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3 edition of Simulation of fatigue crack initiation at corrosion pits with EDM notches found in the catalog.

Simulation of fatigue crack initiation at corrosion pits with EDM notches

Stephen W. Smith

Simulation of fatigue crack initiation at corrosion pits with EDM notches

by Stephen W. Smith

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Published by National Aeronautics and Space Administration, Langley Research Center, Available from NASA Center for AeroSpace Information (CASI) in Hampton, Va, Hanover MD .
Written in English


Edition Notes

StatementStephen W. Smith, John A. Newman, [and] Robert S. Piascik.
SeriesNASA/TM -- 2003-212166., NASA technical memorandum -- 211266.
ContributionsNewman, John A., Piascik, Robert S., Langley Research Center.
The Physical Object
Pagination1 v.
ID Numbers
Open LibraryOL17622955M
OCLC/WorldCa55958450

A numerical simulation of fatigue crack initiation in pure α-iron is presented in this paper. The developed model was adapted from other publications in order to account for multiple slip systems. The mechanical properties of the material were fitted to low-cycle fatigue experimental results with a kinematic hardening model suitable for cyclic Cited by: 7. Effect of average stress on fatigue. The contrast between the minimum and maximum load applied to the material has a key effect on the resistance to fatigue cracking; if the ratio is higher, (R = +1,0), fatigue endurance limit decreases, where R is the relationship between the minimum and maximum stress.

Fatigue crack initiation and growth from artificial pits of different depths has been studied. The experimental results were analyzed using fracture-mechanical models including those for small cracks. The model shows very good agreement with experiment in describing the initiation . The affects of corrosion pits on fatigue life have been studied closely in various other alloys (refs. 7 to 9). In this work, fatigue crack initiation at pits has .

corrosion potentials of inclusions and the matrix may also lead to the preferential corrosion ofone or the other, and to cracking In this paper the results of an investigation into fatigue crack initiation in a maragingsteel are presented, particular emphasis being given to the effect of a corrosive environ ment on the initiation process File Size: 2MB.   Obscure fatigue striations and featureless facets are observed in crack propagation regions. Anodic dissolution is dominantly responsible for the premature crack initiation and stress corrosion cracking leading to the formation of fractured α-Al by: 3.


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Simulation of fatigue crack initiation at corrosion pits with EDM notches by Stephen W. Smith Download PDF EPUB FB2

Elongated pits (higher local kt). The EDM notches used to simulate a corrosion pit stress concentration were semicircular with a height of approximately mm ( inch), a depth (a) and surface width (2c). (See Figure 5.) The depth and width of each EDM notch and corrosion pit is summarized in Tables 1 and 2.

The EDM notches used to simulate a corrosion pit stress concentration were semicircular with a height of approximately mm ( inch), a depth (a) and surface width (2 c). Based on the laboratory fatigue test results, the EDM Jaw (semi-circular disc shaped) produces a local stress state similar to corrosion pits and can be used to simulate a corrosion pit.

NASA/TM ARL-TR Simulation of Fatigue Crack Initiation at Corrosion Pits With EDM Notches Stephen W. Smith Langley Research Center, Hampton, Virginia John A. Newman U.S. Army Research Laboratory Vehicle Technology Directorate Langley Research Center, Hampton, Virginia Robert S.

Piascik Langley Research Center, Hampton, Virginia. In corrosion fatigue crack initiation study of a stainless steel and a high-strength aluminum alloy, even for a crack whose optical micrographs showed that it was initiated from corrosion pit, a micro-crack was sometimes found from AFM images before pit formation.

On the other hand, for a crack whose optical micrographs showed that it was. Available online at ICM11 Evaluation of fatigue crack initiation in a notched single-crystal superalloy component Daniel Leidermarka*, Johan Moverarea,b, Mikael Segersälla, Kjell Simonssona, Sören Sjöströma, Sten Johanssona aDepartment of Management and Engineering, Linköping University, SE Linköping, Sweden bSiemens Industrial.

A case study from a hydro power plant turbine shaft was chosen to illustrate the development of this methodology. The paper illustrates the application of TCD to the fatigue life assessment of a turbine shaft with stress concentrations due to pitting by: 2.

EFFECT OF PITTING CORROSION ON FATIGUE AND CRACK GROWTH BEHAVIOR OF BOTH ALUMINUM ALLOY T62 AND ITS PANEL immersion time was obtained by fitting, which is showed in Fig A relationship of power function between average depth of pre-corrosive pit and the immersion time can be found.

(a) (b) Fig.5 Typical of morphology of corrosion-pit. the critical design parameter. Particularly, initiation of fatigue crack plays a key role.

Furthermore, hardly anything can be found in the literature on the fatigue crack initiation in multiphase microstructures. This work deals with the characterisation of the high cycle fatigue crack initiation in the TIMETAL LCB α/β titanium Size: KB.

The role of grain boundaries on fatigue crack initiation – An energy approach Michael D. Sangida, Hans J. Maierb, Huseyin Sehitoglua,⇑ a Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, W.

Green St., Urbana, ILUSA bLehrstuhl für Werkstoffkunde (Materials Science), University of Paderborn, Cited by: The role of corrosion pit in the corrosion fatigue crack initiation process of martensitic, ferritic, austenitic, duplex and precipitation-hardening stainless steels is briefly summarized.

Uniaxial fatigue tests were conducted to compare the fatigue life of laboratory produced corrosion pits, similar to those observed in the shuttle main landing gear wheel bolt-hole, and an electro-discharged-machined (EDM) flaw. EDM Jaws are used to simulate corrosion pits during shuttle wheel (dynamometer) testing.

First corrosion pits are most frequently obs erved at crack initiation area,if the crack initiation area kept soundly after failure. Secondly several micro-cracks in association with corrosion pits are observed at the surface near corrosion fatigue crack initiation Size: 1MB.

Abstract. Pitting corrosion triggered damage is responsible for the degradation of many metallic materials affecting structural integrity. As pitting and crack initiation processes govern the overall life of such structures and components, particularly at nominal cyclic stresses, there is a need to develop simple models to estimate crack initiation Cited by: In this research, corrosion fatigue crack initiation tests using 13 Cr stainless steel were conducted in synthetic seawater to investigate the corrosion fatigue crack initiation life (Nc).

In addition, a corrosion fatigue crack initiation and propagation model was suggested also. Until now, corrosion fatigue crack initiation life was treated by: 1. Fatigue cracks initiate at corrosion pits due to pre-corrosion, if any, or pits resulting from corrosion in real time during the cyclic loading.

It is shown that under sea water flow, the fatigue life in the gigacycle regime is mainly governed by the corrosion by: The paper presents some aspects about fatigue cracks initiation, based on pitting corrosion.

The experimental researches pointed out that the corrosion wearing is one of the sources of fatigue damage. KEYWORDS: fatigue, crack, corrosion, damage. INTRODUCTION The cracks that appear on the shaft surfaces proved to be dominant damage forms.

short crack regime was investigated using the SDC in combination with a fatigue rig. The mechanism of corrosion fatigue crack growth, which consists of, pit nucleation, pit growth, transition from pitting to fatigue crack initiation, and short crack growth were studied.

This system consists of a fatigue rig, and electrochemical droplet cell. Abstract. Corrosion fatigue emanating from semicircular notches is considered. The studies are focused on the relationship between stress field and electrochemistry in notches with the aim of understanding and prediction of the corrosion fatigue crack nucleation and growth behaviour from a notch by: 6.

in air. In this material, corrosion pits were observed prior to crack initiation, and corrosion fatigue cracks were found to be initiated either at corrosion pits or grain boundaries.

For crack initiation at corrosion pits, it was not nucleated from the deepest point of the pit. The crack initiation site within the pit was also the grain boundary.

Choice of crack initiation is done in accordance with DIN standard that establishes the occurrence of crack initiation of such machines. Is plotted the chart for the two forms of first crack initiation N iA=f(ai), and N iB=f(ai), the crack growth depending on the number of cycles, on figure 3 and figure 4 respectively.The corrosion fatigue crack initiation behavior under passive corrosion is controlled by repassivation kinetics as well as by critical crack depth derived using fracture mechanics [2].

Daeubler et al. [3] developed a model of corrosion fatigue crack initiation under passive electrochemical conditions.Simulation of fatigue crack initiation at corrosion pits with EDM notches (OCoLC) Material Type: Document, Government publication, National government publication, Internet resource: Document Type: Internet Resource, Computer File: All Authors / Contributors: Stephen W Smith; John A Newman; Robert S Piascik; Langley Research Center.