262 



BELL SYSTEM TECHNICAL JOURNAL 



Fatigue Properties of Sheet Non-Ferrous Spring Materials 



Because of the important bearing of fatigue of springs for telephone 

 apparatus, this property has been carefully studied. The stress- 



10^ 



10* 



10^ 



OPERATIONS 



Fig. 3 — Fiber stress vs. fatigue — brass sheet — 24 gage— 10 Nos. hard: 

 A, average of three specimens taken from test without failure. 



lO'' 



I08 



OPERATIONS 



Fig. 4 — Fiber stress vs. fatigue — -nickel silver sheet — -24 gage — 4 Nos. hard: 

 A, average of three specimens taken from test without failure. 



