6-20 



DESIGN OF LAMINATES 



or 



or 



P 

 ft 



A x f t 



P 



A 



(6.12) 

 (6.12a) 



(6.12b) 



Where P = total tensile load - pounds 



A = cross-sectional area - square inches 

 £+ = tensile stress - psi 



DESIGN EXAMPLE 6-4. MAT LAMINATE UNDER TENSILE LOAD 



The fiberglass laminate shown in Fig. 6-15 is made of 2 ounce .mat and is to support a 

 load P, in tension of 10, 000 lbs. The maximum thickness, t of the laminate is to be 1/8 in. 

 Find the width 'a' 1 for a required factor of safety of 2 on the ultimate stress. 



The required area is found by using equation 6. 12b. 



A = 



10,000 



Referring to Table 5-6 the ultimate strength in tension is 11, 000 psi. Higher values of 

 ultimate strength may be used when verified by qualifying tests. Applying a factor of safety 

 of 2 to this ultimate value gives the allowable design stress: 



t = 



11000 



5500 psi 



Therefore A 



_ 1 . 10,000 

 8 ~55oo~ 



from which a = lU.5h in., say llj-5/8 in. wide 



DESIGN EXAMPLE 6-5. ULTIMATE TENSILE STRENGTH OF MAT LAMINATE 



What is the ultimate load carrying capacity of a 2 ounce mat laminate, 1/2 in. thick 

 and 4 in. wide? 



Fig. 6-16. Mat Laminate Under Tensile Load 



