PSI - Issue 19

Yuya Tanaka et al. / Procedia Structural Integrity 19 (2019) 320–327 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

324

5

the tangential force of the left and right of the hysteresis loop changes drastically corresponds to the partial slip or non-slip regime. The area where the relative displacement changes largely keeping the tangential force almost constant indicates the gross slip of the contact surfaces. In this study, μ k was defined as: μ k = F k W (4) where F k is the value of tangential force during the entire slip. With this equation, μ k ≈ 0.8 was obtained.

Fig. 5. (a) Time variations of F and S , which were observed at N ≈ 1000 cycles; (b) relationship between F and S surrounded by dashed area in (a).

3.2. Frictional behavior

In this study, the dependences of p , R a and f on μ k were investigated. Figure 6 shows the relationships between μ k and N that were observed under p = 10 or 100 MPa, R a = 0.2 or 1.7 f = 0.1, 1 or 10Hz and S a ≈ 1 00 μm . All symbols represent the mean values of kinetic friction coefficient as a function of N . As shown by Figure 6, it is clear that all variations of μ k have the same trend except the result for f = 0.1Hz. Under the almost all experimental conditions, the values of μ k converge on a level of about 0.85. However, in the case of low sliding velocity, μ k decreases with increasing N . This specific difference will be discussed further in following section.

Fig. 6. Variations of μ k as a function of N .