DYNAMIC ANALYSIS 



Assumptions 



Because of limited time, the lumped formulation of the system as shown in figure D-5 

 is assumed sufficiently accurate for determining resonant points and approximate maximum 

 loads. To further simplify the analysis, the following assumptions are made: 



1. Assume the system is linear. This implies the following: 



a. The principle of superposition holds. 



b. The fact that the spring rate is constantly changing as the rope 

 is hauled in is ignored; i.e., the system is treated as a discrete, 

 steady state spring-mass system at each incremental change in 

 rope length. 



c. The non-linear spring rate of the nylon rope is linearized at the 

 static load. 



2. Assume transients due to initial conditions and changing parameters to be 

 negligible compared to steady state values. 



3. Assume that the line hangs vertical; i.e., no horizontal current or ship motion. 



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Figure D-5. Analytical Model for Simplified Spring-Mass System. 



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