Fatigue Properties of Non-Loosening Bolt with Double Screw Mechanism

2005 ◽  
Vol 297-300 ◽  
pp. 2525-2532
Author(s):  
Shinichi Nishida ◽  
Nobusuke Hattori ◽  
H. Iwakiri ◽  
A. Uchisako
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Fatigue Failure ◽  
Strength Characteristics ◽  
Fatigue Properties ◽  
Initiation And Propagation ◽  
Bolt Failure ◽  
Screw Mechanism ◽  
Thread Root

Prevention of slack in fastening bolt has been an important researching subject since fatigue failure can be generally caused by loosening nut. According to the above reason, the super lock bolt with double screw mechanism, which is non-loosening, has been developed for preventing such kind of bolt failure. The objects of the present study are as follows: (1) To clarify the fatigue strength characteristics. (2) To investigate the initiation and propagation behaviour of fatigue crack regarding to the thread root of first pitch. In addition, the mechanism of “fatigue strength of super lock bolt” is also discussed in this paper and it is confirmed that this bolt shows excellent fatigue strength and non-loosening properties.

Effect of Pre-Strain on Fatigue Properties of NHH Rail

2004 ◽  
Vol 261-263 ◽  
pp. 1239-1244
Author(s):  
Wen Xian Sun ◽  
S. Nishida ◽  
Nobusuke Hattori ◽  
X.L. Yue
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Fatigue Test ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Slip Lines ◽  
Propagation Behavior ◽  
Strain Process ◽  
Initiation And Propagation

In the present study, fatigue tests have been performed to study the effect of pre-strain on fatigue properties of NHH (New Head-Hardened) rail. The objectives of this study were: (1) to observe the microscopic behavior of specimens during pre-strain process, (2) to research the influence of pre-strain on fatigue strength of NHH rail and (3) to investigate initiation and propagation behavior of the fatigue crack. The results showed that plastic pre-strain decreased the fatigue strength of NHH rail; fatigue limits had no obvious variation among the different pre-strain ratios. Fatigue cracks initiated in the microscopic cracking or slip lines that were originated in the pre-strain process and propagated from these sites in the later fatigue test.

Propagation of Contact Fatigue From Surface and Subsurface Origins

1966 ◽  
Vol 88 (3) ◽  
pp. 624-635 ◽  
Author(s):  
W. E. Littmann ◽  
R. L. Widner
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Failure ◽  
Contact Stress ◽  
Environmental Conditions ◽  
Failure Modes ◽  
Contact Fatigue ◽  
Initiation And Propagation ◽  
Tapered Roller ◽  
Tapered Roller Bearings

Fatigue life of tapered roller bearings and other elements subject to cyclic contact stress reflects the fatigue strength of the selected material under given environmental conditions. The various modes of contact-fatigue failure have been classified according to their appearance and the factors which promote their initiation and propagation. Illustrations of the various failure modes include rig test specimens and bearings representing normal catalog-rated life under laboratory and application environments. Evidence is presented for the propagation of contact fatigue from surface and subsurface origins.

scholarly journals Service Load and Fatigue Strength : Report 11, Effects of Gradually Increasing or Decreasing Load on the Initiation and Propagation of Fatigue Crack

1969 ◽  
Vol 12 (52) ◽  
pp. 683-691 ◽  
Author(s):  
Yoshihiko HAGIWARA ◽  
Kozo HATSUNO ◽  
Itsuro AOKI ◽  
Hiroshi NAKAMURA ◽  
Takeshi KUNIO
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Initiation And Propagation ◽  
Service Load

scholarly journals Simulation of Fatigue Failure of Rail Joint Bolts by FEA

2011 ◽  
Vol 2-3 ◽  
pp. 1035-1040 ◽  
Author(s):  
Xiao Peng Li ◽  
Hui Fan Nie ◽  
Wei Jie Yuan ◽  
Bang Chun Wen
Keyword(s):  
Finite Element ◽  
Fatigue Strength ◽  
Stress Concentration ◽  
Influencing Factors ◽  
Fatigue Failure ◽  
Impact Force ◽  
Working Life ◽  
Analysis Method ◽  
Bolt Failure ◽  
Temperature Force

It is well known that the fatigue failure of bolts can affect the performance of rail joint and the safety of train running. In this work, the influence of the bolt torque and radius of rounded root of rail bolt on the fatigue strength of the rail bolt are studied by Finite Element Contact Analysis method. And the influence effects of the wheel impact and temperature force of the rail caused by temperature changed on bolt failure are studied. The results indicate that properly torque and increasing the radius of rounded root rail bolt can reduce the stress concentration at the root of rail bolt and this will improves the fatigue strength and the working life of the rail bolt and rail joint. The repeated temperature force of the rail and wheel impact force are playing an important role in the influencing factors on fatigue failure of the rail joint bolts. Due to this, the two bolts near the rail joints will to be fatigue failure almost earlier than others. That is one of the reasons why the bolts should be preloaded or replaced regularly.

Change in Tensile and Fatigue Properties of Biomedical Ti-29Nb-13Ta-4.6Zr Alloy Fabricated by Various Processings

2007 ◽  
Vol 561-565 ◽  
pp. 1505-1508 ◽  
Author(s):  
Toshikazu Akahori ◽  
Mitsuo Niinomi ◽  
Masaaki Nakai ◽  
Michiharu Ogawa
Keyword(s):  
Titanium Alloy ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Cold Rolling ◽  
Reaction Layer ◽  
Aging Temperature ◽  
Surface Reaction ◽  
Solution Treatment ◽  
Fatigue Properties

The tensile and plain fatigue properties of the β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), which was subjected to various thermomechanical treatments, and cast TNTZ were investigated in order to judge its potential for biomedical and dental applications. The tensile strengths of TNTZ aged after solution treatment and that aged after cold rolling decrease with an increase in the aging temperature; however, their elongation exhibits an opposite trend. TNTZ composed of the ω phase or the ω and α phases in the β phase exhibits a tensile strength of about 1000 MPa or more. The tensile properties of the cast TNTZ with and without a surface reaction layer is are not significantly different, and are almost identcal to those of as-solutionized TNTZ. The plain fatigue strengths of TNTZ aged after solution treatment and those of TNTZ aged after cold rolling increase with the aging temperature. In particular, TNTZ aged at 723 K after cold rolling exhibits the highest fatigue strength in both the low- and high-cycle fatigue life regions. Further, the plain fatigue limit, which is about 770 MPa, is nearly equal to that of hot-rolled Ti-6Al-4V ELI alloy subjected to aging after solution treatment; Ti-6Al-4V ELI alloy is a representative α+β-type titanium alloy for biomedical applications. The plain fatigue strength of cast TNTZ with a surface reaction layer is considerably less than that of the as-cold-rolled and as-solutionized TNTZ. Consequently, in the low-fatigue life region, the fatigue crack easily occurs at the surface reaction layer, which is brittle, and in the high-fatigue life region, the fatigue crack occurs at the sites of casting defects (shrinkage). The fatigue limits range from 180 MPa to 200 MPa.

scholarly journals Effect of the Depth of Decarburized Layer in SKL15 Tension Clamp on Fatigue Strength

2021 ◽  
Vol 11 (9) ◽  
pp. 3841
Author(s):  
Yeun-Chul Park ◽  
Chang-Beom An ◽  
Mancheol Kim ◽  
Hyoung-Bo Sim
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Fatigue Failure ◽  
Fatigue Cracks ◽  
Fatigue Crack Initiation ◽  
Initial Crack ◽  
Spring Steel ◽  
Urban Transit ◽  
Linear Elastic ◽  
Decarburized Layer

The surface of a quenched and tempered spring steel may have a decarburized layer from which the carbon component has been reduced. The fatigue strength of the decarburized layer is low compared to the base metal, which can easily develop fatigue cracks. Recently, fatigue failure was reported in the tension clamp (SKL 15) of the DFF-300 rail fastening system during use on one urban transit route in South Korea. As a result of measuring the depth of the decarburized layer of the SKL 15 tension clamp where the fatigue failure occurred, a decarburized layer thinner than the manufacturer’s maximum allowable decarburized layer was found in one of the eight tension clamps. To check the depth of the decarburized layer where the fatigue crack may have initiated, the decarburized layer was assumed to be the initial crack, and fatigue crack initiation was assessed based on the linear elastic fracture mechanics. The manufacturer’s maximum allowable decarburized layer depth of 0.2 mm may result in fatigue cracks.

Development of Structural Steel With High Resistance to Fatigue Crack Initiation and Growth: Part 4

2011 ◽  
Author(s):  
Noboru Konda ◽  
Kazushige Arimochi ◽  
Akinori Inami ◽  
Yukichi Takaoka ◽  
Takumi Yoshida ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Crack Growth ◽  
Welded Joints ◽  
Fatigue Properties ◽  
Small Scale ◽  
Material Strength ◽  
Soft Phase ◽  
Conventional Steel ◽  
Steel Material

For many years, fatigue design has been based on the fundamental that the fatigue strength of welded structures is independent of the steel material and/or strength. Nothing has been studied from the viewpoint of material because fatigue strength of welded joints converges much to the same capacity regardless of material strength. For improvement of fatigue lives, the designers have been advised to improve the geometry of the details, to reduce the nominal stress level or to use some post weld improvement method like toe grinding. In 2001, a new steel material was developed that showed extended fatigue initiation life as well as extended crack growth life, and a new alternative method for fatigue life extension appeared. This steel was denoted FCA (Fatigue Crack Arrester) due to the improved fatigue properties. The improved fatigue strength in welded joints is explained by flat hardness distribution and very fine microstructure at heat affected zone (HAZ). It was clarified that fatigue strength of HAZ in FCA where fatigue crack initiates generally was higher than that in conventional steel. And the improved fatigue crack propagation properties in base steel is explained by a decreased crack growth rate when a fatigue crack passes a grain boundary from a soft phase (feritte) to a hard phase (bainite) that is present in these new dual phase steels. FCA steel has now been used for details of a number of newly built ships, where good fatigue properties are required. In order to establish a general design S-N curve that can be used for the FCA steel, it was agreed in 2007 to start a joint industry project among Kawasaki Shipbuilding Corporation, Det Norske Veritas and Sumitomo Metal Industries. This JIP is now being finished and a design S-N curve has been proposed based on 66 data from small scale testing of specimens made from FCA steel, and 18 data from conventional steel. These test results have been supplemented by some large scale tests of relevant ship details. The discussed results from this JIP including a recommended design S-N curve for FCA steel will be shown in this paper.

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