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Framework for cost and weight efficient conceptual design of automotive composite body structures
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.ORCID iD: 0000-0002-1224-3662
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The automotive industry is facing a great challenge - reducing the weight of their vehicles. Carbon fibre composites are regarded by many as the only real option as traditional engineering materials are now running out of potential for further weight reduction. In this doctoral thesis a framework is presented which will provide guidelines for the conceptual phase of the development of an automotive composite body structure. The framework is initiated by defining ideal material diversity, as well as initial partition of the body structure based on process and material selection. Then, a further analysis of the structures is made in order to evaluate whether a more cost efficient solution can be found by further dividing the structure. Such a differential design approach is analysed in the third part of the work, studying both the financial and structural effects of such partitioning. In order to increase the understanding of the intimate relationship between design, material and manufacturing process, balancing manufacturing and structural optimization is addressed. Finally, drape simulation tools are used to assess the geometric complexity of composite structures in order to further quantify suitable split lines in cases of differential design approach.

Different carbon fibre composite material systems and processes are compared and evaluated in the work. The results show that a high-performance material system with continuous fibres is both more cost and performance effective as compared to industrialised, discontinuous fibre composites. Further analysis shows the importance of balancing the design for manufacturing and the structural weight optimization of the structures in order to reach a cost and weight effective design. When restricting composite design freedom with manufacturing constraints, the great benefits of structural composites disappear and with this both weight and cost effectiveness.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2016. , 52 p.
Series
TRITA-AVE, ISSN 1651-7660 ; 2016:18
Keyword [en]
composites automotive cost weight body structure
National Category
Aerospace Engineering
Research subject
Aerospace Engineering; Fibre and Polymer Science; Transport Science
Identifiers
URN: urn:nbn:se:kth:diva-185213ISBN: 978-91-7595-944-3 (print)OAI: oai:DiVA.org:kth-185213DiVA: diva2:919287
Public defence
2016-06-03, Sal E3, Osquars backe 14, KTH-Campus, Stockholm, 10:15 (English)
Opponent
Supervisors
Note

QC 20160418

Available from: 2016-04-18 Created: 2016-04-13 Last updated: 2016-05-16Bibliographically approved
List of papers
1. Method for cost and weight-efficient material diversity and partitioning of a carbon fibre composite body structure
Open this publication in new window or tab >>Method for cost and weight-efficient material diversity and partitioning of a carbon fibre composite body structure
2015 (English)In: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering, ISSN 0954-4070, E-ISSN 2041-2991Article in journal (Refereed) Published
Abstract [en]

A method for the early concept phase is proposed, which is aimed at limiting the financial and performance-related riskswhen designing a carbon fibre composite automotive body structure. The method manages the structural requirementsimposed on the complete body structure and analyses the suitability of different carbon fibre material systems and pro-cesses. It also studies whether a high level of material diversity is desirable and the way in which to identify the optimalpartition of the body structure from a material system and manufacturing process selection point of view. Furthermore,since composite materials include both laminated materials and quasi-isotropic materials, an approach is presented thatenables the comparison of these materials variants during conceptual material selection. A case study exemplifies themethod and the results show that, in spite of the cost-sensitive nature of the automotive industry, utilization of the max-imum performance of these expensive composite materials is more important than efforts to achieve a rapid manufac-turing process.

Place, publisher, year, edition, pages
Sage Publications, 2015
Keyword
Concept phase, diversity of automotive material, body structure, material selection, process selection, structural composites
National Category
Composite Science and Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-145713 (URN)10.1177/0954407015578037 (DOI)000367381700004 ()2-s2.0-84951936233 (Scopus ID)
Funder
XPRES - Initiative for excellence in production research
Note

QC 20150623

Available from: 2014-05-27 Created: 2014-05-27 Last updated: 2017-12-05Bibliographically approved
2. Integral versus differential design for high-volume manufacturing of composite structures
Open this publication in new window or tab >>Integral versus differential design for high-volume manufacturing of composite structures
2015 (English)In: Journal of composite materials, ISSN 0021-9983, E-ISSN 1530-793X, Vol. 49, no 23, 2897-2908 p.Article in journal (Refereed) Published
Abstract [en]

In order to decrease the weight of the automotive body structure and increase the energy efficiency of future cars, attention is now turning towards structural composites, mainly carbon fibre-reinforced plastics. Composites have several advantages such as their excellent weight-specific properties and the possibility to be manufactured in large integral designs for a reduced weight and potentially lower cost. However, carbon fibre composites are expensive and for a cost sensitive industry such as the automotive industry, the challenge lies in creating a favourable business case with a well-balanced trade-off between weight and cost. A method is proposed to visualise the cost and weight advantages of either pursuing an integral design or a differential design, i.e. dividing the structure into a greater number of parts that are later assembled. The method focuses on the impact on cost and weight and considers structures with different part sizes and geometrical complexities. It is shown that, depending on the manufacturing process and series volume, larger and more complex parts may become more cost effective when divided into several, later-joined sub-parts. However, for smaller and/or less complex shapes, an integral design solution is always the best choice.

Place, publisher, year, edition, pages
Sage Publications, 2015
Keyword
Composites, automotive, manufacturing, partition, design
National Category
Composite Science and Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-145714 (URN)10.1177/0021998314557684 (DOI)000360851800007 ()2-s2.0-84941136175 (Scopus ID)
Funder
XPRES - Initiative for excellence in production research
Note

QC 20150004

Available from: 2014-05-27 Created: 2014-05-27 Last updated: 2017-12-05Bibliographically approved
3. Cost and weight efficient partitioning of composite automotive structures
Open this publication in new window or tab >>Cost and weight efficient partitioning of composite automotive structures
2015 (English)In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569Article in journal (Refereed) Published
Abstract [en]

To make carbon fiber composites not only weight but also cost effective in high volume production the different cost drivers need to be addressed and new design philosophies considered. This study analyzes integral and differential design approaches when partitioning large complex composite structures. The influence of different partition philosophies are investigated based on a framework of composites manufacturing cost modelling and structural optimization and the effects are exemplified by a case study. The results show that depending on how the partitioning is made the structural performance and the manufacturing cost is affected. More particularly, if the partitioning is made with the most beneficial philosophy differential designs can improve both these important parameters.

Place, publisher, year, edition, pages
John Wiley & Sons, 2015
Keyword
Carbon, Carbon fibers, Cost effectiveness, Manufacture, Philosophical aspects, Structural optimization, Automotive structures, Carbon fiber composite, Complex composite structures, Composites manufacturing, Differential designs, High-volume production, Manufacturing cost, Structural performance, Costs
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-177772 (URN)10.1002/pc.23795 (DOI)000367381700004 ()2-s2.0-84941710327 (Scopus ID)
Funder
XPRES - Initiative for excellence in production research
Note

QC 20151127

Available from: 2015-11-27 Created: 2015-11-25 Last updated: 2017-11-14Bibliographically approved
4. Effects of manufacturing constraints on the cost and weight efficiency of integral and differential automotive composite structures
Open this publication in new window or tab >>Effects of manufacturing constraints on the cost and weight efficiency of integral and differential automotive composite structures
2015 (English)In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 134, 572-578 p.Article in journal (Refereed) Published
Abstract [en]

The introduction of carbon fibre composites into the high volume automotive sector challenges the design process, since these components not only need to be light but also producible in a cost-efficient manner. One way forward is to introduce manufacturing constraints into the design process, but such constraints affect the freedom of design and opportunities to tailor material properties. This work examines the trade-offs between cost-effective design for manufacturing and the weight optimization of composite structures. This will be achieved by introducing restrictions to the number of plies allowed in structural optimization in order to simplify pre-operations and reduce overall manufacturing investments. Both integral and differential design solutions are considered. It was observed that differential solutions were always more cost and weight efficient than the integral solution, however too severe manufacturing constraints result in an expensive final part due to the additional weight.

Place, publisher, year, edition, pages
Elsevier, 2015
Keyword
Manufacturing constraints, Weight optimization, Composites, Automotive, Multi objective optimization, Cost
National Category
Materials Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-177932 (URN)10.1016/j.compstruct.2015.08.115 (DOI)000363831900058 ()2-s2.0-84941565152 (Scopus ID)
Funder
XPRES - Initiative for excellence in production research
Note

QC 20151203

Available from: 2015-12-03 Created: 2015-11-30 Last updated: 2017-12-01Bibliographically approved
5. Draping simulation supported framework for cost and weight effective composite design
Open this publication in new window or tab >>Draping simulation supported framework for cost and weight effective composite design
(English)Manuscript (preprint) (Other academic)
Keyword
composite weight cost draping
National Category
Aerospace Engineering
Identifiers
urn:nbn:se:kth:diva-185220 (URN)
Note

QS 2016

Available from: 2016-04-13 Created: 2016-04-13 Last updated: 2016-04-19Bibliographically approved

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