6-82 



DESIGN OF LAMINATES 



Case 1. All Edges Simply Supported 



The critical buckling load, P cr , per in. of width can be determined from the equation: 



P = k 

 cr cr 



12 VB2P2 



where k cr = ^o 



2 2 



El + £1 + 2ic 



n 2 r 2 



(6. 50) 

 (6.51) 



and the panel will buckle in 



one half wave if r < v 2 



two hall waves if V2< r<v6 



n half waves if i/n(n - 1) < r< vV n + 1) 



(6. 52) 



Case 2. Loaded Edges Simply Supported - Remaining Edges Clamped 



The critical load is 



12/^57 

 r cr K cr 9 



(6.50) 



where k 



cr 



= V 



7 



♦ lUl 



l6r 2 2 



The plate will buckle in n half waves when 



(6.51a) 



(6. 52a) 



I Wi(n - 1) V^"< r < I V n (n + 1) V3 

 ? 2 



Case 3. Loaded Edges Clamped - Remaining Edges Simply Supported 



When the loaded edges are clamped and the remaining edges simply supported the critical 

 buckling load, P C r» becomes a function of the method in which the surface buckles. Conse- 

 quently for each mode of buckling, there exists a critical load. The critical load then becomes 



k cr 12 v/D^ 



cr 



(6.50) 



where a different value of k cr will exist for each mode of buckling as follows 



a. buckling in one half wave 



•cr 



U8 



3r 2 + ^ ♦ 8v. 

 r 



(6.51b) 



