Spalling Fatigue Life Assessment of Surface Hardened Sintered Gears Based on Fracture Mechanics

2003 ◽  
Author(s):  
Yuji Ohue ◽  
Akira Yoshida ◽  
Masanori Seki
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Testing Machine ◽  
Fem Analysis ◽  
Induction Hardening ◽  
Fatigue Tests ◽  
Rolling Contact ◽  
Life Assessment ◽  
Hertzian Contact ◽  
Ion Nitriding

In order to evaluate the surface durability of surface-hardened sintered gears, the fatigue lives of 5 kinds of sintered gears and 28 kinds of sintered rollers under sliding-rolling contact conditions were examined and estimated based on the fracture mechanics. The sintered gears and rollers were surface-hardened by induction-hardening and ion-nitriding. The fatigue tests were conducted using a power circulating gear testing machine and two cylinder testing machines. The pore distributions included in the sintered materials were observed and were analyzed statistically. The failure mode of the sintered gears and roller was mainly spalling. The stress intensity factor obtained by FEM analysis for the mode II under a condition of Hertzian contact became larger as the crack length became longer. The estimation of fatigue life of the sintered gears and rollers was attempted using the pore distributions and the fracture mechanics. The estimated fatigue lives were almost the same as the tested fatigue ones. Therefore, it could be said that the crack propagation of the sintered gears and rollers depended on the pore size and hardness.

Evaluation of the fatigue life of a sintered machine element under the sliding/rolling contact condition based on fracture mechanics

2002 ◽  
Vol 37 (4) ◽  
pp. 327-336
Author(s):  
A Yoshida ◽  
Y Ohue ◽  
H Ishikawa
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Testing Machine ◽  
Element Model ◽  
Contact Condition ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Stress Intensity Factor Range

In order to evaluate the surface durability of sintered machine elements, the fatigue lives of 28 kinds of sintered roller under a sliding/rolling contact condition were estimated using Paris's law based on linear fracture mechanics. The fatigue tests were conducted using a two-cylinder testing machine. The stress intensity factor for the mode II under the Hertzian contact condition was calculated using the finite element model. The value of the stress intensity factor became larger as the crack length became longer to the contact surface, and the value of the stress intensity factor range was independent of the crack angle. It could be clarified that the fatigue lives of the sintered rollers depended on the pore diameter and the hardness. It was obvious that the pore distribution has to be taken into consideration to estimate the fatigue lives of the sintered rollers more precisely.

Surface Durability of Spur Gears at Hertzian Stresses Over Shakedown Limit

1974 ◽  
Vol 96 (2) ◽  
pp. 359-372 ◽  
Author(s):  
Akira Ishibashi ◽  
Taku Ueno ◽  
Shigetada Tanaka
Keyword(s):  
Fatigue Testing ◽  
Testing Machine ◽  
Carbon Steels ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Load Testing ◽  
Short Period ◽  
Hertzian Contact Stress ◽  
Surface Durability ◽  
Shakedown Limit

Using a new type of gear-load testing machine and a disk-type rolling fatigue testing machine designed and made by the authors, the upper limits of Hertzian contact stress allowable on rolling contact surfaces were investigated. It was shown conclusively that gears and rollers made of soft carbon steels could be rotated beyond 108 revolutions at Hertzian stresses over shakedown limit (≈ 0.4 HB). In the case of gears, pits having a pitting area ratio of 0.04 percent occurred during 1.16 × 108 rotations at a Hertzian stress of 0.50 HB. However, no pitting occurred on the roller rotated through 1.20 × 108 revolutions at a Hertzian stress of 0.71 HB, although appreciable changes in texture were observed at the subsurface. In order to rotate gears or rollers at Hertzian stresses over shakedown limit, their surface must either be very smooth initially or after a short period of running, and an oil film must be formed between contacting surfaces.

scholarly journals Multiaxial fatigue study on steel transversal attachments under constant amplitude proportional and non-proportional loadings

2018 ◽  
Vol 165 ◽  
pp. 16007
Author(s):  
Martin Garcia ◽  
Claudio A. Pereira Baptista ◽  
Alain Nussbaumer
Keyword(s):  
Fatigue Life ◽  
High Strength ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Life Assessment ◽  
Experimental Program ◽  
Proportional Loading ◽  
Load Carrying ◽  
Stress States ◽  
Experimental Values

In this study, the multiaxial fatigue strength of full-scale transversal attachment is assessed and compared to original experimental results and others found in the literature. Mild strength S235JR steel is used and an exploratory investigation on the use of high strength S690QL steel and the effect of non-proportional loading is presented. The study focuses on non-load carrying fillet welds as commonly used in bridge design and more generally between main girders and struts. The experimental program includes 33 uniaxial and multiaxial fatigue tests and was partially carried out on a new multiaxial setup that allows proportional and non-proportional tests in a typical welded detail. The fatigue life is then compared with estimations obtained from local approaches with the help of 3D finite element models. The multiaxial fatigue life assessment with some of the well-known local approaches is shown to be suited to the analysis under multiaxial stress states. The accuracy of each models and approaches is compared to the experimental values considering all the previously cited parameters.

Fatigue Life Assessment of Fastened Composite (FRP and CRP) Plates: A Comparative Study

2011 ◽  
Vol 110-116 ◽  
pp. 1155-1160
Author(s):  
K.N. Pandey ◽  
Yogesh K. Tembhurne
Keyword(s):  
Fatigue Life ◽  
Composite Materials ◽  
Composite Laminates ◽  
Maximum Load ◽  
Butt Joint ◽  
Fatigue Tests ◽  
Life Assessment ◽  
Reinforced Plastic ◽  
Mechanically Fastened ◽  
Subsequent Propagation

Composite materials are now a day most frequently used materials in aerospace structures. Mechanically fastened joints are usually used there for joining process due to number of advantages over other conventional joints. These joints are easy to assemble and dissemble and are cheaper. However, they create stress concentration near the hole, leading to source of nucleation and subsequent propagation of cracks under cyclic loading. They also increase weight of the system tat may nullify the advantages we get from composite materials. The present work intent to find fatigue life of two composite laminates usually employed in spacecraft structures. The composites studies are fiberglass reinforced Plastic (FRP) and Carbon Reinforced Plastic (CRP). After preparing the composites, moisture, tension and fatigue tests were conducted on both composites. To know the behavior under damped condition, absorption tests were conducted. Fatigue tests were done both under as plate and butt joint conditions. It was found that in bolted joint condition, both CRP and FRP plates fails in net tension at minimum load but for maximum load they fail in shear.

Experimental Investigations Upon Fatigue Life of Circular Contacts With Transversal Furrow

2005 ◽  
Author(s):  
Delia F. Cerlinca ◽  
Emanuel N. Diaconescu
Keyword(s):  
Fatigue Life ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Fatigue Tests ◽  
Geometric Parameters ◽  
Rolling Contact ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Contact Fatigue Life

Rolling contact fatigue depends essentially on both surface and subsurface populations of defects. First, this paper describes experimental results obtained in rolling contact fatigue tests in the presence of a furrow oriented transversally to the race-way. Then an attempt to predict theoretically the effect of geometric parameters of the furrow upon contact fatigue life is described.

scholarly journals Influence of the Elastoplastic Strain on Fatigue Durability Determined with the Use of the Spectral Method

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 423 ◽  
Author(s):  
Michał Böhm ◽  
Mateusz Kowalski ◽  
Adam Niesłony
Keyword(s):  
Fatigue Life ◽  
Probability Density ◽  
Spectral Method ◽  
Fatigue Tests ◽  
Life Assessment ◽  
Loading Conditions ◽  
Random Loading ◽  
Elastoplastic Deformations ◽  
Fatigue Life Assessment ◽  
Safe Side

The paper presents experimental static and fatigue tests results under random loading conditions for the bending of 0H18N9 steel. The experimental results were used in performing calculations, according to the theoretical assumptions of the spectral method of fatigue life assessment, including elastoplastic deformations. The presented solution extends the use of the spectral method for material fatigue life assessment, in terms of loading conditions, above Hooke’s law theorem. The work includes computational verification of the proposal to extend the applicability of the spectral method of determining fatigue life for the range of elastoplastic deformations. One of the aims of the proposed modification was to supplement the stress amplitudes used to calculate the probability density function of the power spectral density of the signal with correction, due to the plastic deformation and its use for notched elements. The authors have tested the method using four of the most popular probability density functions used in commercial software. The obtained results of comparisons between the experimental and calculation results show that the proposed algorithm, tested using the Dirlik, Benasciutti–Tovo, Lalanne, and Zhao–Baker models, does not overestimate fatigue life, which means that the calculations are on the safe side. The obtained results prove that the elastoplastic deformations can be applied within the frequency domain for fatigue life calculations.

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