Fatigue and Life Prediction

2005 ◽  
pp. 293-309
Keyword(s):  
Fatigue Life ◽  
Stress Analysis ◽  
Fatigue Failure ◽  
Contact Stress ◽  
Life Prediction ◽  
Gear Tooth ◽  
Gear Train ◽  
Tooth Surface ◽  
Bending Stress ◽  
Surface Durability

Abstract This chapter summarizes the various kinds of gear wear and failure and how gear life in service is estimated and discusses the kinds of flaws in material that may lead to premature gear fatigue failure. The topics covered are alignment, gear tooth, surface durability and breakage of gear tooth, life determined by contact stress and bending stress, analysis of gear tooth failure by breakage after pitting, and metallurgical flaws that reduce the life of gears. The chapter briefly reviews some components in the design and structure of each gear and/or gear train that must be considered in conjunction with the teeth to enhance fatigue life.

Contact Stress Analysis of a Helical Gear

2015 ◽  
Vol 766-767 ◽  
pp. 1070-1075 ◽  
Author(s):  
R. Devaraj
Keyword(s):  
Stress Analysis ◽  
Contact Stress ◽  
Gear Tooth ◽  
Element Model ◽  
Helix Angle ◽  
Helical Gear ◽  
Bending Stress ◽  
Helical Gears ◽  
Modeling Software ◽  
Main Factors

The main factors that cause the failure of gears are the bending stress and contact stress of the gear tooth. Out of these, failure of gears due to contact stress is high compared to bending stress. Stress analysis has been a key area of research to minimize failure and optimize design. This paper gives a finite element model for introspection of the stresses in the tooth during the meshing of gears. Specifically, helix angle is important for helical gears. Using modeling software, 3-D models for different helix angles in helical gears were generated, and the simulation was performed using ANSYS 12.0 to estimate the contact stress. The Hertz equation and AGMA standard was used to calculate the contact stress. The results of the theoretical contact stress values, using Hertz and AGMA are compared with the stress values from the FEA for different helix angles and the results are tabulated and discussed.

Comparative study of stress analysis of gears with different helix angle using the ISO 6336 standard and tooth contact analysis methods

2016 ◽  
Vol 230 (7-8) ◽  
pp. 1350-1358 ◽  
Author(s):  
Layue Zhao ◽  
Robert C Frazer ◽  
Brian Shaw
Keyword(s):  
Stress Analysis ◽  
Contact Stress ◽  
Helix Angle ◽  
Contact Analysis ◽  
Bending Stress ◽  
Contact Ratio ◽  
Tooth Contact Analysis ◽  
Tooth Contact ◽  
Iso Standard ◽  
Analysis Methods

With increasing demand for high speed and high power density gear applications, the need to optimise gears for minimum stress, noise and vibration becomes increasingly important. ISO 6336 contact and bending stress analysis are used to determine the surface load capacity and tooth bending strength but dates back to 1956 and although it is constantly being updated, a review of its performance is sensible. Methods to optimise gear performance include the selection of helix angle and tooth depth to optimise overlap ratio and transverse contact ratio and thus the performance of ISO 6336 and tooth contact analysis methods requires confirmation. This paper reviews the contact and bending stress predicted with four involute gear geometries and proposes recommendations for stress calculations, including a modification to contact ratio factor Zɛ which is used to predict contact stress and revisions to form factor YF and helix angle factor Yβ which are cited to evaluate bending stress. The results suggest that there are some significant deviations in predicted bending and contact stress values between proposal methods and original ISO standard. However, before the ISO standard is changed, the paper recommends that allowable stress numbers published in ISO 6336-5 are reviewed because the mechanisms that initiate bending and contact fatigue have also changed and these require updating.

Research on Commercial Vehicle Clutch Release Bearing Fatigue Life Prediction Model

2013 ◽  
Vol 423-426 ◽  
pp. 1853-1857
Author(s):  
Guo Liang Chen ◽  
Xiao Yang Chen
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Prediction Model ◽  
Contact Stress ◽  
Life Prediction ◽  
High Speed ◽  
Commercial Vehicle ◽  
Smelting Process ◽  
Fatigue Life Analysis ◽  
Life Prediction Model

Commercial vehicle clutch release bearings working at high speed, strong vibration,high temperature, damp and easy pollution conditions. Fatigue life analysis is based on the release bearing rings or rolling body began to appear fatigue spalling, in which this kind of phenomenon is under cyclic stress. The contact stress distribution is not uniform, the contact stress is mainly concentrated near the surface; influenced by the geometry and physical properties and lubrication of the surface significantly. Contact between the two types of fatigue crack extension methods: fatigue crack surface under expansion and surface fatigue crack propagation. The surface crack growth mainly originated from two kinds of cases: crack caused by surface pre crack and contact between the two surface asperity each other. New life prediction model for the release bearing based on L-P theory and Tallian model ,in which influence factors of fatigue life is introduced on the smelting process, surface defect, surface roughness, residual stress, elastohydrodynamic lubrication oil film,environmental cleanliness, temperature, the effect of varying load characteristics and other factors of fatigue life. The results show that: the clutch release bearing life prediction model of new and more close to the real conditions of automobile clutch, provide the theory basis for the development of a new generation high-speed heavy-duty clutch release bearing of the commercial vehicle.

Simulation of Fatigue Life Prediction and Enhancement of Connecting Rod of Car Engine

2012 ◽  
Vol 557-559 ◽  
pp. 2410-2414
Author(s):  
Ojo Kurdi ◽  
Mohd Arif Bin Mat Norman ◽  
Ian Yulianti ◽  
Muhammad Nizam Bin Md Rashid
Keyword(s):  
Finite Element Method ◽  
Fatigue Life ◽  
Stress Analysis ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Connecting Rod ◽  
Modified Model ◽  
Stress Region ◽  
Life Enhancement ◽  
Fatigue Life Enhancement

This paper investigates the fatigue life prediction and fatigue life enhancement of connecting rods of car engine. The fatigue life prediction was simulated by analyzing the stress occur in the connecting rod and then simulate the fatigue life prediction. The stress analysis was done by using finite element method. The results obtained from stress analysis is used as the input to simulate the fatigue life using stress-life method. The simulation was done for two models, the existing model and modified model. The modified model is the existing model with increased thickness in the highest stress region. The results show that the modified model has an improved fatigue life up to 231% compared to that of the existing model.

Fatigue Life Prediction of Serpentine Interconnects on Soft Elastomers for Stretchable Electronics

2019 ◽  
Vol 87 (1) ◽  
Author(s):  
Shuang Nie ◽  
Min Cai ◽  
Chengjun Wang ◽  
Jizhou Song
Keyword(s):  
Fatigue Life ◽  
Prediction Model ◽  
Fatigue Failure ◽  
Life Prediction ◽  
High Performance ◽  
Theoretical Foundation ◽  
Fatigue Behavior ◽  
Fatigue Life Prediction ◽  
Stretchable Electronics ◽  
Life Prediction Model

Abstract Serpentine interconnects on soft elastomers have been widely used to develop high-performance stretchable electronics. A number of applications demand the system to sustain repetitive loadings, which lead to fatigue failure of serpentine interconnects. In this paper, the fatigue behavior of serpentine interconnects on an elastomeric substrate is investigated experimentally and theoretically. It is shown that the fatigue failure of serpentine interconnects is governed by the failure of the encapsulation layer with the fatigue life determined by the strain level. A fatigue life prediction model, validated by experiments, based on the fatigue modulus concept is established to predict the fatigue life of serpentine interconnects. These results provide physical insights into the fatigue failure of serpentine interconnects and paves the theoretical foundation to predict the fatigue life, thus to study the reliability of stretchable electronics.

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