6-46 



DESIGN OF LAMINATES 



Where % = modulus of elasticity of i-th lamina 

 about the neutral axis. 



Ij = moment of inertia of i-th lamina 

 about the neutral axis. 



As = area of i-th lamina. 



G^ = modulus of rigidity of i-th lamina. 



x-j_ = distance from some reference line to the 

 center of gravity of the i-th lamina. 



DESIGN EXAMPLE 6-17. CRITICAL COMPRESSIVE LOAD OF COMPOSITE LAMINATE 



Given the laminate of Fig. 6-30, compute the following constants: x, I, E, r, and the 

 critical compressive load parallel to the warp for simply supported ends. 



1/6"- 



9/16" 



WOVEN ROVING 



-1/16" 

 -3/8" 



Neutral Axis: 



Fig. 6-30. Composite Laminate in Compression 



A, = Area Cloth = 6 x 1/16 = 0.375 in 2 

 A 2 = Area Mat = 6x3/8 = 2.250 in 2 



A 3 = Area W.R. = 6 x 1/8 



0.750 in 2 



Given : 



E l5 Cloth 

 E 2 : Mat 

 E : W.R. 



2.U6 x 10° at 0° or warp direction 

 0.93 x 10° at 0° or warp direction 

 2.hS x 10° at 0° or warp direction 



x = 



Z 5 i A i x i 

 Y E i A i 



(6.24) 



