Force Pulse Testing of Ship Models 



DRIVE 



PITCH -" FORCE GAGES 



POTENTIOMETER 



Fig. 2 - Heave experiment 



Excitation is provided by an electric motor — variable speed drive arrange- 

 ment, with the forces transmitted to the model via a spring and cable. (Tests 

 were conducted at speeds of Fr. = 0, 0,025, 0.05, 0.075, 0.10, 0.15, 0.20, 0.25, 

 0.30, 0.35). Two series of tests were conducted: In one the model was excited 

 in the heave mode only, and in the second the model was excited simultaneously 

 in pitch and heave. In the heave test the excitor cable was attached to the heave 

 staff as shown in Fig. 2. The six motions as well as forces along the heave, 

 surge and sway axis were measured. In the pitch heave experiment, as shown in 

 Fig. 1 , an excitation cable was attached to the bow of the model through a fourth 

 (excitation) force gauge. Measurements were the same as in the heave experi- 

 ment, except for the addition of the excitation force gauge. For each test condi- 

 tion, the frequency of the excitation force was varied manually, adjusting the 



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