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dc.contributor.author
Türk, Daniel-Alexander
dc.contributor.supervisor
Meboldt, Mirko
dc.contributor.supervisor
Ermanni, Paolo
dc.contributor.supervisor
Pellegrino, Sergio
dc.date.accessioned
2017-11-06T06:39:01Z
dc.date.available
2017-11-04T13:20:14Z
dc.date.available
2017-11-06T06:39:01Z
dc.date.issued
2017
dc.identifier.uri
http://hdl.handle.net/20.500.11850/204591
dc.identifier.doi
10.3929/ethz-b-000204591
dc.description.abstract
This thesis presents and explores a set of novel approaches for the development of hybrid, integrated, lightweight, structures by combining additive manufacturing (AM) with fiber-reinforced polymers (FRP) in layup processes. The presented methods combine the strengths of both technologies: While AM takes a forming, structural and functional role, FRPs primarily contribute with their outstanding mechanical properties at low weight to the performance of the structure. From these characteristics three major design concepts are derived, including AM tooling for composite fabrication, AM structural sandwich cores with additional functionalities and AM load introduction elements. The understanding of materials and manufacturing approaches is a precondition for the embodiment of the design concepts. Therefore, various manufacturing routes are investigated including AM technologies such as fused deposition modeling, binder jetting and selective laser sintering. The thermo-mechanical stability of polymeric AM parts is crucial for autoclave curing of hybrid high-performance structures. To successfully design complex AM elements for the curing process of FRP, the thermo-mechanical creep properties of polymeric AM materials are characterized in three-point bending creep and tensile tests. Alternative concepts include sand and salt structures to produce sacrificial tooling. The embodiment of the three design concepts comprises two directions: designing for the performance of the part during service operation and designing to support the manufacturing of the structure. In this thesis both directions are addressed: Design for Performance: The specific mechanical performance of AM-CFRP structures is assessed in comparison to state-of-the Art structures by comparing the weight, the first failure load, the breaking load and the bending stiffness. Hat-stiffeners with structural cores made by AM were over-laminated with CFRP prepregs, cured in an autoclave and tested in three-point bending. AM core designs include honeycombs, trusses oriented along principal stresses, hollow structures filled with salt and a machined PMI foam core with a local load introduction element made by AM. AM-CFRP hat-stiffeners exhibit an increase in the specific fracture load ranging from 54% to 107% compared to the reference. Weights vary from an increase by up to 55% to a reduction of 5%, and the specific bending stiffness is increased by up to 41%. Results thereby confirm the mechanical competitiveness of AM-CFRP structures. Design for Processing: Additive manufacturing can support the production of composite parts along the process chain ranging from tooling, layup, handling, curing and post-processing. Four major design principles are presented and classified into integrated positioning and fixation elements, layup and handling aids, structural curing aids and post processing aids. Case studies show that the consideration of the processing during the design phase can reduce the deformation of the part during curing, the number of parts and the number of work steps and even eliminate drilling operations for the post-processing of inserts. The AM-CFRP approach is validated by incorporating the material data, the design principles and concepts into three components on system level. First, a novel aircraft instrument panel consisting of a multi-functional sandwich core shows that AM-CFRP can reduce the structural weight by 40%, the part count by 50% and the assembly steps by 50%. The second case study validates the mechanical performance of the AM-CFRP approach on component level by assessing the ultimate and the fatigue strength of a novel AM-CFRP prosthetic knee. The third case study consists of a robot leg structure and yields in weight reductions by 54% compared to state-of-the art references. The combination of AM with CFRP thus is a suitable approach for the manufacturing of individualized, lightweight, and geometrically-complex structures with integrated functionalities for low-volume applications, e.g. in the field of aerospace, flying vehicles, robotics and biomedical structures.
en_US
dc.language.iso
en
en_US
dc.publisher
ETH Zurich
en_US
dc.rights.uri
http://rightsstatements.org/page/InC-NC/1.0/
dc.subject
Additive manufacturing
en_US
dc.subject
Lightweight structures
en_US
dc.subject
Fiber reinforced polymers
en_US
dc.title
Exploration and validation of integrated lightweight structures with additive manufacturing and fiber-reinforced polymers
en_US
dc.type
Doctoral Thesis
dc.rights.license
In Copyright - Non-Commercial Use Permitted
dc.date.published
2017-11-06
ethz.size
232 p.
en_US
ethz.identifier.diss
24557
en_US
ethz.publication.place
Zurich
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02130 - Dep. Maschinenbau und Verfahrenstechnik / Dep. of Mechanical and Process Eng.::02665 - Inst. f. Design, Mat. und Fabrikation::03943 - Meboldt, Mirko / Meboldt, Mirko
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02130 - Dep. Maschinenbau und Verfahrenstechnik / Dep. of Mechanical and Process Eng.::02665 - Inst. f. Design, Mat. und Fabrikation::03943 - Meboldt, Mirko / Meboldt, Mirko
en_US
ethz.date.deposited
2017-11-04T13:20:17Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2017-11-06T06:40:55Z
ethz.rosetta.lastUpdated
2018-11-06T00:34:43Z
ethz.rosetta.exportRequired
true
ethz.rosetta.versionExported
true
ethz.COinS
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