DESIGN OF LAMINATES 



6-15 



For 10 ounc° cloth laminate, from Fig. 6-9 the plot of G]_2 indicates a varying 



-i Gr t 



value dependent upon the angle. At 10°, u 30°- 1.650 and 



G 30 o = 1.65 x G LT = 1.650 x 0.520 x 10 6 = 0.858 x 10 6 psi 



Poisson 1 s Ratio 



For mat laminate, from Fig. 6-7 the plot of a is a straight line having a 

 value of 0.3?0. This indicates a constant value of a equal to 0.320. Constant 

 value of a is always true for an isotropic laminate. 



For 10 ounce cloth laminate, Fig. 6-9, indicates a variable plot for the value 

 of a . At 30° the value is a = 0.^60. 



Example 6-2 will be used to indicate further procedures in the use of these graphs. 



DESIGN EXAMPLE 6-2. COMPRESSIVE AND SHEAR STRAINS IN 

 10 OUNCE CLOTH LAMINATE LOADED AT 30 DEGREES TO WARP 



A laminate made of 10 ounce cloth reinforcement is loaded in compression and shear 

 at 30 degrees to the warp, Fig. 6-13. Determine the strains parallel and perpendicular 

 to the direction of load. 



15000 LBS 



DIRECTION OF WARP 



1 5000 LBS 



Fig. 6-13. Cloth Laminate 

 Loaded in Compression and 

 Shear at 30 Degrees to Warp 



