Bending Fatigue Tests of High Speed Spur Gears

1981 ◽  
Vol 103 (2) ◽  
pp. 466-473 ◽  
Author(s):  
I. Yuruzume ◽  
H. Mizutani
Keyword(s):  
High Speed ◽  
Normal Load ◽  
Load Capacity ◽  
Spur Gear ◽  
Fatigue Tests ◽  
Spur Gears ◽  
Bending Fatigue ◽  
Tooth Width ◽  
Bending Load ◽  
Bending Fatigue Strength

Effects of addendum modification of tooth profiles on the bending fatigue strength of high speed spur gear are discussed in this presentation: A JIS Class O Spur gear of m3, α20 deg, Z1 27, and made of AMS 6260 (AISI 9310) steel precisely ground after carburizing and hardening was meshed with the other gear of Z2 77 and operated at 8550 rpm. In this running test, bending load capacity and running performance comparisons between the gear with standard tooth profile and the two shifted gears of which tooth addendum modification coefficients were 0.35 and 0.8. The maximum normal load of the gear with addendum modification coefficient 0.8 at 107 (10 million) cycles was 1.8 kNsmm per unit tooth width. The maximum Hertz stress of this gear was 2.43 × 109 Nsm2. The allowable normal load of the gear with 0.8 was higher than that of the standard gear by 87 percent and higher than of the 0.35 profile shifted gears by 20 percent.

Residual Stress and Bending Fatigue Strength of Case-Carburized Thin-Rimmed Spur Gears With Asymmetric Web Arrangement

2007 ◽  
Author(s):  
Kouitsu Miyachika ◽  
Wei-Dong Xue ◽  
Takao Koide ◽  
Hidefumi Mada ◽  
Kengo Nojima ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Three Dimensional ◽  
Spur Gear ◽  
Fatigue Tests ◽  
Case Depth ◽  
Spur Gears ◽  
3D Fem ◽  
Bending Fatigue ◽  
Bending Fatigue Strength

This paper presents a study on effects of carburized parts on residual stress and bending fatigue strength of case-carburized thin-rimmed spur gears with asymmetric web arrangement. A heat conduction analysis and an elastic-plastic stress analysis for the case-carburizing process of thin-rimmed spur gears with asymmetric web arrangement were carried out by the three-dimensional finite-element method (3D-FEM), and then residual stresses were obtained. Effects of the case depth, the carburized part and the rim thickness on the residual stress of case-carburized thin-rimmed spur gears were determined. Bending fatigue tests were carried out for case-carburized thin-rimmed spur gears with asymmetric web arrangement, and S-N curves and bending fatigue limit loads were obtained. Effects of the case-depth, the carburized part and the rim thickness on the bending fatigue strength of the case-carburized thin-rimmed spur gear with asymmetric web arrangement were determined.

The Evaluation of Bending Fatigue Testing of Austempered Ductile Iron Spur Gear

2019 ◽  
Author(s):  
Qi Zhang ◽  
Jianhua Lv ◽  
Rizwanulhaque Syed ◽  
Jing Zhang ◽  
Yang Xu ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Ductile Iron ◽  
Fatigue Testing ◽  
Spur Gear ◽  
Austempered Ductile Iron ◽  
Spur Gears ◽  
Reliability Design ◽  
Bending Fatigue ◽  
Bending Fatigue Strength ◽  
Number Of Cycles

Abstract An experimental evaluation of bending fatigue strength for austempered ductile iron (ADI) spur gears have been performed using Zwick fatigue tester. The gear material was manufactured by vertically continuous casting, in which the radius of the graphite grains is smaller. The Stress-Number of Cycles curve (S-N curve) for the bending fatigue strength of the ADI spur gears are manufactured without any specific surface treatments, and have been obtained by post-processing software. It was observed that when the reliability was 50%, the fatigue limit was 304.89 MPa. It has provided a reliable basis to rate the reliability design of the small gearboxes in automation later.

Comparative bending fatigue strength of precision forged spur gears

1997 ◽  
Vol 211 (4) ◽  
pp. 293-299 ◽  
Author(s):  
O Eyercioglu ◽  
D Walton ◽  
T A Dean
Keyword(s):  
Fatigue Strength ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Spur Gears ◽  
Test Fixture ◽  
Bending Fatigue ◽  
Gear Teeth ◽  
Root Area ◽  
Bending Fatigue Strength

To determine the bending fatigue strength of precision forged spur gears and to compare the results with those obtained from conventional cut gears, single tooth bending fatigue tests were carried out on both through-hardened and induction-hardened gear teeth. The gears were produced from rolled bar cut blanks, disc forged blanks or precision forged teeth blanks. For this purpose, a special test fixture was designed and built for an Amsler high-frequency vibrophore fatigue testing machine. The results show that the endurance limit of precision forged gears is significantly higher than those obtained from cut gears. The bending fatigue strength of forged gears was some 12.5 per cent higher than the cut teeth in a through-hardened condition and 8.4 per cent higher for the induction-hardened teeth. The effect of surface roughness at the tooth root area on the bending fatigue strength of the forged gears is also shown.

scholarly journals On the determination of the bending fatigue strength in and above the very high cycle fatigue regime of shot-peened gears

2021 ◽  
Author(s):  
D. Fuchs ◽  
S. Schurer ◽  
T. Tobie ◽  
K. Stahl
Keyword(s):  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Load Carrying Capacity ◽  
Cycle Fatigue ◽  
Bending Fatigue ◽  
Very High Cycle Fatigue ◽  
Bending Load ◽  
Load Carrying ◽  
Bending Fatigue Strength ◽  
Very High

AbstractDemands on modern gearboxes are constantly increasing, for example to comply with lightweight design goals or new CO2 thresholds. Normally, to increase performance requires making gearboxes and powertrains more robust. However, this increases the weight of a standard gearbox. The two trends therefore seem contradictory. To satisfy both of these goals, gears in gearboxes can be shot-peened to introduce high compressive residual stresses and improve their bending fatigue strength. To determine a gear’s tooth root bending fatigue strength, experiments are conducted up to a defined number of load cycles in the high cycle fatigue range. However, investigations of shot-peened gears have revealed tooth root fracture damage initiated at non-metallic inclusions in and above the very high cycle fatigue range. This means that a further reduction in bending load carrying capacity has to be expected at higher load cycles, something which is not covered under current standard testing conditions. The question is whether there is a significant decrease in the bending load carrying capacity and, also, if pulsating tests conducted at higher load cycles—or even tests on the FZG back-to-back test rig—are necessary to determine a proper endurance fatigue limit for shot-peened gears. This paper examines these questions.

Bending fatigue strength and impact strength of spur gears with various surface hardening treatments

2021 ◽  
Vol 2021.59 (0) ◽  
pp. 05a1
Author(s):  
Ryo ASAKURA ◽  
Kohei HIBI ◽  
Kenichi SAKAMOTO ◽  
Toshiyasu OMURA ◽  
Ryosuke NISHI ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Impact Strength ◽  
Surface Hardening ◽  
Spur Gears ◽  
Bending Fatigue ◽  
Bending Fatigue Strength

Low excitation spur gears with variable tip diameter

2021 ◽  
Vol 263 (5) ◽  
pp. 1275-1285
Author(s):  
Joshua Götz ◽  
Sebastian Sepp ◽  
Michael Otto ◽  
Karsten Stahl
Keyword(s):  
Transmission Error ◽  
Spur Gear ◽  
Low Noise ◽  
Spur Gears ◽  
Mesh Stiffness ◽  
Helical Gears ◽  
Axial Forces ◽  
Tooth Width ◽  
Drive Trains ◽  
Static Transmission Error

One important source of noise in drive trains are transmissions. In numerous applications, it is necessary to use helical instead of spur gear stages due to increased noise requirements. Besides a superior excitation behaviour, helical gears also show additional disadvantageous effects (e.g. axial forces and tilting moments), which have to be taken into account in the design process. Thus, a low noise spur gear stage could simplify design and meet the requirements of modern mechanical drive trains. The authors explore the possibility of combining the low noise properties of helical gears with the advantageous mechanical properties of spur gears by using spur gears with variable tip diameter along the tooth width. This allows the adjustment of the total length of active lines of action at the beginning and end of contact and acts as a mesh stiffness modification. For this reason, several spur gear designs are experimentally investigated and compared with regard to their excitation behaviour. The experiments are performed on a back-to-back test rig and include quasi-static transmission error measurements under load as well as dynamic torsional vibration measurements. The results show a significant improvement of the excitation behaviour for spur gears with variable tip diameter.

Bending Strength of Carburized Forged Spur Gear

2007 ◽  
Author(s):  
Masashi Yamanaka ◽  
Shinji Miwa ◽  
Katsumi Inoue ◽  
Yoshiki Kawasaki
Keyword(s):  
Fatigue Strength ◽  
Fatigue Test ◽  
Bending Strength ◽  
Surface Hardness ◽  
Spur Gear ◽  
Bending Fatigue ◽  
Precision Forging ◽  
Bending Fatigue Test ◽  
Bending Fatigue Strength ◽  
Gear Profile

This paper deals with the evaluation of influence of the manufacturing methods precision forging and conventional hobbing on the bending fatigue strength of carburized gears. The forging has advantages in productivity and strength. The forged gear has a continuous directed fiber flow which runs along the gear profile. To clarify the effect of strength enhancement, a bending fatigue test is performed for the forged and the hobbed gears. The material of test gears is SCr420H in the JIS and all gears are carburized. The electrohydraulic servo-controlled fatigue tester is used in the constant stress-amplitude fatigue test. The strength is expressed by the fillet stress level, which is calculated by FEM. The obtained strengths of forged and hobbed gear are 1613 MPa and 1490 MPa, respectively. The strength of forged gear is increased 8% in comparison with that of the hobbed gear. The surface hardness is higher and the surface roughness is smaller in the forged gear, however, the residual stress is approximately same. The effect of improvement of the roughness by forging on the strength is small in 1%, and the main reason of the improvement of fatigue strength is considered as the continuous fiber flow.

Pumping Loss of Shrouded Meshed Spur Gears

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Michael J. Hurrell ◽  
Jerzy T. Sawicki
Keyword(s):  
High Speed ◽  
Spur Gear ◽  
Test Facility ◽  
Spur Gears ◽  
Cfd Analysis ◽  
Total Load ◽  
New Approach ◽  
Computational Fluid Dynamics Cfd ◽  
Loss Component ◽  
Swept Volume

Abstract High speed rotorcraft transmissions are subject to load-independent power losses consisting of drag loss and pumping loss. Tightly conforming shrouds enclosing the transmission gears are often incorporated to reduce the drag component of the total load-independent losses. However, tightly conforming axial shrouds can result in an increase in the pumping loss component. Quantifying the pumping loss of shrouded gear transmissions has been the subject of many studies. This study presents a new approach for estimating pumping loss based on the concept of swept volume and examines the applicability of the approach to various shroud configurations. The drag loss and pumping loss of a shrouded spur gear pair have been determined through testing using the NASA Glenn Research Center (GRC) Gear Windage Test Facility. The results from this testing have been compared to theoretical results using the formulations presented in this study. In addition, computational fluid dynamics (CFD) analysis has been conducted for the various shroud configurations tested at NASA GRC. The results from the CFD analysis confirm the theoretical and empirical results and provide insight into the applicability of the swept volume approach for estimating pumping power loss of shrouded gear transmissions.

scholarly journals Tooth Root Bending Fatigue Strength of High-Density Sintered Small-Module Spur Gears: The Effect of Porosity and Microstructure

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 599 ◽  
Author(s):  
Vigilio Fontanari ◽  
Alberto Molinari ◽  
Michelangelo Marini ◽  
Wolfgang Pahl ◽  
Matteo Benedetti
Keyword(s):  
Fatigue Strength ◽  
Surface Defect ◽  
Detrimental Effect ◽  
Case Hardening ◽  
Spur Gears ◽  
Tooth Root ◽  
Near Surface ◽  
Bending Fatigue ◽  
Microstructural Constituent ◽  
Bending Fatigue Strength

The present paper is aimed at investigating the effect of porosity and microstructure on tooth root bending fatigue of small-module spur gears produced by powder metallurgy (P/M). Specifically, three steel variants differing in powder composition and alloying route were subjected either to case-hardening or sinter-hardening. The obtained results were interpreted in light of microstructural and fractographic inspections. On the basis of the Murakami a r e a method, it was found that fatigue strength is mainly dictated by the largest near-surface defect and by the hardness of the softest microstructural constituent. Owing to the very complicated shape of the critical pore, it was found that its maximum Feret diameter is the geometrical parameter that best captures the detrimental effect on fatigue.

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