Micro Manufacturing Colloquium - 16 December 2021

Join us at 16:45 Central European Time (7:45 am Pacific Standard Time) on December 16, 2021 via Zoom link: https://uci.zoom.us/j/97774757269

Aditya Nagaraj

Department of Mechanical Engineering

University of Wisconsin-Madison

Aditya Nagaraj is a Ph.D. candidate in the Department of Mechanical Engineering, University of Wisconsin-Madison, Wisconsin, United States. His research interests include ultra-precision machining of single crystalline ceramics, residual stresses, and subsurface damage formation during machining.

STUDY ON ANISOTROPY IN SUBSURFACE DAMAGE AND RESIDUAL STRESSES IN MACHINED SAPPHIRE

Single crystalline sapphire is a promising material for use in various applications due to its superior performance under harsh environments. However, processing ceramics such as sapphire is challenging due to pronounced brittleness, crystal anisotropy and subsurface damage that builds up with each machining operation. Due to crystalline attributes of single crystal sapphire, the residual stress and subsurface damage is hypothesized to be anisotropic and dependent on machining parameters such as cutting direction. This study tests the hypothesis through spectroscopic evaluation of ultra-precision machined sapphire substrates in different cutting directions and a slip-fracture activation model is used to explain the observations.

Vishnu Narayanan S

Department of Mechanical Engineering

IIT Bombay

Vishnu Narayanan S is a Ph.D. researcher in the Department of Mechanical Engineering, IIT Bombay. His work mainly involves experimental and numerical investigations to understand the fundamental mechanisms involved in the laser rust removal process. His work has been presented at various international conferences and published in renowned journals.

COMPUTATIONAL MODELLING TO PREDICT SURFACE TOPOGRAPHY DURING PULSED LASER PROCESSING

Laser surface processing is a versatile non-conventional manufacturing process that is widely used in many industries for applications such as cleaning, engraving, surface treatment, etc. Surfaces processed by scanning with a pulsed laser have an inherent roughness due to the partial overlap of discreet pulses and the surface roughness has to be kept in check for many applications. Experimentally optimizing the parameters to minimize roughness is challenging because of the time and effort required.

In this talk, the development of a physics-based computational model, to predict surface topography when a pulsed laser is scanned over a surface will be discussed. The model solves the fundamental governing equations of heat flow and fluid dynamics, captures the effect of laser ablation and dynamics of the melt pool, and the effect of overlapping of individual pulses during laser scanning.

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