Appendix B 

 STRUCTURAL DESIGN 



Using the force loadings determined in Appendix A, the candidate 

 designs for the boom connector, tow assembly, and bulkhead-attachment 

 assembly were analyzed structurally to determine component size for 6061- 

 T6 aluminum. 



BOOM CONNECTOR 



Structural calculations for the boom connectors included sizing 

 the connector to withstand tensile loads along the boom, and transverse 

 bending loads. The clamping area required to secure the boom end to the 

 connector was also determined. 



The structural analysis procedure applied to each of the four candi- 

 date connectors of Figure 1 is outlined below. For purposes of conservative 

 design, the tensile force loads appearing in Table A-1 for the Type II 

 boom were used to size each of the candidate connectors. Connector cross- 

 sections sized for these loads can be used for the smaller booms and 

 still provide adequate strength when subjected to smaller loads that 

 occur when Type I, Class 1 and 2 booms are used. Extrusions of 6061- 

 T6 aluminum with a modulus, E, of 10 x 10" psi and a yield strength of 

 35,000 psi were used for all calculations. The procedure used to determine 

 connector size required to withstand tensile and transverse loads is 

 outlined below. 



1. Assume a nondimensional connector configuration from Figure 1. 



2. Determine connector dimensions such that it will withstand 



the tensile load created by Type II boom as shown in Table A-1. 



3. Determine the cross-sectional moment inertia required of 

 the connector and its associated clamping plate to withstand 

 transverse hydrodynamic loads. 



4. Adjust the cross-sectional dimensions of connector and clamping 

 plate to produce a moment of inertia equal to required moment 

 of inertia developed in step 3 above. 



The analysis outlined above is applied to the first candidate in 

 the following discussion. 



The maximum tensile load on the connector occurs during catenary 

 tow. Using the load estimate for Type II boom from Table A-1, each tow- 

 line exerts a tensile force of 13,600 pounds on the connector assemblies 



38 



