DESIGN OF LAMINATES 



6-21 



From Table 5-6 the value for the ultimate strength of a 2 ounce mat laminate is given 

 as 11,000 psi. Referring to Fig. 6-16 and using equation 6.12. 



P = Axf t = Ux-ix L1,000 = ??,000 lbs. 



Examples 6-4 and 6-5 outline the procedure for analyzing simple tension members of 

 isotropic materials. In using equations 6.12 to 6.12b it is recommended that the value of 

 the tensile ultimate stress be a test determined value. 



Orthotropic Laminates 



The following design examples illustrate the method of analysis for orthotropic lami- 

 nates. All plies are parallel laminated; the direction of warp is the same for all plies. 



DESIGN EXAMPLE 6-6. WOVEN ROVING LAMINATE 

 UNDER TENSILE LOAD AT 30 DEGREES TO WARP 



A woven roving laminate, with the fibers oriented as shown in Fig. 6-17 is to support 

 a load of 15,000 lbs. What is the required width for a 1/4 in. thick laminate with a factor 

 of safety of 2 on the ultimate strength? Laminate not restrained. 



o 15000 LBS 



Dl RECT I ON OF WARP 



<1/l" 



15000 LBS 



Fig. 6-17. Woven Roving Laminate 

 Under Tensile Load 



Since the warp is oriented at an angle of 30 degrees to the applied load, the ultimate 

 tensile strength of the woven roving, at 30 degrees, is required. This value was computed 

 in example 6-3 and was found to be 13,300 psi. 



The allowable design stress, for a factor of safety of 2, is then =la^2z P S1 = 6650 psi. 



Using equation 6-12b, A = _ 



A = axi = i5000 

 k 6650 



or a = 9.0 in. 



