Publication Date
2023
Document Type
Dissertation/Thesis
First Advisor
Gau, Jenn-Terng
Degree Name
M.S. (Master of Science)
Legacy Department
Department of Mechanical Engineering
Abstract
Stainless steel micro channels have received a lot of intrigue for a variety of applications such as fuel cell bipolar plates, or parts in medical devices, refrigeration cooling, and hydrogen storage to name a few. It is desired to have the channels with a large depth/width ratio and extremely thin thickness (100µm or less) while the width is 2mm or less and pitch is 4mm or less. In this study, stainless steel 304 (SS304L) foil with thickness of 100 µm was used for a series of multistage micro channel forming experiments. Simultaneously, LS-Dyna was employed to simulate the process and determine which material model would result in optimal predictions for the experimental data in terms of deformation geometry and thickness distributions. To evaluate the strain on a microscopic scale, the clean room semiconductor procedures of photolithography were modified to print a circular microgrid (⌀20µm) onto the specimen and their deformation was evaluated after testing. This deformation analysis involved taking images of the failure region using a tabletop SEM and then measuring the major and minor true strains of the effected grids near the crack to find the plane strain forming limit FLC₀. This is the value that is frequently used in manufacturing today to determine formability as it is typically the lowest point of a forming limit curve and thus the safest selection for punch depth. From the experimental deformation results, coupled with LS-Dyna simulation results, a multistage forming process was developed to achieve maximum depth/width ratio. The 2-hit forming processes with an 85% or 90% preform punch were determined to provide the best results experimentally and numerically.
Recommended Citation
Callahan, Levee, "Numerical and Experimental Study on a Multistage Process for Micro Channel Forming" (2023). Graduate Research Theses & Dissertations. 7816.
https://huskiecommons.lib.niu.edu/allgraduate-thesesdissertations/7816
Extent
95 pages
Language
en
Publisher
Northern Illinois University
Rights Statement
In Copyright
Rights Statement 2
NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.
Media Type
Text
