DESIGN OF LAMINATES 6-177 



For the bending moment, m x : (6.68) 



a = E L = 1.81 x 10 6 = 0tl8l 



6 ^ E 1 E 2 6 A. 81 x 106 x 1.5U x 10 6 



From the graph of Fig. 6-50b: 



rn 



A = 0.1255 



m x = 0.1255 x 1.10 x 122 = 19.88 in. -lbs. (6.67) 



For the bending stress: 

 Stress due to m x : 



fbx'£ (6 - 31> 



Z = ^r- = 1 x °' l = .OlOla in. 3 for a 1 in. unit width (6.32) 



. 19.8! _ 1912 . 

 f bx - TT^TCTH - ^ 1Z pS1 



c. Using the modified isotropic method for the unit load p: 



Ox ~ Oy = 0.19 



E = E x ; E x and Ey as previously given 



b - 2h - 2 



From Table 6-19 for a = 0.20: 



a = 0.1167 

 From Table 6-20 for woven roving: 

 K a = 1.119 



and p = 12 x 0.125 x 1.8 1 x 10* x (1 x 0.2$3)/l2 = ^ psi (g> ?2a) 



1.119 x 0.1167 x 12 u 



For the bending moment, m x 



From Table 6-19 for = 0.20, P x = 0.100 

 From Table 6-20 for woven roving, K x = 1.121 

 and m x = 1.121 x 0.100 x 1.30 x 12 2 = 20.96 in. -lbs. (6.73a) 



For the bending stress: 



Similar to the orthotropic method (5) above; f^x = 2017 psi 



