COMPLEX STRESS DISTRIBUTIONS IN ENGINEERING MATERIALS. 209 
67 Sankey, H.R. 1905 Vibratory Testing Machine. ‘Mech, Eng.,’ Nov. 11, 
1905. 
68 Do. 1907 Hand Bending Test. ‘ Engineering,’ Dec. 20, 1907. 
‘ Engineering, Feb. 15, 1907. 
See No. 10. 
69 Schuchart, A. 1908 Resistance of Wire to Repeated Bending. ‘Stahl und 
(Sen.) Kisen,’ July 1 and 8, 1908. 
Tests of wire, gripped in jaws with curved faces, over which the wire 
was bent backwards and forwards into contact with the faces. 
70 1908 Olsen Vibrating Testing Machine. ‘Elect. Rev., 
April 17, 1908. 
71 1909 Landgraf-Turner Alternating Impact Machine. ‘ Iron 
and Steel Times,’ June 24, 1909. 
See No. 51. 
72 Smith, J. H. 1905 Testing Machine for Reversals of Stress. ‘ Engineer- 
ing,’ March 10, 1905. 
73 Do. 1909 Fatigue Testing Machine. ‘Engineering,’ July 23, 
1909. 
For direct stresses of any required range with any required mean stress 
of range. The specimen is motionless. The machine has been (or is being) 
used for various speeds of alternation. 
74 Do. 1910 Experiments on Fatigue of Metals, ‘Journ. Iron and 
Steel Instit.,? 2, 1910. ‘Sci. Abs.,’ 1911, No. 568. 
Tests with machine of No. 73. Speed of repetitions, 1,000 per minute ; 
various values, both + and —, of the mean stress being used. An extenso- 
meter was kept in position during the tests. A range of steels, of from 0-13 
to 0-79 per cent. carbon content was tested ; also some nickel steels. Most 
of the specimens were without heat treatment; a few were tested both in 
the untreated state and also after annealing. 
The author proposes a new and very quick method of finding the Wéhler 
safe ranges. The validity of the method depends entirely on the experi- 
mental agreement between the Wohler safe ranges, determined by the 
endurance test, and what the author calls ‘yield ranges.’ A description 
of the method of finding the latter is given in the paper. Very briefly, the 
“yield range’ is reached when the specimen first shows, by the extenso- 
meter indication, a small change of length, which appears to be similar to 
that found by Mr. L. Bairstow (No. 4), and called by him ‘ permanent ex- 
tension.’ It is shown, however, in No. 4, that these ‘ permanent extensions ’ 
may occur even if the range isa safe one. If Bauschinger’s theory be accepted 
it is difficult to see why these ‘ yield ranges’ should be the same as the 
Wohler limiting (or safe) ranges. In Dr. Smith’s method the successive 
changes of mean stress from + to — will give little opportunity for the 
adjustment of the elastic limits to the upper and lower limits of the range ; 
whereas it is established that (Nos. 4, 7, and 82) such adjustment does take 
place when the range is in the neighbourhood of the safe range, and the mean 
stress is constant. 
It would appear that before the method can be generally relied upon 
the experiments should be repeated, preferably on a machine of another 
type. The correspondence between the quickly determined ‘ yield ranges ’ 
and the Woéhler limiting range promises, however, to fulfil the need for a 
commercial substitute for the tedious Wohler fatigue test. 
75 Sondericker, J. 1899 Repeated Stresses. ‘Massachusetts Inst. of Tech- 
nology Quarterly Journ.,’ 1899. (Description of 
machine, 1892, ditto.) 
Machine of rotating-bar type, with constant bending moment over a short 
length. The materials tested were wrought iron and steels of carbon con- 
tent 0-08 to 0-50 per cent., and the speeds 350 to 500 r.p.m. Two pointers were 
clamped to the part under uniform bending moment, and the extreme fibre 
strains measured ; such measurements were taken at intervals during each 
a test. The fibre stresses were high, often considerably above the observed 
3. B 
