363 
1911-12.] The Elastic Strength of Flat Plates. 
delicate way of determining the point at which any part of the substance 
passes the yield point. 
The two formulae that give the maximum stress are : — 
( 1 ) 
( 2 ) 
p. 
• P • 
(The latter is only true if m = 3; in the present case it requires to be 
multiplied by 1*01, but for simplicity of calculation the original form is 
retained and the slight correction made afterwards.) 
-03 
•02 
•A 
•Ol 
o 
20 
~30 
40 
XT 
~ 40 
- 
Z/Tl ^ 
' s. 
2SL 
No. (1) holds good if the elastic strength of the plate depends on the 
maximum principal stress, and No. (2) if it depends upon the maximum 
principal strain. 
H is a plate 6 in. diameter, *065 in. thick ; when continued back, its 
permanent set curve cuts the horizontal ordinate at p = 20. 
I is a plate 6 in. diameter, '066 in. thick ; its permanent set curve cuts 
the horizontal ordinate at p = 20. 
J is a plate 6 in. diameter, ‘063 in. thick ; its permanent set curve cuts 
the horizontal ordinate at p — 19. 
Putting these values of p into the two formulae, we have for 
Plate H (1) f 1 = 31,000 
(2) / 2 = 27,500 
Plate I (1) f x = 32,000 
(2) f 2 = 28,400 
(1) /j = 32,300 
(2) /,=* 28,700 
Plate J 
