a major task and the output is voluminous. One tends to be overwhelmed by it 

 all and jumps to the very convenient conclusion that since a successful run 

 is finally obtained and it was done using an "all powerful black box" using a 

 computer, then the answers obtained must be correct. These are two aspects of 

 the "black box syndrome" and they tend to reduce the amount of intelligence 

 put into the formulation of an analysis .... Without some careful control, they 

 may lead to a very costly pile of garbage! 



Typical Solution Forms 



The most common approach to analyzing mooring dynamics begins with a 

 static analysis to establish a stable initial or reference state of the cable 

 system. The dominant nonlinearities are present in the static equations and 

 all effects mentioned earlier must be accoionted for except the dynamics. 

 Because of the strong geometric nonlinearity present in most deep water moors, 

 this may be a very difficult step in the analysis. Often the static reference 

 state is not well defined by a simple connection of the unstretched elements. 

 Usually the unpreloaded system represents a mechanism which is unable to 

 support loads in one or more directions and/or it violates boundary conditions 

 and compatibility constraints. Load resistance (stiffness) is only developed 

 as the elements rotate and stretch. 



Once the static reference state is obtained, various dynamic solution 

 options are available. Some of them are: 



1. Linearize equations and solve for small displacement perturbations 

 about the static reference in the time domain. 



[M]{Aq} + [C]{a4} + [K]{Aq} = {Af (t) } (3) 



30 



