Thus, using Equations (107) through (109), one can calculate a value of 

 stress-intensity ^^^ as a linear function of applied pressure p; this is 

 plotted as a straight line on a p versus ^^ plot. Next, the uniaxial stress- 

 strain curve of the material is entered with the value of ^^ given by- 

 Equation (107), and this determines Eg and E^. These values are then 

 used in conjunction with Equations (103) to determine the plastic buckling 

 pressure p from Equation (105), In this fashion, a plot of p versus <3^ 

 is obtained. The intersection of the two curves, p versus ^^ and Pp versus 

 ^ ■, gives the desired value of plastic buckling load. This is shown in 

 Figure 14 for the two general classes of material mentioned before. 



Equations (105) through (109) define the buckling pressure for the 

 fully plastic case corresponding to V = — . By employing an empirical 

 correction factor wherein Poisson's ratio is regarded as a variable, one 



can arrive at an expression which defines the buckling pressure in the 



43 

 inelastic range. Gerard and Wildhorn have found that V can be accu- 

 rately expressed as a function of E in the inelastic region by the equation 



which reduces to 1/2 when Eg/E is zero and to the elastic value 1/ ^ when 

 E /E is unity. For the general inelastic case where i/ is a variable de- 

 fined by Equation (110), Reynolds gives the following formula for buckling 

 pressure: 



71 



