Recent international journal of fatigue articles elsevier. Citescore values are based on citation counts in a given year e. Founded in 1904 and headquartered in farmington hills, michigan, usa, the american concrete institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensusbased standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design. Mechanism of fatiguecrack growth under compressive. In general crack is thought to close under compressive stress condition. Under such conditions the rate of fatigue crack growth per cycle, dadn, is governed by the stress intensity factor range. Fatigue properties of plain concrete under triaxial. In materials science, fatigue is the weakening of a material caused by cyclic loading that results in progressive and localised structural damage and the growth of cracks. This page provides the chapter on fatigue crack growth and life prediction from. They conclude that it is not possible to describe crack growth in terms of the theoretical stress at the tip of the crack since the crack length affects the rate of growth. Crack face contact not modelled on first node release, hence overclosure, but. Fatigue crack propagation resistance of highly crosslinked.
The above discussed fatigue crack growth models can be used to predict the crack growth due to the application of constant amplitude loading which occur rarely in real loading scenario. Shot peening effect on fatigue crack repaired weldments. Fatigue crack propagation rate an overview sciencedirect topics. When steels compressive strength is exceeded, the steel will fail in a brittle fashion. Fatigue tests were performed on plain concrete under triaxial tension compressioncompression tcc cyclic loading with constant and variable amplitude using a large multiaxial machine. Plasticity originating from the crack tip does not induce crack closure and. A crack growth equation is used for calculating the size of a fatigue crack growing from cyclic loads. Mcclung and sehitoglu 25 also published the only result known to the authors on short crack closure under variable amplitude loading. This project was created with explain everything interactive whiteboard for ipad. Astm e64795a 8 denotes that only the tension loading has effect on the fatigue crack propagation and believes that the crack growth rate under stress rate r0 is the same as the one under stress. The study of fatigue crack propagation in metals has been of foremost importance in regards to how well engineering structures withstand the complex loading conditions that they often encounter. The irreversible deformation or induced compressive strains evolve.
A crack growth equation can be used to ensure safety, both in the design phase and during operation, by predicting the size of cracks. Solid mechanics fatigue crack propagation anders ekberg 2 20 stress intensity factors and fracture in static loading, the stress intensity factor for a small crack in a large specimen can be expressed as kf ai. Analysis of fatigue crack growth retardation due to. 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, residual concrete strength, steel crack growth, fatigue secant modulus, damage, strain evolution. Abstractthe effect of the load ratio, r, on fatigue crack growth behaviour is. Box 116, wuxi, china abstract load cycle interactions can have a very signi. Once a fatigue crack has initiated, each loading cycle will grow the crack a small amount, typically producing striations on some parts of the fracture surface. Following this work, in the early 1970s, elber 23 pioneered the concept of premature. The crack will continue to grow until it reaches a critical. Fatigue crack propagation tests under random loading were conducted by kikukawa et al. It may be recalled that the general principle of mechanically induced residual stresses is that tensile yielding under an applied load results in compressive residual stresses when the load.
Cyclic loading is applied in the form of a stress history. Why is the compressive fatigue strength of a material more. Crack growth under compression may cause a lot of problems. Discerning the fatigue crack growth behavior of api x65 steels. Static mode i was superimposed as a tensile load on fatigue loading with mean stress equal to zero, thus resulting in rvalues of 1, 0. Finite element analysis of the effect of the compressive. Crack growth due to cyclic loading is called fatigue crack growth and is the. The fatigue life of a component can be expressed as the number of loading cycles required to initiate a fatigue crack and to propagate the crack to critical size. Region ii encompasses data where the rate of crack growth changes roughly linearly with a change in stress intensity fluctuation.
The periodic inspectionassessment cycle can lead to the implementation of a fatigue crack repair by crack removal. Logarithmic scales are used because fatigue crack growth rates can vary from millions of cycles to advance a crack by one millimeter to only tens of cycles to grow the same distance just before failure. Fatigue crack growth in polymers subjected to fully. Fatigue tests were performed on plain concrete under triaxial tensioncompressioncompression tcc cyclic loading with constant and variable amplitude using a large multiaxial machine. Gamma irradiation induced crosslinking is associated with a reduction in the fatigue crack propagation resistance that is related to the irradiation dose. Analysis of fatigue crack growth under compression. The influence of static mode i and static mode ii loading on mode i fatigue crack growth has been studied with 12 weight % chromium steel. Results at 1,300c indicate that hexoloy fails as it does as 25c, i. Therefore, it can be said that fatigue failure occurs in three stages crack initiation. A seemingly puzzling type of fatigue crack is one that grows in a part, or a region of a part, that is stressed in compression when the part is under load. This is the current mechanistic understanding of the crack growth behavior under compression loading.
K,a a,xma,x dx 6 where ma,x is the weight function. The conclusion is that both models behave well only under special conditions. Concrete elements degrade due to the continuous application of compressive fatigue loads. The crack growth rate is calculated at each stress cycle, and the crack is grown until failure. To improve the fatigue performance of the crack repair, residual compressive stresses induced by peening can be considered. Under tension compression fatigue loading, experimental test results have also shown that the fatigue crack closure concept cannot explain the fatigue crack propagation behaviour and the materials plastic response is responsible for the increased fatigue crack growth rate under a negative applied stress ratio compared to under a tension.
The compressive stress effect on fatigue crack growth. In this paper, elasticplastic finite element analysis has been performed in order to obtain the fatigue crack tip parameters under tensioncompression loading. Fatigue crack growth due to overloads in plain concrete. Two centrecracked highstrength aluminum alloy with a crack length of 2mm under different tensioncompression loading are analyzed. Compressive stress is important in the forging, stamping, coining, and cold heading industries as compression stress is used to change the shape of the product, unlike machining, where the shape is made by subtracting material by some means of stock removal.
Many studies have been carried out to investigate fatigue crack propagation due to a single or mixedmode only. Fatigue crack growth under compressive loading 183 deduction of residual stress from measured growth rates the residual stress intensity factor, ks, may be calculated from the residual stress profile, using bueckners principle, 14. When the stress ratio r is negative, there is a compressive component to the loading. The applicable fatigue crack growth rate expression. Recent advances in fatigue crack growth modeling 167 1. They showed that a crack is still open at the minimum stress of small cycles following a large one although the minimum stress of the small cycles is lower than the crack opening stress produced by the large cycle. A typical fatigue crack growth experiment result is shown in the fatigue crack growth rates graph, where log. Fatigue crack propagation an overview sciencedirect topics. Fatigue crack propagation tests in the paris region were performed in order to get compressive loading effect on fatigue crack growth at negative stress ratio r in 2a12 aluminum alloy. This paper explores the strain response and damage behavior of concrete under uniaxial compression.
Fracture mechanics calculations are required to validate the safety level defined in design codes to prevent a fatigue failure. The normalized equivalent stress intensity factor solution can be used for estimation of fatigue lives in a fatigue crack growth model under mixed mode. Fatigue of concrete under uniaxial compression cyclic loading. This curve may be divided into three regions, which are discussed in the following sections. Schematic showing the typical variation of crack length, measured from the notchtip, as a function of compression cycles. This paper presents the effect of sequence loading on fatigue crack growth of api. This calculator allows for fatigue crack growth analysis of a cracked part. Region i is the fatigue threshold region where the dk is too low to propagate a crack. Fatigue and fatigue crack growth behavior of tool steel. Understanding compressive stress in steel speaking of. This intermittent growth process in cyclic compression is analogous to the formation of discontinuous growth bands during the tension fatigue of many crazeable polymers.
Imig experimental considerations crack growth analysis results and discussion concluding remarks 236 237 240 243 247 247 251 252 255 259 263 life prediction and applications prediction of fatigue crack growth under irregular loadingud. Fatigue crack growth under combined mode i and mode ii loading. Inthis study, fatigue andfatigue crack growth behavior of krupp 2510 steel was investigated in laboratory environment. Moreover, energybased parameters need to be taken into account to analyse the fatigue crack growth of concrete as these are more appropriate for quasibrittle.
Fatigue lives of rotorcraft components are generally spent initiating small fatigue cracks that propagate slowly under nearthreshold crack tip loading conditions. In general, a crack does not grow under compressioncompression loads. Abstract in this literature survey report an overview of di. Fatigue crack growth threshold testing of metallic. This page provides instructions on the use of the fatigue crack growth calculator. A specimen with a crack shaped like a thin long defect with parallel edges and a rounded tip of finite radius is considered. Basedonthe fatigue crack growth curve obtained, fatigue life of round bar specimens under constant amplitude loading was predicted.
For these values, fatigue crack growth curves were determined in the threshold regime with. The exhaustion of the neartip residual tensile field and the increase in the level of crack closure with increasing crack length cause the fatigue crack to arrest. Cyclic tensile compression loading is the most critical fatigue loading. Crack initiation crack propagation and fracture due to unstable crack growth. Fatigue of concrete under uniaxial compression cyclic loading authors. The growth of fatigue cracks can result in catastrophic failure, particularly in the case of aircraft. Conse quently, prediction of crack growth at these lower stress levels may be erroneous if the calculations are based on constantamplitude data. Fatigue crack growth with overload under spectrum loading x. Fatigue crack growth with overload under spectrum loading. Crack growth does not typically occur for stress intensity ranges below the. References appendices aindustry survey results and priority list b fatigue crack growth data and curve fits c fatigue crack growth database software operation.
Fatigue crack growth how is fatigue crack growth abbreviated. Preliminary simulation of fatigue crack growth under smallscale yielding dk15 mpa rootm, r0. The analysis shows that the compressive loading has a significant contribution towards the crack tip. But, if there is a tensile residual stress field in the specimen, the crack can open and grow to a considerable length. Experimental results show that, under constant amplitude fatigue loads, the development of residual strain in the fatigue loading direction depends mostly on the lateral compressive stress ratio and is nearly.
To make life estimations for fatigue crack growth and damage tolerant design, the following information are often needed. When the specimen is subjected to compressive cyclic loads, the stresses in zones adjacent to the crack tip vary according to a signvariable cycle because of plastic strains occurring at the crack tip. Fatigue crack growth and arrest under highcycle thermal. In order to understand the fatigue crack propagation behaviour of materials. Insert shows the sample and the loading cycle in compression load. Research on fatigue crack propagation of conventional and highly crosslinked uhmwpes has confirmed a detrimental effect of increasing radiationcrosslinking levels on the resistance to crack inception and crack growth 5, 33, 35, 4042.
Fatigue crack growth under compressive loading sciencedirect. Particular cmphasis is placed on compressive excursions, i. The fatigue crack propagation behavior of many materials can be divided into three regions as shown in the image. Concrete damage under fatigue loading in uniaxial compression. Fatigue, plain concrete, cyclic loading, modified maekawa concrete. Influence of load ratio r on fatiguecrack propagation in 40 sa5423 steel. Mode i fatigue crack growth under biaxial loading r. This paper describes a possible fatigue crack growth even under fully compressive stresses.