Numerical modeling and analysis of laser-matter interactions in laser-based manufacturing and materials processing with short and ultrashort lasers

Benxin Wu, Purdue University

Abstract

Short and ultrashort-pulsed lasers (with the duration of ~10 nanosecond or even less) have been developing rapidly in recent years, for which many competitive applications have been found and explored, such as laser shock peening, pulsed laser ablation for micromachining, and thin film deposition, etc. Although a lot of research has been carried out in literature, the numerical modeling work is far from being sufficient for many laser-matter interaction processes that are important for laser-based manufacturing and materials processing. The following models, although very important for the investigations of laser-matter interactions and the relevant laser materials processing applications, have been rarely reported in literature, and have been developed and described in this dissertation: 1. A complete and self-closed model for laser shock peening. 2. A low-fluence nanosecond laser ablation model with both rigorous boundary conditions at the liquid-vapor interface and plasma formation considerations. 3. A one-dimensional hydrodynamic model for the early-stage evolution of high-fluecne laser-induced metal plasma in air. 4. A two-stage and self-closed model for high-fluence nanosecond laser-induced metal plasma in vacuum. The model can simulate both the early stage evolution and the long-term behavior of the laser-induced plasma. 5. A simplified model for ultrashort laser ablation that is easy to apply and computationally efficient, while can still reflect the dominant physics in the process and produce reasonably accurate predictions. The above developed models have been compared with experimental measurements, and the agreements are reasonably good compared with the typical accuracy of models in literature for short and ultrashort pulsed laser-matter interactions. Preliminary experimental work has also been performed for laser shock peening and picosecond laser micromachining using a developed nanosecond laser processing system and a picosecond laser processing system, respectively.

Degree

Ph.D.

Advisors

Shin, Purdue University.

Subject Area

Mechanics|Mechanical engineering|Plasma physics

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