Compressive behavior and failure mechanisms of freestanding and composite 3D graphitic foams

Fleck, NA; Nakanishi, K

Compressive behavior and failure mechanisms of freestanding and composite 3D graphitic foams

cam.issuedOnline	2018-08-09
dc.contributor.author	Fleck, NA
dc.contributor.author	Nakanishi, K
dc.contributor.orcid	Fleck, Norman [0000-0003-0224-1804]
dc.contributor.orcid	Nakanishi, Kenichi [0000-0003-3816-1806]
dc.date.accessioned	2018-11-10T00:30:20Z
dc.date.available	2018-11-10T00:30:20Z
dc.date.issued	2018-10-15
dc.description.abstract	Open-cell graphitic foams were fabricated by chemical vapor deposition using nickel templates and their compressive responses were measured over a range of relative densities. The mechanical response required an interpretation in terms of a hierarchical micromechanical model, spanning 3 distinct length scales. The power law scaling of elastic modulus and yield strength versus relative density suggests that the cell walls of the graphitic foam deform by bending. The length scale of the unit cell of the foam is set by the length of the struts comprising the cell wall, and is termed level I. The cell walls comprise hollow triangular tubes, and bending of these strut-like tubes involves axial stretching of the tube walls. This length scale is termed level II. In turn, the tube walls form a wavy stack of graphitic layers, and this waviness induces interlayer shear of the graphitic layers when the tube walls are subjected to axial stretch. The thickness of the tube wall defines the third length scale, termed level III. We show that the addition of a thin, flexible ceramic Al2O3 scaffold stiffens and strengthens the foam, yet preserves the power law scaling. The hierarchical model gives fresh insight into the mechanical properties of foams with cell walls made from emergent 2D layered solids.
dc.description.sponsorship	We acknowledge funding from EPSRC (Grant No. EP/K016636/1, GRAPHTED) and the ERC (Grant No. 279342, InsituNANO; Grant No. 669764, MULTILAT). A.I.A. acknowledges the 2014 Green Talents Research Stay program from The German Federal Ministry of Education and Research (BMBF) and the EU Marie Sklodowska-Curie (Grant No. 645725, FRIENDS2). K.N. acknowledges funding from the EPSRC Cambridge NanoDTC (Grant No. EP/G037221/1).
dc.identifier.doi	10.17863/CAM.32267
dc.identifier.eissn	1873-2453
dc.identifier.issn	1359-6454
dc.identifier.uri	https://www.repository.cam.ac.uk/handle/1810/284897
dc.publisher	Elsevier
dc.publisher.url	http://dx.doi.org/10.1016/j.actamat.2018.08.012
dc.subject	Cellular solids
dc.subject	Chemical vapor deposition (CVD)
dc.subject	Graphene
dc.subject	Micromechanical modeling
dc.subject	Structural hierarchy
dc.title	Compressive behavior and failure mechanisms of freestanding and composite 3D graphitic foams
dc.type	Article
dcterms.dateAccepted	2018-08-07
prism.endingPage	196
prism.publicationDate	2018
prism.publicationName	Acta Materialia
prism.startingPage	187
prism.volume	159
pubs.funder-project-id	EPSRC (1504244)
pubs.funder-project-id	European Commission Horizon 2020 (H2020) ERC (206409)
pubs.funder-project-id	European Research Council (279342)
pubs.funder-project-id	Engineering and Physical Sciences Research Council (EP/K016636/1)
pubs.funder-project-id	Engineering and Physical Sciences Research Council (EP/G037221/1)
rioxxterms.licenseref.startdate	2018-10-15
rioxxterms.licenseref.uri	http://www.rioxx.net/licenses/all-rights-reserved
rioxxterms.type	Journal Article/Review
rioxxterms.version	AM
rioxxterms.versionofrecord	10.1016/j.actamat.2018.08.012