TORSION OF CERTAIN FORMS OF SHAFTIM: 



Hence \vi- h.-tvr. t'.n- tin- lull i-lli|.sc 



381 



If we compare this with the previous table, we see that for the flattest ellipse, 

 a = 7T/6, the ratio of the torsional rigidity to the torsional rigidity of the circular 

 section of equal area, which I propose to call for brevity the relative torsional rigidity, 

 is greater for the truncated than for the full ellipse, except in the last case, ft = ir/2. 

 This last must necessarily be, since the strength of the section should be reduced by 

 cutting two slits into it along the major axis. For the higher values of a we see 

 that the relative torsional rigidity is always greater for the full than for the 

 truncated ellipse. 



11. Values of the Stresses at the Points of Symmetry. 



Passing now to the values of the stress, the values of S B /ftTC are given, for the 

 sixteen symmetrical sections, in the table below. 



TABLE of S 



The values of S A //ITC were only calculated for ft = ir/6 and /J = ir/4, it being clear 

 1 1 i;it for the given values of a, S A would be less than S B for ft ir/3. The values of 

 S A /(/ATC) are given in the following table : 



TABLE of S A //ITC. 



2 u 2 



