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LONDON, EDINBURGH, akd DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



ISDEXEU 



J'J'S 



[SIXTH SERIES.]^L *& 



DECEMBER 190(5. 







LXI. The Strength and Behaviour of Ductile Materials Wider 

 Combined Stress. By Walter A. Scoble, A.R.C.Sc, 

 B.Sc, Whitworth Scholar *. 



1. Previous Tests and their Differences from those given. 



I^HIS branch of the testing of materials, although of con- 

 siderable theoretical and practical importance, has been 

 seriously neglected until quite a recent date. Experiments on 

 wires under combined tension and torsion are mentioned in 

 Lord Kelvin's article on Elasticity in the Encyclopaedia 

 Britannica, but numerical results are not given. Excellent 

 work was done by Mr. J. Guest t using thin tubes under 

 tension, torsion, and internal pressure. A preliminary report 

 has also recently appeared of tests on the effect of combined 

 stresses on the elastic properties of steel, by Mr. E. L. Han- 

 cock {. In addition to the above there are the experiments 

 by Tresca upon the ultimate strength under combined stress. 

 The ultimate practical value of experiments of the kind 

 under consideration will greatly depend on the limiting con- 

 dition of the material which is selected as the basis for 

 comparison. Reasons are given below for selecting the yield- 

 point. This point was taken by Mr. Guest, the choice being 

 justified in his paper. This being so, it may appear that the 

 present results will only be a confirmation of previous tests, 



* Communicated by the Physical Society : read October 26, 1906. 

 | Proc. Phvs. Soc. vol. xvii. p. 202, and' Phil. Mag. [5] vol. 1. p. 69. 

 X Phil. Mag. Feb. 1906. 



Phil. Mag. S. 6. Vol. 12. No. 72. Dec. 1906. 2 N 



