DESIGN OF LAMINATES 



6-149 



3\ a 2 



(6. 55) 



k « E T h 



q cr = s L — 

 a 1 



where k„ = _ 

 3 3X 



'E1VE2 



. E J E L 



1 

 I 



(6. 55a) 

 (6. 56) 



where E^ and E2 are measured parallel to the sides a and b respectively. For a 

 laminate with the warp oriented parallel to the side b, the values of E^ = Em and 

 E2 = Er. The value for k s now becomes: 



3X 



1 



H 



and 



( E T E L )? 



Pa = 1 

 b 



(6. 56a) 



(6. 53a) 



(6. 54a) 



The dimensions a and b are assigned to the panel in such a way that (3 a is less than or 

 equal to unity. 



DESIGN EXAMPLE 6-22. CRITICAL SHEAR BUCKLING OF A 10 OZ. CLOTH 



OR ORTHOTROPIC PANEL 



Compute the critical shearing stress for the plate shown in Fig. 6-45 when: 



a = ?0 in. 



b = U0 in. 



t = 0.50 in. 



Laminate: 10 oz. cloth 



Warp parallel to side "b" 



5 1 = E T = 1.96 x 10 6 



G TL = 0.5? x lO^ 



LT " TL 



E 2 = E L = 1.70 x 10 6 (Table 5-10) 



(Table 5-14) 



= 0.20 (Average of Tables 5-8 and 5-13) 



