Spherical nanoindentation protocols for extracting microscale mechanical properties in viscoelastic materials

Abba, Mohammed Tahir

Title:

Spherical nanoindentation protocols for extracting microscale mechanical properties in viscoelastic materials

dc.contributor.advisor	Kalidindi, Surya R.
dc.contributor.author	Abba, Mohammed Tahir
dc.contributor.committeeMember	Zhou, Min
dc.contributor.committeeMember	Gall, Ken
dc.contributor.committeeMember	Wegst, Ulrike G. K.
dc.contributor.committeeMember	Jacob, Karl I.
dc.contributor.department	Mechanical Engineering
dc.date.accessioned	2016-01-07T17:23:37Z
dc.date.available	2016-01-07T17:23:37Z
dc.date.created	2015-12
dc.date.issued	2015-08-25
dc.date.submitted	December 2015
dc.date.updated	2016-01-07T17:23:37Z
dc.description.abstract	Nanoindentation has a high load resolution, depth sensing capabilities, and can be used to characterize the local mechanical behavior in material systems with heterogeneous microstructures. Recently nanoindentation has been used to extract useful stress-strain curves, primarily in hard materials such as metals and ceramics. To apply these indentation stress-strain methods to polymer composites, we have to first develop analysis techniques for materials that exhibit viscoelasticity. In a lot of current research the viscoelastic material properties are extracted after the material has been deformed enough to initiate plasticity and in some cases the time dependence of the deformation is ignored. This doesn’t give an accurate representation of the material properties of the undeformed sample or the local deformation behavior of the material. This dissertation develops analysis protocols to extract stress-strain curves and viscoelastic properties from the load-displacement data generated from spherical nanoindentation on materials exhibiting time-dependent response at room temperature. Once these protocols are developed they can then be applied, in the future, to study viscoelastic and viscoplastic properties of various mesoscale constituents of composite material systems. These new protocols were developed and tested on polymethyl methacrylate, polycarbonate, low-density polyethylene, and the bio-polymer chitosan. The properties extracted were consistent under different conditions and we were able to produce stress-strain curves for different loading rates and different indenter tip sizes. This dissertation demonstrates that a set of protocols can be used to reliably investigate the mechanical properties and deformation behavior of time-dependent materials using nanoindentation.
dc.description.degree	Ph.D.
dc.format.mimetype	application/pdf
dc.identifier.uri	http://hdl.handle.net/1853/54359
dc.language.iso	en_US
dc.publisher	Georgia Institute of Technology
dc.subject	Nanoindentation
dc.subject	Viscoelastic
dc.subject	Polymers
dc.subject	Stress-strain
dc.subject	Mechanical properties
dc.title	Spherical nanoindentation protocols for extracting microscale mechanical properties in viscoelastic materials
dc.type	Text
dc.type.genre	Dissertation
dspace.entity.type	Publication
local.contributor.advisor	Kalidindi, Surya R.
local.contributor.corporatename	George W. Woodruff School of Mechanical Engineering
local.contributor.corporatename	College of Engineering
relation.isAdvisorOfPublication	e5ad79b6-4761-4f35-86c3-0890d432fe44
relation.isOrgUnitOfPublication	c01ff908-c25f-439b-bf10-a074ed886bb7
relation.isOrgUnitOfPublication	7c022d60-21d5-497c-b552-95e489a06569
thesis.degree.level	Doctoral