6-30 DESIGN OF LAMINATES 



DESIGN EXAMPLE 6-12. ELONGATION OF COMPOSITE LAMINATE 



Find the elongation of the composite laminate described in Design Examples 6-10 and 6-11. 



From Design Example 6-10 the total load P is 3520 lbs. per in. of width. From Design 

 Example 6-11, the final modulus of elasticity, E is 1. 10 x 10° psi and the area of the com- 

 posite, A is 0.4375 sq. in. Substituting these values in equation 6.13 the following elonga- 

 tion results: 



PL 



AE 



3520 x 2U 



O.U375 x 1.10 x 10 £ 



= 0.176 in. 



Where L = 2k in. from Fig. 6-21 



DESIGN EXAMPLE 6-13. ELONGATION OF COMPOSITE LAMINATE AT ANGLE TO WARP 



A composite laminate is made up of 2 laminae of 10 ounce cloth reinforcement and one 

 lamina of mat reinforcement as shown in Fig. 6-22. The following properties of the com- 

 posite are required: 



1. Total ultimate tensile load, per in. of width, that the laminate can carry when the 

 load is applied at an angle of 15 degrees to the warp direction. 



2. Elongation of the composite in the direction of the applied load. 



Dl RECTI ON OF WARP 

 FOR ALL PLIES 



Fig. 6-22. Composite Laminate Under Tensile Load 

 at an Angle to Warp 



Information required for solution of problem: 



Tensile strength of mat and cloth laminates at 15 degrees to warp direction. 



Moduli of elasticity for mat and cloth laminates at 15 degrees to warp direction. 



Properties of Mat Laminate: Since mat laminates are considered to be isotropic in 

 behavior, the values for F t and E can be chosen from Tables 5-6 and 5-7. 



F mat = 660 ° P si 



E^ at = 0.81 x 10 6 psi 



