PSI - Issue 60

Nagaraja Bhat Y V et al. / Procedia Structural Integrity 60 (2024) 345–354 351 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

Fig. 7. Comparison K H of colmonoy-5 with 440C

Fig. 8. Friction equation fit with experiment data at running in region

4.2. Theoretical

From experiments it is seen that the coefficient of friction varies with respect to sliding distance in the running in region i.e. the initial sliding distance of approximately 120 m. To consider frictional effects as in the Sarkar model, coefficient of friction is modelled using a set of three straight line equations corresponding to different ranges of sliding distances to capture the variation of the friction coefficient in the running in region as shown Fig. 8. The straight line equations used in the model are given in Appendix B. Once steady state condition is reached, friction coefficient becomes constant and the value remains around 0.8 for rest of the sliding distance. Hence, for the Sarkar model, modified specific wear coefficient ‘K mh ’ is estimated as per equation-4 considering coefficient of friction as 0.8 and K H value obtained from the experiment.

Fig. 9. Comparison of experimental result (case-3) with different theoretical prediction

Wear depth was predicted with GIWM using both Archard equation & Sarkar wear model and compared with the experimental results. Two different values of K H were considered for the Arhcard wear equation, i.e. K H = 2.68×10 -14 m 3 /N-m which is obtained from the case-3 experiment and another 2×10 -14 m 3 /N-m which is slightly less than the experimental value. In the Sarkar model, as explained in the previous section K mh is estimated from K H = 2.68×10 -14 m 3 /N-m and friction value of 0.8. The comparison of experimental result obtained for case-3 with theoretical