DESIGN OF LAMINATES 



6-31 



Properties of 10 Ounce Cloth Laminate: Cloth laminates are considered to behave as 

 orthotropic materials therefore the values for F and E at 15 degrees must be calculated since 

 they vary with the angle chosen. 



(a) Value of the tensile strength can be found by using the method of Design Example 6-3, 

 based on equation 6. 11 as follows: 



1 cos^ a 



. 2 CT 2 



sin 



ka 



. o 9 



sin' a cos' a 



F T ' 



(6.11) 



Finding first the value of F s from the physical properties given for 0°, IS' 

 and 90°, where F]_ is the value at u5°: 



1 



F„ 2 sin 2 a cos' 



where sin k5° = 0.70711 

 sin? 15° = 0.U998 

 sinlj h5° = 0.22498 



sin'J a 



(6.11a) 



sin 2 a cos 2 a = 0.2U98 



and from Tables 5-6 and 5-7: 



P L = 17,^00 psi F ± = 81*00 psi F T = 11*000 psi 



E r = 1.1*0 x 10 6 psi 



Therefore 



1 



F 2 



0.2U98 



0.21*98 



81*00' 



17900 



2 



0.21*98 

 ll*0C0 2 



from which F = 1*5U0 psi, 



The value at 15 degrees can now be computed; again using equation 6.11a. 



*2* 



_ rh a 

 2 



. 9 9 



sui' a cos' a 



(6. 11a) 



where sin 15 ° = 0.25882 



.n 2 15"° = 0.6^99 



sin^ 15° = 0.001*1*9 



cos 15° = 0.96593 

 cos2 15° = 0.93302 

 cos 1 * 15° = 0.8705 



