DESIGN OF LAMINATES 



6-179 



Uniform load: 

 _ E x bh 



h3 



6.k\™ 20.6 E a w3 

 XE x h + \E x h3 



, , 20.6 E a w 3 

 6.1iE 1 w + j-^- 3 — 



where 



n = 2.778 



*I 



1 

 E 



1 cosh t^-1 



"n? cosh ri 



1 / f oosh^^ \ 



n 2 \ i^ri^cosh T^ jr y 



and 



E a = modulus in tension parallel to the x-axis, E^ x 

 E]_ = modiolus in bending parallel to the x-axis, E bx 



The value of a can be chosen from Fig. 6-5la. 



The above expressions are applicable when the ratio _ = — 



3. 3. 



(6. 78) 

 (6.78a) 



(6.79) 



(6. 80) 



E2 



Z 2 



1.75. 



Case 2. Plates with Clamped Edges Under Uniform Load 



For a plate with clamped edges and uniformly loaded the following formulas have 

 been derived: 



Uniform load: 



XaC 



\a 



32 E x w 



23 E a w3 

 h^~ 



(6.81) 



Maximum bending stress: 



f b = a — 



w 'g'Exh 

 h xa2 



16 Evw ♦ 2 - 98E ^ E ^ 3 



El 



(6. 82) 



Mean direct stress: 



El h? 2 

 II a? n 



(6. 83) 



Total maximum stress : 



where t\ = t- 



L Total 

 Ea" 

 El 



f b + f £ 



2 x 



0.366 



(6. 84) 



