Laser -assisted high precision bending and its applications
Abstract
Laser bending is a much more refined and controllable bending technique compared to conventional techniques. Laser bending has been applied to micro-scale bending in the microelectronics industry as well as large scale bending in automobile production due to its high levels of accuracy and reproducibility. In this dissertation, experimental techniques and numerical models are developed to study pulsed and CW laser microbending. The experimental set-up includes a laser beam delivery system, an optical system for bending angle measurement, and a 2-D optical scanner with a computer-based motion controller. Relationships between the bending angle and laser operating parameters are studied. Ceramic, silicon and stainless steel samples are chosen for the experiments. The bending results for the different materials are compared. Numerical calculations were performed using the finite element method to calculate the thermomechanical effect induced by laser irradiation and the resulting bending. An uncoupled thermo-mechanical FEA model for simulations of laser bending is discussed. Four laser bending simulations are presented in detail: 3D finite element analysis of pulsed laser bending, 2D finite element analysis of the effect of melting and solidification in pulsed laser bending, simulation of laser curvature adjustment of hard disk drive suspension, and simulation of microscale densification during femto-second laser processing of dielectric materials. During the research on laser high precision bending, it is found that our experimental techniques and fundamentals of the thermo-mechanical process involved can also be applied to many other areas of laser applications and nano-technology. For example, the technique of optical deflection measurement can be used to develop a microcantilever-based biosensor for biological molecular detection. By transplanting the optical deflection measuring technique, we show that it is possible to detect a cantilever deflection as small as 1 nm. Polymer materials are used to machine the microcantilevers, which are proven to be a cheaper and more sensitive alternative to the traditional material, i.e., silicon.
Degree
Ph.D.
Advisors
Xu, Purdue University.
Subject Area
Mechanical engineering|Industrial engineering
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