National Transport Library Research Database

Förprojekt av nya materialkoncept för byggnation av energisnåla fartyg (Pre-study of new construction materials concepts for construction of ships with low energy consumption)

Subject(s): Online resources: Abstract: Bakgrunden till detta förprojekt är att krav på lättare, snabbare och bränslesnålare fartyg har tvingat varvsindustrin att flytta fokus mot lättare och starkare material och nya fartygskoncept. Tre principiellt olika skeppsbyggnadsmaterial för energisnåla fartyg, FRP (Fibre Reinforced Polymer) kom-posit, aluminium och en vidareutveckling av Volvos patenterade material HSSA (Hybrid Stainless Steel Assembly), ett materialsystem bestående av en sandwich i rostfritt stål, har jämförts sinsemellan och också med stål, som är det vanligaste skeppsbyggnadsmaterialet idag. En referensgrupp med representanter för varv, rederier, konstruktionsföre-tag, klassningssällskap och Sjöfartsverket har bildats och tre ”brainstorming-workshops” har genomförts. Inom projektet har olika tester med HSSA-materialet genomförts, där tjockleken var 1,2 mm. Brand- och röktester genomfördes av SP Sveriges Provnings- och Forskningsinstitut och tester av tätning och kantförslutning genomfördes av Institute for Textile Technology and Process Engineering Denkendorf (ITV Denkendorf) och av State Material Testing Institute Stuttgart (MPA Stuttgart). En sammanställning av data för HSSA-materialet och olika jämförelser med andra skeppsbyggnadsmaterial redovisas. En funktionssystemanalys avseende nya materialkoncept med fokus på egenskaper såsom deformationer, vibrationer och utmattning har genomförts. Quality Function Deployment (QFD) användes som metod för att underlätta ”brainstorming” och koncept-utvärdering. Följande slutsatser dras i denna förstudie: 1. När olika materialsystem värderas kan man konstatera att de flesta fartyg i världen byggs av stål och att stål är överlägset i de flesta fartygsapplikatio-ner på grund av låg kostnad och goda strukturella egenskaper. 2. För några mycket exklusiva användningsområden med krav på hög fart och låg vikt kan kostnadsbilden ge utrymme för lättviktsmaterial, såsom FRP och aluminium. 3. Det finns en potential för marginell användning av HSSA inom varvsindustrin, om en tjockare panel utvecklas. Användningsområden där låg vikt, vibrationsdämpning och korrosionsmotstånd värderas högt är då tänkbara. En fortsättning av detta förprojekt för marina applikationer måste fokuseras på en tjockare (ca 6 mm) HSSA panel. Projektet presenterades vid Transportforum 2003 i Linköping, och delar av det vid RoRo 2002 i Lübeck, och det diskuterades vid Sixth International Conference on Sandwich Structures, 2003, Ft. Lauderdale, Florida USA. Abstract: Demands for lighter, faster and more fuel-efficient ships have forced the focus of the ship industry over to lighter and stronger materials and new concepts. Three principally different ship construction materials, FRP (Fibre Reinforced Polymer) composite, aluminium, and a further development of Volvo’s patented material HSSA (Hybrid Stainless Steel Assembly), which is a material system consisting of a stainless steel sandwich, were compared. Comparisons were also made with steel, which is the most com-monly used ship construction material today. A Project Reference Group, representing ship yards, ship owners, ship design companies, classification societies and the Swedish National Maritime Administration, was established and three brainstorming workshops were organised. Different tests with the HSSA material, with a thickness of 1.2 mm, were carried out in the project. Fire resistance, smoke generation, non-combustibility, spread of flame and rate of heat release were tested at SP Swedish National Testing and Research Institute, see Appendix A-D. Testing of welding properties of the HSSA material was performed at the Institute for Textile Technology and Process Engineering Denkendorf (ITV Denkendorf) and at the State Material Testing Institute Stuttgart (MPA Stuttgart), see Appendix E. For the local strength and deformations in smaller ships it is easy to show the benefit of sandwich structures or aluminium before steel. For larger ships, larger than 100 m in length, steel is usually the best alternative for the hull girder as the strength requirements are dominated by the longitudinal hull girder bending, which causes large in-plane stresses in the deck plating. When a new material concept is introduced the natural thing to do is to make a functional system analysis. This introduces new deign problems with regards to deformation, vibration, buckling and fatigue. The project used an early phase of radical redesign based on the QFD process. The Quality Function Deployment (QFD) assessment was performed to secure an optimal solution for the customers involved. The QFD breakdown contained several steps in order to facilitate brainstorming and evaluation of concepts. It was necessary to determine properties for the material system in a reasonable range of geometric variations (thickness of each layer, thickness of core material) and a range of reasonable change of properties in each layer (mainly shear stiffness of the core). In other projects the buckling and ultimate load capacity of the HSSA panel has been investigated. The information from these studies was used in order to perform some calculations on stiffness and strength. These evaluations show that the HSSA panel is efficient as a panel with lateral load, i.e. load normal to the plate. Also it is difficult to emphasize that the existing geometry, i.e. the 1.2 mm thick sandwich, can be of much use in large ship structures. If the thickness is increased to about 6 mm the usefulness will increase as the need of supporting stiffeners reduces to what is normal in ship structures. However, when it is to be used as part of a box beam or other structural composed structure the benefit reduces compared to aluminium. The comparison between aluminium and steel is known from other ship structural studies and shows that steel is usually beneficial for ships larger than about 100 m. The cost of aluminium is much higher and the benefit only shows up for extremely high speed ships. The report is written in Swedish with an English summary. The following conclusions are drawn in the project: 1. When different material systems are assessed it is demonstrated that most of the ships in the world are built in steel and steel is superior in most applications due to low cost and good structural behaviour. 2. For some very exclusive uses with requirements on high speed and low weight the cost preferences may give room for lightweight materials. Then there is competition from FRP and aluminium. 3. There is a potential for marginal use of the HSSA material within shipping, if a thicker panel is developed. The application may appear where low weight, vibration damping and corrosion resistance are highly valued. A continuation of this pre-project for marine applications must focus on a thicker (ca 6 mm) HSSA panel. The project was presented at Transportforum 2003 in Linköping and part of it at RoRo 2002 in Lübeck, Germany, and it was discussed at the Sixth In-ternational Conference on Sandwich Structures, 2003, Ft. Lauderdale, Florida USA.
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