Fretting fatigue crack initiation behavior of titanium alloy, ti6al4v was investigated by using different geometries of the fretting pad. Fretting induced fracture of coupling driven shafts james s. Several studies have been conducted on the fretting fatigue limit characteristics of inconel alloy tube material used in steam generators of. The mechanical performances of welded joints were obtained using uniaxial tensile and forcecontrolled constant amplitude axial fatigue tests. Considering that the fretting contact region has a high stress gradient along.
By using the crack analogue model of rigid flatended contact, crack initiation inf,in fretting fatigue is analyzed. While there is still a debate on the proportion of life time taken by these two phases, most of the. Experimental and numerical investigation of fretting fatigue crack initiation abdelwaheb ferjaoui supervisor. Fretting damage influence of the fatigue crack initiation and growth. Crack initiation is the forming of a crack and crack propagation is when the crack grows away from its initiation site. Experimental and numerical investigation of fretting. Fretting fatigue crack initiation and propagation behavior of inconel. The crack initiation angle in general decreases with increase in coefficient of friction at the interface. Numerical modelling of fretting fatigue crack initiation. Crack path prediction under fretting fatiguea theoretical and. For estimation of life in fretting fatigue problems the complete process is usually divided in two phases, namely, crack initiation and crack propagation. Analysis of crack initiation in fretting fatigue specimen. This is done by means of an experimental set up and.
Crack path prediction under fretting fatiguea theoretical. Fretting is caused by small relative movement between connected parts and fatigue is due to alter. The effect of interferencefit on fretting fatigue crack. In this study, crack growth tests of fretting fatigue are conducted, and the characteristics of fatigue crack initiation and propagation are analyzed on inconel 690 alloy. A fretting fatigue failure scenario can be explained by accumulation of damage, which leads to formation of initial macrocracks at the contact interface and. The coefficient of friction at the edge of contact which characterizes the. The aim of this work is to study the initiation and propagation of fatigue cracks during fretting tests in partial slip conditions, and to compare the fretting fatigue behaviour to conventional. In order to predict fretting fatigue crack initiation lifetime, many researchers have dealt with stress or strain at a point, the value of parameter at a point or the stress or parameter at some distance beneath the contact surface critical distance approach or an average value over some surface area or volume. It was found that the improvement of the fatigue crack initiation life was directly related to the magnitude of residual stress. Prediction of fretting fatigue crack initiation and propagation lifetime. Abstract fretting fatigue crack initiation in titanium alloy, ti. Fretting fatigue crack initiation in titanium alloy, ti.
Prediction of crack initiation in fretting problem l. Effect of understress on fretting fatigue crack initiation. By using the crack analogue model of rigid flatended contact, crack initiation in fretting fatigue is analyzed. Predicting structural life under fretting fatigue loading conditions is a complex analysis requirement that cannot be performed using simplified methods. Features of fretting fatigue strengthlife and its mechanical considerations t. Yue1 1ghent university, laboratory soete, ghent, belgium abstract. Issues such as crack initiation location and crack growth life under frictional contact require coupling the contact mechanics with.
While on the subject of dislocations, it is appropriate to briefly discuss fatigue. Combination of fatigue due to bulk stress which cause gross alternating movement, and microsliding due to fretting. Methods for characterising crack initiation using asymptotic analysis are discussed, together with short. Fretting fatigue properties and detection of crack initiation of inconel alloy. Prediction of fatigue crack initiation in complete contact. Zairyojournal of the society of materials science, japan, 50 7, 758763. The life of a fatigue crack has two parts, initiation and propagation. Therefore, both crack initiation and propagation phases are important in analyzing fretting fatigue problem. The role of interference ratio was investigated alongside friction coefficient through finite element. To investigate the fretting fatigue mechanism in the threaded connection, a fundamental fretting fatigue test was conducted. The problems of fretting fatigue crack initiation in a pressfitted axle have not been completely solved even though uptodate fatigue design methods are employed. An analytical simulation of fretting fatigue crack propagation has.
In each case fatiguecrack initiation has been examined and related to the fretting damage on the surface of the specimen, and the microstructure of. Finite element simulation of phase difference effects on. Sem scanning electron microscope was then employed to observe fatigue crack surfaces and identify crack initiation, crack propagation, and transient fracture zones. Fretting fatigue strength and life estimation considering. It is a cumulative effect that causes a material to fail after repeated applications of stress, none of which exceeds the ultimate tensile strength.
This work aims to investigate the fretting fatigue life and failure mode of steel q235b plates in singlelap bolted joints. Fretting fatigue crack initiation mechanism in ti6al4v. This cited by count includes citations to the following articles in scholar. The experimental work enabled the fretting conditions to be known and the site of initiation and crack trajectory to be viewed. Fretting fatigue crack initiation behavior of ti 6al 4v. Received 2nd june 2012, revised 15 th june 2012, accepted 19 th june 2012 abstract. Prediction of fretting fatigue crack initiation location and direction using cohesive zone model. Citeseerx analysis of fretting fatigue crack initiation. Fretting causes a considerable reduction in fatigue strength.
On crack initiation mechanisms in fretting fatigue. The residual stress relaxation and the contact stress evolution are both considered. However, normal stress on the critical plane also seems to play a role in fretting fatigue life. The fatigue process in metals may induce the generation of surface and subsurface cracks, which after a critical number of cycles results in a severe damage, such as large fragments leaving the surface1,2. Initiation and propagation behavior of fretting fatigue cracks t. The current work focuses on the study of fretting fatigue crack formation in common 6xxx aluminum alloys, used in land transportation equipments, and the determination of the characteristic crack initiation sites by means of both experimental and numerical methods. In general, fretting fatigue failure process can be divided into two main portions, namely crack initiation and crack propagation. Read fretting fatigue crack initiation behavior using process volume approach and finite element analysis, tribology international on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
In fretting fatigue there are two major factors which must be studied the first is crack initiation and the second is crack propagation. Citeseerx document details isaac councill, lee giles, pradeep teregowda. Fatigue wear is a type of wear where a number of cycles is needed to generate debris. Fretting is a considerable failure mode in many mechanical components, in which two contact surfaces undergo a small relative fluctuating motion due to cyclic loading. Inservice fretting damage influenced the fatigue crack origination in materials under the damaged surface for the veryhighcycle fatigue. Fatigue is one of the primary reasons for the failure of structural components. Microstructural and fractographic analyses were conducted to document the influence of the. It has been identified as the cause of serious damage in dovetail connections of aerospace engines.
Study of fretting fatigue crack initiation for riveted al. Corrosionpedia explains crack initiation in materials science, fatigue is the weakening of a material. Sanjay and pathak sunil swami vivekanand college of engineering, indore mp, india available online at. The crack initiation angle experimentally obtained through the scanning electron micrographs of the failed fretting fatigue specimens compare well with the predicted crack initiation angle using the strain energy density criteria.
In fretting fatigue experiments, it is very difficult to detect the crack initiation phase. In this paper, the direction of crack growth under fretting fatigue loading is studied through an experimental and theoretical approach. Analysis of crack initiation in fretting fatigue specimen purkar t. Fretting induced fracture of coupling driven shafts. Mendeley data fatigue performances of fsw and gmaw. This article focuses on measures to avoid or minimize crack initiation and fretting fatigue. Analysis of fretting fatigue crack initiation in a riveted.
Based on the existing experiment results, the fretting fatigue contact geometry of a riveted two aluminum specimen was studied using the finite element method. Fretting fatigue properties and detection of crack. Numerieke modelleringstechnieken voor scheurinitiatie en propagatie in frettingvermoeiing. The fatigue properties of gas metal arc welded and friction stir welded assemblies made of aluminum alloy 6061t6 structural extrusions were examined. Fretting fatigue crack initiation and propagation tribos. Fretting fatigue fatigue and fracture handbooks asm. Fretting fatigue strength and life estimation considering the fretting wear process t.
The coefficient of friction at the edge of contact, which characterizes the asymptotic stress field, is considered as the primary controlling parameter in the process. Prediction of fretting fatigue crack initiation and. Prediction of fretting fatigue crack initiation location. The contact stress fields of the inner and outer contact edges on the two specimens up and down surface under different contact friction coefficient and the.
An experimental and theoretical study, international journal of fatigue on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Fretting fatigue crack initiation lifetime predictor tool. By comparing with the experimental results, it was found that the initial fatigue crack should occur at the point of maximum shear stress range near the contact edge, and would propagate in the direction of maximum tangential stress range. Critical values of slip amplitude were found for which fretting fatigue crack propagation is high pel lerin, 1990. There are many factors influencing fretting fatigue, including all kinds of fretting parameters, displacement amplitude and environmental factors etc 58, the driving force of crack initiation is micro power, including tangential force caused by surface friction, the tensile. Also, plain fatigue crack growth tests are performed on the same material, and the results are compared with those of fretting fatigue crack growth tests. So, the prediction of fretting fatigue crack initiation and crack propagation. Fretting fatigue crack initiation and propagation behavior. Although there is ample descriptive material on the mechanism and examples of fretting, there is limited availability of generalized techniques or modeling methodology for the prediction of crack initiation due to fretting. Fretting fatigue is the phenomenon of crack initiation and propagation from the region of stress concentration in reciprocating frictional contacts. From these comparisons, fretting fatigue crack initiation mechanism in the tested titanium alloy appears to be governed by shear stress on the critical plane. Observations and analysis of fretting fatigue crack. This study analyzes the effects of shot peening on the crack initiation behavior under fretting loading by using a numerical method.
The crack initiation life is predicted by the critical plane smithwatsontopper swt model. Tongyan yue abstract this article gives an insight in fretting fatigue crack initiation. Fretting fatigue crack initiation characteristics are very difficult to detect because damages such as microcracks are always hidden between two contact surfaces. At relatively lower stress amplitude region, the crack originated at the middle of the thread root because of fretting fatigue. Prevention of fretting fatigue in the design process is essential. The ones marked may be different from the article in the profile. Nishimura department of mechanical and system engineering, gifu university, gifu, japan abstract the fretting fatigue process has many features such as early stage crack initiation. Prediction of fretting fatigue crack initiation and propagation lifetime for cylindrical contact configuration. The importance of the size effect is highlighted and an analogy is made between fretting and notch fatigue.
There is some question as to what actually separates initiation. The effect of interferencefit on fretting fatigue crack initiation and k was studied numerically for available experimental results in a single pinned plate in alalloy 7075t6. The objective of the present study is to clarify the effect of understress on fretting fatigue crack initiation behavior in the pressfitted axle. Ten specimens were prepared and tested to fit the sn curve. Specimens were examined to determine the crack initiation location and the crack angle orientation along the contact surface.
Experimental and numerical investigations of fretting. Fretting is a special wear process that occurs at the contact area between two materials under load and subject to slight relative movement by vibration or some other force. In this paper, finite element modeling is used in conjunction with smith watson topper swt criterion to estimate crack initiation in fretting. And fretting fatigue life is dominated by the propagation process of small cracks.