To determine what reinforcing was necessary to prevent transverse 

 bending of the connector, some assumptions were made about the applied 

 load. The connector was assumed to be a simply supported beam subjected 

 to a point load of 52 pounds as shown in Figure B-2C (see Appendix 

 A for details of this calculation). 



The greatest stress occurs at the outside fiber of the beam at 

 point A as indicated in Figure B-2B. The required moment of inertia 

 about the neutral axis of the connector and any necessary reinforcing 

 is given by 



Mr 

 I = — (B-3) 



where M = maximum bending moment in the connector 

 c = outer radius of the connector tube (in.) 

 a = allowable stress (psi) 



Inserting the values of these variables as determined in Appendix A 

 the required moment of inertia, I, to prevent exceeding the allowable 

 stress is 



I = 0.46 in.^ 



The moment of inertia of the connector, using the dimensions of Figure 

 B-IA, is 



I = 1.12 in.^ 



and no additional reinforcing is necessary. 



Similar computations were made for the other connector candidates. 

 Dimensions for these are shown in Figure B-2. 



Figure B-3 shows schematically the clamping and connector plates 

 as they would be attached to a boom end. The connector plate has holes 

 to accept the primary tension members (e.g., cable or chain) of a boom 

 of a particular vendor. The boom end has a rod embedded in the fabric 

 to assist in preventing the boom fabric from being torn loose by the 

 tension force, T. 



In order to conservatively size the width of the clamping plate, 

 the friction force developed by clamping the fabric between two pieces 

 of aluminum was assumed to be the only force available to keep the 

 fabric from being pulled from between the two aluminum pieces. The 

 required magnitude of this force can be calculated from Equation B-4 

 below which relates the width of the clamping plate to the force required 

 per inch of height of the fabric. 



40 



