DESIGN OF LAMINATES 



6-183 



2. Deflection due to bending of the facings only, ignoring shear deflection and the effect 

 of the core: 



Eflf = E xf 



n bt3 x . ,, /t + c 

 2 x „_ + 2 x bt x I — 2" 



(6. 16) 



= 0.1270 x 10" 



PL 



d = nw y ' = 0.0262 in. This is considerably less than the more 



accurate method above. (6. 89) 



3. Deflection due to bending and shear of the facings, ignoring the effect of the core: 



E f l f = 0.1270 x 10 6 



fi f A f = 0.52 x 10 6 x 2 x 1 x .25 = 'J. 13 x 10 6 



d = IkL ♦ PL 



3E^I|- Gj-Ap 

 = 0.0262 + 0.0003 = 0.0270 in. 



(6. 90) 



4. Deflection due to bending and shear considering the facings and core acting together: 



3 



Exc YT~ + ^ x *" 



bt3 



I x jj- + 2 x bt x , — * 



EI -J^Eili 



= 0.1397 x 10° 

 GA =2_ ( h A ± = G c x be + G f x ?bt = 0.138 x 10 6 



H PIj3 + ZL 

 lEl GA 



= .0239 + 0.0007 = .0216 in. 



t + c 



(6. 16) 



(6.91) 

 (6. 90) 



5. Deflection as the sum of the bending deflection of the facings only and the shear deflec- 

 tion of the core only: 



E f I f - E xf 



G C A C = G c bc 



2 x 



bt3 



+ 2 x bt x 



M 



, PL 3 PL 



" 1E7T7 G^A7 



(6. 16) 



(6.90) 



= 0.0262 + .0125 

 = 0.0387 in. 



Alternatively, since the flexural modulus of the balsa wood is large, the bending deflec- 

 tion above may be modified to include its effect. The resulting deflection is then: 



d = 0.0239 + 0.0125 = 0.036U in. 



