2. SHIP STRUCTURES REPORTS 



Abranison, H.N, and Chu, W.H-, ^'Effects of the Froo 

 Surfaro on tho Fluttor of Submorgod Hydrofoils,** Journal 

 of Ship Kpsoaroh, VoU 3, No* 1, Juno 1959. 



Expressions for the unsteady lift and moment acting on an 

 oscillating hydrofoil submerged under a free surface are derived by an 

 extension of classical ^^steady thin-airfoil theory. The results of 

 flutter compulations are presented for a hypothetical example. 



Abramson, H.N. and Chu, W^H., "A Discussion of the 

 Fluttor of Submerged Hydrofoils," Journal of Ship 

 Rosoarch, VoU 3, No. 2, October 1959. 



This paper presents the results of a review and analysis of the 

 problem of flutter of submerged surfaces. It is noted that certain rather 

 serious discrepancies exist between theory and experiment leading to 

 highlv unconservative predictions of flutter speeds. A number of 

 possible reasons for these discrepancies are investigated and discus- 

 sed in detail. 



A4ani:r, Emily J,, *'The Steady-State Response of a 

 Ship's Hull to a Simple Harmonic Driving Force Computed 

 by a Digital Process," DTMB Report 715, 1959. 



A numerical method of finding the steady-state response of the 

 hull of a ship to a sinusoidal driving force is described. Results of 

 calculations for the vertical flexural vibration of the USS NIAGARA 

 (APA 87) are given and compared with experimental data. It is also 

 shown that the vibration of the hull at a frequency other than one of 

 the natural mode frequencies may be calculated as the sum of the vibra- 

 tions of the natural modes compounded by a normalization process. 



Adams, E.J., and Welch, A.R*, "Calculation of Flex- 

 ural Critical Frequencies ofShip Hulls by Prohi's Method,** 

 DTMB Report 5S2, July 1947. 



This report extends Prohl's method for the calculation of the 



Rexural critical frequencies of flexible rotors to the calculation of the 

 flexural critical frequencies of ship hulls. The method is simplified 

 and set up so that the computations can be readily made with a punch- 



Allnutt, R^B*, "Investigation of Hull Vibrations of 

 USCGC PONTCHARTRAIN (WPG 70)," DTMB Report 

 R-294, August 1946. 



Because two rather severe critical series of vibrations were 

 encountered during the trials of a recent class of U.S. Coast Guard 

 vessels, vibrations produced in the PONTCHARTRAIN by a vibration 

 generator were measured to determine the various critical frequencies of 

 the hull. It is concluded that a 4- or 5-bladed propeller would reduce 

 the hull vibration to acceptable levels. 



Allnutt, Ralph B„ '^Vibration Survey of the USS CORAL 

 SEA (CVB 43), Conducted During Ship Trials," DTMB 

 Report C-268, October 1949. 



TTlis vibration survey was made to determine the vibration char- 

 acteristics of the hull and machinery with different propellers and to 

 determine the effect of various bottom paints on the inflow to the propel- 

 lers and thereby effecting the ship's vihraaon. It was found that four- 

 bladed propellers outboard and five inboard was the best arrangement, 

 and that the effect of different bottom paints was negligible. 



Anderson, R,Aj and Houbalt, JaC, ''Effects of Shear 

 Lag on Bending Vibration of Box Beams," NACA TN 1583, 

 May 1948. 



Andrews, John N^, "A Method for Computing the 

 Response of a Ship to a Transient Force," DTMB Report 

 1544, November 1936, 



A method for determining the elastic body response of a ship to 

 a seaway is presented. The force generated by the seaway is con- 

 sidered' to consist of two parts, i.e., an unsteady hydrodynamic force 

 obtained from the measured rigid body motions, and a hydrostatic 

 force. The force and mass-elastic parameters representing the hull 

 are used as input quantities on a digital computer to obtain the ship's 



Baier, L,A, and Ormondroyd, J., "Suppression of Ship 

 Vibration by Flow Control,*' Third Mid-Western Conference 

 on Fluid Mechanics, 1953* 



Albright, CX*, Jr,, "Underway Hull Vibration Survey 

 of ISS MITSCHER (DL-2)," DTMB Report 1154, September 



Baier, L.A^ and Ormondroyd, Jj, "Vibration at the Sler: 

 of Single Screw Vessels,** Trans SNAME, VoU 60, p.lO, 

 1952* 



Hull vibrations measured at the bow and stem under various 

 ->perating conditions were within tolerable limits. The hull exhibited 



Vertical resonances at 69 and 140 cpm and athwartships resonances at 

 114 and 236 cpm. Some equipment vibrated excessively, such as the 



radar indicator for the Mk 67 director. 



Albright, Clayton L^, Jr., "Underway Hull Vibration 

 Survoy of USS PLYMOUTH ROCK (LSD-29)," DTMB 

 Ropon 10-29, May 1956. 



Hull vibration measurements were made for various operating 

 conditions. A maximum of 11 mils vertical vibration single amplitude 

 was noted on the how, and 42 mils on the stem. Hull vibration was 

 within tolerable limits, and there was little vibration of shipboard 



"his paper dis 

 t Lakes bulk < 



used to reduce the sten 



Bales, Nathan K,, "A Method for Predicting the 

 Probable Number and Severity of Collisions between Foil- 

 borne Craft and Floating Debrife," DTMB Report 1723, 

 August 1963, 



This report derives a method for predicting the approximate 

 number of collisions producing a structural response of given severity 

 to be anticipated over a long operating period. The derivation is 

 based on certain assumed debris item frequency distributions. 



Bales, N.K., "The Ordinary Wave-Induced Responses 

 a Victory Cargo Ship," DTMB Report 1734, December 

 1963. 



The ordinary wave-induced midship vertical bending stress 

 pitching, rolling, and heaving motions of a Victory cargo ship are 

 presented. Short-term, long-term, and maximum-value statistical 

 analyses are described. 





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