Nonlinear viscoelastic materials : bioinspired applications and new characterization measures

Viscoelastic materials, such as biomaterials and non-Newtonian fluids, typically experience mechanical loading which evokes a nonlinear rheological response. Rheologically complex materials can provide novel functionality in biological and engineered systems. However, it is found that standard characterization techniques are insufficient to appropriately describe nonlinear viscoelasticity. The goal of this thesis is to transcend the limitations of current characterization methods as well as demonstrate applications of nonlinear viscoelastic materials, including reversible adhesion and snail-like wall climbing. PART ONE of this thesis introduces a complete language and framework (or ontology) for characterizing nonlinear viscoelasticity using large amplitude oscillatory shear (LAOS) deformation. The LAOS protocol spans the 2D parameter space of deformation amplitude and frequency, known as a Pipkin space. Physically meaningful material measures are proposed, corresponding to clearly defined language such as strain-stiffening/softening and shear-thickening/thinning. The new ontology is general enough to be applied to any viscoelastic material, mapping behaviors from purely elastic to purely viscous, and any complex response in-between. The framework has been packaged into a distributable data analysis program (MITlaos) to widen its use in both academic and industrial settings. PART TWO examines the nonlinear rheological response of various soft materials and constitutive models.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Ewoldt, Randy H. (Randy Harold)

Advisor dc:contributor.advisor

• Gareth H. McKinley and Anette E. Hosoi.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/49556

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/49556