ssc-367 - Ship Structure Committee

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Sample Wave scatter Diagram s 12 +..-..+---.-+-----+-w---+-----+-_---+-----+-----+-.---+.----+-.-_-+ i 1111111 11111 9 11 +---..+----.+-----+-..--+----.+-----+----.+-----+-.---+-.---+-----+ n 111111 10.511.01 I I I i 10 +-----+-----+-..--+----.+.----+-..--+-----+-.---+-----+---..+----.+ f 111[11 11.012.011.51 I I i 9 +----.+.----+...--+--...+-----+-.-.-+-----+..---+--..-+---.-+---..+ c 1111 10.511.512.513.010.51 I I a 8 +-----+-----+-----+-----+-----+-----+-----+-----+-----+--.--+---.-+ n 1111 11.015.015.512.510.51 I I t 7 +-----+-----+-----+-----+-----+-----+-----+-----+-----+---.-+-----+ 1111 I 5.0 113.0 111.0I 2.0 I I I I w 6 +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-.---+ a II I 0.5 I 6.0 118.0 123.0 I 8.5 I 1.0 I I I I v 5 +-----+-----+-----+-----+-----+-----+-----+-----+---.-+-----+-----+ e II I 4.0 126.5 148.5 126.5 I 7.0 I 2.5 I 0.5 I 0.5 I I 4 +-----+-----+-----+-----+-----+-----+-----+-----+-..--+-----+-----+ H I 1 1.5 139.5 179.5 163.5 120.0 I 6.0 I 3.0 I 1.5 I 0.5 I 0.5 I e 3 +-----+-----+-----+-----+-----+-----+-----+-----+-----+---.-+-----+ i I 0.5 150.0 I105.OI95.5 135.0 111.5 I 5.5 I 2.0 I 1.5 I I I — 9 ,2+-----+-----+-----+.----+-----+-----+-----+-----+-----+.----+---..+ h I 1.5 159.5 189.0 134.5 112.0 I 7.0 I 4,0 I 1.5 I 0.5 I I I t 1 +-----+-----+-----+-----+-----+-----+-----+-----+-.----+-----+-----+ 12.5118 .018.012.512.511.510.5 I I i I I (m) O +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ 2 3 4 5 6 7 8 9 10 11 12 13 Zero Up-crossing Period, Tz (see) Sum of Occurances 999.5 Figure A-2 A Typical Wave Scatter Diagram for the Central North Sea A-20
Using the significant wave height and zero up-crossing period from the wave scatter diagram and selecting a representative sea spectrum formulation, the energy of each sea state can be reconstructed. A*6 WAVE EXCEEDANCE CURVE A wave exceedance curve shows the number (percentage)of waves that are greater than a given wave height ‘for consistent wave height intervals. Table A-1 shows the type of data contained on a wave exceedance curve. Wave Height (ft) Cl 5 10 15 20 25 30 35 40 Number of Waves 35,351,396 3,723,300 393,887 41,874 4,471 480 51 5 1 (N) Table A-1 Wave Exceedance Data for Campos Basin (Number of Waves from Northeast) This data can be plotted on semi-log paper and closely approximated by a straight line plot. Typically, a wave exceedance H-N curve can be defined with the following equation. H = Hm+mz * 109 f!h where Hm is the maximum wave height for the design life, ‘z is the slope of the H-log N curve, -Hm/log Nh, MIC:500400CC-A A-21
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SSC-367 - FATIGUE TECHNOLOGY ASSESS
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SHIP STRUCTURF COMMllTFF The SHIP S
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—.--— 1. Report No. 2. Gowotnmr
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FATIGUE TECHNOLOGY Assessment AND D
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6. FATIGUE STRESS HISTORY MODELS 6,
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APPENDICES A. REVIEW OF OCEAN ENVIR
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D. VORTEX SHEDDING AVOIDANCE AND FA
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LIST OF FIGURES (cent.) FIGURE TITL
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HOT-SPOT STRESS . The hot-spot stre
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QA/Qc : Quality Assurance/QualityCo
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1. INTRODUCTION 1.1 BACKGROUND The
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general assessmentof fatiguewhile t
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2. OVERVIEW OF FATIGUE 2.1 FATIGUE
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2.2 FATIGUE ANALYSIS 2.2.1 Anal.vsi
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● Loads generated as affected by
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A deterministic method is sometimes
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1 APPLICATION OF NUMEROUS CYCLIC ST
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I MOBiLEANDSTATIONARY MARWE STRUCTU
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3. FATIGUE DESIGN AND ANALYSIS PARA
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and in-plane/out-of-planeangles,and
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the general quality of fabrication,
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3.2 REVIEW OF FATIGUE ANALYSIS PARA
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frequencies of interest, requiring
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● Reqular Waves in FrecjuencvDoma
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The finite element models of increa
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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
Page 220 and 221: Additional areas requiring further
Page 222 and 223: GROUP Modification of Weld Profile
Page 224 and 225: 400 ‘,, . . 350 - I I 300r [ ~ ,0
Page 226 and 227: TOPIC SUBJECT INVESTIGATOR COMPLETI
Page 228 and 229: 3.1 Soyak, J. F., Caldwell, J. W.,
Page 230 and 231: 4.12 Daidola, J.C., and Basar, N.S.
Page 232 and 233: 5.4 Papanikolaou,A. and Zaraphoniti
Page 234 and 235: 5.21 -”’ ” ”---”---”
Page 236 and 237: “7.2 Jordan, C.R., and Cochran, C
Page 238 and 239: 7.19 Niemi, E.J., “FatigueTests o
Page 240 and 241: 9.1 Skaar, K.T., “ContributingFac
Page 242 and 243: COMMllTEE ON MARINE STRUCTURES Comm
Page 244 and 245: U.S.Department of Transportation Un
Page 246 and 247: Member Agencies: United States Coas
Page 248 and 249: ‘ METRIC CONVERSION FACTORS Appro
Page 250 and 251: APPENDIX A REVIEW OF OCEAN ENVIRONM
Page 252 and 253: The most distinctive feature-of a r
Page 254 and 255: s(w) = 2*(4*112) - For a “height
Page 256 and 257: common probability distributions, t
Page 258 and 259: T: v. Visually Observed Period, or
Page 260 and 261: The characteristic wave heights of
Page 262 and 263: H~ is the significantwave height, a
Page 264 and 265: a = 0.09, for UJ>wm The U value of
Page 266 and 267: H~ is the significant height, ‘m
Page 268 and 269: If the wind duration is less than t
Page 272 and 273: Nm is the total number of waves in
Page 274 and 275: turbulence largely a function of te
Page 276 and 277: Applied Wind Speed Vz(t) ft/s (m/s)
Page 278 and 279: A.1O REFERENCES A*I Mechanics of Wa
Page 280: APPENDIX B REVIEW OF LINEAR SYSTEM
Page 283 and 284: Awhite noise function-may be used t
Page 285 and 286: Multiplication of the wave spectrum
Page 287 and 288: B.2.2.2 Response Amplitude Operator
Page 289 and 290: 0.2.3 Wave Spectra The wave spectru
Page 291 and 292: 9 is the acceleration of gravity in
Page 293 and 294: The following is..a. sample...of..a
Page 295 and 296: is the damping ratio,..the ratio of
Page 297 and 298: the set of extreme conditions, and
Page 299 and 300: A response scatter diagram could be
Page 301 and 302: 2.4 2.2 2 1 ‘Sen &-”Swull$p~ctr
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Page 305 and 306: o Kuang (ReferenceCl) “ o Wordswo
Page 307 and 308: C.2 STRESS CONCENTRATION FACTOR EQU
Page 309 and 310: C.3 PARAMETRIC STUDY RESULTS . C.3.
Page 311: 30. 2s , 20. 15. 10. 5. & wORDSWORT
Page 314 and 315: ChordSide Brace Side K-Joints SCFU
Page 316 and 317: Definition of Parameters, Validitv
Page 318 and 319: -, 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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