6-60 DESIGN OF LAMINATES 



fs.I'b'. Et 



v __i i 1 (6.43) 



where Q'. = / A'.y'. = equivalent weighted static moment of the 



'— equivalent areas between the extreme edge and 



the plane being considered, about the neutral 

 axis. 



Woven roving at neutral axis! 



v 2600 x 0.00078 x 1.0 „ 1.8l x 10 6 , fto ., 



Vl ' 1.0x0.102x0.05 X 1.81 x 10° " 389 ' 91bs - 

 Shear plane between woven roving and mat laminae: 



Woven roving: 



2600 x 0.0 0078 x 1. 000 1.81 x 10 6 , Po , ,, 



V l " 1.0x0.^8x0.028 X x.81 x 106 = U89 - U lbs * 



Mat: 



.. 2780 x 0.00078 x O.U751 1.81 x 10 6 co-i n iy, 



V 2 = 1.0 X0.1U8 x 0.028 X 0.86 x 106 " >ZJ ' llds ' 



Shear plane between mat and cloth laminae: 

 Mat: 



2780 x 0.00078 x 0.U751 1.81 x 10 6 noo ^ _, ,. 



V = ; ; — x 7 = 1097.5 lbs. 



2 1.0829 x 0.016 x 0.11U 0.86 x 106 



Cloth: 



2570 x 0.00078 x 1.0829 1.81 x 10 6 nonl _ _. 



Vo = x ; 7 = 101U.9 lbs. 



J 1.0829 x 0.016 x O.llU 1.96 x 10° 



The minimum shear strength of the laminate is, ^rnxn = 389.9 lbs. 



The ultimate uniform load for the minimum shear strength and simply supported laminae: 



P = ^m (6.30a) 



r u L 



2 x 389.9 „ H ,,- 



P u = g = 97.5 lbs. 



The ultimate flexural stress controls and the ultimate carrying capacity per in. of 

 width of the composite laminate is 22.9 lbs. per in. 



In order to eliminate the work required in calculating the flexural strength of a given 

 composite laminate, the graphs of Figs. 6-31 through 6-33 may be used. Given the bending 

 moment and the bending stress for a particular laminate various values of section moduli 

 can be found for the components mat, cloth and woven roving. Entering the graphs with the 



