OPEN-CONTACT PERFORMANCE OF TWIN CONTACTS 



1381 



wipe, if the average displacement per operation is x, the number of opera- 

 tions required to clear an open is N = X/x. Since, howe\'er, the initial 

 location of the particle r has a triangular probability distribution, ^ 

 r ^ To , and the direction of wipe 6 has a rectangular distribution, ^ 

 d ^ 27r, the number of operations for clearing must have a corresponding 

 pr()bal)ility distribution. This has lieen determined graphically and is 

 shown in Fig. 4. This is an accumulative probability distribution of the 

 fraction cleared "/" versus (Nx<p/d). It indicates that 50 per cent of the 

 opens will clear at (Nx<p/d) = 0.8 and 100 per cent at 2.0. The cor- 

 responding number of operations N can be determined only if .r is known* 

 under the operating conditions. By increasing the contact wipe w one 

 may expect x, the average displacement per operation, to increase. Also 

 by increasing the force, the frictional driving force will increase and x 

 should also increase. One may, therefore, tentatively assume that x is 

 proportional to iv"F and the distribution function may be put in the 

 form/ = fiNivT ), keeping all the other parameters fixed. This suggests 

 that bv varying the contact wipe w and the contact force F, the distribu- 



uj 0.60 



O 



O 0.40 

 < 



0.30 



2 4 6 8, 



10 10 



NUMBER OF OPERATIONS, N 



Fig. 5 — Effect of wipe. 



For a certain surface roughness <f> and particle size d. 



