DESIGN OF LAMINATES 6-59 



Section moduli to various laminae: 



Z, = - x % (6.41) 



7i E 



i 



where Z± = section modulus of i-th lamina 



Ej_ = modulus of elasticity of i-th lamina 



Cloth top fiber: 



m 0,00078 x i.8l x 106 = 0>Q059in 3 

 Cl °.122 1.96 x 10 6 



Plat top fiber: 



Z = '^2°2Z3 x LSI x 106 m . n 3 



m 0.106 o.36 x 10 6 



Woven roving bottom fiber: 



= 0.00078 x 1.81 x 106 = . 00?6in 3 

 0.102 1.31 x 10 6 



The ultimate moments for the ultimate flexural stresses are obtained from: 



M = F b x Z (6.31b) 



Cloth, Mei = 31,100 x 0.0059 ■ 183 in- lbs. 



Mat, M m = 20,500 x 0.0155 = 318 in- lbs. 



Woven Roving, %R = 28,200 x 0.0076 = 2lU in- lbs. 



The minimum resisting moment of the laminate is ^\ n j l _ n = 183 in-lbs. 



The ultimate uniform load for the minimum resisting moment and simply supported 

 laminate: 



BHmin 



(6.42) 



'* ~ L2 



where P u = maximum uniform load, lbs. per in. 

 Mm = maximum resisting moment, in-lbs. 

 L = span length, in. 



P u = 8 X 2 183 = 22 * 9 lbs * P er in * 



The ultimate vertical shear that the composite laminate will resist due to the ultimate 

 horizontal shear at the neutral axis and at the shear planes between the different laminae is 

 obtained from: 



