DESIGN OF LAMINATES 



6-147 



d. 



cr. 



2 



515 



,, 2 1059 



l6r + — p- + 136K 



7.1 



P cr = 7.12 x 311.28 = 2217 lbs/ in. 



(6. 51i) 

 (6. 50) 



Summary: 



Case 1 

 Case 2 

 Case 3 

 Case 4 



1, 112 lbs. /in. 

 1,985 lbs. /in. 

 1,326 lbs. /in. 

 2,217 lbs. /in. 



The critical buckling values, P C r. for Design Example 6-21 can be obtained very 

 quickly from Tables 6-4 through 6-7. For a = 20 in. , b = 40 in. and h = 0. 50 in. , the 

 values are: 



B. Plates Loaded In Uniform Shear 



The critical shearing stresses in a rectangular plate under a uniform shear load was 

 investigated and reported by March (16). The discussion presented here is for loads 

 applied parallel to or at 90 degrees to the warp direction, Fig. 6-45. 



Fig. 6-45. Flat Plate 

 in Uniform Shear 

 Load Parallel to Warp 



The following terminology not previously given will apply: 



q = uniform shearing stress and is positive when directed 

 as indicated in Fig. 6-45. 



q^p = value of q for which buckling occurs. 



