Programs RADAC and RAMSC 



Based on the mathematic developments, computer programs RADAC and 

 RAMSC were written to analyze the double-armored and multistrand cables, 

 respectively. The computer programs simulate the laboratory cable tests 

 used to obtain rotational and torsional data. They can be used to determine 

 the rotational and extensional response to a combined tensile and 

 torsional loading. The rotational stiffness can be estimated using these 

 programs without actual cable testing. 



Detailed cable construction dimensions and wire material elastic 

 properties are needed as input. The programs compute the elongation and 

 end rotation or torque for a predetermined tension increment. These 

 programs are available on loan from CEL. 



CABLE TESTS 



The main purpose of the cable testing program was to generate 

 reliable data on the rotational response of electromechanical cables 

 commonly in use. These data have three applications: first, to predict 

 kinking; second, to verify analytical cable models; and finally, to design, 

 select, specify, and improve the handling of future electromechanical 

 cables. 



Six cables were selected for rotational property measurements, and 

 their essential mechanical properties are presented in Table 1 . They 

 cover the spectrum of typical oceanic electromechanical cables in use 

 today. Availability was an important factor that affected cable selection 

 (for example, the newly developed Kevlar cables were not available for 

 measurement). By selecting these cables and measuring their rotational 

 properties, representative sampling of the majority of electromechanical 

 cables was obtained. 



The tests were conducted at the Naval Research Laboratory using the 

 method and facilities described in detail in Reference 3; the test 

 samples were 6 feet long. An extension tower was added to the top end 

 of the standard 60, 000 -pound test machine. The elongation was measured 

 by the Electro-optical Extensiometer , and the top of the lower end socket 

 was used as a lower target. The rotation was monitored by a dial attached 

 to a lockable swivel at the lower end. The tension and torque were 

 measured by a load cell at the top end. The end sockets of the test 

 samples were potted with zinc. Two X-Y plotters were used to plot the 

 tension-versus-elongation and torque-versus-elongation curves. 



Each cable went through the conventional axial stress -strain test 

 with end conditions as specified in Table 2. 



The free-end tests were characterized by a zero moment in the cable. 

 Based on this principle, free-end tests can be conducted in a regular 

 test machine. The method involved a trial -and -error procedure. The lower 

 end rotation was adjusted until the torque reading was zero. The process 

 was repeated for different tension loadings to develop a free-end 



