332 REPORTS ON THE STATE OF SCIENCE, ETC. 
main feature of all these experiments was measurement of the ranges of cyclic 
bending and twisting strain. 
The machine used was the one described in the paper above referred to, and 
the frequency of the cycles of stress was, as previously, 200 per minute. The 
apparatus for measurement of the strains is also substantially the same, and the 
ranges of strain simultaneously measured are the angle of twist, and the angular 
deflection due to bending between two sections about 4 in. apart. The 
bending moment was uniform over this length, which included 2) in. turned 
parallel between shoulders. The mirrors for measuring these strains were fixed 
to the squared shoulders of the specimen. 
All the conditions were the same as for the experiments previously made in 
bending and twisting separately; the specimens were cut from the same two 
bars A and B, the number of specimen denoting the position of the specimen 
in the uncut bar. These conditions allow a systematic comparison to be made 
between these tests and those done previously—a procedure of obvious advantage 
in saving of time and labour, especially since simultaneous measurement of the 
two sets of cyclic strains entails considerable patience. 
Phase Angles of Bending and Twisting in Combined Clycles. 
A set of six specimens (Tables I. and IV.) was tested, foar of which were 
solid and two hollow. These were of similar shape and dimensions, and the 
surfaces were finished in the same manner as previously. It will be seen that 
in four of these the phase angle (i.e. the angle between the crank giving the 
simple harmonic alternating bending moment and the crank which applied the 
8.H. alternating torque) was 90°; and in two of them the phase angle of them 
was zero. In the case of Specimens A6, A13, and B31, the maximum direct 
stress calculated from the bending moment was approximately twice the 
maximum shear stress calculated from the torque. In calculating the stresses, 
the usual simple formule for bending and twisting were used. 
TABLE IV. 
PRELIMINARY DEAD-wEIGHT TESTs AND DrameTERS OF SPECIMENS. 
Specimen Preliminary Dead-weight Test 
Z Eby bey [Zo ee sic 
s (swe [Beg] e8el4 [Bear] .Be 
& = ofgalas | Sag) Ss. las | ons 
E g SEHR I | Gee | eH Se | age ees 
5 = segiies & | s8e| sSl jes &| ess 
A A GAS ras) || ame jets Ro H | H#8o 
agi | s8| (a2 0 | 28 
} | | 
| tons per | cm. on | tons per] cm. on ‘ : 
inch lb.-in. | sq. in. | scale Ib.-in. | sq. in. | scale [sts Bene { 
| / See pre- , } 
| B31| 0-3125 solid | + 54 |+ 800) 5-70 | + 54 | 44-00 | 7-90 | vious test ames 
| 141 e 
| Pp. Mech. Eng. | 
Jan.-May,t917 * 
| | | 
A13) 0-4375 solid | +183 | +10-:00| 6-60 +183 | +5-00 | 7-20 | Accidentally bent and 
/ afterwards straightened 
A6 | hollow, see | +172 |+10-00} 4-90 | +172 | +5-00 | 5-60 
below | 
B24! hollow, see +149 | + 8-54 4-20 |} +149 | 44:27 4-90 =a. 
below | 
AQ 0-4376 solid +183 | +10-00 5:90 | +183 | #5-00 | e720 <— 
| B17} 0-4371 solid +179 | 9°75 5-95 | +179 | 14:87 6-80 ae 
* I=Moment of Inertia of Section about a diameter, (inch)4. 
+ J=Polar Moment of Inertia of Section, (inch)4. 
Thickness ‘of Wal! 
Number External Internal 
of Diameter Diameter : 
= ;. . Max. Min. Mean 
Specimen | (inch) (inch) (inch) Gnch) * (inch) Remarks 
A6 0-5760 0-5050 0-0360 00355 0-0357 
B24 0:5770 0-5050 0-0380 0-0340 0-0360 Bore eccentric 
