Crack Propagation in Gear Tooth Root

2008 ◽  
pp. 1237-1238
Author(s):  
S. Pehan ◽  
B. Zafosnik ◽  
J. Kramberger
Keyword(s):  
Crack Propagation ◽  
Gear Tooth ◽  
Tooth Root

Dynamic characteristics of cracked gear and three-dimensional crack propagation analysis

2012 ◽  
Vol 227 (6) ◽  
pp. 1341-1361 ◽  
Author(s):  
Renping Shao ◽  
Purong Jia ◽  
Feifei Dong
Keyword(s):  
Crack Propagation ◽  
Dynamic Characteristics ◽  
Gear Tooth ◽  
Three Dimensional ◽  
Beam Theory ◽  
Circular Crack ◽  
Propagation Path ◽  
Tooth Root ◽  
3D Crack Propagation ◽  
Three Dimensional Finite Element

The dynamic model and three-dimensional finite element analytical model of cracked gear structure are established respectively according to the cracked beam theory, and the dynamic characteristics (natural frequency, vibration shape) of cracked gear body are investigated. Further the influences of crack position and crack length on the dynamic characteristics of gear structure are simulated and discussed. On this basis, the fracture and damage of gear structure are investigated according to the theory of fracture mechanics. Using FRANC3D software, the three-dimensional (3D) propagation of crack at tooth root for involute gear is simulated, and stress intensity factor (SIF)s of semi-circular crack at tooth root including three types are analyzed, their variation laws are gained, then the expressions of SIFs are obtained by numerical fitting FEM results. Based on this, the 3D crack propagation path at tooth root is simulated and discussed, then, it is verified by comparing to experimental results, according to the mutation of the maximum SIF at crack tip, the fracture and damage of gear tooth are judged, and its work life also is predicted. These have very important value for damage monitoring and diagnosis of gear.

Numerical Modelling of the Crack Propagation Path at Gear Tooth Root

2003 ◽  
Author(s):  
Damir T. Jelaska ◽  
Srecko Glodez ◽  
Srdjan Podrug
Keyword(s):  
Fatigue Crack ◽  
Service Life ◽  
Crack Propagation ◽  
Experimental Testing ◽  
Gear Tooth ◽  
Fatigue Crack Initiation ◽  
Propagation Path ◽  
Tooth Root ◽  
Stress Cycles

A numerical model for determination of service life of gears in regard to bending fatigue in a gear tooth root is presented. The Coffin-Manson relationship is used to determine the number of stress cycles Ni required for the fatigue crack initiation, where it is assumed that the initial crack is located at the point of the largest stresses in a gear tooth root. The simply Paris equation is then used for the further simulation of the fatigue crack growth, where required material parameters have been determined previously by the appropriate test specimens. The functional relationship between the stress intensity factor and crack length K = f(a), which is needed for determination of the required number of loading cycles Np for a crack propagation from the initial to the critical length, is obtained numerically. The total number of stress cycles N for the final failure to occur is then a sum N = Ni + Np. Although some influences were not taken into account in the computational simulations, the presented model seems to be very suitable for determination of service life of gears because numerical procedures used here are much faster and cheaper if compared with the experimental testing.

Dynamic Simulation of Planetary Gearbox With Tooth Root Crack Based on a Rigid-Flexible Coupled Model

2019 ◽  
Author(s):  
Jianchuan Dai ◽  
Hang Niu ◽  
Chenggang Hou ◽  
Xiaodong Zhang
Keyword(s):  
Crack Propagation ◽  
Dynamic Models ◽  
Gear Tooth ◽  
Coupled Model ◽  
Vibration Signal ◽  
Propagation Path ◽  
Tooth Root ◽  
Crack Propagation Path ◽  
Planetary Gearbox ◽  
Root Crack

Abstract Tooth root crack is one of the most common failures in the gearbox which can lead to the failure of the whole transmission system. However, it is difficult to simulate the gear fault impact in practical work. To solve this problem and to study the relationship between tooth crack propagation and vibration features, various dynamic models have been built. However, the crack propagation path and the bearings are simplified in most of the models, which leads to obvious deviation in the dynamic response. In this paper, a rigid-flexible coupled model of a single-stage planetary gearbox in normal and fault conditions are built by ADAMS software. The crack propagation path is considered a parabolic curve and the thickness of the crack decreases along the path. As a reference, a rigid-body model has also been built to prove that the rigid-flexible coupled model can be more accurate and suitable for analyzing the response of the planetary gearbox with fault. Afterward, the effects of gear tooth root crack size on the gear dynamics are simulated and the corresponding changes in statistical indicators are investigated. By studying the torsional vibration signal of the planetary gearbox with varying severity of the damage, the fault characteristics and damage evolution mechanics can be analyzed and by comparing the fault sensitivity of these indicators, the critical and sensitive fault indicators are screened out.

scholarly journals Gear tooth root fatigue test monitoring with continuous acoustic emission: Advanced signal processing techniques for detection of incipient failure

2017 ◽  
Vol 17 (3) ◽  
pp. 423-433 ◽  
Author(s):  
Davide Crivelli ◽  
John McCrory ◽  
Stefano Miccoli ◽  
Rhys Pullin ◽  
Alastair Clarke
Keyword(s):  
Acoustic Emission ◽  
Early Detection ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Gear Tooth ◽  
Low Frequency ◽  
Frequency Noise ◽  
Tooth Root ◽  
Polynomial Decomposition ◽  
Processing Techniques

The phenomenon of fatigue in gears at the tooth root can be a cause of catastrophic failure if not detected in time. Where traditional low-frequency vibration may help in detecting a well-developed crack or a completely failed tooth, a system for early detection of the nucleation and initial propagation of a fatigue crack can be of great use in condition monitoring. Acoustic emission is a potentially suitable technique, as it is sensitive to the higher frequencies generated by crack propagation and is not affected by low-frequency noise. In this article, a static gear pair is tested where a crack was initiated at a tooth root. Continuous acoustic emission was periodically recorded throughout the test. Data were processed in multiple ways to support the early detection of crack initiation. Initially, traditional feature–based acoustic emission was employed. This showed qualitative results indicating fracture initiation around 8000 cycles. A rolling cross-correlation was then employed to compare two given system states, showing a sensitivity to large changes towards the final phases of crack propagation. A banded fast Fourier transform approach showed that the 110- to 120-kHz band was sensitive to the observed crack initiation at 8000 cycles, and to the later larger propagation events at 22,000 cycles. Two advanced data processing techniques were then used to further support these observations. First, a technique based on Chebyshev polynomial decomposition was used to reduce each wavestream data to a vector of 25 descriptors; these were used to track the system deviation from a baseline state and confirmed the previously observed deviations with a higher sensitivity. Further confirmation came from the analysis of wavestream entropy content, providing support from multiple data analysis techniques on the feasibility of system state tracking using continuous acoustic emission.

Analytical procedure for the optimization of plastic gear tooth root

2021 ◽  
Vol 166 ◽  
pp. 104496
Author(s):  
Luca Landi ◽  
Alessandro Stecconi ◽  
Giulia Morettini ◽  
Filippo Cianetti
Keyword(s):  
Analytical Procedure ◽  
Gear Tooth ◽  
Tooth Root

scholarly journals Optimization of Tooth Root Profile Using Bezier Curve with G2 Continuity to Reduce Bending Stress of Asymmetric Spur Gear Tooth

2018 ◽  
Vol 237 ◽  
pp. 03010 ◽  
Author(s):  
Priyakant Vaghela ◽  
Jagdish Prajapati
Keyword(s):  
Stress Concentration ◽  
Gear Tooth ◽  
Spur Gear ◽  
Bézier Curve ◽  
Bezier Curve ◽  
Tooth Root ◽  
Geometric Continuity ◽  
Bending Stress ◽  
Gear Design ◽  
G2 Continuity

This research describes simple and innovative approach to reduce bending stress at tooth root of asymmetric spur gear tooth which is desire for improve high load carrying capacity. In gear design at root of tooth circular-filleted is widely used. Blending of the involute profile of tooth and circular fillet creates discontinuity at root of tooth causes stress concentration occurs. In order to minimize stress concentration, geometric continuity of order 2 at the blending of gear tooth plays very important role. Bezier curve is used with geometric continuity of order 2 at tooth root of asymmetric spur gear to reduce bending stress.

Fatigue Crack Propagation in a Gear Tooth in the Presence of an Inclusion

2014 ◽  
Vol 15 (3) ◽  
pp. 247-252 ◽  
Author(s):  
Vineet Agarwal ◽  
Pramod R. Zagade ◽  
Danish Khan ◽  
B. P. Gautham
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Gear Tooth

42CrMo Hard Surface Gear Intensity Tests and Modified Parameter Correction

2012 ◽  
Vol 246-247 ◽  
pp. 145-148
Author(s):  
Nai Gen Li ◽  
Nan Xu ◽  
Nian Jun Zhang ◽  
Meng Guo Zhu
Keyword(s):  
Fatigue Strength ◽  
Gear Tooth ◽  
Coincidence Degree ◽  
High Strength ◽  
Tooth Root ◽  
Bending Fatigue ◽  
Hard Surface ◽  
Basic Parameters ◽  
Bending Fatigue Strength ◽  
Research Intensity

Hard surface gears drive is considering mainly how to improve the tooth root bending fatigue strength and wear resistance of the teeth. Based on the analysis of sliding ratio, coincidence degree and the gear tooth root bending fatigue strength, basic parameters of gear can be modified to improve strength. Although these gears must be cut by the standard tools, high strength gears are needed in machinery. In this research, intensity experiments were conducted with 42CrMo modified and standard hard surface gears. Experiment results show that the improvements of 42CrMo gear parameters are effective and teeth strength is improved for the modified parameters of gears.

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