OTH 91 358

THICKNESS EFFECT IN'RELATIVELY THIN'

WELDED JOINTS

Author

T R Gurney

The Welding InstituteAbington Hall

AbingtonCambridge CB1 6AL

HSE BOOKS

Health and Safety Executive - Offshore Technology Report

© Crown copyright 1995Applications for reproduction should be made in writing to:

Copyright Unit, Her Majesty's Stationery Office,St Clements House, 2-16 Colegate, Norwich NR3 1BQ

First published 1995Second impression (with amendments) 1997

ISBN 0-7176-0978-2

All rights reserved. No part of thispublication may be reproduced, stored in aretrieval system, or transmitted in any formor by any means (electronic, mechanical,photocopying, recording, or otherwise)without the prior written permission of thecopyright owner.

This report is published by the Health and Safety Executive aspart of a series of reports of work which has been supported byfunds provided by the Executive. Neither the Executive, or thecontractors concerned assume any liability for the report nor dothey necessarily reflect the views or policy of the Executive.

Results, including detailed evaluation and, where relevant,recommendations stemming from their research projects arepublished in the OTH series of reports.

Background information and data arising from these researchprojects are published in the OTI series of reports.

CONTENTS

33APPENDIX B7.

31APPENDIX A6.

TABLES AND FIGURES

15REFERENCES5.

13CONCLUSIONS4.

9ANALYSIS OF TEST RESULTS3.2

9THEORETICAL RESULTS3.1

9METHOD OF ANALYSIS AND RESULTS3.

7SUMMARY OF WORK CARRIED OUT2.

5INTRODUCTION1.

3SUMMARY

PAGE

1

2

SUMMARY

Although it has been known for a very long time that the fatigue strength of notched(but unwelded) specimens is dependent on size, it is only relatively recently that itbecame apparent that the fatigue strength of at least some types of welded joints isdependent on thickness. As a result, the first time that a thickness correction factorwas introduced into fatigue design rules was with the publication of the Departmentof Energy Guidance Notes in 1984.

The way in which that correction factor was derived was to compare all theavailable results, which had been obtained for joints of more than one thicknesstested in a single investigation, and then to plot those results in terms of relativefatigue strength, normalised to a thickness of 32mm.

For design purposes it was assumed that for tubular joints the base thickness was32mm but that for other types of joint this thickness was 22mm. It has to be notedthat this is consistent with the data which were actually used for tubular joints, butfor other types of joint the chosen value of the base thickness may well be rather anillogical approximation. This arises from the fact that the thickness correction factorwas added to the standard design S-N curves, which were derived fromexperimental results for specimens which were, in the main, around 13mm thick. Atthe time, however, it was considered that basing the thickness correction on athickness of only 13mm might have been too severe, particularly as the experimentalevidence to support such a correction was relatively limited.

Since that time, however, far more experimental evidence has become available and,the theoretical basis of the need for a thickness correction is also better understood.The results in this report confirm that the thickness effect can be extended back toat least 16mm (which is the base thickness recommended in the recently publishedfatigue guidance).

The value of the thickness exponent for the limited thickness range analysed in thisstudy was 0.25, although the actual values for individual sets of data variedsignificantly.

3

4

THICKNESS EFFECT IN 'RELATIVELY THIN' WELDED JOINTS

1. INTRODUCTION

Although it has been known for a very long time that the fatigue strength of notched(but unwelded) specimens is dependent on size, it is only relatively recently that itbecame apparent that the fatigue strength of at least some types of welded joints isdependent on thickness. As a result, the first time that a thickness correction factorwas introduced into fatigue design rules was with the publication of the Departmentof Energy Guidance Notes in 1984.

The way in which that correction factor was derived was to compare all theavailable results, which had been obtained for joints of more than one thicknesstested in a single investigation, and then to plot those results in terms of relativefatigue strength, normalised to a thickness of 32mm. The resulting diagram is shownin Fig. 1 and it was on the basis of the data shown there that the form of thethickness correction was chosen to be:

[1]S = SB( tBt )0.25

where

is the fatigue strength of the joint under considerationS is its thicknesst

is the fatigue strength of the joint using the basic S-N curveSB

is the thickness corresponding to the basic S-N curve.tB

For design purposes it was assumed that for tubular joints = 32mm but that fortB

other types of joint = 22mm. It has to be noted that this is consistent with thetB

data which were actually used for tubular joints, but for other types of joint thechosen value of may well be rather an illogical approximation. This arises fromtB

the fact that the thickness correction factor was "bolted on to" the standard designS-N curves, which were derived from experimental results for specimens whichwere, in the main, around 13mm thick. At the time, however, the Committeeconsidered that basing the thickness correction on a thickness of only 13mm mightbe too severe, particularly as the experimental evidence to support such a correctionwas relatively 'thin'.

Since that time, however, far more experimental evidence has become available and,in the main, it has tended to confirm the 1984 decision. In addition, the theoreticalbasis of the need for a thickness correction is also better understood. In the light ofthis situation active consideration is being given to changing the 'basic' thickness fornon-nodal joints from 22 to 16mm and there is therefore a need to assess thepotential impact of that change.

5

6

2. SUMMARY OF WORK CARRIED OUT

In view of the situation outlined above it was decided that a literature survey shouldbe carried out, based upon the data already available in the Welding Institute fatiguedatabase, to establish the influence of thickness on fatigue strength over thethickness range 12-26mm. For the purposes of this exercise only two types of jointwere considered:

a) transverse cruciform K butt welds, Fig. 2ab) transverse non-load-carrying fillet welds, Fig. 2b.

From the point of view of their overall geometry these two joint types are of coursevirtually identical, so they would be expected to yield very similar results. However,there are far more data available for the fillet welded joint.

The data which were considered were restricted to:

1) constant amplitude loading2) in air3) under axial loading or unidirectional bending4) with stress ratio between 0 and 0.55) on as-welded (AW) or stress relieved (SR) joints

The numbers of test series which were located were as follows:

01

3

232

2

36

5

1632 1 4 2 2 6 7

0001

1

13

1011121314151619202526

SRAWSRAWSRAWSRAW

BendingAxialBendingAxial

Transverse FilletK Butt

Thickness, mm

Note: AW = As welded; SR = Stress relieved.

7

8

3. METHOD OF ANALYSIS AND RESULTS

3.1 THEORETICAL RESULTS

Before considering the analysis of the available test results it is worth noting that thisparticular problem can also be approached theoretically using fracture mechanics,although that did not form any part of this particular survey. Nevertheless, relevantresults have, in the past, been published for transverse non-load-carrying fillet weldsboth by Smith and Hurworth (2) and by Maddox (3), while more recently a similar(but unpublished) analysis has been carried out by Gurney.

In the work by Smith and Hurworth it was shown that the thickness effect didindeed continue to smaller thicknesses than 22mm but that there was a transition inslope at T=22mm. Thus, expressing the variation in fatigue strength with platethickness as:

S 1S 2

= T1T2

r

where is the predicted fatigue strength for thickness and is the predictedS1 T1 S2

strength for thickness , they showed that, for infinitely long cracks with =T2 a i

0.15mm,

r = -9.09 for 6 < T < 22and r = -0.14 for 22 < T < 100

Subsequently Maddox, assuming semi-elliptical rather than continuous initial defects,did not show any slope transition in the fatigue strength v. thickness relationship butfound that the thickness exponent over the whole range of thickness consideredcould be adequately represented as 0.2. The work did not specifically considerthickness less than 11mm. Later again Gurney obtained a very similar value (0.21)for T>20mm and a slightly lower value (0.18) for T<20mm. For all practicalpurposes these values are equivalent to the overall value of 0.2 proposed byMaddox.

It will be noted that all these theoretical values are less than the exponent value of0.25 in the Guidance Notes.

3.2 ANALYSIS OF TEST RESULTS

For each individual set of results (S-N curve) the Welding Institute programFATANPRIME was used to compute the mean curve and hence to derive thecorresponding mean fatigue strengths at 105 and 2 x 106 cycles. This calculationwas, however, only performed for those series consisting of 5 or more test results.Individual results outside the range 5 x 104 to 3 x 106 cycles were ignored, since itwas considered that they might be outside the linear region of the Log S v. Log Nrelationship. The results of these calculations, expressed in terms of the relevantthickness of main plate, are shown in Figs 3-11.

In order to provide a basis of comparison each of the Figures also shows the meanfatigue strength for Class F, for 105 or 2 x 106 cycles as appropriate, derived byapplying the current thickness correction formula (equation [1]) with the basic

9

thickness (tB) assumed to be 13mm and the present Class F mean fatigue strengthassumed to apply to that thickness.

In general, it will be seen from Figs 3-11 that the slope of that relationship, ie.between fatigue strength and thickness, which (from equation [1]) is 0.25, is in quitegood agreement with the available results, although there is inevitably a considerabledegree of scatter and although the majority of the results tend to be above the meanClass F design stresses, derived in the manner outlined above. The fact that most ofthe results are above the derived Class F mean line they may well be fortuitous,since it is notable that, for as-welded transverse fillet welds with T = 13mm, which isthe only thickness for which there is a large number of results, the mean curve isobviously quite close to the mean of the experimental results (Figs 5-7). On theother hand it will be seen that the lower limit of the experimental results for T = 13 isstill above the corresponding mean - 2 SD fatigue strength for Class F, namely 185and 68 N/mm2 at 105 and 2 x 106 respectively.

In view of the known tendency, certainly for thicker joints, for the fatigue strength ofboth the joint types under consideration to be dependent both on plate thickness andon attachment 'length' (in the direction of the applied stress), the results which wereconsidered were mainly restricted to those relating to 'large' attachments. Thus, inmost instances the length (L) of the 'attachment' (weld toe to weld toe) in thedirection parallel to the direction of stress was greater than or equal to 2T, where Tis the thickness of main plate. In a few instances, however, it was smaller than 2Tand previous work has suggested that, in that situation, fatigue strength under axialloading is more dependent on the attachment size than on the plate thicknessbecomes T' = 0.5 L. Figures 7-9 show the relevant results replotted after makingthat correction, and it will be noted that this correction procedure appears to result ingood correlation of the corrected results with the remainder. For example,comparison of Figs 6 and 7 shows that, after correction, the high results atT = 25mm (Fig. 6) fit much better, as also do the relevant results at T = 10, 12 and13mm. The same is equally true of the results shown in Figs 8 and 9. At this stageno corresponding correction has been made for joints tested in bending, sinceinsufficient work has, as yet, been carried out to define the necessary correctionfactor.

On the other hand, for the tests in bending (Figs 10 and 11) the results which havebeen taken into account ranged in thickness from 6.4 to 26mm rather than from 10to 25mm as in the axially loaded specimens. This was due to the perceived need toincrease the database as a result of the small number of results available in thetarget range. It will be noted, however, that on the basis of the available results the'thickness effect' appears to extend over the whole thickness range considered.

As was expected, it was found that the slopes of the individual S-N curves variedquite widely. This was probably due to differences in residual stresses resulting, forexample, from the use of different sizes of specimen. It was anticipated that theinfluence of this variable could be reduced by making the comparisons of strength ata relatively high stress/short life (say 105 cycles), since it is known that S-N curvesfor as-welded and stress relieved joints, and joints with intermediate levels ofresidual stress, tend to converge in that region. In view of this situation it isencouraging to note the tendency for the strengths at 105 cycles to be less scattered

10

than those for 2 x 106 cycles, although both appear to justify the extension of the'thickness effect' criterion to thicknesses below 22mm.

As indicated above, visual inspection of the results in Figs 3-11 shows a cleartendency for fatigue strength to decrease with increasing thickness over the wholerange of thickness considered. However, an attempt was made to define therelationship between thickness (T) and fatigue strength (S) more accurately bycalculating the best fit relationship for each type of joint both at 105 and 2 x 106

cycles, assuming the relationship to be of the form:

Log S = Log A + B Log T [2]

The values of the resulting coefficients and the mean fatigue strengths at T = 10 andT = 25 are summarised in Table 5, and the relevant relationships have been added toFigs 3-11.

While it will be noted that, in all cases, these calculations confirmed the tendency forfatigue strength to decrease with increasing thickness, with B varying from - 0.073to -0.397, it will also be noted that, in most instances, the correlation was not good;indeed, the correlation coefficient ranged from 0.31 to 0.92.

Following consideration of the results for individual test series, the results wereamalgamated into sets relating to each thickness of main plate and were re-analysedas a group. At this stage specimens which were ignored in the previous analysis,because they were in series containing less than 5 results, were also incorporated.In this part of the analysis both the best fit curve, with undefined slope, and the bestfit curve with a slope m=3 were calculated and the relevant results are summarisedin Tables 1-4.

For the axially loaded as-welded fillet welded joints the relevant results aresummarised in Figs 12 and 13, but for the remaining joint types insufficient series ofany one thickness were tested to make any further plotting of the results necessary.However, as far as Figs 12 and 13 are concerned, it is clear that the 'averaged'results again confirm the existence of the thickness effect over the lower range ofthicknesses under consideration. Figures 12 and 13 again show the best fitrelationship for the averaged results, the relevant values of the coefficients inequation [2] again being included in Table 5. In will be seen that, in this case, thevalue of the thickness exponent (B) was -0.196 and -0.242 at 105 and 2 x 106 cyclesrespectively.

It will be appreciated that all the results outlined above were derived from test dataemanating from several sources since, in general, very few results have beenobtained for a range of joint thicknesses in any single investigation. Nevertheless, afew such results do exist and those results are summarised in Figs 14-16. Figure 14relates to transverse fillet welds of three different thicknesses subjected to axialloading at R = 0. In each series the ratio between the weld toe to weld toedimension (L) and plate thickness was approximately the same, namely 2.25.Meanwhile Figs 15 and 16 both relate to transverse fillet welds in bending. It will beseen that in each case there was a clear tendency for fatigue strength to decreasewith increasing thickness, certainly at long life, although with the axially loaded jointsthe 25mm thick specimens clearly gave a much steeper S-N curve than the 8 or

11

12.7mm specimens, so that the thickness effects was not so apparent at short life inthis instance. In generally, however, these sets of results tend to confirm the trendsof the previous analysis.

In one instance (Fig 16) the S-N curves for the three series are approximatelyparallel so that it is possible to deduce a valid value of the thickness exponent forthose results. (When the S-N curves are not parallel, as in Figs 14 and 15, the valueof the exponent would vary with the particular endurance chosen for making thecomparison.) Thus, considering the results for the 13 and 25mm thick specimenswith the same attachment and weld sizes, the relevant strengths at (say) 106 cyclesare 146 and 128 N/mm2 respectively. For these two sets of results the thicknessexponent therefore becomes 0.20.

For record purposes the sources of the data used in this survey are listed inAppendix A. In addition, since many of the data were extracted from unpublishedWelding Institute sources, the relevant database reference numbers (CAR) arelisted in Appendix B.

12

4. CONCLUSIONS

The analyses carried out in this work were restricted to results which had beenobtained for K butt joints under axial loading and transverse non-load-carrying filletwelds under both axial and bending loads. However, by far the greatest amount ofdata examined was that relating to as-welded transverse fillet welds under axialloading. In all cases the thickness range considered did not extend beyond10-26mm, since the main objective was to establish whether or not a thicknesseffect continued to smaller values of thickness than those allowed for in the 1990 4thedition Guidance.

In the light of these analyses it seems reasonable to draw the following conclusions:

1. There is clear evidence that the 'thickness effect' extends back at least to athickness of 10mm and probably further.

2. The choice of the 'basic thickness' ( ) can be arbitrary, but it is notable that thetB

mean curve for transverse fillet welds agrees well with the mean of the data forT = 13mm. This is not surprising given that the majority of the data used in theformulation of the basic S-N curves in BS 5400 related to specimensapproximately 13mm thick.

3. Various theoretical analyses have been carried out to define the influence ofthickness on fatigue strength by fracture mechanics methods. Although thevalues of the thickness exponents have varied, depending upon the particularassumptions made (eg with regard to initial crack shape), they have all shownthat:

a) the 'thickness effect' extends to smaller thicknesses than 22mm; and

b) the value of the exponent is less severe than the value of 0.25 assumed in theGuidance Notes.

4. Nevertheless, the value of 0.25 in 4th edition Health and Safety ExecutiveGuidance appears to represent a reasonable approximation to the available dataconsidered in this investigation, over the particular thickness range considered,although the values of thickness exponent in fact ranged from approximately0.075 to 0.4 (see values of B, Table 5). However, more weight should obviouslybe attached to the results based upon mean values for each thickness for theaxially loaded transverse fillet welds, which formed by far the largest part of thedatabase; those values ranged from approximately 0.2 to 0.24.

13

14

5. REFERENCES

1. Gurney T R: 'The influence of thickness on fatigue of welded joints - 10 yearson'. 8th OMAE Conf., The Hague, March 1989.

2. Smith I J and Hurworth S J: 'The effect of geometry changes upon the predictedfatigue strength of welded joints'. Weld Inst Members Report 244/1984.

3. Maddox S J: 'The effect of plate thickness on the fatigue strength of fillet weldedjoints'. Weld Inst, 1987.

15

16

TABLE 1

CALCULATED MEAN FATIGUE STRENGTHS OF AS-WELDEDK BUTT JOINTS UNDER AXIAL LOADING

104107 92 89

283291250243

118124 90 86

259251252251

3.8264.2482.9022.794

1112

5 8 510

10132025

2 x 1061052 x 106105Slope, m

Assuming m = 3.0Best fit curveNo ofseries

No ofresults

Platethickness

mm

TABLE 2

CALCULATED MEAN FATIGUE STRENGTHS OF AS-WELDEDTRANSVERSE NON-LOAD-CARRYING FILLET WELDS UNDER

AXIAL LOADING

135109 98 91119 95 91 90

367297265247322257247244

130114 95110132 96 92 87

379284272216289252246252

2.8033.2972.8454.4653.8243.0903.0292.824

31431 1 5 2 6 6

44188226 5 31 8 27 58

101212.5-131415-16192025

2 x 1061052 x 106105Slope, m

Assuming m = 3.0Best fit curveNo ofseries

No ofresults

Platethickness

mm

17

TABLE 3

CALCULATED MEAN FATIGUE STRENGTHS OFSTRESS RELIEVED TRANSVERSE NON-LOAD-CARRYING

FILLET WELDS UNDER AXIAL LOADING

111 86 90

300234244

121 88101

258228217

3.9573.1423.889

331

2641 7

132025

2 x 1061052 x 106105Slope, m

Assuming m = 3.0Best fit curveNo ofseries

No ofresults

Platethickness

mm

TABLE 4

CALCULATED MEAN FATIGUE STRENGTHS OF AS-WELDEDTRANSVERSE NON-LOAD-CARRYING FILLET WELDS IN

BENDING

141125119120144111102

382339324325390303277

149131120124163105106

337320323309326322254

3.6623.3623.0123.2914.3352.6733.442

1113232

8 6 619 918 8

6.481113202526

2 x 1061052 x 106105Slope, m

Assuming m = 3.0Best fit curveNo ofseries

No ofresults

Platethickness

mm

18

TABLE 5

SUMMARY OF VALUES OF THE COEFFICIENTS IN THE EQUATION S=ATB

246.097.3

294.4121.5

0.52140.5540

-0.196-0.242

462.3211.9

105

2 X 106TNLCFW,Axial, AW

Results based upon mean values for each thickness

299.3115.2

320.3132.2

0.37750.5210

-0.073-0.151

379.7187.1

105

2 x 106TNLCFW,Bending

220.992.0

272.0132.3

0.92490.8032

-0.227-0.397

459.4329.8

105

2 x 106TNLCFW,Axial, SR

228.086.6

282.0116.3

0.42650.4690

-0.231-0.321

480.5243.5

105

2 x 106TNLCFW,Axial, AW

241.489.8

258.7123.8

0.31260.8538

-0.075-0.351

307.7277.6

105

2 x 106K Butt,Axial, AW

T=25mmT=10mm

Mean fatigue strengthN/mm2Correlation

coefficientBAEndurance (cycles)Specimen Type

Note: AS = As welded; SR = Stress relieved; TNLCFW = Transverse non-load-carrying fillet weld.

19

20

Fig 1 - Influence of plate thickness on fatigue strength (normalised to a thickness of32mm). (All tests at R=0 except where stated.)

Fig 2 - Joint types considered:a) Transverse K butt weld; b) Transverse non-load-carrying fillet weld.

21

Fig 3 - Fatigue strengths of as-welded K butt joints (axial loading, 105 cycles).

Fig 4 - Fatigue strengths of as-welded K butt joints (axial loading, 2 x 106 cycles).

22

Fig 5 - Fatigue strengths of as-welded transverse non-load-carrying fillet welds (axialload, 105 cycles).

23

Fig 6 - Fatigue strengths of as-welded transverse non-load-carrying fillet welds (axialload 2 x 106 cycles).

Fig 7 - Fatigue strengths of as-welded transverse non-load-carrying fillet welds (axialload, 2 x 106 cycles), including corrected results for specimens with smallattachments.

24

Fig 8 - Fatigue strengths of stress relieved transverse non-load-carrying fillet welds(axial load, 105 cycles).

Fig 9 - Fatigue strengths of stress relieved transverse non-load-carrying fillet welds(axial load, 2 x 106 cycles).

25

Fig 10 - Fatigue strengths of as-welded transverse non-load-carrying fillet welds inbending (105 cycles).

Fig 11 - Fatigue strengths of as-welded transverse non-load-carrying fillet welds inbending (2 x 106 cycles).

26

Fig 12 - Mean fatigue strengths for each thickness (transverse fillet welds, as-welded,105 cycles).

Fig 13 - Mean fatigue strengths for each thickness (transverse fillet welds, as-welded2 x 106 cycles).

27

Fig 14 - Results for transverse non-load-carrying fillet welds under axial loading at R=0obtained in a single investigation.

Fig 15 - Results for transverse non-load-carrying fillet welds in bending at R=0obtained in a single investigation.

28

Fig 16 - Results for transverse non-load-carrying fillet welds tested in bending at R=0.

29

30

APPENDIX A

SOURCES OF PUBLISHED DATA USED IN THECOMPILATION OF THIS SUMMARY

Anon. IIW Commission XV Survey, 1962.

Anon. 'Fatigue investigation of higher strength structural steels is notched and inwelded condition'. ECSC Report EUR 5357, 1975.

Anon. 'Fatigue investigation of typical welded joints in steel Fe E460 as compared toFe E355'. ECSC Report F4.1/73, April 1977.

Anon. NRIM (Japan) Data Sheet No. 18.

Anon. NRIM (Japan) Data Sheet No. 20.

Abtahi A, Albrecht P and Irwin G R: 'Fatigue of a periodically overloaded stiffenerdetail'. Proc. ASCE J. Struct. Div. 102 (11), 1976, pp 2103-2119.

Benoit D, Lieurade H P and Truchon M: 'Fatigue behaviour under programmedloading of welded cruciform and butt joints in steel E355'. ECSC Final Report6210-KD/3/302, Nov. 1977.

Berge S: Univ. Trondheim Report SK R/54, 1981.

Chapeau W et al: 'Fatigue investigation of higher strength structural steels in notchedand in welded condition'. ECSC Report CECA 6210-45 (F4.3/73), 1974.

Frank K H: 'The fatigue strength of fillet welded connections'. PhD Thesis, LehighUniv., Oct. 1971.

Friis L E and Steneroth E R: 'Fatigue strength of welded joints in mild and highstrength structural steels'. Jernkontorets Ann. 152, 1968, pp 157-169.

Haibach E: 'The fatigue strength of welded joints as depending on the loadspectrum'. LBF Report FB 79, 1968.

Harrison J D: 'Further techniques for improving the fatigue strength of weldedjoints'. British Welding J. 13 (11), 1966, pp 642-647.

Harrison J D et al: 'Fatigue performance of welded high strength steels'. WeldingInstitute Report Series 215, 1974.

Iwaswaki T, Katoh A and Kawahara M: Conf. Fatigue of Engineering Materials andStructures, Sheffield, 1986, (IMechE), Paper C279/86.

Kado S, Ishiguro T and Ishii N: 'Fatigue strength improvement of welded joints byplasma arc dressing'. IIW Doc. XIII-774-1975.

31

Knight J W: 'Improving the fatigue strength of fillet welded joints by grinding andpeening'. Weld. Res. Int. 8 (6), 1978.

Knight J U: 'Some basic fatigue data for various types of fillet welded joints instructural steel'. Weld. Res. Int. 9 (3), 1979.

Kobayashi K et al: 'Improvement in the fatigue strength of fillet welded joints by useof the new welding electrode'. Weld. Res. Int. 8 (1), 1978, pp 53-75.

Lieurade H P: 'Programmed fatigue behaviour of cruciform welded joints in E24 andE36 steels'. Soud. Tech. Conn. 29, Ab. 9-10, Sept/Oct. 1975, pp 325-337.

Navrotskii D I, Savelev V N and Lavochkin G V: 'Determination of the stresses atpoints where transverse stiffening ribs are welded on'. Svar. Proiz. (5), 1963,pp 1-6.

Nilsson H, Larsson B and Westerlund R: 'Investigation into the fatigue strength ofwelded specimens'. Swedish Shipbuilding Research Foundation, Report 46, 1965.

Trufyakov V I: 'The endurance of welded joints in low alloy steels'. Avt Sv, Vol. 19,No. 11, November 1996, pp 1-6.

Trufyakov V I and Yakubovskii V V: 'Low cycle fatigue strength of welded jointsunder zero tension loading'. Avt Sv 34 (10), October 1981.

Usami S and Kusumoto S: 'Fatigue strength at roots of cruciform, tee and lap joints'.IIW Doc. XIII-833-1977.

Weck R: 'Results of fatigue tests on mild steel specimens with welded attachments'.IIW Doc. XIII-154-1958.

Yamada K and Hirt M A: 'Fatigue crack propagation from fillet weld toes'. Proc.ASCE, July 1982.

Yamaguchi I, Terada Y and Nitta A: 'On the fatigue strength of steels for shipstructures'. IIW Doc. XIII-425-1966.

32

APPENDIX B

LIST OF TEST SERIES REFERENCE (CAR) NUMBERSIN THE WELDING INSTITUTE DATABASE WHICH

WERE USED IN THE COMPILATION OF THISSUMMARY

1. Axially loaded K butt welds, as-welded

T=10 3392T=13 1538T=20 2086T=25 1366, 1539, 2294

2. Axially loaded transverse fillet welds, as-welded

T=10 631, 670, 907T=12 209, 211, 728, 730, 732, 783, 786, 810, 849, 873, 3018, 3250, 3557,

3559T=13 158, 199, 225, 229, 232, 233, 264, 281, 282, 466, 467, 468, 469, 470,

471, 472, 499, 935, 1006, 1007, 1011, 1499, 1705, 2289, 2293, 2558,2559, 2561, 3510 (5566, 5573)

T=14 3582T=15 3730, 3731, 3732T=16 1909, 2427T=19 959, 991T=20 2087, 2088, 3442, 3444, 3571, 3572T=25 1012, 1013, 1014, 1016 (5566)

3. Axially loaded transverse fillet welds, stress relieved

T=13 394, 1020 (5566)T=20 402, 404, 406T=25 1021, 1024 (5566)

4. Transverse fillet welds in bending

T=6.4 665T=8 664T=11 663T=13 623, 624, 995T=20 Iwasaki (2 series)T=25 625, 3054 (5566)T=26 3666, 3668

33

Printed and published by the Health and Safety Executive 100 1/97

34

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