SOLDERLESS WRAPPED CONNECTIONS — PART I 



537 



sion. The force WF is the tension in the wrapped wire. This force can 

 be determined by dividing the torque necessary to twist the terminal 

 by the effective moment arm. Since the elongation of the wire cannot 

 readily be measured, the terminal twist was chosen to determine the 

 force exerted at the terminal edge. The 39° terminal twist shown in Posi- 



80 



0.0148" X 0.062" NICKEL SILVER 



TERMINAL WRAPPED WITH 



100 TURNS OF 24 GA (0.020") 



TINNED COPPER WIRE 



600 800 1000 1200 1400 1600 1800 

 APPLIED WRAPPING TENSION, AF, IN GRAMS 



2000 2200 2400 



Fig. 13 — Angle of twist in terms of applied wrapping tension. 



tion 3, however, cannot be used for determining the force since the ter- 

 minal may be overstressed as is shown in Position 4. Instead of return- 

 ing 39° the unwrapped terminal returned only 30°. In other words the 

 terminal has taken a set of 9°. Fig. 12 illustrates the deformation of wire 

 and terminal only for one value of applied tension, namely 1300 grams. 

 If the angle of twist is measured for applied tension ranging from 100 

 to 2400 grams, a set of curves is obtained as shown in Fig. 13. Curve A 

 shows the angle of twist immediately after the terminal is wrapped. 

 Curve B shows the relaxation after eight days aging at room tempera- 

 ture. Curve C represents the terminal set. The value between Curves 

 B and C is the elastic reserve. For 1300 grams applied tension the elastic 

 reserve is expressed as 30° reserve twist. 



Using the before mentioned ratio of torque and moment arm, the 

 force WF can now be determined. The torque required to twist the 

 terminal 30° is 37.2 inch grams. (See Fig. 14.) The effective moment 



