14 



C. General Comments 



Some question may be raised as to the effect of the plug arrange- 

 ment for sealing the cable penetrations. The pressure acting on the hole 

 walls between the convex surface and the "O" ring seal can easily be 

 shown to have a negligible effect on the overall or local stress distribution, 

 intensity, or direction. 



The 0. 005" clearance provided between the plug and the hole wall 

 was demonstrated in the Gilmore strain plot to be adequate. The strain- 

 pressure plots for the gages around each hole were linear, but the plots 

 would have been nonlinear with the occurrence of binding between the 

 plugs and the perforation walls. 



Note should be made of the fact that since the reported stresses 

 were computed using measurements from strain gages which have a definite 

 gage length, the stresses as given are the integrated stresses over that 

 gage length, and not the stress at a point. Also, to have installed the 

 gag'es with the gage centerline at the boundaries of the discontinuities was 

 physically impossible and the actual locations are given in the tables. 

 Comparing the reported results with experience in this area of experi- 

 mental stress analysis, the true stress at a point on the boundaries of the 

 discontinuitities could be as much as 35% higher than the stresses reported 

 herein. 



In the absence of flexural stresses, the theoretical stress per unit 

 load at the penetration boundary would be 15. 8 psi/psi, based on a stress 



