design considerations for aluminum hull structures - Ship Structure ...

More documents

Recommendations

Info

-122-redistribution of the still water buoyancy to reflect the wave. Therefore,such a calculation maybe used to evaluate the levels of totalbending moments (static plus dynamic) to be expected. Accordingly, standardbending moment calculations for several waveheights and for still watermay be made to produce an Mj vs Q log (M>Mj) plot by plotti~ ~he obtained( hebending moments at the probabilities corresponding to the X ~ values at)which the bending moments have been calculated. The sense (hog or sag) ofthis curve of expected moments will be the same as that of the still waterbending moment. By subtracting 2 times the still water bending from itsordinates a curve of expected moments of the opposite sense may be obtained.The foregoing procedure should be based upon the load condition of thedesign yielding the highest still water bendi~ moment, since the effectof load distribution is more significant to the calculated wave bendingmoment than is the draft at which it occurs. Finally, if the base scaleof probability is multiplied by the expected number of oscillations in theintended life of the ship, the resultant log 10 base scale will indicatethe numbers of oscillations during the life of the ship in which it shouldbe expected the Mj lev-elsof bending moments are reached.4. In applyi~ the foregoing proceduz-es to the subject designit was considered that probabilities based on average North Atlanticweather would be realistic yet not overly conservative, in view of contemplatedtramp operations in the various seas of the world. Accordingly,the values given by Figure 18 of Refereme (Al) for a 600 foot ship areconsidered valid for this application, subject to minor correction forFroude number. Based on Figure 12 of Reference (Al), increasing theFreud rnunberfrom 0.1 to about 0.2hwould increase the ~ value atLQ = lo-lofrom about .0485 shown on Figure 18 of Reference (Al) to .O~.5. Bending moment estimates for the various loadings of theMV CHALLENGER were reviewed. Noti,ngthat the subject design will have adeeper load line than the loadings reviewed, and further that light shipweight is expected to be about 2900 tons less than that used in the estimates,Mandelli methods were used to correct for the effects of these.Accordingly, the design bending moment was estimated to vary from 1S0,000foot tons (sagging) in still water to 67~,ooo foot tons for anhe— = .O.!J wave. The resulting Mj vs Q log 10 (M>Mj) plot is shown onLFigure Al. Based upon an expectancy of 1.26 x 108 cycles in as computedthereon for the designis lifetime, it may be expected that once in itslifetime the bending moment will exceed S7S,2~0 foot tons. Also in itslifetime, -thereis a 99 per cent probability that the bending moment willnot exceed 680,2s0 foot tons. This is obtained by a statistical methodgiven in Appendix A of Reference (A2) and is recommended as the bendingmoment to be used in yield stress considerations. However, for fatigueconsiderations the values in the probability range from 1 to 1.26 x 10-8are considered appropriate.
FIG. 1A Long Term Distribution ofVertical Bending Moment (For Preliminary Design)16 “ “ //Q(M>Mj) —5 ““-” ‘“”-” ““--”7 “-~”Lj ____w-{-I2 ‘“I1 .—-..--—-——--.—~ s1 tI# q1o-1o 10-810 -6 ~o-b 10-2 1 s: .tn.--MN(M >Mj)— I I I 1 !1 I02 104 ~’06 108+N(M>Mj)is probablenumberof Wnes Mj will-be exceededby shipsbendingmomentin its lifettieof n cycles.(n=20 Yrsx 200 Sea Days/Yr x 864oo Sec/Dayx-123-w+-.3666 cm = 1.26x 108 Cyc.)M-%Average North AtlanticNote:Fatigue Factor R Value Z(2 ~~.Wa~. - ~)‘j
Page 5:
CONTENTSI.. II.III.Iv.v.VI ●VII.I
Page 9 and 10:
LIST OF FIGURES(Cent’d)FIGURE NO.
Page 11 and 12:
I. INTRODUCTIONThis report summariz
Page 13:
art in fabricating and maintaining
Page 16 and 17:
MONTEROSSO GRANA /17VALGRANA / CARA
Page 18 and 19:
-8-Numerous references have been re
Page 20 and 21:
.10.TABLE 2. Mechanical Properties
Page 22 and 23:
TABLE 2 Mechanical Properties of Al
Page 24 and 25:
TABLE 3 Mechanical Property Limits
Page 26 and 27:
-16-l?igures5, 6, 7 ati 8 present f
Page 28 and 29:
-18-ti-’”’-”-””””-L
Page 30 and 31:
-20-60 .r---.— ..,.— -——,L-
Page 32 and 33:
.22-each stress level, rate of load
Page 34 and 35:
-24-!Z456-H321 = 0.485083-H321 = 0.
Page 36 and 37:
-26-(c)Members with partial or cont
Page 38 and 39:
-28-AllOyS 5083 and 54.56(~ content
Page 40 and 41:
-30-The previous paragraphs have de
Page 42 and 43:
-32-The problem of cargo hold abras
Page 44 and 45:
-34-The question of residual stress
Page 46 and 47:
.36-Each alloy was given a relative
Page 48 and 49:
-38-GENERAL OBSERVATIONSFYior to a
Page 50 and 51:
-40-The question of comparative imp
Page 52 and 53:
-42-(d)(e)Poor quality welds due to
Page 54 and 55:
-44-The ABS criteria noted above we
Page 56 and 57:
-46-DNV would consider fatigue in e
Page 58 and 59:
-48-is less, for the exposed side s
Page 60 and 61:
Equation (2):-50-Hu1l SMa~um = Hull
Page 62 and 63:
-52-Another aspect of vibrations wh
Page 64 and 65:
-54-000000000Bottom Shell PlateSide
Page 66 and 67:
-56-at the deck and keel. This stre
Page 68 and 69:
-58-AT is the change inUT= Thermal
Page 70 and 71:
-60-SUl@!ARYAll parties contacted f
Page 72 and 73:
-62-(c)(d)(e)(f)T~e exterior side o
Page 74 and 75:
TABLE 12 Aluminum Bulk Carrier - Su
Page 76 and 77:
.66-INSUT.ATION AND SHEATHINGShell8
Page 78 and 79:
-68-(b)(c)(d)(e)(f)(g)(h)(i)(j)At l
Page 80 and 81:
-70-IIF.INSTALLATION OF SYSTEMS AND
Page 82 and 83: Rudder Assembly -carrier should be
Page 84 and 85: -74-(b)MechanicalTensile Strength 6
Page 86 and 87: -76-(e)The steel piping must be of
Page 88 and 89: -78-Other Piping Systems and Valves
Page 90 and 91: -80-struetion for the aluminum hull
Page 92 and 93: -82-Large heavy type machine~ must
Page 94 and 95: suffers attack in an alkaline envir
Page 96 and 97: -86-REPAIRSObtaining proper repairs
Page 98 and 99: -88-The design of the midship s~cti
Page 100 and 101: -90-assuming the increase is applic
Page 102 and 103: LIGHT SHIP WEIGHT ESTIMATE-92-In or
Page 104 and 105: -94-TABLE 20 Aluminum Bulk Carrier
Page 106 and 107: TABLE 22 Trim and StabilityFull Loa
Page 108 and 109: -98-TABLE 24 Price of Steel Bulk Ca
Page 110 and 111: GaseNumber. . . -.,- .TABLE 27 Comp
Page 112 and 113: -1o2-TABLE 28CarriersComparison of
Page 114 and 115: 12 ---n..T.[T7%l,=LEGS IU ORF=ErY
Page 116 and 117: -106-such as iron ore, on two of th
Page 118 and 119: -108-7)is,zg~ gg~5e mzz~E’4E!~K2j
Page 120 and 121: -11o-(a)(b)(c)(d)Inerting system fo
Page 122 and 123: -112-fatigue, particularly in the p
Page 124 and 125: -114-2k* Installation of Systems an
Page 126 and 127: -116-LIST OF REFERENCES(7)Fatigue P
Page 128 and 129: -11.8-LLST OF REFERENCES(Cent’d)(
Page 130 and 131: -120-ADDITIONAL SOURCES OF INFORMAT
Page 134 and 135: -124-APPENDIX BEXCERPTS FROMRULES A
Page 136 and 137: -126-92.07-10(d)(~) Interior stairs
Page 138 and 139: -128-~gE1+0102030- .. ..—405060
Page 140 and 141: ectintyclassification4KEYWORDSROLEL
Page 142: SHIP STRUCTURE COMMITTEE PUBLICATIO
show all

design considerations for aluminum hull structures - Ship Structure ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?