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(Unpublished)
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Unpublished |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: |
|
| ETD Committee: |
|
| 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: |
13 Jun 2023 05:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/40576 |
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