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A design for a lightweight sandwich panel for ice-going ships
KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lättkonstruktioner, marina system, flyg- och rymdteknik, rörelsemekanik.ORCID iD: 0000-0002-1743-0686
KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lättkonstruktioner, marina system, flyg- och rymdteknik, rörelsemekanik.ORCID iD: 0000-0002-1187-4796
KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lättkonstruktioner, marina system, flyg- och rymdteknik, rörelsemekanik.ORCID iD: 0000-0002-9110-9401
Lightness by Design.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Lightweight composite ship design has gained in popularity in the marine industry over the years, especially for high-speed crafts and ferries. Very few or none are designed for operating in icy conditions even there are reports on composite ships that occasionally, and successfully, have to navigate in such conditions. Light weight designs are generally beneficial from an economical point of view with reduced fuel consumption and reduced maintenance cost in comparison to steel ships. In the ‘marine impact on marine composites’ categories, ice impact on sandwich panel is still an unresolved problem. In this paper, a case specific ship design subjected to ice impacts are studied. The reference ship design is in steel, and a new light weight composite sandwich solution is proposed. The objective is put forward a feasible method that includes the modelling of ice impact on a sandwich panel into the overall ship design. A numerical and parametric study, using finite element analysis, is used to find a lightweight panel candidate. Three parameters were selected, the face thickness, the core thickness and the core quality (i.e. density). The face material was selected as a carbon fibre reinforced polymer for all cases.The laminated composite sandwich panel is assumed to be subjected to a quasi-static (QSI) pressure load and the ice load is applied on a small load patch area as constant pressure. The final design results in a panel weight of 35.4 kg/m2 which compared to the original steel panel of 214 kg/m2, resulting in a weight save of 83.5%. This may be a crucial and important measurement when setting up the next generation of the shipping industry in order to cope with climate change.

Keywords [en]
Ship design, lightweight structure, ice load, impact, composites, sandwich structure
National Category
Vehicle and Aerospace Engineering
Identifiers
URN: urn:nbn:se:kth:diva-316583OAI: oai:DiVA.org:kth-316583DiVA, id: diva2:1689555
Note

QC 20220902

Available from: 2022-08-23 Created: 2022-08-23 Last updated: 2025-02-14Bibliographically approved
In thesis
1. Efficient hull design for ice conditions in inland waterways
Open this publication in new window or tab >>Efficient hull design for ice conditions in inland waterways
2022 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

With increasing interest in utilizing the inland waterways (IWW) in European countries, the design of IWW vessels gains attention both from a transport efficiency and an emission control point of view. Usually, IWW ships are designed without ice operation concerns and are structurally weaker than ships designed according to ice-class notifications from the classification societies. It poses a potential danger for countries with long winter seasons and frozen waterways. Designing such ships requires particular concerns since there are no strict requirements regarding ice-class notifications for IWW ships. Among all the design issues, the primary challenge is to estimate the ship resistance and impact load on the ship hull structure.

To consolidate the design challenges for IWW ice-going ships, Lake Mälaren is selected. The mechanical properties of ice have a significant influence on the ice load. Ice conditions, e.g. ice type and concentration, and ice data, e.g. thickness and flexural strength, are extracted and analyzed for the ice load estimation. Ice characteristics are studied based on empirical formulae and calibrated by reference data.

Determination of the ice impact load is the first vital step in designing a lightweight structure. A deterministic approach and a probabilistic approach are used to predict the ice loads. The Finnish Swedish Ice Class Rule (FSICR) is the deterministic approach used for the first-year freshwater ice conditions. The probabilistic approach includes a probabilistic and a numerical method. The probabilistic method simplifies the ice pressure in relation to the contact area between the ice and the ship hull. The numerical method investigates the idealized ship-ice impact model regarding the ice failure process, ice conditions, and ship geometry. Given the impact load, a lightweight panel is designed, and it saves almost 83.5% weight compared to a stiffened steel panel. This is achieved by using a sandwich structure with a composite face and PVC core.

Ship resistance in ice-covered water plays a significant role in assessing the operational scenario. It is essential for ship owners and operators to evaluate ship economics. In order to estimate ship resistance in ice-covered water, an Artificial Neural Network (ANN) model is developed by using suitable ship and ice parameters. A statistical model is designed to account for the most important ship operation variables, i.e. ship speed and ice thickness. Combined, the two models provide a very promising way to estimate a ship's Operation Time Window.

Abstract [sv]

Med ökande intresse för att använda de inre vattenvägarna (IVV) i europeiska länder uppmärksammas IVV-fartyg både ur transporteffektivitets- och utsläppssynvinkel. Vanligtvis är IVV-fartyg konstruerade utan hänsyn till is och är strukturellt svagare än fartyg designade med isklass från klassificeringssällskapen. Det utgör en potentiell fara i länder med lång vintersäsong. Utveckling av IVV-fartyg för nordiska förhållanden kräver därför speciella hänsyn eftersom det inte finns några strikta krav på isklass för IVV-fartyg. Bland alla designfrågor är den primära utmaningen att uppskatta fartygets motstånd och belastningen på skrovet vid gång i is. 

 För att konkretisera designproblemen för isgående IVV-fartyg väljs Mälaren. Isens mekaniska egenskaper har stort inflytande på belastningarna. Isförhållanden (som istyp och koncentration) och isdata (som istjocklek och isens böjhållfasthet) extraheras och analyseras för isbelastningsberäkningarna. Isens karakteristika studeras med hjälp av empiriska formler som kalibreras med referensdata.

Att bestämma ispåverkansbelastningen på strukturer är det första viktiga steget i utformningen av en lätt struktur. En deterministisk metod och en probabilistisk metod används för att bestämma islasterna. Den finsk-svenska isklassen (FSICR) är den deterministiska metod som används för förstaårs-isförhållanden i sötvatten. Den probabilistiska metoden inkluderar både en probabilistisk och en numerisk metod. Den probabilistiska metoden förenklar istrycket i förhållande till kontaktområdet. Den numeriska metoden undersöker den idealiserade fartyg-is-interaktionssmodellen och inkluderar isens skademoder, isförhållanden och skrovgeometri. Med den givna slagbelastningen så designas en lättviktspanel som sparar närmare 83.5% vikt jämfört med en stålpanel. Denna lättviktpanel består av en sandwichstruktur vilken har en kompositytskikt och en kärna av PVC-material.

Fartygsmotstånd i is spelar en viktig roll i bedömningen av operabiliteten. Det är viktigt för fartygsägare och operatörer att utvärdera fartygsekonomin. För att uppskatta fartygsmotstånd i istäckt vatten med hjälp av lämpliga fartygs- och isparametrar utvecklas en modell baserad på ett artificiellt neuralt nätverk (ANN). En statistisk modell är utformad för att ta hänsyn till de viktigaste driftsvariablerna, vilka är fartygets hastighet och istjockleken. Dessa två modeller utgör tillsammans ett mycket lovande verktyg att uppskatta framtida fartygs driftsfönster.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2022. p. 85
Series
TRITA-SCI-FOU ; 2022:36
Keywords
Inland waterway ship, ice conditions, ice properties, ice-hull interaction, ice resistance, impact load, numerical method, operation time window, lightweight design, composites and sandwich structure
National Category
Vehicle and Aerospace Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-316585 (URN)978-91-8040-309-2 (ISBN)
Public defence
2022-09-15, https://kth-se.zoom.us/webinar/register/WN_TovFYkRZR-KdX4GpJXwGCA, F3, Lindstedtsvägen 26, KTH Royal Institute of Technology, Stockholm, Sweden., 10:00 (English)
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Note

QC 220823

Available from: 2022-08-23 Created: 2022-08-23 Last updated: 2025-02-14Bibliographically approved

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Zhang, MengBurman, MagnusGarme, Karl

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