MK.\8l'RIXG FORCKS .\N'D WK.M? IN' SWITCHING .Vl'l'.V K.VTUS 



49 



attaching a velocity inicroplionc jjickiip to the transducer. The force 

 voltage was placed on one set of plates of an oscillograph while th(> 

 integrated output from the velocity pickup was placed on the other set. 

 A series of oscillographs were taken for various amplitudes of motion 

 and the pictures are shown by Fig. 22. Since the force and displacement 

 measurements were separately calibrated, the area of the curves in inch 

 pounds could be evaluated and are shown by Fig. 23. For amplitudes of 

 motion near the gross slip amplitude, the area agree well with that 

 calculated from Equation (20) from which the dotted line is obtained. 

 For lower amplitudes the measured area is larger than the calculated 

 area. Possibly a stick-slip process is causing the displacement to lag be- 

 hind the applied force. The measured areas are nearly propoi'tional to 

 the square of the amplitude. The mechanical resistance associated with 

 the stress-strain hysteresis curves of this sort is of the same type that 



0.30 

 0.28 

 0.26 

 0.24 

 0.22 

 0.20 

 0.18 

 0.16 

 0.14 

 0.12 

 0.10 

 0.08 

 0.06 

 0.04 

 0.02 

 



0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 



Fig. 21— Plot of 1 — (o'/o)' against ratio of tangential and normal forces. 



