PSI - Issue 60

Nagaraja Bhat Y V et al. / Procedia Structural Integrity 60 (2024) 345–354 349 Y V N Bhat, M A Davinci, A Kumar, N L Parthasarathi, S I S Raj, D Samataray, B.K. Sreedhar / StructuralIntegrity Procedia 00 (2019) 000– 000

(equation-15) and added to total wear depth estimated from the previous iteration. Total depth is the sum of wear depth and depth due to elastic deformation. ℎ=       (12) ℎ=   1+3      (13) ℎ   =ℎ   +    ∆ (14) ℎ   =ℎ   +  1+3    ∆ (15) Since pin contact tip is spherical, the change contact area as wear progress is estimated using cap formulae (equation-16). The new contact area is then used in the next iteration for estimation of average contact stress, elastic deformation and the wear depth. This iteration continues till sliding distance reaches the set value. A code is written in Python to perform this numerical integration.   =  ℎ  ℎ    (16) In the literature, Finite Element Method (FEM) with subroutines to update contact stress as wear progress in non conformal contacts is also used for prediction of wear depth [Priit Podra, et.al., 1999, Mona Oqvist 2001 & Kunal Kumar Boase, et.al., 2019]. However, in the present study GIWM is considered because it is a quick and computationally inexpensive method as compared to FEM.

Fig. 3. Coefficient of friction versus sliding distance

Fig. 4. Pin wear depth versus sliding distance

4. Results and Discussion

4.1. Testing

In all the testing, irrespective of load and speed, the Coefficient of Friction (COF) value steadily increased from 0.1 and stabilized upon reaching a value 0.8. The sliding distance from zero to approximately 120 m, during which coefficient of friction changes, is called as running in region and the portion of sliding distance at which friction force remains constant is called as steady state region . Plots for the COF versus travel distance for case-3 of experimental is given in Figure 3. The wear plot is shown in Figure 4. The wear depth in the disc was found negligible. From the tests, it was noticed that with the escalation in load from 10N to 20N, the wear depth in the pin increases from 130 µ m to 200  m. However, the wear depth remained constant when the velocity was increased from 15mm/s