498 



THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1952 



Fig. 22 — Force displacement loops. 



occurs in an assemblage of granular particles such as in a telephone 

 transmitter for which the motion is so small that gross slide does not 

 occur. 



Since the theoretical displacement of Equation (19) has been verified 

 by the glass lens experiment, we can use it to determine some of the 

 quantities involved in the oscillographs of Fig. 9 and the displacement- 

 normal force curve of Fig. 15. To obtain the relation between the total 

 displacement 8x and the normal force A^, we have to eliminate a from 

 Equation (17) since a is also a function of the normal force as shown by 

 Equation (13). Introducing this equation, and neglecting l//i2 as com- 

 pared to l//ii , since for the wire jU2 is 40 times m of a plastic, 



5. = 



(ff 



(2 - cr)f 



8^yr(l - a) 



1 - ~^. 



Tn 



2/3-1 



(22) 



