability assessment of fatigue failure based on the sn curve. This paper compares the fatigue performance results of sour fatigue crack growth rate tests on cmn pipeline steel with sour fatigue endurance data. For fatigue, fatiguecrack propagation, and fracture data, however, design allowable values are usually not available and the data are presented in terms of typical or average values. This thesis is on fatigue crack growth experiments and assessments of fatigue crack growth rates.
Citeseerx fatigue crack growth rates for nickel base alloys. This type of growth occurs by fatigue processes during cyclic loading of the structure. When defects are detected by inservice inspections of the nuclear power plants in japan, allowable flaws are evaluated according to the rules on fitnessforservice for nuclear power plants of japan society of mechanical engineers jsme maintenance rules 1. To obtain a fatigue crack growth curve, it is necessary to establish reliable fatigue crack growth rate data. Fatigue crack growth life analysis with the method of fracture mechanics. Recent advances in fatigue crack growth modeling 169 s a b 6 9 ii figure 1. The applicable fatigue crack growth rate expression. The crack growth rate accelerates as the maximum stress intensity factor approaches the fracture toughness of the material.
The effect of grain size on fatigue crack propagation in copper. As superheater header is exposed to high pressure and temperature in power plant boilers, it is one of the most sensitive parts in a power plant. Fatigue and crack propagation life mechanical engineering. Stp 1539 creepfatigue interactions astm international. The fatigue crack growth analysis is an important part of the flaw acceptance evaluation. Failure and fatigue crack propagation analysis with marc. Moreover, always according to fracture mechanics, when a crack already present into the material starts growing, it means that the fatigue crack growth threshold dthi, dthii, or dthiii, which is a material property, is exceeded. A model has been created to allow the quantitative estimation of the fatigue crack growth rate in steels as a function of mechanical properties, testspecimen characteristics, stressintensity range and testfrequency. Root cause failure analysis understanding mechanical failures. Analysis and predictions 215 because the same k cycle is applicable. Investigation of fatigue crack growth in a power plant steel under.
Fatigue crack propagation in some ultrahighstrength steels. The collection of data, their analysis and the interpretation of. Fatiguecrack propagation in steels of various yield. Some systems may be designed to allow for some crack growth before repair and replacement.
226 1030 301 1393 943 661 1245 453 312 1251 1665 615 165 61 1279 1051 29 1455 646 1113 747 971 1540 1147 1109 196 431 1183 1041 245 1334 1056 1488 12 251 1265 1171 272 81