Thesis Defence: A Novel Application of Schlieren Imaging: Leakage Localization in Composite Manufacturing Vacuum Bags

Brett Cosco, supervised by Dr. Homayoun Najjaran, will defend their dissertation titled “A Novel Application of Schlieren Imaging: Leakage Localization in Composite Manufacturing Vacuum Bags” in partial fulfillment of the requirements for the degree of Master of Applied Science in Mechanical Engineering.

An abstract for Brett’s thesis is included below.

Examinations are open to all members of the campus community as well as the general public.

Please email homayoun.najjaran@ubc.ca to receive the zoom link for this defence.

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ABSTRACT

Schlieren imaging is an imaging technique brought to prominence in 1864, still in use today. Schlieren imaging allows for density variations in transparent mediums to be visualized. This technique has been used to study subjects such as supersonic motion in aerospace applications, as well as visualizing airflow in speech. Despite the diversity in application and reference to its use as a leak localization tool, there is no literary support for its use localizing leakages in composite manufacturing vacuum bags. The purpose of this study is to explore an alternative means for definitively locating leakages in composite manufacturing vacuum bags. An introduction to vacuum bag based composite manufacturing and the importance of leakage localization is provided. Furthermore, a novel method of leakage localization in vacuum bags premised on the use of Schlieren imaging is the main scope of this thesis. The standard methods of leakage detection and localization are discussed and analyzed. The analysis culminates in the identification of the need for a noninvasive, quick, and definitive method of leakage localization. Research around methods of detection satisfying these criteria led to the hypothesis that Schlieren imaging is capable of visualizing flow into a leakage allowing for definitive localization. The process of testing this hypothesis is documented, including the construction of a Schlieren system and the experimentation conducted. An analysis of the data recorded during the experiments demonstrates the ability for Schlieren imaging to visualize flow entering a vacuum bag at a leak.