Download or read book An Investigation of Fretting Fatigue Crack Initiation Behavior of the Titanium Alloy Ti 6A1 4V written by Christopher Douglas Lykins and published by . This book was released on 1999 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fretting Fatigue Crack Initiation Behavior of Ti 6Al 4V written by SA. Namjoshi and published by . This book was released on 2003 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fretting fatigue crack initiation behavior of titanium alloy, Ti-6Al-4V was investigated by using different geometries of the fretting pad. Specimens were examined to determine the crack initiation location and the crack angle orientation along the contact surface. Fretting fatigue experiments were analyzed with the finite element analysis. Several critical plane based parameters were used to predict the number of cycles to fretting fatigue crack initiation, crack initiation location and crack orientation angle along the contact surface. These predictions were compared with the experimental counterparts to study the role of normal and shear stresses on the critical plane in order to characterize fretting fatigue crack initiation behavior. From these comparisons, the fretting fatigue crack initiation mechanism in the tested titanium alloy appears to be governed by the shear stress on the critical plane. However, the role of normal stress on the critical plane at present appears to be unclear.
Download or read book Fretting Fatigue Behavior of a Titanium Alloy Ti 6AL 4V at Elevated Temperature written by Onder Sahan and published by . This book was released on 2002-03-01 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this research is to investigate the fretting fatigue behavior of the titanium alloy Ti-6Al-4V at elevated temperature is investigated. Fretting and plain fatigue experiments are conducted at 260 . Crack initiation location and crack initiation orientation is measured and fretting and plain fatigue life data of the specimens from these tests are obtained. Fatigue parameters capable of predicting the number of cycles to specimen failure, the crack location and the crack orientation along the contact surface are analyzed. The parameters are calculated by using the computed stresses and strains obtained from the finite element analysis. The mechanisms responsible for the fretting fatigue crack initiation are determined. The effect of elevated temperature is examined by comparing room and elevated temperature fretting and plain fatigue data.
Download or read book Fretting Fatigue Crack Nucleation Criterion for Ti 6Al 4V written by S. Mall and published by . This book was released on 2003 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fretting fatigue crack nucleation behavior in titanium alloy Ti-6A1-4V was investigated by using two contact configurations: cylinder or flat with rounded edge pad on flat substrate. Both experiments and finite element analyses were conducted. A muiltiaxial fatigue parameter involving shear stress and normal stress on the critical plane was examined about its capability to predict the number of cycles to fretting fatigue crack initiation, crack initiation location and crack orientation angle along the contact surface. Also, the effects of two factors, crack nucleation process volume and coefficient of friction, on predictions were investigated.
Download or read book Investigation Into Fretting Fatigue Under Cyclic Contact Load and in Conjunction with Plain Fatigue of Titanium Alloy written by Abdulla Al-Noaimi and published by . This book was released on 2008 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Microplasticity and Fatigue Crack Initiation in Titanium Alloy Ti 6Al 4v written by Philip Dilan Littlewood and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Titanium alloys are often used in aerospace applications in which they are subjected to cyclic loading. It has been found that the addition of a hold at peak load greatly decreases the fatigue life of these alloys. This is referred to as "cold-dwell fatigue". In order to improve component life prediction, it is desirable to understand the mechanisms leading to initiation of fatigue cracks. Due to the high anisotropy of a-titanium, it is expected that deformation on a microstructural scale will he significantly heterogeneous. To understand the process of crack nucleation, the mecha- nisms of this deformation must first he understood. This thesis will present a series of experiments which will attempt to give some insight into this process. Two main lines of inquiry have heen undertaken. The first method uses electron hackscat- tered diffraction (EBSD) to obtain the crystal orientations within a selected region. Optical mi- croscopy and digital image correlation methods were then used to track the accumulation of strain in the region during deformation. Results were obtained for monotonic tension, cyclic fatigue, and cold-dwell fatigue. Behaviour in local strain peaks differed hetween loading modes, hut strain concentrations in the range of 2-4 times mean strain were typical. The second method uses the cross-correlation based EBSD technique developed by Wilkinson et al [1] to derive the dislocation densities present in a crystal. By tracking the changes in dislocation density after different deformation regimes, some insight can be gained into the local deformation processes that produced the dislocation densities. Strong links were found between the local crystallography and inhomogeneities in strain and dislocation density accumulation. In particular, interactions between grains of differing orientations was found to have a strong impact on deformation behaviour. Additionally, a link was found between high strain accumulation and crack initiation in both fatigue and dwell fatigue.
Download or read book Fretting Fatigue written by Steven E. Kinyon and published by ASTM International. This book was released on 2003 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contains 29 contributions drawn from the Third International Symposium on Fretting Fatigue held in Nagaoka, Japan in May 2001. Sections of the volume address fretting wear and crack initiation; fretting fatigue crack and damage; life prediction; fretting fatigue parameter effects; loading condition
Download or read book Fretting Fatigue Characteristics of Titanium Alloy Ti 6Al 4V in Ultra High Cycle Regime written by S. Shirai and published by . This book was released on 2003 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the present study, fretting fatigue behavior of a Ti-6Al-4V alloy under high stress ratios in the ultra high cycle regime (up to 109 cycles) has been investigated. The slope of S-N curve decreased with increasing stress ratio. The slope was steeper in short fatigue life region and became flatter in longer life region. The test results under various stress ratios followed the modified Goodman diagram for both the fatigue strengths defined at 107 cycles and 108 cycles. The so-called non-propagating cracks, which were often observed in steels and aluminum alloys, could not be found in the run-out specimens tested up to 107 cycles. In the further loading cycles up to 109 cycles at the same stress amplitude, no crack initiation and propagation could be observed, which indicated that the conventional fretting fatigue strength defined 107 cycles was still effective at least up to 109 cycles. Different behavior between the titanium alloy used and the other materials mainly results from the different crack initiation behavior.
Download or read book Characterization of Fatigue Crack Initiation and Propagation in Ti 6Al 4V with Electrical Potential Drop Technique written by and published by . This book was released on 1988 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fretting Fatigue Behavior of Shot Peened Ti 6Al 4V and IN100 written by J. L. Ng and published by . This book was released on 2008 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shot-peened titanium alloy Ti-6Al-4V and nickel-based super alloy IN100 were subjected to plain and fretting fatigue under cylinder-on-flat contact condition at room temperature. Measurement of compressive residual surface stress from shot-peening before and after fretting showed relaxation, which was significant in IN100 and near the contact surface. The fretting fatigue life of IN100 did not improve significantly due to shot-peening, while there was considerable improvement for Ti-6Al-4V and relatively less relaxation of the residual surface stress. Further, fretting had a relatively more detrimental effect on the fatigue performance of Ti-6Al-4V than in the case of IN100. A critical plane-based fatigue crack initiation model, a modified shear stress range parameter, was computed from finite element analysis for two levels of residual surface stress relaxation: no relaxation and complete relaxation. This analysis suggested that not only crack initiation but also propagation should be considered to characterize fretting fatigue behavior of shot-peened specimens; however, it showed an appropriate trend with the measured fretting fatigue life and agreement with several other experimental observations.
Download or read book An Investigation of the Propagation Behavior of Fretting Fatigue Cracks in Ti 6Al 4V written by Hassan A. Fadag and published by . This book was released on 2005 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Comparison of Microstructural Effects on Fatigue Crack Initiation and Propagation in Ti 6Al 4V written by G. R. Yoder and published by . This book was released on 1982 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue-crack initiation and propagation studies were conducted on commercial purity (0.20 weight percent interstitial oxygen) Ti-6Al-4V rolled plate, heat treated to produce three differing microstructures. The three heat treatments were an as-received mill anneal (MA), a recrystallization anneal (RA), and a beta anneal (BA). The fatigue-crack propagation results show a distinct ordering of crack growth rate (da/dN) versus stress-intensity range (delta K) curves on the basis of microstructure. The coarse-grained Widmanstatten BA material exhibits the greatest resistance to crack propagation, and the finer-grained MA material offers the least crack propagation resistance. For fatigue-crack initiation, results obtained from blunt-notch WOL-type fracture mechanics specimens reveal a different ordering in relation to microstructure. The MA and RA materials are indistinguishable in their resistance to crack initiation; moreover, their crack initiation resistance is moderately superior to that of the BA material in the low-cycle regime (i.e., less than 100000 cycles to crack initiation). However, at approximately 1000000 cycles to crack initiation, the fatigue resistance of the BA material appears equivalent to that of the MA and RA materials. In the crack initiation specimens, a theoretical stress concentration factor (K(t)) of 4.1 was used. This corresponds to Kt values determined for titanium alloy jet engine components. The influence of surface roughness in the crack initiation region of blunt-notch specimens was examined; no difference in cycles-to-initiation behavior was observed for 16 and 72 micron-in. finishes, regardless of microstructure.
Download or read book The Effects of Slip Character and Crack Closure on the Growth of Small Fatigue Cracks in Titanium aluminium Alloys written by James M. Larsen and published by . This book was released on 1990 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation was performed to study the effects of slip character and crack closure on the propagation of small fatigue cracks in titanium- aluminum alloys. The materials examined were solution-treated Ti-4Al and Ti-8Al, as well as aged Ti-8Al. The propagation of naturally initiated surface cracks of depths as small as 25 micrometers was compared with the behavior of large through-thickness cracks. An extensometer was used to monitor crack closure throughout the large crack tests, and the closure behavior of the small cracks was measured using a computerized laser interferometric displacement gage having a displacement resolution of 0.01 micrometer. The measurements of crack closure were used to compute an effective stress intensity factor range. In all three alloys and for all test conditions, which included a range of stress levels and stress ratios, small cracks propagated faster than large cracks subjected to an equivalent Delta K, and the small cracks propagated under conditions that were significantly below the large-crack threshold, Delta K(th). Although the character and distribution of slip in Ti-Al alloys may have a dramatic influence on fatigue crack initiation and on the propagation of large cracks, this effect was minimal for small cracks.
Download or read book Le Ciel ouvert tous les hommes ou Trait th ologique written by and published by . This book was released on 1768 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fretting Fatigue written by David W. Hoeppner and published by ASTM International. This book was released on 2000 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume includes 36 of the 40 papers presented at the symposium, and a collection of six keynote papers providing background on the subject. Topics covered include parameter effects, environmental effects, crack nucleation, material and microstructural effects, damage analysis, fracture mechanic
Download or read book Investigation of Fretting Fatigue Mechanisms on 7075 T6 Aluminum Alloy and Ti 6Al 4V Titanium Alloy written by Saeed Adibnazari and published by . This book was released on 1991 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is generally believed that fretting accelerates crack nucleation. However, a method to precisely determine the end of a crack nucleation stage has not been developed. It is therefore currently difficult to determine the exact affect of fretting on the stages of fatigue. This research started by hypothsizing that fretting fatigue cracks nucleate after the damage threshold (the amount of fretting damage required to bring a reduction to fatigue life) has been reached. Similar to the fretting fatigue damage threshold concept, it was hypothesized that there exists a normal pressure threshold as well. As a consequence of verifying these hypotheses, many other valuable facts related to fretting fatigue damage production and growth, crack nucleation and propagation were discovered.
Download or read book Fretting Fatigue Behavior of Nickel Alloy IN 100 written by Elhoucine Madhi and published by . This book was released on 2006 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt:
