Transverse vibrations of ship’s propulsion systems, Part II: Experimental analysis

REPORT No. 203 M

December 1974

NEDERLANDS SCHEEPSSTUDIECENTRUM TNO

NETHERLANDS SHIP RESEARCH CENTRE TNO

ENGINEERING DEPARTMENT

LEEGHWATERSTRAAT 5, DELFT

*

TRANSVERSE VIBRATIONS OF

SHIP'S PROPULSION SYSTEMS

PART II

EXPERIMENTAL ANALYSIS

(BUIGTRILLINGEN IN SCHEEPSVOORTSTUWINGSSYSTEMEN)

DEEL II

(ANALYSE VAN UITGEVOERDE PPJKTIJKMETINCEN)

by

IR. L. J. WEVERS

(Institute TNO for Mechanical Constructions)

RESEARCH COMMITTEE

IR. J. P. CORVER DR. IR. S. I-IYLARIDES

DRS. C. A. M. VAN DER LINDEN IR. E. F. VAN RANDWIJCK

IR. J. D. Rus

IR. A. DE Vos

IR. E. VOSSNACK

PROF. DR. IR. R. WERELDSMA

IR. A. DE MooY (ex officio)

VOORWOORD

Als gevoig vari de tendens naar grotere en snellere schepen met hoog geïnstaHeerd vermogen nernen de dimensies van het voort-st uwingssyvoort-steem toe. Hierdoor nemen de resonantie-frekwenties van het schroefassysteem af. Wanneer tegelijkertijd sprake zou

zijn van een hiermee evenredige afname van de

schroetblad-frekwentie (astoerental x aantal bladen) dan zouden geen em-stige mesonantiepmoblemen optmeden. Vanwege de noodzaak het

aantal schroefbladen te verhogen met het oog op de doom te

leiden hoge vermogens gekombineerd met een bepaald minimum schmoefastoerenta (bepaald door o.a. machinetype en schroef-afmetingen), za! de schroefbladfrekwentie nauwe!ijks enige wijzi-ging ondemgaan en za! in somniige geva!!en ze!fs toenemen. Doom deze ontwikkelingen woidt men gekonfronteerd met de omstan-digheid dat stemke re!atieve vemschuivingen van excitatie en resonantie fmekwenties het dynamisch gedrag niet

extrapoleem-baam maken uit vmoegeme konstrukties.

Dit ge!dt niet a!leen voor torsie- en axia!e tri!lingen, maar ook voor de vee! s!echtem toeganke!ijke buigtrillingen.

Dynamische versterking t.g.v. resonantieverschijnse!en dient

dan ook in het ontwerpstadium bemekend te kunnen worden, zonder dat men zich baseert op praktijkgegevens omdat deze

door de genoemde re!atieve verschuivingen onbetmouwhaar zijn geworden. Omdat een groot aanta! faktoren bu het dynamisch gedmag in dwarsrichting een ro! spelen (aanta! en plaats van de !agers, smeemo!iefl!m- en !agerstoe! e!asticiteit, gymoskopische en hydmo-dynamische effekten van de schmoef etc.) dient gebruik ge-maakt te worden van computers met een grote geheugenkapaci-teit. De ter berekening van het dwamstmi!!ingsgedmag opgeste!de methode is in mapport no. 197 M heschreven en werd toegepast voor het assysteem van de 3e gencratie containerschepen van de N.S.IJ.

Ter verifikatie van de ontwikkelde berekeningsmethode wer-den metingen vermicht aan het voortstuwingssysteem van zowel s.s. "Ned!!oyd De!ft" a!s s.s. "Ned!!oyd Dejima". Ter bepa!ing

van de be!angrijkste eigenfrekwenties en trï!vormen werden

stootexcitatiemetingen verricht aan het assysteem van s.s.

"Ned!!oyd Dejima" tijdens de afl,ouwperiode.

Tijdens de eerste kustreis van s.s. "Nedl!oyd De!ft" werden

tri!!ingsmetingen verricht aan de as onder normale bedrijfs-omstandigheden. Uit de verrichte metingen kon worden

ge-konkludeerd dat een duidelijk verband bestaat tussen de middels de stootexcitatie methode gedetekteerde eigcnfrekwenties bij

"schip te water" en de berekende eigenfrekwenties. Dit ge!dt

eveneens voom de gemeten eigenfrekwentie (II Hz) bu varend

schip en de overeenkomstige eigenfrekwentie bu

"schip te

water" hepaa!d met de stootexcitatie methode. Dit betekent dat een invloed van de smeerfl!m in de as!agers niet onderkend kon worden.

Bij varend schip waren de !agere eigenfrekwenties(8,5 Hzen 9,2 Hz) s!echts na enige moeite waar te nemen.

De stootexcitatiemetingen bu "schip in droog-dok" resulteer-den in !iogere frekwenties dan bij "schip te water" (geen mee-tri!lend water).

Samenvattend kon echter worden gesteld dat de berekenings-methode redelijk nauwkeurige resultaten geeft.

Wat de toegepaste meettechniek betreft kon met vo!doening

worden vastgesteld dat de stootexcitatie methode, gezien de

afmetingen van de onderhavige konstrukties. uitstekend heeft vo!daan.

NEDERLANDS SCHEEPSSTUDIECENTRUM TNO

PREFACE

As a resu!t of increasing ship dimensions and insta!!ed propulsion

powers, dimensions of the shafting also increase, causing the

resonance-frequencies of the propeller-shaft system to decrease.

If these are accompanied with a proportional decrease of the blade frequency (RPM times the number of propeller blades)

no serious resonance problems would arise. Due to the necessity to increase the number of propeller blades in order to absorb the higher power and due to the physical lower limit of shaft RPM (depending on engine type, propeller dimensions etc.) the blade frequency can not practically be reduced and in fact increases sometimes. Therefore nowadays one has to face the problem that large relative shiftings of excitation and resonance frequencies make it impossible to extrapolate the dynamic behaviour from earlier constructions.

This holds not only for axial and torsional vibrations, but

particularly for lateral vibrations.

Dynamic magnifiers due to resonance phenomena have to be calculated in the design stage without the help of known practical

data since these data have become unreliable due to the

men-tioned relative shiftings. Since a large number of factors influence the lateral dynamic behaviour (number and location of bearings, oil film- and bearing pedestal elasticity, gyroscopic- and hydro-dynamic effects of the propeller etc.) use has to be made of com-puters with large memory storage together with the finite element

techniq Lie.

The theory for calculating the dynamic behaviour in lateral direction is presented in Report No. 197 M and was applied to the propulsion system of the third-generation containerships of the Netherlands Shipping Union.

To verify the calculated results, measurements were carried out onboard s.s. "Nedlloyd Delft" as well as onboard s.s, "Nedlloyd Dejima". To determine the most important natural frequencies and modes of vibration, impact excitation measurements were carried out on the shafting of s.s. "Nedlloyd Dejima" whilst the ship was nearly ready for delivery. During the first coastal voyage of s.s. "Nedlloyd Delft", vibration measurements were carried out under normal operating conditions of the ship.

Measurements indicate a good agreement between natural

frequencies obtained by the impact excitation method with ship

afloat and those of the calculations. This also holds for the measured natural frequency (11 Hz) under sailing conditions

and the corresponding frequency obtained by the impact

exci-tation technique with ship afloat. This means that there is no

explicit influence of the oil film in the bearings. The lower natural frequencies (viz. 8.5 Hz and 9.2 Hz) could hardly be detected

from the measurements taken during sailing conditions, The impact excitation measurements with "ship in dry-dock" gave higher natural frequencies than with "ship afloat" (no en-trained water).

Summarizing, it may be stated that the calculation method has given fairly accurate results.

As far as the applied measuring techniques are concerned the impact excitation method gave quite satisfactory results regarding the rather large dimensions of the structure.

CONTENTS

I page Summary 5

Introduction

5 2

Ship data

5

3

The impact excitation measurements

6

4

The propeller excitation measurements

8

5 Results iO

5.1

The impact excitation measurements

10

5.2

The propeller excitation measurements

10

6

Comparison of the results of impact excitation and propeller excitation

measurements 10

7 Conclusions

Il

8 Acknowledgements I 2

I

Introduction

Due to increased ship dimensions, installed propulsive

powers and shipspeeds, it is absolutely necessary to

have a fair estimate of the vibratory behaviour of the

propulsion system in order to take appropriate

mea-sures in the design stage of the ship.

To predict the dynamic behaviour, numerical

cal-culations as accurately as possible have to be carried

out.

To make the structure accessible for such

calcula-tions, simplifications must be carefully introduced.

Modelling, however, introduces errors which are

diffi-cult to quantify.

To verify the results of a calculation method applied

to the propulsion system of the twin-screw

turbine-driven containerships "Nedlloyd Dejima" and

"Ned-lloyd Deift" (both owned by the Netherlands Shipping

Union), measurements were carried out under different

conditions.

The main purpose of these measurements was to

determine the most important natural frequencies and

modes of vibration of the propulsion system under the

following three conditions:

- non-rotating shaft with ship in dry dock (in this

con-dition there is no oilfllm between shaft and bearings

and there is not an influence of entrained water);

- non-rotating shaft with ship afloat (with influence of

entrained water);

- rotating shaft with ship afloat (normal operating

conditions).

For the first two conditions impact excitation

measure-ments were carried out aboard s.s. "Nedlloyd Dejima";

whereas for the third condition, measurements were

TRANSVERSE VIBRATIONS OF SHIP'S PROPULSION SYSTEMS

PART Il

EXPERIMENTAL ANALYSIS

by

Ir. L. J. WEVERS

Summart'

Due to increasing ship dimensions and installed propulsive powers, resonance frequences of the propeller-shaft system tend to decrease.

Regarding transverse vibrations one has nowadays to be aware of the fact that resonance frequencies may be within the operating range of the shaft rpm.

Therefore a calculation method was designed to have a fairly accurate estimate of the resonance frequencies in the design stage. This method, presented in part I of this report, was applied to the shafting of the third-generation containerships owned by the Netherlands Shipping Union.

To verify the results of the calculation, impact excitation measurements were carried out on the non rotating shaft with ship in dry dock and with ship afloat. Measurements were also performed with ship in operating condition.

This report presents the used methods and the results.

The results of the calculation and those of the measurements show a corresponding picture.

performed aboard s.s. "Nedlloyd Delft" during the

first coastal voyage from Bremerhafen to Gotenborg.

Impact excitations of the shaft were executed in

vertical and horizontal directions inside the port-side

bossing pipe.

The bossing pipe was also internally excitated

hori-zontally.

Vertical excitation could not be accomplished due

to lack of space.

Furthermore the bossing pipe was excited

horizontal-ly outside near the propeller.

The propeller excitation measurements were also

executed on the portside bossing pipe. All the signals

were recorded on magnetic tape.

A special-purpose computer was used for processing

of the signals. The analyzing of the signals and the

interpretation of the results was concentrated in the

frequency range between 5 and 25 Hz. This report

presents the results of the measurements; the results of

the calculations have been published in report number

197 M (I).

2

Ship data

Length overall:

287.02 m

Length b.p.:

273.00 m

Breadth molded:

32.24 m

Depth molded:

25.00 m

Draught loaded:

12.04 in

Dead weight:

42,900 ton

Gross tonnage:

57,535 ton

Net tonnage:

37,573 ton

Container capacity:

2952 of 20 ft

6

Fig. la. Impact hammer.

force pulse was measured by a "Kistler"

piezo-electric force transducer.

ad b.

The velocity response was measured with so

called "geo-space" transducers (Hall Sears,

fre-quency range 4.5 till 300 Hz, sensitivity 20 mV

per i mm/s1) chosen for their high sensitivity.

ad c.

The measured time functions are transformed

to frequency functions with the Fourier

trans-formation according to:

F(w)

=

Sr(t).eitdt

r(t)

=

measured time function

=

_cos

_{cot- j}

_{sin cot}

In the frequency domain, force and velocity quantities

are vectors at a given frequency with an

amplitude-and a phase relationship.

Mobility expresses the amplitude relationship of the

vectors as follows:

114(w)

IF{v (t)}I

IF{R(t)}I

w

=

radial frequency

F

=

Fourier transformation

ve(i) =

velocity time function point

K1(t) =

force time function point

_j

i =j

=

delivers

=

Driving-point Mobility

i

j =

delivers

=

Transfer Mobility

The Mobility might not give enough information about

complicated structures, so phase relationships must be

determined.

Fig. lb. Mounted impact hammer for horizontal shaft

excitation.

2 Turbines:

Stai- Laval

power 40,550 HP at 136 rpm

2 Propellers:

5 blades

3

The impact excitation measurements

To determine the dynamic properties of a structure the

impact excitation method is useful. The impact

excita-tion method applied to a structure delivers the mobility

of the considered structure. Mobility is defined as the

quotient of the velocity response of the structure and

the excitation force. Mobility presented in the

fre-quency domain delivers the dynamic properties of the

considered structure (2,3). Mobility can be written as:

M

Ivelocity responce (w)I limpact force (w)I

To determine the Mobility of a structure the following

procedures are required:

Excite the structure by a force. Measure and record

the forcing function.

Measure and record the velocity response of the

structure.

Transform, after digitizing, the signals into

func-tions in the frequency-domain by Fourier

Trans-form methods.

Divide the functions to obtain the Mobility

func-tion.

ad a.

Usually the excitation of a structure by a

sineso-idal

force with variable frequency

is used.

Sometimes a force pulse is applied. The latter

excitation method is called

impact excitation"

whereby high demands are made upon pulse

height and pulse time.

The "impact excitation" method was chosen

in our measurements.

A specially developed hammer with a mass of

approximately 40 kg was used (Figure 1). The

n

Frequency meter

Registration- recorder

Low - pass filter

f0 r 25 Hz

2/. dB /actove

Analog- Digital Crv-i 102/. Samples At = 10 mc T 10.2/. s Fm05 50 Hz At r 0.1 Hz Fourier Analyser F)f)

ffr)t); x)t)}e2mtt.d

)trequericy range 5-25 Hz) Mobility (M) - Voltmeter

lK)t)I

M(f) dividing bij n

Fig. 2. Lay-out of measuring system for impact excitation.

Mobility - and Phase diagram

OscilLoscope iflside

¡ the bassing pipe

* r Velocity transducers K r Force transducer iMPAcT ExcinenioN race MeoSur!flg-StGt!Cfl Excitotior - Staten MeaSurng-ond excitation-station

Fig. 3. Lay-out of ana'ysing system for impact excitation. Fig. 4. Cross-section bossing pipe.

PROPELLER EXCITATION cd3Lo- Moosxring-siotiott 7 Vert icol Horizontal Amplifier Registration

with filter recorder

Vert ical

100 Hz

Record speed

375=.-1

Hor izo n to L Display

amplifier UIt ra-Viotetrecorder Vertical nr Horizontal

Horizontal

Charge omplitier Power-supply

Colib roC on

Voice-frequency

tenero to r Oscilloscope

8 V UV References H UH / 44

/

Oil A1H [1H Propel [er 5-BLades

/ LH

/

[1V / Bearing (Li)

The analog-digital conversion of the measured

sig-nals and the computations for the Fourier-transforms

and for the Mobilities were carried out with a

special-purpose computer (Hewlett and Packard 504A).

The block diagrams of the measuring and recording

Fig. 6a. Outside view of the bossing pipe.

Fig. 6b. Inside view of the bossing pipe. On the shaft one can see a horizontally and a vertically placed velocity

transducer. The impact excitation hammer is mounted above the shaft.

TOP-VIEW PORT-SIDE BOSSING-PIPE AND SHAFT

A2H [2H

A1,2H A2V L2V

/1 L2V

L2H

/

/Bearing(L2) _.._- /Bearinq (U)

-Midship

system as was used and of the analysing procedure are

presented in figure 2 and 3 respectively.

Figure 4 and 5 give the excitation- and measuring

points.

Figure 6 shows several measuring situations.

Fig. 6e. Bearing support in the bossing pipe.

4

The propeller excitation measurements

During the first coastal voyage of the ship,

measure-ments were carried out to determine the vibratory

be-haviour of the bossing pipe shafting system under

normal operating conditions.

The bossing pipe was thought to he excited by the

propeller forces.

To determine the most important natural

frequen-cies and vibration modes measurements were carried

out at shaft speeds ranging from 60-140 rpm. A 20

minutes uninterrupted measuring run was carried out

at Il different shaft speeds. Before starting a

measure-ment, a 15 minutes period at constant speed was

practised to obtain stable general ship conditions.

AGi AG2

Impact excitation measurements HorizantaL

Propeller excitation measurements Vertical

Accelerometer

t Ve-i cci I

Fig. 8. Construction for measuring transverse vibrations of

rotating shaft.

The measuring points are given in figure 5. Also inside

the bossing pipe geospace velocity transducers were

used.

Figure 8 shows the construction specially made to

measure the shaft transverse velocity. Figure 7 shows

the accelerometers mounted in the oil chamber of the

tailshaft bearing near the propeller.

To analyse the recorded signals the special-purpose

Hewlett and Packard computer mentioned in chapter 3

was used.

The flow diagram of the analysing procedure which

was mainly an averaging process, is given n figure 9.

Using these averaging techniques, it is important that

/

-: Accelerometer IHorrzonioi)

/

Fig. 7. Accelerometers placed in the oil chamber of the propeller shaft bearing near the propeller.

Measurement signa Is V s

y-D g it izi n g Fourier secrrum Divided by 100

Printing of the ist,

2nd and 3rd harmonics

of the propelter-blade

frequencies and

phase-a ng les

Fig. 9.

Lay-out of processing signals obtained aboard s.s.

"Nedlloyd Delft".

digitizing per revolution is carried out for the same

shaft position (4,5). To ensure this, a one-pulse and a

256-pulses per revolution "pulstrain" were recorded

in addition to the signals on magnetic tape. These

pulstrains were used

to trigger

the analog-digital

convertor of the special-purpose computer. These

pulses were generated by means of an optical system

and marks mounted on the shaft at equal spaces.

9 Summation over 100 revolutions Start pulses digitizing le per revolution

256o per revolution

Co[ibrot ion

lo

5 Results

5.1

The impact excitation measurements

This chapter describes the results of the impact

excita-tion measurements. As menexcita-tioned already, the

re-corded signals were transformed in drivingpoint and

transfer mobility diagrams with a special-purpose

computer.

For the measuring points described in chapter 3,

the diagrams were produced for ship in dry dock and

ship afloat. A set of such diagrams is presented on the

inserted drawing (figure 13).

Natural frequencies and vibration modes were found

from inspection of these diagrams. They appear

ii the

diagrams as amplitude maxima.

From the diagrams, three natural frequencies of the

whole structure are recognized:

Ship afloat:

8.5, 9.2 and 11.0 Hz.

Ship in dry dock:

10.0, 10.5 and 12.6 Hz.

The influence of entrained water appears as a

reduc-tion of the natural frequency values. Graphs of the

measured modes of vibration are also shown in the

inserted drawing.

These modes of vibration and the associated

Mobility-values demonstrate:

The maximum bossing-pipe amplitude near the

propeller appears at 8.5 and 9.2 Hz.

The maximum bossing-pipe-, bearing- and shaft

amplitudes between the strut and shiphull appear

at 11.0 Hz.

The natural frequency of the bearing supported shaft

only appears to be 23 Hz for ship afloat and

approxi-mately 22 Hz for ship standing dry.

The inserted drawing also presents the associated

vibration mode.

120 Velocity i - -1 ilO ms

t ::

60 40 20 Horizoniol L 2H O 60 80 100 120 1/.0 -Ø Number of revolutions [rpm.

Fig. 10. Difference between horizontal and vertical vibrations.

Besides the mentioned natural frequencies of the whole

system, the diagrams show above 13 Hz more

frequen-cies with a maximum amplitude. These frequenfrequen-cies

were identified as local natural frequencies. A

discus-sion of these frequencies does not fall under the scope

of this investigation.

5.2

The propel/er excitation measurements

The most important results of the digitizing and

cal-culation procedure applied to the recorded signals

measured under normal operating conditions

are

shown in the inserted drawing. These results show out

that:

The first harmonic amplitudes of the propeller

blades frequency are important. Higher harmonics

amplitudes are negligible.

A very clear natural frequency is found at 11 Hz

(± 133.3 rpm). This phenomenon occurs mainly in

horizontal direction. An example is given in figure

lO.

The maximum amplitudes occur at the

bossing-pipe and the bearings between the struts and the

hull.

6

Comparison of the results of impact excitation and

propeller excitation measurements

6.1

An obvious correlation exists for the natural

fre-quency at approximately II Hz (133.3 rpm)

be-tween the impact excitation measurements with ship

afloat and the measurements under operating

condi-tions which has proved to be the most significant

result of the experiment since the ship operating

con-ditions occur mainly in the shaft rotation speed range

from 120 to 138 rpm.

120 Velocity r-4 -1 110 ms

t

60 40 20 Vertical LIV 60 80 100 120 140 -0. Number of revolutions [rpm.

Fig. I L Area of preferable direction of vibration after impact

excitation.

6.2

The preferable free vibration direction of the

bossing-pipe is approximately parallel to the ship

hull.

Vector summation of the mobility-values belonging

to the velocity response in vertical and horizontal

direction leads to the preferable vibration sector shown

in figure 11.

Illustrative

is the lissajous picture (figure

12)

re-corded after impact excitation in the horizontal

direc-tion.

During

operating

condition

the situation

had

Vertical

changed from free to forced vibrations. In this case

the vibrations appear mainly in horizontal direction

(figure 10).

6.3

Other natural frequencies established with the

impact excitation measurements with ship afloat

were 8.5 Hz (102 rpm) and 9.2 Hz (110.4 rpm). These

natural frequencies appear to be weak at the measuring

points in the oil chamber of the tail shaft bearing during

normal operating conditions. There are two reasons to

explain this phenomenon:

The rpm-step between two measuring runs in this

range was about 10. These steps were too great to

detect the natural frequencies at about 102 and

110.4 rpm exactly.

Comparing the circumstances at 133.3 rpm (11.0

Hz), the excitation forces at 102 and 110.4 rpm

were very small which resulted in small transverse

velocity amplitudes.

7 Conclusions

An obvious correlation exists between the natural

frequencies established with the impact testing method

with ship afloat and the results of the calculations. Also

the correlation is remarkable between the main

natu-ral frequency (11 Hz) measured during ship in

opera-ting condition and established with the impact tesopera-ting

method with ship afloat. This means also that no oil

film influence was foLind. Lower natural frequencies

(8.5 and 9.2 Hz) were weak only during ship in

opera-ting conditions.

The influence of entrained water was evident.

The impact excitation measurements with ship in

dry dock deliver higher natural freqtiency values than

the measurements with ship afloat.

Horizontal

Fig. 12. Lissajous picture showing that initial horizontal vibration turns into vertical vibration.

12

8 Acknowledgements

The Netherlands Ship Research Centre TNO

acknowl-edges the cooperation and assistance of the

Nether-lands Shipping Union, the crews of both ships and the

Bremer VLIIkan shipyard for making possible to carry

out the work reported herein.

References

I. HYLARIDES, S.: Transverse vibrations of ships propulsion systems, Part I. Netherlands Ship Research Centre TNO.

October 1974, report no. 197 M.

HARRIS. C. M.,and C. E. CREDE,Shock and vibration hand-book, 3 volumes. Mc Graw-Hill 1961.

'T HART,H. H., Hull vibrations of the cargo-liner

"Koude-kerk". Netherlands Ship Research Centre TNO, report no.

143 S. October 1970.

DOLFIN, E. R., and H. H.'T HART, Torsional-axial vibrations

of a ships propulsion system. Netherlands Ship Research

Centre TNO, December 1968. report no. 116 M.

Gou. H., and G.

RADER, Digital processing of signals.

Lincoln Laboratory Publications.

HYLARIDES, S., Damping in propeller-generated ship vibra-tion. Thesis Delft Technological University, October 1974.

PUBLICATIONS OF THE NETHERLANDS SHIP RESEARCH CENTRE TNO

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Reports

1 14 S The steering of a ship during the stopping manoeuvre. J. P.

Hooft, 1969.

I 15 S Cylinder motions in beam waves. J. H. Vugts, 1968.

I 16 M Torsional-axial vibrations of a ship's propulsion system. Part I. Comparative investigation ofcalculated and measured torsional-axial vibrations

in the shafting of a dry cargo motorship.

C. A. M. van der Linden, H. H. 't Hart and E. R. Dolfin, 1968.

117 S A comparative study on four different passive roll damping

tanks. Part II. J. H. Vugts, 1969.

I I 8 M Stern gear arrangement and electric power generation in ships propelled by controllable pitch propellers. C. Kapsenberg. 1968. I 19 M Marine diesel engine exhaust noise. Part IV. Transferdamping

data of 40 modelvariants of a compound resonator silencer.

J. Buiten, M. J. A. M. de Regt and W. P. Hanen, 1968. 120 C Durability tests with prefabrication primers in use for steel plates.

A. M. van Londen and W. Mulder, 1970.

121 S Proposal for the testing of weld metal from the viewpoint of

brittle fracture initiation. W. P. van den Blink and J. J. W. Nib-bering, 1968.

122 M The corrosion behaviour of cunifer 10 alloys in seawaterpiping-systems on board ship. Part I. W. J. J. Goetzee and F. J. Kievits,

1968.

123 M Marine refrigeration engineering. Part III. Proposal for a specifi-cation of a marine refrigerating unit and test procedures. J. A. Knobbout and R. W. J. Kouffeld, 1968.

124 S The design of U-tanks for roll damping of ships. J. D. van den Bunt, 1969.

125 S A proposal on noise criteria for sea-going ships. J. Buiten, 1969. 126 S A proposal for standardized measurements and annoyance rating of simultaneous noise and vibration in ships. J. H. Janssen, 1969. 127 S The braking of large vessels II. H. E. Jaeger in collaboration with

M. Jourdain, 1969.

128 M Guide for the calculation of heating capacity and heating coils for double bottom fuel oil tanks in dry cargo ships. D. J. van der 1-leeden, 1969.

129 M Residual fuel treatment on board ship. Part III. A. de Mooy,

P. J. Brandenburg and G. G. van der Meulen, 1969.

130 M Marine diesel engine exhaust noise. Part V. Investigation of a double resonatorsilencer. J. Buiten, 1969.

131 S Model and full scale motions of a twin-hull vessel. M. F. van

Sluijs, 1969.

132 M Torsional-axial vibrations of a ships propulsion system. Part II. W. van Gent and S. Hylarides. 1969.

133 S A model study on the noise reduction effect of damping layers aboard ships. F. H. van ToI, 1970.

134 M The corrosion behaviour of cunifer-lO alloys in seawaterpiping.

systems on board ship. Part II. P. J. Berg and R. G. de Lange.

1969.

135 5 Boundary layer control on a ship's rudder. J. H. G. Verhagen,

1970.

136 S Observations on waves and ships behaviour made on board

of Dutch ships. M. F. van Sluijs and J. J. Stijnman, 1971. 137 M Torsional-axial vibrations of a ship's propulsion system. Part III.

C. A. M. an der Linden, 1969.

138 S The manoeuvrability of ships at low speed. J. P. Hooft and

M. W. C. Oosterveld, 1970.

139 S Prevention of noise and vibration annoyance aboard a sea-going

passenger and carferry equipped with diesel engines. Part I.

Line of thoughts and predictions. J. Buiten, J. H. Janssen.

H. F. Steenhoek and L. A. S. Hageman, 1971.

140 5 Prevention of noise and vibration annoyance aboard a sea-going

passenger and carferry equipped with diesel engines. Part II. Measures applied and comparison of computed values with

measurements. J. Buiten, 1971.

141 S Resistance and propulsion of a high-speed single-screw cargo liner design. J. J. Muntjewerf, 1970.

142 S Optimal meteorological ship routeing. C. de Wit, 1970.

143 S Hull vibrations of the cargo-liner "Koudekerk". H. H. 't Hart,

1970.

144 S Critical consideration of present hull vibration analysis. S. Hyla-rides. 1970.

145 5 Computation of the hydrodynamic coefficients of oscillating

cylinders. B. de Jong, 1973.

146 M Marine refrigeration engineering. Part IV. A Comparative stuyd on single and two stage compression. A. H. van der Tak, 1970. 147 M Fire detection in machinery spaces. P. J. Brandenburg. 1971. 148 S A reduced method for the calculation of the shear stiffness of a

ship hull. W. van Horssen, 1971.

149 M Maritime transportation of containerized cargo. Part II. Experi-mental investigation concerning the carriage of green coffee from Colombia to Europe in sealed containers. J. A. Knobbout. 1971.

150 S The hydrodynamic forces and ship motions in oblique waves.

J. H. Vugts, 1971.

151 M Maritime transportation of containerized cargo. Part I. Theoretical and experimental evaluation of the condensation risk

when transporting containers loaded with tins in cardboard

boxes. J. A. Knobbout, 1971.

I 52 S Acoustical investigations of asphaltic floating floors applied on a steel deck. J. Buiten, 1971.

153 S Ship vibration analysis by finite element technique. Part II. Vibra-tion analysis. S. Hylarides, 1971.

154S Canceled.

155 M Marine diesel engine exhaust noise. Part VI. Model experiments on the influence of the shape of funnel and superstructure on the radiatedexhaust sound. J. Buiten and M. J. A. M. de Regt, 1971. 156 S The behaviour of a five-column floating drilling unit in waves.

J. P. Hooft, 1971.

157 S Computer programs for the design and analysis ofgeneral cargo ships. J. Holtrop. 1971.

158 S Prediction of ship manoeuvrability. G. van Leeuwen and

J. M. J. Journée, 1972.

159 S DASH computer program for Dynamic Analysis of Ship Hulls. S. Hylarides, 1971.

160 M Marine refrigeration engineering. Part VII. Predicting the con-trol properties of water valves in marine refrigerating installations A. H. van der Tak, 1971.

161 S Full-scale measurements of stresses in the bulkcarrier m.v. 'Ossendrecht'. Ist Progress Report: General introduction and

information. Verification of the gaussian law for stress-response to waves. F. X. P. Soejadi, 1971.

l62S Motions and mooring forces of twin-hulled ship conìgurations. M. F. van Sluijs, 1971.

163 5 Performance and propeller load fluctuations of a ship in waves. M. F. van Sluijs, 1972.

164 S The efficiency of rope sheaves. F. L. Noordegraaf and C. Spaans, 1972.

165 S Stress-analysis of a plane bulkhead subjected to a lateral load. P. Meijers, 1972.

166 M Contrarotating propeller propulsion, Part I, Stern gear, line

shaft system and engine room arrangement for driving contra-rotating propellers. A. de Vos, 1972.

167 M Contrarotating propeller propulsion. Part

II. Theory of the

dynamic behaviour of a line shaft system for driving

contra-rotating propellers. A. W. van Beek, 1972.

169 S Analysis of the resistance increase in waves of a fast cargo ship. J. Gerritsma and W. Beukelman, 1972.

170S Simulation of the steering- and manoeuvring characteristics of a second generation container ship. G. M. A. Brummer, C. B.

van de Voorde, W. R. van Wijk and C. C. Glansdorp, 1972.

172 M Reliability analysis of piston rings of slow speed two-stroke

marine diesel engines from field data. P. J. Brandenburg, 1972. 173 S Wave load measurements on a model of a large container ship.

Tan Seng Gie, 1972.

174 M Guide for the calculation of heating capacity and heating coils for deep tanks. D. J. van der Heeden and A. D. Koppenol, 1972. 175 S Some aspects of ship motjons in irregular beam and following

waves. B. de Jong, 1973.

176 5 Bow flare induced springing. F. F. van Gunsteren, 1973.

177 M Maritime transportation of containerized cargo. Part III. Fire

tests in closed containers. H. J. Souer, 1973. 178 S Fracture mechanics and fracture control for ships.

179 S Effect of forward draught variation on performance of full ships. M. F. van Sluijs and C. Flokstra, 1973.

180 S Roll damping by free surface tanks with partially raised bottom. J. J. van den Bosch and A. P. de Zwaan. 1974.

182 S Finite element analysis of a third generation containership.

A. W. van Beek, 1973.

183 M Marine diesel engine exhaust noise. Part VII. Calculation of the acoustical performance of diesel engine exhaust systems. J. Buiten, E. Gerretsen and J. C. Vellekoop, 1974.

184 S Numerical and experimental vibration analysis of a deckhouse. P. Meijers. W. ten Cate, L. J. Wevers and J. H. Vink, 1973. 185 S Full scale measurements and predicted seakeeping performance

of the containership "Atlantic Crown". W. Beukelman and

M. Buitenhek, 1973.

186S Waves induced motions and drift forces on a floating structure. R. Wahab. 1973.

187 M Economical and technical aspects of shipboard reliquefaction of cargo "Boil-off" for LNG carriers. J. A. Knobbout, 1974. 188 S The behaviour of a ship in head waves at restricted water depths.

J. P. Hooft, 1974

189 M Marine diesel engine exhaust noise. Part VIII. A revised mathe-matical model for calculating the acoustical source strength of the combination diesel engine - exhaust turbine. P. J. Branden-burg, 1974.

190 M Condition monitoring, trend analysis and maintenance prediction for ship's machinery (literature survey). W. de Jong, 1974.

191 S Further analysis of wave-induced vibratory ship hull bending

moments. F. F. van Gunsteren, 1974.

192S Hull resonance no explanation of excessive vibrations, S. Hyla-rides, 1974.

193 S Wave induced motions and loads on ships in oblique waves.

R. Wahab and J. H. Vink, 1974.

194 M On the potentialities of polyphenylene oxide (PPO) as a

wet-insulation material for cargo tanks of LNG-carriers. G. Opschoor, 1974.

195 5 Numerical hull vibration analysis of a Far East container ship. P. Meijers, 1974.

196 S Comparative tests of four fast motor boat models - in calm

water and in irregular head waves and an attempt to obtain full-scale confirmation. J. J. van den Bosch, 1974.

197 M Transverse vibrations of ship's propulsion systems. Part I. Theoretical analysis. S. Hylarides, 1974.

198 M Maritime transportation of containerized cargo. Part IV.

Evalu-ation of the quality loss of tropical products due to moisture

during seatransport. P. J. Verhoef, 1974.

199 S Acoustical effects of mechanical short-circuits between a floating floor and a steel deck. J. Buiteri and J. W. Verheij, 1974. 200 M Corrosivity monitoring of crankcase lubricating oils for marine

diesel engines. L. M. Rientsma and H. Zeilmaker, 1974. 201 S Progress and developments of ocean weather routeing. C. de Wit,

1974.

202 M Maritime transportation of containerized cargo. Part V. Fire

tests in a closed aluminium container. H. J. Souer, 1974.

203 M Transverse vibrations of ship's propulsion systems. Part II. Experimental analysis. L. J. Wevers, 1974.

Communications (Mededelingen)

18 S An experimental simulator for the manoeuvring ofsurface ships. J. B. van den Brug and W. A. Wagenaar, 1969.

19 S The computer programmes system and the NALS language for numerical control for shipbuilding. H. le Grand, 1969.

20 S A case study on networkplanning in shipbuilding (Dutch). J. S. Folkers, H. J. de Ruiter, A. W. Ruys, 1970.

21 S The effect of a contracted time-scale on the learning ability for manoeuvring of large ships (Dutch). C. L. Truijens, W. A. Wage-naar, W. R. van Wijk, 1970.

22 M An improved stern gear arrangement. C. Kapsenberg, 1970. 23 M Marine refrigeration engineering. Part V (Dutch). A. H. van der

Tak, 1970.

24 M Marine refrigeration engineering. Part VI (Dutch). P. J. G. Goris and A. H. van der Tak, 1970.

25 S A second case study on the application of networks for pro-ductionplanning in shipbuilding (Dutch). H. J. de Ruiter, H.

Aartsen, W. G. Stapper and W. F. V. Vrisou van Eck, 1971.

26 S On optimum propellers with a duct of finite length. Part H.

C. A. Slijper and J. A. Sparenberg, 1971.

27 S Finite element and experimental stress analysis of models of shipdecks, provided with large openings (Dutch). A. W. van

Beek and J. Stapel, 1972.

28 S Auxiliary equipment as a compensation for the effect of course instability on the performance of helmsmen. W. A. Wagenaar, P. J. Paymans, G. M. A. Brummer, W. R. van Wijk and C. C. Glansdorp, 1972.

29 S The equilibrium drift and rudder angles of a hopper dredger

with a single suction pipe. C. B. van de Voorde, 1972. 30 S A third case study on the application of networks for

production-planning in shipbuilding (Dutch). H. J. de Ruiter and C. F. Heu-nen, 1973.

31 S Some experiments on one-side welding with various backing

materials. Part 1. Manual metal arc welding with coated

electro-des and semi-automatic gas shielded arc welding (Dutch).

J. M. Vink, 1973.

32 S The application of computers aboard ships. Review of the state of the art and possible future developments (Dutch). G. J. Hoge-wind and R. Wahab, 1973.

33 S FRODO, a computerprogram for resource allocation in network-planning (Dutch). H. E. 1. Bodewes, 1973.

34 S Bridge design on dutch merchant vessels; an ergonomic study.

Part I: A summary of ergonomic points of view (Dutch).

A. Lazet, H. Schuffel, J. Moraal, H. J. Leebeek and H. van Dam, 1973.

35 5 Bridge design on dutch merchant vessels: an ergonomic study. Part II: First results of a questionnaire completed by captains, navigating officers and pilots. J. Moraal. H. Schuffel and A. Lazet.

1973.

36 S Bridge design on dutch merchant vessels: an ergonomic study.

Part III: Observations and preliminary recommendations. A.

Lazet, H. Schuffel, J. Moraal, H. J. Leebeek and H. van Dam, 1973.

37 S Application of finite element method for the detailed analysis of hatch corner stresses (Dutch), J. H. Vink, 1973.

38 S A computerprogram for displacement and stress analysis with membrane elements on constructions consisting of plates and trusses. Users manual (Dutch). G. Hommel and J. H. Vink. 1974.

39 S Some experiments on one-side welding with various backing

materials. Part Il. Mechanised gas-shielded arc welding in the flat and horizontal position (Dutch). J. M. Vink, 1974.

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