The study of the response of ship structures to the various exciting forces imposed on 

 it during normal operation constitutes a major field of interest at the Model Basin. The ob- 

 jectives of the Laboratory in this area are concerned with: 



1. Mechanical Suitability (strength adequacy) 



2. Habitability and Operability (effects on performance) 



3. Detection and Detectability (underwater noise) 



It immediately becomes obvious from the complexity of the mass-elastic system, the 

 various types of exciting forces, and the alternate objectives of the program that this field 

 of study becomes too broad to handle as a single project. Consequently the total program at 

 DTMB has been broken down into a number of smaller programs which may be identified as: 



1. Hull Vibration (Response to Steady-State Forces) 



2. Structural Seaworthiness (Hull Response to Heavy Seas) 



3. Slamming (Ship Response to Wave Impact) 



4. Hydroelasticity (Flutter Prediction) 



5. Radiation (Study of Hull Vibration for Noise) 



Although many factors, analysis techniques, and fundamental theoretical concepts are com- 

 mon to more than one program, nevertheless, the resolution of the total program is suffi- 

 ciently broad as to warrant the subdivision shown. This has also been recognized by the 

 Ship Structure Committee of The Society of Naval Architects and Marine Engineers which 

 has divided the HS-2 Panel (Dynamic Loadings and Responses) into three Task Groups: 



1. HS-2-1 (Vibrations) 



2. HS-2-2 (Surge Loadings) 



3. HS-2-3 (Slamming) 



The Hull Vibration Program reviewed in this presentation concerns itself with the limited 

 field of interest. Response to Steady-State Forces, and corresponds to the interest of the 

 Vibration Task Group of the HS-2 Panel. 



In the development of the Hull Vibration Program we are primarily (although not ex- 

 clusively) concerned with the second objective, Habitability and Operability, By this we 

 mean the steady-state forces are generally of more concern for their annoyance to personnel 

 or malfunction of equipment. In some cases damage or danger of damage to ship structures 

 and equipment has occurred. However, most cases of structural damage have resulted from 

 transient excitation and would be covered in either the TMB Structural Seaworthiness Program 

 or the Slamming Program. The TMB Radiation Program concerns itself with modes of hull 

 vibration which are of particular significance in underwater noise. This program is directed 

 primarily to submarines and is concerned with amplitudes which are generally of no concern 

 in regard to mechanical suitability or habitability and operability. 



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