I oiliowit/,, Ralph C, ''Comparison of Thoory and 

 ExptTinuMil for Slaiiiniin^ of a Dutch Dostroyor," DTMB 

 Report IT)!!, Juno 19612- 



This report presents a theoretical analysis and computation of 

 the slamming forces acting on a ship, based on an experimental know- 

 lodfte of the ship's motions. In addition, a computation is made of the 

 transient elastic response and associated hull girder stresses of the 

 ship due to the total force exerted by the fluid on the ship. Comparisor 

 of theoretical and measured stresses shows good agreement. 



Loihowitz, R,C*, "Effects of Dampine on Modes of 

 \ ortical \ ihration of Hull of USS THRESHER (SSN 593)," 

 DTMB Report 1384, March 1960/ 



The normal modes of verti 

 the steady-state damped respons 

 Results show that the damping c 

 resonance, of the vibration respo 



lexural vibration of the hull and 

 re calculated on a digital computer, 

 s appreciable phase changes, at 

 along the beam; furthermore, at the 



hi^iher modes the frequency of peak respons 

 Lorresponding normal mode. 



- than that of the 



Leihowitz, R.C*, "Natural Modes and Frequencies of 

 \ crtical \ ihration of a Beam with an Attached Sprung Mass,' 

 DTMB Report 1-215, 1958. 



A study was made of the vibration characteristics of a beam with 

 an attached sprung mass. The purpose was to explore the possibility of 

 a more adequate representation of a ship hull as a mass-elastic system 

 subject to vibration. Analytical and electrical-analog methods are de- 

 vised to determine the natural frequencies and mode shapes of a beam- 

 sprung-mass system. These methods are shown to give resultB that are 

 reasonably accurate. 



Lpihowitz, R.C, "USS ALBACORE (AGSS 569), Modes 

 of Ruddor \ibration," DTMB Report 1540, August 1961. 



With the addition of a motor-propeller system to the lower mdder 

 of the ALBACORE the possibility existed that local resonance frequen- 

 cies of the rudder within the operating speed range of the ship would 

 occur and hence increase the vibratory response of the ship to propeller- 

 blade forces acting on the rudder. Theoretical analysis indicates, how- 

 e\er, that the addition of the motor-propeller system to the rudder would 

 not cause excessive vibrations. This conclusion was verified experi- 

 mentally. 



Lfihonitz, Ralph C. and Delz, Donald J,, "A 

 Procedure for Computing the Hydroclastic Parameters for a 

 Rudder in a Free Stream," DTMB Report 1508, April 1962. 



Methods for evaluating the hydroelaslic parameters for a rudder 

 moving in a free stream are described. As an example the rudder of the 

 ALBACORE is used. By means of a theory referenced in this report, 

 computations of mdder-hull vibrations (including flutter) can then be 

 made on a digital and/or analog computer. 



Leibovvitz, Ralph C. and Bolz, Donald J,, "Comparison 

 of Thoor\ and Experiment for Marine Control-Surface 

 Fluucr," DTMB Report 1567, Augu.st 1962. 



B'jlh the Extended Simplified Flutter Analysis and Modified Theo- 

 d'-rsen Flutter Analysis, proposed by McGoIdrick and Jewell, are 

 applied to the DTMB Control Surface Flutter Apparatus. Predictions of 

 vibrational stability and instability based on these analyses are com- 

 pared with stable and unstable vibrations observed in the apparatus for 

 lowing speeds in the range of to 20 knots. The Modified Theodorsen 

 FluttiT Analysis shows better agreement with experimental data. 



Lelhowitz, R.C. and Kennard, E.H., "Theory of Freely 

 Vibrating Nonuniform Beams Including Methods of Solution 

 and Application to Ship.s," DTMB Report 1317, May 1961. 



A comprehensive study which reviews and extends previous work, 

 was made of the derivation of equations for digital and electrical-analog 

 solutions of the natural frequencies and mode shapes of a ship's hull 

 idealized as an elastic beam. Effects of bending, shear, rotary inertia, 

 coupled torsion and bending, initial curvature of the elastic axis, applied 

 forces and torques, sprung masses, and other inertias are included. The 

 calculation of the physical parameters from ship plans is described and 

 the accuracy of results is discussed. 



Leibowitz, Ralph C. and Standhagen, A.G., "Theory of 

 Static and Dynamic Loads on a Rudder in a Steady Turn," 

 DTMB Report 1647, February 1963. 



A rapid approximate procedure is given for predicting the static 

 and dynamic loads on a rudder of a surface ship or submarine in a 

 steady horizontal turn as a function of the rudder angle of attack. 



Lewis, F.M., "Dynamic Effects," Chapter 2, Vol, 2 of 

 Marine Engineering, edited by H.L. Seward, published by 

 SNAME, 1944. 



This chapter includes a basic treatment of vibration theory, 

 discusses torsional vibrations of reciprocating engine systems and of 

 geared turbine drives, balancing problems, and hull vibration. 



Lewis, F.M„ "Propeller Vibration," Trans SNAME, 

 Vol. 43, 1935. 



As a result of tests on a model of the PRESIDENT HOOVER the 

 vibration generating forces of blade frequency were divided into three 

 types of forces, listed in order of magnitude: bossing forces, hull 

 suction forces, bearing forces. This is reported in this and the 1936 

 paper of the same name. 



Lewis, P.M., "Propeller Vibration," Trans SNAME, 

 Vol, 44, 1936, 



As a result of tests on a model of the PRESIDENT HOOVER the 

 vibration generating forces of blade frequency were divided into three 

 types of forces, listed in order of magnitude: bossing forces, hull 

 suction forces, bearing forces. This is reported in this and the 1935 

 paper of the same name. 



Lewis, F«M*, "The Inertia of the Water Surrounding a 

 Vibrating Ship," Trans SNAME, Vol. 37, 1929. 



The inertia of the water surrounding a vibrating ship is theoretic- 

 ally derived on the basis of the effects of certain geometric shapes 

 moving in a fluid. 



Lewis, F.M*, "Vibration and Engine Balance in Diesel 

 Ships," Trans SN.AME, 1927. 



Lewis, F*M,, and Auslaender, J,, "Virtual Inertia of 

 Propellers," JSR, March 1960. 



On the basis of theoretical and experimental results this paper 

 proposes empirical formulas for longitudinal and torsional virtual inertia 

 for vibrating propellers. 



65 



