A Surface Pitting Life Model for Spur Gears: Part I—Life Prediction

1991 ◽  
Vol 113 (4) ◽  
pp. 712-718 ◽  
Author(s):  
J. W. Blake ◽  
H. S. Cheng
Keyword(s):  
Life Prediction ◽  
Spur Gears ◽  
Empirical Methods ◽  
Contact Conditions ◽  
Gear Design ◽  
Metallic Inclusions ◽  
Life Model ◽  
Service Behavior ◽  
Semi Empirical ◽  
Surface Breaking Crack

Surface pitting is a major failure mode for gears. Estimation of failure probability and service life are important in gear design. Current techniques give only a pass/fail rating based on semi-empirical methods. A predictive model for estimating service lives and failure probabilities has been developed. This paper discusses the life prediction analysis, which is based on propagation of a surface breaking crack under rolling/sliding contact conditions. The effects of both surface roughness and non-metallic inclusions can be included. While predicted lives are lower than expected, trends observed through parametric variation are consistent with service behavior.

A Surface Pitting Life Model for Spur Gears: Part II—Failure Probability Prediction

1991 ◽  
Vol 113 (4) ◽  
pp. 719-724 ◽  
Author(s):  
J. W. Blake ◽  
H. S. Cheng
Keyword(s):  
Size Distribution ◽  
Failure Probability ◽  
Spur Gear ◽  
Crack Size ◽  
Initial Crack ◽  
Spur Gears ◽  
Probability Estimates ◽  
Probability Prediction ◽  
Life Model ◽  
Service Behavior

A predictive pitting model for estimating failure probabilities and service lives has been developed. This paper presents the failure probability analysis and a discussion of the model’s application to spur gears. Probability estimates are based on an initial crack size distribution and on possible interaction between cracks and inclusions. Plots of the fraction of components experiencing pitting (percent) versus life show less spread than would be expected. However, trends predicted based on parametric variation are consistent with service behavior. The model is applied by linking the pitting model with a spur gear performance code. Results are compared with AGMA standards.

Gear Pitting Life Prediction and Comparison With Experiments

2005 ◽  
Author(s):  
Dong Zhu ◽  
Michael Bujold ◽  
Leon M. Keer
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Life Prediction ◽  
Mixed Lubrication ◽  
Prediction Methods ◽  
Gear Design ◽  
Surface Fatigue ◽  
Life Model ◽  
Von Mises ◽  
Von Mises Stresses

Predicting gear surface fatigue life is vital to gear and transmission design. Although simplified approaches based on the smooth-surface Hertzian contact stress calculations are available, the trend of compact design of high-power gear systems requires the gear design calculation to consider severe operation and lubrication conditions and detailed surface topography. It is needed, therefore, to upgrade the life prediction methods. The research presented in this paper aims to develop a gear pitting life prediction approach based on the rough-surface mixed lubrication model developed by Hu and Zhu [1] and the fatigue life model developed by Zaretsky and modified by Epstein et al [2] with accurate surface-subsurface stress analyses. With this approach, gear design parameters, operating conditions, materials, lubricant, and real tooth surface topography are used as input data. When conducting surface fatigue life prediction, three modules are employed: the mixed lubrication module, the stress analysis module, and the fatigue life module. In the mixed lubrication module, machined gear surfaces are digitized and used for calculating the pressure distribution and lubricant film thickness in the mixed lubrication. The mixed-lubrication pressure distribution is inputted into the stress module to obtain surface and subsurface von Mises stresses. These stresses are then integrated in the fatigue life module for estimating the fatigue life corresponding to a certain failure probability (50% in the present study). In other words, the life prediction is now based on subsurface von Mises stresses in the lubricated rough surface contacts, instead of smooth contact Hertzian pressure. There are a few materials constants involved in the fatigue life module. They are calibrated by comparing the prediction results with available Eaton experimental data. Table 1 lists the experimental data for 15 gear sets (most of them are hobbed and shaved) under combined rolling and sliding. The Hertzian stress ranges from 0.8554 GPa to 2.9494 GPa. It has been found that most conventional pitting life prediction methods tend to give conservative life estimates. With optimized materials parameters in the present life model, predicted pitting life results well agree with available Eaton gear test data, and the correlation appears to be 96.3%. Figure 1 shows the comparison between experimental and prediction data. Obviously, the model prediction well represents the performance of this group of gear surfaces in contact and mixed lubrication.

Semi-empirical methods versus dynamic load testing in piles

Geotecnia ◽  
2015 ◽  
Vol 135 ◽  
pp. 89-113
Author(s):  
Jean Felix Cabette ◽  
◽  
<br>Heloisa Helena Silva Gonçalves ◽  
<br>Fernando Antônio Marinho ◽  
◽  
...  
Keyword(s):  
Dynamic Load ◽  
Load Testing ◽  
Empirical Methods ◽  
Semi Empirical

Using Constraint Management Techniques to Design Spur and Helical Gears

1992 ◽  
Author(s):  
Rajiv Agrawal ◽  
Natarajan Sridhar ◽  
Gary L. Kinzel
Keyword(s):  
Mathematical Formulation ◽  
Spur Gears ◽  
Helical Gears ◽  
General Design ◽  
Gear Design ◽  
Constraint Management ◽  
Management Techniques

Abstract This paper presents the use of constraint management techniques to design spur and helical gears. The constraints for gear design are presented in a declarative manner such that they can be incorporated in a general Design Shell environment. A declarative representation allows the designer to experiment with a number of different designs and perform “what-if” scenarios. Since spur gears form a subset of helical gears, the mathematical formulation is presented for helical gears only. The analysis of helical gears is based on the AGMA/ANSI Standard 2001-B88.

Excited-state localization and energy transfer in pyrene core dendrimers with fluorene/carbazole as the dendrons and acetylene as the linkages

2016 ◽  
Vol 18 (5) ◽  
pp. 4134-4143 ◽  
Author(s):  
Linyin Yan ◽  
Yan Wan ◽  
Andong Xia ◽  
Sheng Hien Lin ◽  
Ran Huang
Keyword(s):  
Energy Transfer ◽  
Excited State ◽  
Theoretical Model ◽  
Empirical Methods ◽  
Multi Scale ◽  
Td Dft ◽  
Semi Empirical

Multi-scale theoretical model and spectra simulation for dendrimers combining TD-DFT/DFT and semi-empirical methods.

scholarly journals VERIFICAÇÃO DO DESEMPENHO DAS ESTACAS INJETADAS AUTOPERFURANTES EXECUTADAS EM SOLOS ARENOSOS PARA CONSTRUÇÃO DE USINA EÓLICA

2017 ◽  
Vol 13 (2) ◽  
Author(s):  
Rodrigo Cerqueira Rogerio
Keyword(s):  
Structural Characteristics ◽  
Load Capacity ◽  
The Self ◽  
Executive Processes ◽  
Empirical Methods ◽  
Deep Drilling ◽  
Load Tests ◽  
Different Diameters ◽  
Semi Empirical

RESUMO: Apresenta-se neste trabalho a solução adotada para execução das fundações do Parque de Usina Eólica localizado no Ceará, com a utilização das estacas injetadas autoperfurantes, executadas em presença de solos arenosos. No qual consiste em perfurar o solo com altíssima velocidade por rotação e “pull down”, através da injeção simultânea de nata de cimento com medias pressões. Ocasionando na estaca um diâmetro final que pode obter o dobro do bit de perfuração, de acordo com o tipo de solo, gerado pelo efeito do jato da nata de cimento. Detalhando os processos executivos, verificando os aspectos técnicos e operacionais, para melhor compreender as características estruturais deste elemento. De forma a verificar “in situ” o desempenho deste novo tipo de fundação profunda, foram realizadas provas de carga, em estacas com diferentes diâmetros e comprimentos, realizadas em perfis estratigráficos de solos arenosos, para melhor avaliação de sua capacidade de carga. Analisando-se os ensaios das provas de carga interpretados a base da extrapolação da curva carga versus recalque e das previsões da capacidade de carga, obtidas por meio dos métodos semi-empíricos de correlação com ensaios de penetração (SPT), avaliando os padrões de execução desta tipologia de estaca injetada para comunidade geotécnica. ABSTRACT: This paper aims to establish the selected solution to except the foundations of the Wind Energy Park in Ceará (Brazil), with an executive methodology of the self-drilling injection piles framed in loco in Sandy soil. In which the soil drilling is done with the highest speed by rotation and pull down, through the simultaneous injection of grouting with medium pressures. This kind of drilling causes in the pile a final diameter that can get the double bore bit, according to the type of soil, done by the grouting blast. The executive processes are detailed as a whole, and also presenting the pile materials composition, in order to understand the structural characteristics of this element. To verify the performance of this new kind of deep drilling, instrumentations were done: settlement control and load tests in constructions with different structural characteristics, in self-drilling injected piles with different diameters and length, done in stratigraphical sandy, for a better evaluation of its load capacity. Analyzing the essays of load tests interpreted in the basis of curve extrapolation load versus settlement and the previsions of the load capacity, obtained by semi-empirical methods correlating with the penetrations methods (SPT), offering information to the geotechnical community.

scholarly journals STRUCTURAL AND ELECTRONIC PROPERTIES OF BRIDGED BITHIOPHENE S-OXIDES (BTO) WITH S, S=O, O, SiH2 and BH2 BRIDGE: SEMI-EMPIRICAL AND AB INITIO STUDY

2010 ◽  
Vol 18 (18) ◽  
pp. 1-10
Author(s):  
Banjo Semire ◽  
Isaiah Ajibade Adejoro ◽  
Olusegun Ayobami Odunola
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Ab Initio Study ◽  
Empirical Methods ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Semi Empirical ◽  
Good Agreement

In this paper, we theoretically studied the geometries, stabilities, electronic and thermodynamic properties of bridged bithiophene S-oxide (BTO-X) derivates (with X = BH2, SiH2, S, S=O, and O) by using semi-empirical methods, ab-initio, and Density functional theory. The geometries and thermodynamic parameters calculated by PM3 were in good agreement with that of B3LYP/6-31G(d). The bandgap calculated by B3LYP/6-31G(d) ranged from 3.94eV (BTO-O)-3.16eV (BTO-BH2). The absorption λmax calculated suing B3LYP/6-31G(d) shifted to longer wavelength with X=BH2, SiH2, and S=O due to enhancement of π-conjugated system whereas, BTO-S and BTO-O shifted to shorter wavelengths as compared to dimmer thiophene S-oxide (2TO).

scholarly journals Experimental and Computational Vibration Study of Amino Acids

2013 ◽  
Vol 15 ◽  
pp. 1-17 ◽  
Author(s):  
Musa E. Mohamed ◽  
Abdelhafeez M.A. Mohammed
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Ab Initio ◽  
Vibrational Frequencies ◽  
Empirical Methods ◽  
Vibrational Studies ◽  
Semi Empirical

Vibrational studies of amino acids experimentally and theoretically have been performed. The Semi-empirical methods optimization by PM6 and RM1 on the l- and d-amino acids (alanine, phenylalanine, aspartic and glutamic acid), showed no difference in energy between l-and d-isomers. The vibrational frequencies were calculated by semi-emprical methods (PM6 and RM1) and Ab Initio methods (B3LYP/6-31+G(d) and were scaled down by factors of 0.925 (RM1), 1.09 (PM6) and 0.89 (B3LYP/6-31+G(d)). The calculated and experimental vibrational frequencies have shown good general agreement.

scholarly journals Study on Life Model of MOV Based on Multiple Parameters and Surge History

2021 ◽  
Author(s):  
RUAN Xiaofei ◽  
Shaoyun JIN ◽  
WEN Weigang ◽  
CHENG Weidong
Keyword(s):  
Life Prediction ◽  
Residual Life ◽  
Cumulative Effect ◽  
Degradation Process ◽  
Life Assessment ◽  
Lightning Protection ◽  
Multiple Parameters ◽  
History Information ◽  
Life Model ◽  
Metal Oxide Varistor

Abstract With the advance of intelligent operation and maintenance in china railways, the requirement of condition monitoring and remaining life prediction for lightning protection equipment has become increasingly urgent. MOV(Metal Oxide Varistor) is the key component of railway surge protector, and it is necessary to study the description model of its degradation process. The output of the model that uses a single parameter to characterize degradation is more prone to contingency, and cannot truly and fully reflect the life state of the MOV. The degradation of MOV is a cumulative effect, and its life model should consider the surge history information. In view of the above problems, a prediction model of the residual life value of MOV is given by combining various degradation related parameters and surge history. Firstly, nine degradation related parameters are fused to construct degradation core. Then, the degradation core and surge history are fused through Markov chain to build a life model of MOV. Then, the model is calibrated with experimental data. Finally, the model is validated and analyzed by experiments. The model can describe the degradation process of MOV more comprehensively and accurately, and can predict the residual life value at the same time, and it has potential application in the life assessment of surge protective devices.

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