ssc-367 - Ship Structure Committee

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SHIP STRUCTURF COMMllTFF The SHIP STRLfCTURE COMMllTEE is constituted to prosecute a research program to improve the hull structures of ships and other marine structures by an extension of knowledge pertaining to design, materials, and methods of construction. RADM A. E. Henn, USCG (Chairman) Chief, Office of Marine Safety, Security and Environmental Protection U. S. Coast Guard Mr. Thomas 1-1,Peirce Mr. H. T, Hailer Dr. Donald Liu Marine Research and Development Associate Administrator for Ship- Seniqr Vice President Coordinator building and Ship Operations American Bureau of Shipping Transportation Development Center Maritime Administration Transport Canada Mr. Alexander Malakhoff Mr. Thomas W. Allen CDR Stephen E. Sharpe, USCG Director, Structural Integrity Engineering Offmer (N7) Executtie Dkector Subgroup (SW 05P) Military Sealift Command Shi Structure Committee Naval Sea Systems Command U. i . Coast Guard CONTRACTING OFFICER TEC HNICAL REPRESENTATIVE Mr. WNiam J. Slekierka SEA05P4 Naval Sea Systems Command ~Hl P STRUCTURF SUBCOMMIITFF The SHIP STRUCTURE SUBCOMMllTEE acts for the Ship Structure Committee on technical matters by providing technical coordination for determinating the goals and objectives of the program and by evaluating and interpreting the results in terms of structural design, construction, and operation. AMERICAN BUREAU OF SHIPPING NAVALSEA SYSTEMS COM MAND TRANSPORT CANADA Mr. Stephen G. Amtson (Chairman) Dr. Robert A Sielski Mr. John Grinstead Mr. John F. ConIon Mr. Charles L Null Mr. Ian Bayly Dr. John S. Spenmr Mr. W. Thomas Packard Mr. David L. Stocks Mr. Glenn M. M.he Mr. Allen H. Engle Mr. Peter Timonin MILITARY SFAI IFT COMMAN~ E ADMINISTRATION U. S, COAST GUARD Mr. Rolwt E. Van Jones Mr. Frederick Seibold CAPT T. E. Thompson Mr. Rickard A. Anderson Mr. Norman O. Hammer CAPT W. E. Colburn, Jr. Mr. Michael W. Touma Mr. Chao H. Lin Mr. Rubin Scheinberg Mr. Jeffrey E. Beach Dr. Walter M, Maclean Mr. Il. Paul Cojeen SHIP STRUCTURE SUBCOMMlmEE LIAISON MEMBERS U. S. COAST GUARD ACADEMY NATI ONAL ACAD~Y OF SCIENCES - LCDR Bruce FL Mustain Mr. Alexander B. Stavovy U.S. MFRCHAN T MARINF ACADFMY Dr. C. B. Kim u. S, NAVAL ACADEMY Dr. Rarrrswar Bhattacharyya STATE UNIVERSITY OF NEW YORK ~ Dr. W. R. Porter SOCIETY OF NAVAL ARCHITECTS AND MARINE ENGINEERS ~TION#.&AEC~~EMY OF SCIENCES - MARINE STRUCTURES Mr. Peter M. Palermo WFI IIING RFSFARCHCOUNC II Dr. Ma_tin Prager ~ L INSTITUTE Mr. Alexander D. Wilson DEPARTMENTOF NATIONAL DEFENCE - CANADA Dr. William Sandberg Dr. Neil G. Pegg OFFICE OF NAVAI RFSEARG H Dr. Yapa D. S. Rajapaske
MemberAgencies: United States Coast Guard Naval Sea Systems Command Maritime Administration American Bureau of Shipping Miiitaty Sealift Command Transport Canada ~ c Ship Structure Committee An Interagency AdvisoryCommittee May 17, 1993 AddressCorrespondence to: Executive Director ShipStructure Committee U.S.CoastGuard(G-Ml/R) 2100SecondStreet, S.W. Washington, D.C.20593-0001 PH:(202)267-0003 FAX:(202)267-4677 SSC-367 SR-1324 FATIGUE TECHNOLOGY ASSESSMENT AND STRATEGIES FOR FATIGUE AVOIDANCE IN MARINE STRUCTURES This report synthesizes the state-of-the–art in fatigue technology as it relates to the marine field. Over the years more sophisticated methods have been developed to anticipate the life cycle loads on structures and more accurately predict the failure modes. As new design methods have been developed and more intricate and less robust structures have been built it has become more critical than ever that the design tools used be the most effective for the task. This report categorizes fatigue failure parameters, identifies strengths and weaknesses of the available design methods, and recommends fatigue avoidance strategies based upon variables that contribute to the uncertainties of fatigue life. The report concludes with recommendations for further research in this field. Gmdvwm A. E. HENN Rear Admiral, U.S. Coast Guard Chairman, Ship Structure Committee
Page 1: SSC-367 - FATIGUE TECHNOLOGY ASSESS
Page 6 and 7: —.--— 1. Report No. 2. Gowotnmr
Page 8 and 9: FATIGUE TECHNOLOGY Assessment AND D
Page 10 and 11: 6. FATIGUE STRESS HISTORY MODELS 6,
Page 12 and 13: APPENDICES A. REVIEW OF OCEAN ENVIR
Page 14 and 15: D. VORTEX SHEDDING AVOIDANCE AND FA
Page 16 and 17: LIST OF FIGURES (cent.) FIGURE TITL
Page 18 and 19: HOT-SPOT STRESS . The hot-spot stre
Page 20 and 21: QA/Qc : Quality Assurance/QualityCo
Page 22 and 23: 1. INTRODUCTION 1.1 BACKGROUND The
Page 24 and 25: general assessmentof fatiguewhile t
Page 26 and 27: 2. OVERVIEW OF FATIGUE 2.1 FATIGUE
Page 28 and 29: 2.2 FATIGUE ANALYSIS 2.2.1 Anal.vsi
Page 30 and 31: ● Loads generated as affected by
Page 32 and 33: A deterministic method is sometimes
Page 34 and 35: 1 APPLICATION OF NUMEROUS CYCLIC ST
Page 36 and 37: I MOBiLEANDSTATIONARY MARWE STRUCTU
Page 38 and 39: 3. FATIGUE DESIGN AND ANALYSIS PARA
Page 40 and 41: and in-plane/out-of-planeangles,and
Page 42 and 43: the general quality of fabrication,
Page 44 and 45: 3.2 REVIEW OF FATIGUE ANALYSIS PARA
Page 46 and 47: frequencies of interest, requiring
Page 48 and 49: ● Reqular Waves in FrecjuencvDoma
Page 50 and 51: The finite element models of increa
Page 52 and 53: The stressmodel parametersdiscussed
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While API S-N curves are applicable
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DESIGN Osn40H rAnNsirsR8 FAMcA~ M P
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Primarily Affect .--------+’ & In
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MOTIONS MODEL — .—. ● ;LOADS
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loa 1 10 -— — — -t-i-nT 1[ -t
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4. GLOBAL REVIEW OF FATIGUE 4.1 APP
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An allowable stress method, also co
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esults of work covering assessment
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location. Thus, the method should b
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1. SDectral FaticlueAnalvsis Althou
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2. Weibull AtIDroach The Weibull sh
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energy about the central direction
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Although considered to be an emergi
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many design rules implement this ap
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Detailed Anal.vsisMethods The detai
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The DnV X-curve and the DEn Guidanc
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ending restrictions. Cruciform and
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period, are also designed tomeet th
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incorporates inspection-strategy(Re
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‘Thereare numerous finite element
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LOCATIONs oF FATIGUE CMCKS Figure 4
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TW=’T ——— ———___ __ r
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1 —. — — — — -.. - .. - .
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TOP[C U.K.DEPARTMENTOF ENERGY(OEn)
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:1 U.K.DEPARTMENTOF ENERGY(DEn) AME
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TOPIC U.K.DEPARTMENJOFEIWRGV(oEn) O
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5. FATIGUE STRESS MODELS 5.1 REVIEW
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● The water particle kinematicsar
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“radiation pressure” of waves,
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influence on the applied loading. H
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their function, selecting appropria
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hydrostatic stiffness is introduced
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structure is unique and an allowabl
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loads directly. Since the diffracti
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typically from 0.6 to 0.8 and 1.5 t
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therefore be defined uniformly alon
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load analysisof adetailed three-dim
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esponsesare required , or where con
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either multiple stick elements (for
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Braces may have stubs or cones, whi
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Whatever the basis for an empirical
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The SCF equations currently in use
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life. During the comprehensive desi
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?.s I z - ]LEvE~ ~ 1,5 \ i i+ 11 Is
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-. Figure 5-5 Comparison of Detaile
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( -t ) ( T-JOINT Y-JOINT ( \ I / K-
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SMEDLEY-WORDSWORTH 0 d =— = D 600
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Wave Records Older wave and wind in
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In many cases wind informationmay b
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q = 3.3 s = 0.07, for f< fm s = 0.0
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Seasonal Variation The annual wave
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4. ~arpkaya spreading. (Reference 6
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~. \“ life of a structure,cannot
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6.3 TIME-DOMAIN ANALYSES Nonlinear
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The wave environmentdefinitionsbase
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.,..,, ....- ., ;., .. .... .- .. .
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● Fatiguetest data should be care
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assessmentis typically identifiedas
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damage accumulation similar to that
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“FabricationRestrictions Fabricat
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Fatigue strength of a tubular joint
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Current recommendations,rules and s
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n NB=T 1 [p=+pi Ei . ‘c where: NB
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(2) Damage computation does not acc
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DNB = (f. T/K) (2/2 U)m r (f+ 1) wh
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interactionof multiple fatigue crac
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amplitude loading and loading seque
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n“ CAP PASSES ROOT = * { A A 4 I
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It should be pointed out that the e
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v= flow velocity normal to the cyli
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8.4 METHODS OF MINIMIZING VORTEX SH
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Ra < S REGIME OF UNSE?ARATE~ FLOW 5
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ages. The designer has no control o
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failure data on various structures,
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connections, knife edge crossings,
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9.3.1 Fabrication Effects The fatig
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● Controlled Erosion An alternate
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after a given number of stress cycl
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A second pass with polishingdisc is
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others. Extensive analytical and ex
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d) Stress SDectrum Hot-spot stresse
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Cumulativefatiguedamagecomputations
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as a parametric study intended to i
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Additional areas requiring further
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GROUP Modification of Weld Profile
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400 ‘,, . . 350 - I I 300r [ ~ ,0
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TOPIC SUBJECT INVESTIGATOR COMPLETI
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3.1 Soyak, J. F., Caldwell, J. W.,
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4.12 Daidola, J.C., and Basar, N.S.
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5.4 Papanikolaou,A. and Zaraphoniti
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5.21 -”’ ” ”---”---”
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“7.2 Jordan, C.R., and Cochran, C
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7.19 Niemi, E.J., “FatigueTests o
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9.1 Skaar, K.T., “ContributingFac
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COMMllTEE ON MARINE STRUCTURES Comm
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U.S.Department of Transportation Un
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Member Agencies: United States Coas
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‘ METRIC CONVERSION FACTORS Appro
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APPENDIX A REVIEW OF OCEAN ENVIRONM
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The most distinctive feature-of a r
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s(w) = 2*(4*112) - For a “height
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common probability distributions, t
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T: v. Visually Observed Period, or
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The characteristic wave heights of
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H~ is the significantwave height, a
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a = 0.09, for UJ>wm The U value of
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H~ is the significant height, ‘m
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If the wind duration is less than t
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Sample Wave scatter Diagram s 12 +.
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Nm is the total number of waves in
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turbulence largely a function of te
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Applied Wind Speed Vz(t) ft/s (m/s)
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A.1O REFERENCES A*I Mechanics of Wa
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APPENDIX B REVIEW OF LINEAR SYSTEM
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Awhite noise function-may be used t
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Multiplication of the wave spectrum
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B.2.2.2 Response Amplitude Operator
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0.2.3 Wave Spectra The wave spectru
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9 is the acceleration of gravity in
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The following is..a. sample...of..a
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is the damping ratio,..the ratio of
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the set of extreme conditions, and
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A response scatter diagram could be
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2.4 2.2 2 1 ‘Sen &-”Swull$p~ctr
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L ‘2
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o Kuang (ReferenceCl) “ o Wordswo
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C.2 STRESS CONCENTRATION FACTOR EQU
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C.3 PARAMETRIC STUDY RESULTS . C.3.
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30. 2s , 20. 15. 10. 5. & wORDSWORT
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ChordSide Brace Side K-Joints SCFU
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Definition of Parameters, Validitv
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-, l— I + ?1 -— I . 4> a ,- I I
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Kuang SCF Computdion 1 L u UI \ f-
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., I , 1- out— FIano SCF m tg n I
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— 6 Smedley-Wordswoti SCF Computa
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T ln— Plan- SCF CrOwn POsltlon o
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C.3.l(C) Kuang Chord SCF’S for T-
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5 Kuang SCF Computation 4 IL u M 3
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C.3.l(d) Smedley-WordsworthChord SC
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. ,i 5 Smedley-Wordsworth SCF Compu
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I I K Out— Plan= SCF —— Saddl
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- 10 Smedley-Wordsworth SCFComputat
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‘\, ?v x out— Plan- SCF ——
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C.3.2(a) Kuang Chord SCF’S for T-
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KuwqSE _im T-joint In%neW UrrdSicko
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C.3.2(b) Smedley-HordsworthChord SC
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T-joint Axial SF Saddle Posiiim
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-— T-joint CtkuHlane ELFSaddlePci
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I 1 1 1 1 ~. l~o ~ ha= 1s0 : ~. ~J
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1 ! ! O.fi ;0.762 %841 0,769 O,= !0
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Ikrdwth-kdlw SF l%quiaiifm K-joint
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hdsmthqwdhy W Camputatim l-joint Ax
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Ejrnnt flkf+lane SF SaddlePmitim ~,
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MAXIMUM PRINCIPAL STRESS SCF = ----
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‘-W, .\ I Ill I : II m -,, !) .
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’ \./ ““’ w~”mm m ““-
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. . I Column L’ Longitudinal Gird
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C.8 Underwater Engineering Group,
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APPENDIX D VORTEX SHEDDING AVOIDANC
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a an b d f“ f ar f~ ‘bmax f~ fn
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D. VORTEX SHEDDING 0.1. INTRODUCTIO
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Vortex Shedding Frequency (f”) fv
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waves. When only isolated members u
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member’s nominal diameter and thi
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\Lf-! of cycles. Thus, the reduced
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s ; J steady current, by substituti
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Step 3: Obtain a new valueof 1/10 b
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vortex shedding will occur, i.e., V
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h. The fatigue life may -be modifie
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NOTE: The relationship given is bas
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CELL C7: KINEMATIC VISCOSITY = U CE
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COLUMN N: THE STRESS AMPLITUDE IS C
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D.8.3 Devices and Spoilers Devices
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D*9 REFERENCES D.1 King, R., “A R
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Fint Insmbility Rtgion I !%mmd Inat
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.—____ *U.S. E.P.O. :1993-343-273
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COMMllTEE ON MARINE STRUCTURES Comm
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4!! . ,—.-.,
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