Tham khảo tài liệu 'friction and lubrication in mechanical design episode 2 part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Some Experimental Studies 505 values of d are then used to calculate . This kinetic coefficient of friction is also plotted against the striker velocity V in Fig. . Its value is found to be pLk and is independent of the normal force. Equation is then used to obtain a theoretical plot of d versus V beyond gross slip. This is shown by the solid lines in Fig. . The correlation between the calculated curves and the experimental data is evident. The peak force and the time duration of the impact corresponding to gross slip are listed in Table as a function of the normal force. It can be Figure Ball displacement for impacts causing gross slip. From Ref. 10. 506 Chapter Ì3 Table Pulse Characteristics N lb v0 in. sec Vo2 Vo2 Fmax Ibl T nsec easily seen that the coefficient of static friction based on the peak of the Hertzian pulse checks very closely with the value obtained from energy consideration. It should be noted here however that the pulse duration in this investigation varies between and where r is the equivalent natural period of the ball suspended on the frictional support as calculated from _ 2 l 2 324 _6 r 2 X1O sec At this ratio of pulse duration to natural frequency the shape of the pulse is not of significant value and the transient response of the system is the same as the static response to the pulse within the range of this test 13 . It is interesting to note that the gross slip coefficient of friction under impulsive loading is equal to for the materials used and is independent of the normal load for the range investigated. This is more than three times higher than the corresponding value under static or vibrating loads. The experimental results also show that at gross slip the frictional joint undergoes a sudden drop in frictional .
