Probabilistic Method for Predicting Ship Collision Damage

More documents

Recommendations

Info

The energy absorbed is then:66∆ KE1,n= 47 .1×10 RT1,n= 47.1×10 A1, nt(25)where:DKE- kinetic energy absorbed by decks, bottoms and stringers (J)R T - damaged volume of structural members (m 3 )A - damaged area of the decks or bottoms swept by each bow segment (m 2 )t- total thickness of impacted decks or bottoms (m)Forces and moments acting on other segments are calculated similarly. The total exerted force, F n , is the sum of the forcesand moments on each segment:4∑{ Fξi, n , Fηi,n , M i,n }F =(26)ni=1These forces are added to the side shell, bulkhead and web forces. Internal forces and moments are calculated for the struckship in the local coordinate system and transformed to the global system. The forces and moments on the striking ship havethe same magnitude and the opposite direction of those acting on the struck ship.3. COLLISION SCENARIOSA collision scenario is described using random variables with varying degrees of dependency. The data sources used to determinethe probabilities and probability density functions necessary to define these random variables were obtained from anumber of sources [Sandia National Laboratories 1998; Lloyds 1993; ORI 1980; ORI 1981 and Engineering Computer Optecnomics,Inc (ECO) 1996]. In this paper pdfs generated from this data are used to develop 10000 collision cases that areapplied to four struck tanker designs, for a total of 40000 SIMCOL runs. SIMCOL calculates damage penetration, damagelength, oil outflow and absorbed energy for each of these runs.14
Striking ShipBow HEACollision AngleStrike Location4Striking ShipBow HeightStruck ShipDesign1Striking ShipTypeStriking ShipBow Stiffness2Striking ShipDwtStriking ShipLBP, B, D3Struck ShipSpeedStruck ShipTrimStriking ShipDisplacement,Mass,Draft,TrimStriking ShipSpeedStruck ShipDraftFigure 9. Collision event variablesCollision event variables are not expected to be independent, but their interdependence is difficult to quantify because oflimited collision data. Figure 9 provides a framework for defining the relationship of scenario variables. Available data isincomplete for quantifying this relationship. Strike location must often be inferred from the damage description because reliablerecords of the precise location are not available. Ship headings and speeds prior to the collision are often included in accidentreports, but collision angle and ship speed at the moment of collision are frequently not included or only estimated anddescribed imprecisely.Figure 10 provides probabilities of the struck ship encountering specific ship types. These probabilities are based on thefraction of each ship type in the worldwide ship population in 1993 [Lloyds 1993]. Each of the general types includes anumber of more specific types:• Tankers – includes crude and product tankers, ore/oil carriers, LPG tankers, chemical tankers, LNG tankers, andoil/bulk/ore carriers• Bulk carriers - includes dry bulkers, ore carriers, fish carriers, coal carriers, bulk/timber carriers, cement carriers andwood chip carriers• Cargo vessels (Break Bulk / Freighters) – includes general freighters and refrigerated freighters• Passenger – includes passenger and combo passenger/cargo ships15
Page 2 and 3: ABSTRACTThis paper describes a meth
Page 7 and 8: Web frames acting as a vertical bea
Page 9 and 10: where:e i - strain in leg iq bi - b
Page 11 and 12: where j is the number of webs count
Page 13: collision angle, and extents of dam
Page 17 and 18: Figure 11. Striking ship displaceme
Page 19 and 20: applied to each of the four ships.
Page 21: Giannotti, J.G., Johns, N., Genalis

Probabilistic Method for Predicting Ship Collision Damage

Create successful ePaper yourself

Delete template?

Save as template?