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Surface Wrinkling Based Method of Measuring Thin Film’s Mechanical Properties

Niu, Jiani (2012) Surface Wrinkling Based Method of Measuring Thin Film’s Mechanical Properties. Master's Thesis, University of Pittsburgh. (Unpublished)

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The main goal of this project is to develop a wrinkle-based method to measure mechanical properties of thin interfacial polymeric films. Instead of working on a mechanically equilibrium system, this study is focusing on the case where mechanical equilibrium is hard to reach due to the very high viscosity of the bulk phases.
This thesis describes an air/viscous polymer system with a few-micron scale thick polymer film placed at the interface. We have developed a method to generate dynamic wrinkle patterns on the film via compressing the high viscous substrate. Two experiment parameters are controlled: the substrate thickness H and the compressing strain rateε ̇. This thesis developed an accurate method to measure H while avoiding the interference from the edge effect of the fluid. The compressing strain rate is calculated upon a Matlab program.
We report the value of wrinkle number under different compressing strain rate and different substrate thickness. Critical strains under different compression strain rate and substrate thickness has been obtained via analyzing the strain for the onset wrinkle.
We normalize the wrinkle number as well as the compressing strain rate in order to compare them with previous works. With dimensional analysis, a power law relation has been demonstrated between normalized wrinkle number and normalized strain rate.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairVelankar, Sachin velankar@pitt.eduVELANKAR
Committee MemberVeser, Götzgveser@pitt.eduGVESER
Committee MemberLi, Lei LEL55
Thesis AdvisorVelankar, Sachin velankar@pitt.eduVELANKAR
Date: 26 September 2012
Date Type: Publication
Defense Date: 23 July 2012
Approval Date: 26 September 2012
Submission Date: 20 July 2012
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 82
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Chemical Engineering
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: wrinkling based measurement thin film properties
Date Deposited: 26 Sep 2012 13:50
Last Modified: 15 Nov 2016 14:00

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