Off-campus UMass Amherst users: To download campus access dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.
Non-UMass Amherst users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
Dissertations that have an embargo placed on them will not be available to anyone until the embargo expires.
ORCID
https://orcid.org/0000-0002-2922-672X
Access Type
Open Access Thesis
Document Type
thesis
Degree Program
Mechanical Engineering
Degree Type
Master of Science in Mechanical Engineering (M.S.M.E.)
Year Degree Awarded
2019
Month Degree Awarded
September
Abstract
In the laser-induced cavitation (LIC) technique, a vapor-gas cavity is generated in water, or a soft material by focusing an intense laser pulse into the sample. The high-strain-rate mechanical properties of these samples can be investigated through a real-time size measurement of the expanding cavity bubble. Although this LIC technique has been applied to multiple research fields such as mechanical, biological and medical areas. It is possible to simplify and improve this LIC method by introducing optical-fibers. In this approach, we propose to employ an optical-fiber to deliver the intense laser pulse to an arbitrary position of an optical opaque specimen. At the same time, we also attempt to generate LIC at one end of the optical-fiber. This optical-fiber based LIC is achieved by dip-coating of the laser absorbing film on the fiber end. Thus, the film can absorb the laser pulse and generate LIC within the sample.
In this study, the development of the coating material, the introduction of the optical-fiber into the existing LIC system, and the optical-fiber based LIC experiments are performed to characterize high-strain-rate mechanical properties of soft materials. We investigate the coating conditions and verify the consistency of the ablation based on the optimized coating materials. By conducting LIC experiments with gelatin samples, the feasibility of developed LIC method is investigated, LIC events are successfully formed at the fiber end which is inserted into the sample, and the rapid expanding dynamics are imaged with ultrafast stroboscopic microscopy. Using the multiple-exposure images, the expanding speeds and maximum cavity sizes are quantified to provide high-strain-rate characteristics of the soft materials. The inconsistency of the cavitation behavior resulted by the fluctuation of the coating condition and the high power intense laser conducting optical-fiber destruction can be improved by developing new coating method and new protective coating on the fiber end in the future.
DOI
https://doi.org/10.7275/15221121
First Advisor
Jae-Hwang Lee
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Feng, Qian, "Optical-Fiber-Based Laser-Induced Cavitation for Dynamic Mechanical Characterization of Soft Materials" (2019). Masters Theses. 830.
https://doi.org/10.7275/15221121
https://scholarworks.umass.edu/masters_theses_2/830