Effect of Pins with Flats and Resin-Bonded Polytetrafluorethylene Coatings on the Fatigue Strength of Large Pinned Connections Made from Alloy Steel FV520B

1970 ◽  
Vol 185 (1) ◽  
pp. 709-716 ◽  
Author(s):  
D. J. White
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Thin Layer ◽  
Systematic Investigation ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Strength Ratio ◽  
Critical Importance ◽  
Prolonged Fatigue ◽  
Pinned Connections

Results are presented of fatigue tests made on large lugs 4·25 in wide, loaded by means of a 2-in diameter pin. The effect on fatigue strength of a thin layer of resin-bonded p.t.f.e. stuck to the bore of the lug was studied and a systematic investigation was made of flats milled opposite to one another on the pin. The size of the flat is described by the angle (±θ) subtended by the flat at the pin centre and values from zero to +40° were covered. Two conditions of mean stress were investigated, namely, pulsating or repeated tension and 15 tonf/in2mean tension. Although resin-bonded p.t.f.e. coatings prolonged fatigue life, they did not offer a reliable means of improving fatigue strength. Pins with flats were found to be of great benefit and for ±40° flats, as compared with a round pin, the strength ratio in pulsating tension was 3·6 and, at 15 tonf/in2, mean tension was 2·9. The combination of mean stress and size of flat is of critical importance because the strength can be increased or decreased by the addition of flats to a round pin.

Fatigue Strength of Small Pinned Connections Made from Alloy Steel Fv 520B

1967 ◽  
Vol 182 (1) ◽  
pp. 615-630 ◽  
Author(s):  
D. J. White
Keyword(s):  
Fatigue Strength ◽  
Alloy Steel ◽  
Design Method ◽  
Systematic Investigation ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Interference Fit ◽  
Cadmium Plating ◽  
Engineering Sciences ◽  
Pinned Connections

Published work on pin-loaded lugs is reviewed, particular attention being given to photoelastically determined stress distributions and to results of fatigue tests for the purpose of identifying those factors that affect fatigue strength. Fatigue tests have been conducted on lugs of width 1 [Formula: see text] in made from alloy steel FV 520B and loaded by means of a [Formula: see text]-in diameter pin. A systematic investigation was made of pin fit for both clearance and interference and the effect of various treatments was investigated; these included cadmium plating the lug bore and pin, applying the ‘Sulfinuz’ process to the lug and overstraining the lug bore. Two conditions of mean stress were investigated, namely, pulsating or repeated tension and 15 tonf/in2 mean tension. Strength comparisons are based on the fatigue strength at 108 cycles, for the appropriate mean stress, of untreated lugs with exact-fit pins, these showing the lowest strength of all the lugs tested. It was found that clearance-fit pins and interference-fit pins were beneficial and with the larger values of clearance and interference tested the fatigue strength was almost doubled. Cadmium plating was ineffective while both Sulfinuz treated lugs and lugs with overstrained bores gave strength ratios of at least 1.6. An increase in mean stress from pulsating tension to 15 tonf/in2 mean tension, significantly reduced fatigue strength in most cases. On the basis of the present experimental results, the design method proposed for lugs with interference-fit pins in Royal Aeronautical Society Data Sheet A.05.02, amended by Engineering Sciences Data No. 67012, may sometimes prove to be unsafe and caution is warranted in interpreting the safe loads predicted.

The Fatigue Strength of Large Single-Pinned and Double-Pinned Connections Made from Alloy Steel FV520B

1968 ◽  
Vol 183 (1) ◽  
pp. 563-578 ◽  
Author(s):  
D. J. White
Keyword(s):  
Fatigue Strength ◽  
Size Effect ◽  
Alloy Steel ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Pinned Connections ◽  
Close Fit ◽  
Considerable Size

Fatigue tests have been conducted on single-pinned and double-pinned lugs made from alloy steel FV520B and loaded by means of 2 in diameter pins. The effects of pin fit for both clearance and interference and of various treatments were investigated. The treatments included side relieving the lug hole, bushing the bore, applying the Sulfinuz process to the lug or overstraining the lug bore. Two conditions of mean stress were investigated, namely, pulsating or repeated tension and 15 tons/in2 mean tension. Basing comparison on the fatigue strength at 30 × 106 cycles, the untreated lugs with close fit pins showed the lowest strength of all. Both clearance and interference fits were beneficial and by appropriate choice, the fatigue strength could be at least doubled and in some cases trebled. Lugs which had side relief, had been bushed, Sulfinuz treated or which had overstrained bores also gave worthwhile increases in fatigue strength and the strength ratios were generally in excess of 2. An increase in mean stress significantly reduced fatigue strength for all lugs tested, except for those with close fit or clearance fit pins. Comparing the present results with those obtained on lugs one-quarter the size, a considerable size effect is evident for some conditions, large lugs being weaker than small lugs.

Effect of Processing Layer on Fatigue Strength of Extruded AZ61 Magnesium Alloy

2013 ◽  
Vol 577-578 ◽  
pp. 429-432 ◽  
Author(s):  
Yukio Miyashita ◽  
Kyohei Kushihata ◽  
Toshifumi Kakiuchi ◽  
Mitsuhiro Kiyohara
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Magnesium Alloy ◽  
Crack Initiation ◽  
Crack Growth ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Crack Growth Resistance ◽  
Az61 Magnesium Alloy

Fatigue Property of an Extruded AZ61 Magnesium Alloy with the Processing Layer Introduced by Machining was Investigated. Rotating Bending Fatigue Tests were Carried out with the Specimen with and without the Processing Layer. According to Results of the Fatigue Tests, Fatigue Life Significantly Increased by Introducing the Processing Layer to the Specimen Surface. Fatigue Crack Initiation and Propagation Behaviors were Observed by Replication Technique during the Fatigue Test. Fatigue Crack Initiation Life of the Specimen with the Processing Layer was Slightly Longer than that of the Specimen without the Processing Layer. Higher Fatigue Crack Growth Resistance was also Observed when the Fatigue Crack was Growing in the Processing Layer in the Specimen with the Processing Layer. the Longer Fatigue Life Observed in the Fatigue Test in the Specimen with the Processing Layer could be Mainly due to the Higher Crack Growth Resistance. it is Speculated that the Fatigue Strength can be Controlled by Change in Condition of Machining Process. it could be Effective way in Industry to Improved Fatigue Strength only by the Cutting Process without Additional Surface Treatment Process.

The Effects of Periodic High Loads on Fretting Fatigue

1981 ◽  
Vol 103 (3) ◽  
pp. 223-228 ◽  
Author(s):  
A. Kantimathi ◽  
J. A. Alic
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Growth Retardation ◽  
Fretting Fatigue ◽  
Fatigue Tests ◽  
Constant Amplitude ◽  
Axial Loads ◽  
Prolonged Fatigue ◽  
Stress Ratios ◽  
Crack Growth Retardation

Fretting fatigue tests have been conducted on 7075-T7351 aluminum alloy coupons with fretting pads of the same material. Three different stress ratios were used, the otherwise constant amplitude axial loads being interrupted every 1000 cycles by either tensile overloads to 400 MPa or compressive underloads to −200 MPa. Tensile overloads greatly prolonged fatigue life for low stresses where the overload ratios were 1.6 and above; compressive underloads had comparatively little effect. The results are discussed in terms of crack growth retardation phenomena.

S–N curves for fatigue life estimation of friction stir welded 19501 aluminum alloy T-joint

2018 ◽  
Vol 233 (2) ◽  
pp. 664-674
Author(s):  
Prakash Chandra Gope ◽  
Harshit Kumar ◽  
Himanshu Purohit ◽  
Manish Dayal
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Weld Zone ◽  
Stress Effect ◽  
Mean Stress ◽  
Friction Stir ◽  
Fracture Surfaces ◽  
Mean Stress Effect ◽  
Metallic Bonding

In this study, the mechanical properties and fatigue life of 19501 aluminum alloy friction stir welded T-joint is investigated. Tensile properties of friction stir welded joint show that there is a marginal reduction of about 5% in strength and ductility as compared to unwelded 19501 aluminum alloy. Fatigue test results of T-joint specimen at two stress ratios of 0 and -1 show that there is a reduction of 15% in fatigue strength due to change of stress ratio from -1 to 0. Also, higher variation is seen in fatigue strength in low cycle zone than the high cycle zone. Effect of mean stress on fatigue life is discussed on the basis of different mean stress effect models. Morrow’s mean stress effect model is found to be better than other models. Micrographs from the fracture surfaces of retreating side, mid weld zone, and advancing side of the T-joint indicates that fracture surfaces are cleavage fracture. Different sizes of inter-metallic bonding are seen in the micrographs, which indicate that fracture is initiated due to breaking of the brittle inter-metallic bonding.

Effects of Extremes of Hardness and Mean Stress on Fatigue of AISI 4340 Steel in Bending and Torsion

1989 ◽  
Vol 111 (2) ◽  
pp. 119-122 ◽  
Author(s):  
W. N. Findley
Keyword(s):  
Fatigue Strength ◽  
Linear Relation ◽  
Brinell Hardness ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Aisi 4340 Steel ◽  
4340 Steel ◽  
Aisi 4340

Experiments are reported for fatigue tests in bending and in torsion at hardness levels from fully annealed to fully hard and super quenched. Results indicate a linear relation between fatigue strength and Brinell hardness. The relation between bending and torsion and the effects of mean stress and size are also examined.

Fatigue Failure and Strength Evaluation of Traction Drive Rollers

2000 ◽  
Author(s):  
Masana Kato ◽  
Gang Deng ◽  
Masashi Yamanaka ◽  
Ryoji Yamamoto ◽  
Noboru Ono ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Crack Growth ◽  
Surface Crack ◽  
Traction Force ◽  
Fatigue Tests ◽  
Slip Ratio ◽  
Traction Drive ◽  
Surface Fatigue ◽  
Surface Crack Growth

Abstract The surface fatigue failures of the traction drive rollers are different to that of gears and bearings because of the high traction force, skew and small slip ratio. In this research, fatigue tests of traction rollers were performed in different slip ratios and skew angles. The effects of running conditions on the fatigue lives of traction drive rollers are clarified and explained based on the surface crack growth and wear situations. Although a higher slip ratio will make a lower fatigue life, the fatigue strength will increase inversley under the skew conditions, because of the differences in mechanical and tribological condition for surface crack growth and the severe surface wear, which diminishes the surface crack length. For evaluation of the effects of such as slip ratio and skew on the fatigue strength of traction rollers, a new method is put forward in which the relationship between the surface temperature index and fatigue life is used instead of S-N curve.

scholarly journals Multiaxial fatigue behavior of 2618 aluminum alloy

2019 ◽  
Vol 300 ◽  
pp. 09003
Author(s):  
Benaïssa Malek ◽  
Catherine Mabru ◽  
Michel Chaussumier
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Internal Pressure ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Mean Stress ◽  
Research Project ◽  
Pressure Tests

The purpose of the present research project is to study multiaxial fatigue behavior of 2618 alloy. The influence of mean stress on the fatigue behavior under tension and torsion is particularly investigated. Fatigue tests under combined tensile-torsion, in or out of phase, as well as combined tensile-torsion-internal pressure tests have also been conducted. Multiaxial fatigue results are analyzed according to Fatemi-Socie criterion to predict the fatigue life.

scholarly journals Cyclic Tests of Smooth and Notched Specimens Subjected to Bending and Torsion Taking into Account the Effect of Mean Stress

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2141 ◽  
Author(s):  
Roland Pawliczek ◽  
Dariusz Rozumek
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Regression Equations ◽  
Allowable Stress ◽  
Cyclic Tests ◽  
Mean Values ◽  
Notched Specimens ◽  
Fatigue Characteristics

The paper contains the results of fatigue tests of smooth and notched specimens made of 10HNAP (S355J2G1W) subjected to proportional cyclic loading with use of mean values stress. The results obtained for specimens under bending, torsion and one combination of bending with torsion for four mean values have been compared. The experimental data have been collected in the tables and shown in the figures with use of various σa(τa)-N fatigue characteristics for which parameters of the regression equations have been determined. The influence of average values on the allowable stress amplitudes and amplitude of moments at the level close to the fatigue limit depending on the angle α determining loading combination and the average stress is also shown. The greatest effect of the notch on fatigue life compared to smooth specimens is observed at symmetrical loads. At unsymmetrical loads with non-zero mean stress, this effect clearly weakens or disappears.

Fatigue Strength of Thick-Walled Cylinders Containing Cross Bores with Blending Features

1992 ◽  
Vol 206 (5) ◽  
pp. 299-309 ◽  
Author(s):  
L M Masu ◽  
G Craggs
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Tests ◽  
Cylinder Wall ◽  
Cylinder Bore

This paper reports on an investigation into the fatigue strength of thick-walled cylinders that contain a small transverse hole or cross bore in the cylinder wall having either a chamfer or a blending radius at its intersection with the main cylinder bore. Fatigue tests surprisingly show that plain cross-bore cylinders having thickness ratios K = 1.4 and 2.0 have a fatigue life that is marginally greater than comparable cylinders with blending features. A finite element investigation shows that local high stresses are produced on the surface of blending features and these stresses are considerably greater in magnitude than those found in plain cross-bore cylinders. These stress findings are used to explain the experimental fatigue life results obtained.

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