Experimental analysis of contact fatigue damage using fractal methodologies

• Published in: Wear 2020-06, Vol.450-451, p.203262, Article 203262
• Main Authors: Prajapati, Deepak K., Tiwari, Mayank
• Format: Article
• Language: English
• Subjects: Boundary lubrication; Coalescing; Damage; Fatigue failure; Fractal analysis; Fractal signature; Fractals; Gear failure; Gears; Macropitting; Micropitting; Resistance factors; Rolling contact; Rolling resistance; Slide-to-roll ratio; Surface properties; Tribology
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2020.203262

Gears are used in high power density (power throughput/weight) machines for continuous power transmission. The efficiency and reliability of gears significantly depend on tribological performance. Micropitting is a type of rolling contact fatigue damage mechanism that occurs at the asperity scale in lubricated contacts and highly prevalent in gears. A detailed surface characterization study is essential to get an insight into the incident of micropitting. In this work, factors affecting resistance to micropitting are investigated by performing series of twin disk experiments. The effect of disc geometry and slide-to-roll ratio on resistance to micropitting is discussed in detail. It is observed that micro pits coalesces occur when components run for very large number of fatigue cycles. A positive correlation is found between autocorrelation length and surface damage. Rose plot and area-scale fractal analysis is employed on damaged surfaces, and it is concluded that there exists a certain scale, below which fractal theory is applicable. •Damaged surfaces exhibit fractal nature below a particular scale. .•Surface texture changes from anisotropic to isotropic, after 6 million cycles. .•Fractal dimension is positively correlated with surface damage. .•Surface damage decreases with an increase in crown radius. .•Both micro pits and macro pits are observed in damaged surfaces. .