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In-Situ Ultrasonic Monitoring for Viscoelastic Properties of Being-printed Part during Digital Light Processing based Photopolymer Additive Manufacturing

Su, Tong (2021) In-Situ Ultrasonic Monitoring for Viscoelastic Properties of Being-printed Part during Digital Light Processing based Photopolymer Additive Manufacturing. Master's Thesis, University of Pittsburgh. (Unpublished)

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Abstract

Photopolymer additive manufacturing (PAM) processes such as Stereolithography (SLA)
and Digital Light Processing (DLP) employ photopolymerization reactions to crosslink monomers
layer by layer under light exposure schemes corresponding to the cross-sections of a target object.
Such processes have been widely used in various applications, from rapid prototyping to
biomedical implants, soft robotics, and flexible electronics. In-situ process monitoring is critical
for process optimization and control to achieve precise structures and desired properties via PAM.
As existing research focuses on the online measurement of part geometry, there lack in-situ
monitoring technologies to obtain real-time information about the material properties of PAM
printed parts, especially the viscoelastic properties that will affect the stress-strain and deformation
behaviors of curing and cured parts. This work develops the first-ever in-situ ultrasonic
measurement (IUM) method, cost-effective and non-destructive, for DLP process monitoring.
Experimental study is performed for monitoring a variety of process conditions (i.e., exposure
time, intensity, layer thickness, and build stage speed) to exemplify that the developed IUM
method based on ultrasonic longitudinal wave sensing can probe the evolving Young’s modulus,
viscoelastic damping ratio, and loss factor of a being-printed part. Standard measurement and
nanoindentation testing results are obtained offline to validate the IUM results. This novel IUM
method will offer unique insights into process-property relationships for PAM processes modeling
and real-time feedback control, facilitating 3D and 4D printing of sophisticated products such as
soft robots that require localized manipulation of mechanical properties.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Su, Tongtos28@pitt.edutos28
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Thesis AdvisorZhao, Xiayunxiayun.zhao@pitt.edu
Committee MemberWang, Qing-Mingqiw4@pitt.edu
Committee MemberJacobs, Tevistjacobs@pitt.edu
Date: 13 June 2021
Date Type: Publication
Defense Date: 6 April 2021
Approval Date: 13 June 2021
Submission Date: 8 April 2021
Access Restriction: 2 year -- Restrict access to University of Pittsburgh for a period of 2 years.
Number of Pages: 98
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Mechanical Engineering
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: Additive Manufacturing, Viscoelastic, In-situ Monitoring
Date Deposited: 13 Jun 2021 18:52
Last Modified: 21 Jun 2021 11:38
URI: http://d-scholarship.pitt.edu/id/eprint/40576

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