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From aviation to automotive - a study on material selection and its implication on cost and weight efficient structural composite and sandwich designs
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.ORCID iD: 0000-0001-6729-8604
Volvo Car Corporation.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. Saab AB.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.ORCID iD: 0000-0002-6616-2964
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The structural design of composite materials is often challenging as its driven by a trade-off between lightweight structural performance and production costs. Addressing this design trade-off, this paper presents a methodology and case study that compares the weight- and production cost-potential of different composite materials and structural designs solutions through the use of a proposed application-bound design cost. Representative design solutions; monolithic, u-beam-, sandwich-insert- and sandwich-stiffened, are each optimized with respect to bending and torsional stiffness of increased severity to chart an extrapolated application map with respect to cost and stiffness. Optimized sandwich designs are shown to have lowest design cost where full stiffness is achieved. Alternative fibre materials researched; glass fibre, recycled carbon fibre, lignin-based fibres and hemp fibres, all reduce costs but at compromised stiffness. Ultimately, the case study demonstrates the impact of early design and material selection and justifies introducing novel fibre systems to reduce design cost.

Keywords [en]
Carbon fibres; Sandwich structures; Natural fibres; Recycled carbon fibres
National Category
Vehicle Engineering Composite Science and Engineering
Identifiers
URN: urn:nbn:se:kth:diva-244384OAI: oai:DiVA.org:kth-244384DiVA, id: diva2:1290200
Funder
XPRES - Initiative for excellence in production research
Note

QC 20190220

Available from: 2019-02-20 Created: 2019-02-20 Last updated: 2019-02-20Bibliographically approved
In thesis
1. Technical cost modelling and efficient design of lightweight composites in structural applications
Open this publication in new window or tab >>Technical cost modelling and efficient design of lightweight composites in structural applications
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A lightweight transport design reduces fuel costs and emissions and can be achieved through the use of fibre-reinforced composite materials. Although lightweight, the composite raw material can be expensive and the sequential component production challenging and costly. To design weight- and cost-efficient composite structures and find ways to reduce production costs, technical cost modelling must be applied. In this thesis, a technical cost model for composite manufacture, assembly and basic inspection is proposed and implemented to identify cost drivers, evaluate trending design strategies and suggest appropriate composite design guidelines for transport and aeronautical applications. 

Among identified cost drivers, material costs dominates at 50-90 % of the total part cost also for low annual volumes. Tooling costs are second in importance for slow processes and large parts while the importance of investment and labour depends on degree of automation. Part integration is shown to only marginally reduce cost. Traditional composite assembly is in turn found to potentially reduce costs by 30 % through the elimination of non-value-adding processes such as shimming and part positioning. In comparison to part integration, sandwich design exhibits superior cost- and weight-efficiency for low-to-intermediate stiffness levels. Moreover, the industry impact of a sustainable, circular recycling flow of composite materials is estimated and shown to give up to halved raw material costs as well as cost returns also for virgin carbon fibre users. Low-cost fibres such as glass, lignin-based carbon, hemp and recycled carbon fibres are found to be highly cost-competitive also for structural adaptions.

The technical cost model, method and results presented in this thesis provide important composite design conclusions and a foundation for further modelling work needed to reach that elusive weight- and cost-optimal composite design.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. p. 62
Series
TRITA-SCI-FOU ; 2019:9
Keywords
Technical cost modelling; composite materials; carbon fibre; lightweight design; optimization
National Category
Vehicle Engineering Composite Science and Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-244386 (URN)978-91-7873-104-6 (ISBN)
Public defence
2019-03-14, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:15 (English)
Opponent
Supervisors
Funder
EU, FP7, Seventh Framework Programme, 314003XPRES - Initiative for excellence in production research
Note

QC 20190220

Available from: 2019-02-20 Created: 2019-02-20 Last updated: 2019-02-20Bibliographically approved

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Karlsson Hagnell, MathildaNyman, TonnyÅkermo, Malin

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