THREE-DIMENSIONAL MICROFABRICATION OF MECHANICAL METAMATERIALS VIA STEREOLITHOGRAPHY AND TWO-PHOTON POLYMERIZATION
With the advent of femtosecond lasers in the early 1990s, ultrafast laser processing has proven to be an imperative tool for micro/nanomachining. Two-photon lithography (TPL) is one such unique microfabrication technique exploiting the nonlinear dependency of the polymerization rate on the irradiating light intensity to produce true three-dimensional structures with feature sizes beyond the diffraction limit. This characteristic has revolutionized laser material processing for the fabrication of micro and nanostructures. This research first gives a general overview of TPL, including its operating principle, experimental setup, compatible materials, and techniques for improving the final resolution of the fabricated structure. Insights to improve throughput and speed of fabrication to pave a way for the industrialization of this technique are provided.
Following that, the report delves into the process of fabricating two true three-dimensional mechanical metamaterials via the stereolithography technique. This chapter encompasses the design, fabrication, and experimental analysis of a three-dimensional axisymmetric structure with elliptical perforations distributed periodically on the walls of the structure with varying thicknesses. Furthermore, this study discusses the significance of the elliptical perforations in terms of auxetic behavior and load-bearing capacity against a so-called plain structure under quasistatic compression loading.
Finally, the report explores the technique of fabricating a true three-dimensional cylindrical auxetic structure via two-photon polymerization. This section of the report examines the optical setup utilized, the sample preparation procedure, and calibration experiments performed in order to fabricate a three-dimensional thin-walled right cylinder with bowtie like perforations arranged on the walls to promote the exhibition of symmetric negative Poisson’s ratio under uniaxial quasistatic compression loading.
- Master of Science
- Mechanical Engineering
- West Lafayette