Reliability of Spur Gears - Determination of Stress-Dependent Weibull Shape Parameters for Tooth Root Fracture

2021 ◽  
Author(s):  
Axel Baumann ◽  
Jochen Juskowiak ◽  
Bernd Bertsche
Keyword(s):  
Spur Gears ◽  
Tooth Root ◽  
Shape Parameters ◽  
Root Fracture ◽  
Stress Dependent

scholarly journals Fast tooth root load capacity optimization based on improved design of hob geometry

2019 ◽  
Vol 287 ◽  
pp. 01011 ◽  
Author(s):  
Ray Uelpenich ◽  
Peter Tenberge
Keyword(s):  
Load Capacity ◽  
Optimization Methods ◽  
Spur Gears ◽  
Tooth Root ◽  
Manufacturing Costs ◽  
Root Fracture ◽  
Computational Speed ◽  
Performance Ability ◽  
Improved Design ◽  
Root Stress

The competitiveness of gearboxes is significantly influenced by their performance ability. Increasing the tooth root load capacity has always been in focus of current research because in case of a failure of the gearwheel due to a tooth root fracture, the complete gearbox fails. This paper presents a new calculation method that enables the optimization of hob geometries within a few minutes so that they lead to reduced stresses in the tooth root fillet of spur gears. This results in reductions of the maximum tooth root stress of 10% and more for most gearwheels. The manufacturing costs for the optimized hob are only influenced slightly. In order to increase the computational speed compared to purely FE-based optimization methods, the present paper shows a method in which the decisive part of the optimization process is based on an analytical equation which are derived by a small number of FE-calculations.

Immediate implantation in a patient with chronic generalized parodontitis and apical granuloma

2019 ◽  
Vol 24 (2) ◽  
pp. 145-149
Author(s):  
A. I. Musienko ◽  
K. I. Nesterova
Keyword(s):  
Tooth Extraction ◽  
Tooth Root ◽  
Duration Of Treatment ◽  
Promising Direction ◽  
Aesthetic Result ◽  
Bone Atrophy ◽  
Alveolar Tissue ◽  
High Level ◽  
Immediate Implantation

Relevance. Rehabilitation of patients with moderate to severe generalized periodontitis is a leading problem in periodontology. It was the determination of the prospects for immediate implantation in patients with chronic periodontitis, combined with the pathology of the tooth root and maxillary sinus.Materials and methods. A group of 94 people with periodontitis and chronic odontogenic rhinosinus was observed who underwent sinus surgical treatment, tooth extraction and one-stage implantation with FRP growth factor according to the author's technology.Results. The method showed high efciency on the basis of assessing the clinical, aesthetic result and restoration of bone density after surgery.Conclusions. The developed technology is a promising direction, it allows to combine a high level of sanation of alveolar tissue with the advantages of immediate implantation, prevents bone atrophy, helps reduce the duration of treatment and the number of surgical and orthopedic interventions.

The Effect of Notches at the Tooth Root Fillet on the Endurance Strength of Gears

1978 ◽  
Vol 100 (3) ◽  
pp. 417-422
Author(s):  
H. Winter ◽  
X. Wirth
Keyword(s):  
Shot Peening ◽  
Calculation Procedure ◽  
Special Importance ◽  
Spur Gears ◽  
Tooth Root ◽  
Characteristic Parameters ◽  
Uniform Heat ◽  
Endurance Strength

Notches at the tooth root fillet can be caused by shaving or grinding. The influence of different notches at the root fillet on the endurance strength of case hardened spur gears was investigated in back-to-back tests and pulsator tests. Data of the test gears: MnCr and CrNi Steels, module 3 (8 DP) and module 8 (3 DP). Besides the a.m. tests photo elastic investigations were performed. On the basis of some characteristic parameters, it was possible, to find a calculation procedure, to determine the loss of endurance strength due to the effect of various kinds of notches. Moreover it was investigated to what extent the endurance strength of notched gears could be increased by regrinding or shot peening the root fillet. It is known that notches at the tooth root fillet can essentially reduce the endurance strength of gears. This is of special importance for case hardened gears. It is desirable that such notches should be avoided, but sometimes notches are produced by shaving or grinding due to inadequacy of tooling or non-uniform heat distortion. Therefore the influence of geometry and position of notches at the root fillet on the endurance of case hardened spur gears was investigated in back-to-back and pulsator tests. Additionally the extent the endurance strength of notched gears could be increased by regrinding or shot peening the root fillets was studied.

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.

A Reconsideration of the Geometry Factor for the Standard and Profile Shifted Teeth

1989 ◽  
Vol 111 (3) ◽  
pp. 402-413 ◽  
Author(s):  
J. H. Kuang ◽  
Y. T. Yang
Keyword(s):  
Stress Concentration ◽  
Stress Distribution ◽  
Stress Concentration Factor ◽  
Empirical Equation ◽  
Design Parameters ◽  
Spur Gears ◽  
Geometry Factor ◽  
Gear Teeth ◽  
Semi Empirical

A semi-empirical equation for the determination of the stress concentration factor for spur gears is introduced. The effects of some design parameters such as fillet radii of rack cutters, teeth number, and profile shifting factor, on the stress distribution at the fillets of gear teeth are investigated. Values of the modified geometry factors for the standard and profile shifted teeth are also derived. It is hoped that the present investigation may yield a more accurate prediction of the localized stresses at tooth fillets than the results thus far available.

Stereophotogrametric Determination of Crack Initiation and Propagation in Tooth Root

2010 ◽  
Vol 452-453 ◽  
pp. 761-764 ◽  
Author(s):  
Boris Aberšek ◽  
Nenad Gubeljak ◽  
Jožef Predan ◽  
Jože Flašker
Keyword(s):  
Service Life ◽  
Complex Structure ◽  
Tooth Root ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation ◽  
Almost All ◽  
The Mathematical Model ◽  
Multiaxial Loadings ◽  
Real Complex

For designing machines and devices the dimensioning with respect to service life is increasingly taken into account. This applies also for gearing which are still today one of very important components of almost all machines. The problem of determination of the service life of gearing is directly related to geometry of gears, multiaxial loadings, materials and appropriate models for prediction of the crack propagation.Obviously gears and gearing belong to the real complex structure, by correctly selected and carefully planned experiments we obtained results with which we can confirm and justified the mathematical model for calculating different parameters, i.e. service life.

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