APPENDIX IV 



THE EFFECTS OF BENDING AND TENSION ON THE 

 STABILITY OF CABLE FAIRING 



INTRODUCTION 



A trailing type fairing, attached to a strut of circular 

 cross section and moved through a fluid, trails directly be- 

 hind the strut if hydrodynamically stable. Only the hydro- 

 dynamic forces are of interest in determining the static or 

 "zero-frequency" stability. If^ however, the strut is per- 

 mitted to curve in the direction of motion, forces are in- 

 duced in the fairing which tend to rotate it relative to 

 the strut o The relevant forces are those due to the bending 

 of the fairing and those due to externally imposed axial loads, 

 The nature of these effects is discussed below. 



ASSUMPTIONS 



For the purpose of this discussion, the following 

 assvimptions are made: 



1. The axial load carried by the cable, relative to 

 that carried by the fairing, is so great that the 

 cable can be considered a rigid member; 



2. The fairing is constructed of a hanogeneous material ^ 

 the elastic modulus of which is quite small com- 

 pared to that of the cable; 



IV. 2 



