﻿430 



Tests of Metals in Reverse Jorsion, 







Reversed 



Direct 



Reversed 



Direct 



Reversed 



Specimen. 



Stressed 



after 



after 



after 



after 



after 



to 



— days 



■ — days 



— days 



— days 



— days 







tO- 



to 



to 



to 



to 



1 D 



e.l. 



held. 



158 y.p. 



5 y.p. 







1 



e.l. 



7e.i. 



173 yp. 









10 



e.l. 



le.l. 



151 y.p. 



6 y.p. 



6 rupture. 



2 rupture. 



1 E 



fe.l. 



69, | e.l. 



113 y.p. 



H3y.p. 



4 y.p. 





1 B 



e.l. 



Oe.l. 



164 y.p. 



6 rup. 







2 



yp- 



30 y. p. 



151 y.p. 



113 y.p. 



4 y.p. 



71 



Stress 



in pounds 



jper sq. in 



ch at the elastic limit 



for above cases. 



ID 



32,600 



30,500 



25,000 



14,000 







1 



30,500 



14,400 



31.200 









10 



36,000 



35,100 



34,400 



13,200 



14,000 



13,600 



1 E ...... 



not 



reached. 



31,800 



18,800 



14,000 





1 B 



32,500 



26,500 



30,400 



14,000 







2 



Average... 



33,000 



18,450 



24,000 



24,000 



15,900 



25,350 



i 



32,900 



Conclusions. 



The curves show that when wrought-iron or mild-steel is 

 stressed in torsion below its elastic limit (proportional limit), 

 its elastic properties in the opposite direction are not impaired. 

 I£ the original stress be below the yield-point but above the 

 elastic limit, the elastic limit in the reverse direction is 

 lowered but does not disappear even when the stress is reversed 

 immediately. If the original stress be above the yield-point, 

 the elasticity in the reverse direction is destroyed but 

 reappears, gradually, after some rest. The modulus of 

 elasticity is unchanged when the stress in the first test is 

 below the yield-point. It is not constant, for reverse tests, 

 when the original stress is carried beyond the yield-point, but 

 comes back to its normal value alter a period of rest. 



The results obtained in these tests are in accord with those 

 already worked out for tension and compression ; and, indeed, 

 the present case of torsion may be considered as a unique way 

 of changing from compression to tension, or from tension 

 to compression, as is easily seen by considering the particles 

 of the cylindrical test-piece on the 45 degree helix. 



