About me

I am an assistant professor in the Department of Mechanical and Industrial Engineering at the University of Iowa, Iowa City. My research interests are: manufacturing process modeling, hybrid machining, laser-based material processing, and micro/nano materials processing, etc.

Click HERE to know more about my research.

Click HERE to my lab website.

I received the ASME Best Paper Award at MSEC2011(the 6th ASME 2011 International Manufacturing Science and Engineering Conference) in Corvallis, Oregon, for the paper entitled "Dislocation density-based grain refinement modeling of orthogonal cutting of commercially pure titanium". It was selected out of more than 200 papers. Video

One of my recent papers on micromachining titled "Thermal and mechanical modeling analysis of laser-assisted micro-milling of difficult-to-machine alloys" is the most downloaded paper in the Journal of Materials Processing Technology. Video

My PhD advisor is professor Yung C. Shin at Purdue University.

Professional activities

Associate Editor for the International Journal of Materials Forming and Machining Processes.

Editorial Board Member for the Journal of Applied Mechanical Engineering.

Symposium Organizer for the ASME International Manufacturing Science and Engineering Conference (MSEC2013, MSEC2014).

Research

Click HERE to know more about my research.

One of my primary research interests is to experimental analysis and predictive modeling of nanocrystalline microstructures in metallic materials undergoing cutting and other severe plastic deformation (SPD) processes, such as cold rolling and laser shock peening. To quantitatively predict the microstructural evolution in workpiece materials, I have developed a dislocation density-based numerical framework to simulate the change of grain size, grain misorientation and material strengthening mechanisms during cutting and other SPD processes. The models developed in these studies are among the first quantitative predictive models in their relevant fields and agree well with experimental measurements. These models can effectively help study, design and optimize the relevant materials processing and other manufacturing processes, which include, but are not limited to, large strain cutting, hard machining, LAM, multi-pass cold rolling, laser shock peening and other SPD processes. For the excellence of this work, I received the ASME Best Paper Award at the 6th ASME 2011 International Manufacturing Science and Engineering Conference (MSEC2011) in Corvallis, Oregon, in June 2011 for the paper entitled "Dislocation density-based grain refinement modeling of orthogonal cutting of commercially pure titanium". It was selected out of more than 180 papers in the manufacturing area.

My current research project is geared toward modeling phase transformation for machining steels using a metallo-thermo-mechanical coupled material model. I have developed a numerical framework to model phase transformation, heat transfer and plastic deformation in the cutting of steels, which solves for cutting temperature, phase composition, chip morphology, and cutting force simultaneously by considering the thermo-mechanical properties and constitutive models of constituent phases such as ferrite, pearlite, austenite and martensite. The model will be a useful numerical tool in analyzing surface integrity issues like residual stress and white layer that are developed in hard machining, thermally enhanced machining and high speed machining.

My Ph.D. research is concerned with the experimental investigation and numerical modeling of laser-assisted machining (LAM) and micromachining processes of difficult-to-machine materials. LAM is a viable industrial option for precision machining of unmachinable ceramics and difficult-to-machine metal alloys. As an innovative alternative, LAM can replace grinding in semi-finishing and finishing processes, which greatly reduces the cost, consumes less energy, and eliminates the need for coolant. At Purdue University, I have conducted many projects for industries to help them design, setup, and optimize LAM processes for a variety of difficult-to-machine materials. Precise temperature control is the key for LAM. To achieve this goal, I have developed 3D finite volume heat transfer models using FORTRAN for various LAM processes such as facing, profile turning, and boring, to accurately predict the temperature field in the workpiece during the operation.

To analyze the surface defects caused by the size effect in micromachining using conventional micro tools, I have developed a novel finite element model with a strain gradient plasticity analysis to simulate the continuous chip formation for a complete micromilling cycle using Abaqus Explicit. My model was able to predict the steady-state tool and workpiece cutting temperatures in micromilling and laser-assisted micro milling. It was shown to be a useful tool in predicting size effect, tool wear, and surface integrity issues in micromachining.

Teaching

Along with research, teaching has been integral to my graduate training, and I have taught a variety of subjects to diverse groups of students. For my excellent academic and research record, I have been awarded the Lambert Teaching Fellowship from Purdue University. Currently I am teaching a core mechanical engineering course, ME365 "Measurement Systems", as the course instructor.

I have been a teaching assistant for the labs of ME576 "Computer Control and Manufacturing Processes" and ME363 "Principles and Practice of Manufacturing Processes". In these courses, I taught students experimental and technical skills. I also taught calculus and ordinary differential equations as a recitation instructor in the Department of Mathematics, so I am familiar with instructing students in purely analytical concepts. Student evaluations have been consistently surpassing 4.6 out of 5, stressing my knowledge of the material, accessibility and effectiveness in teaching. Through my five years of service as a teaching assistant both in ME and MATH departments, I have forged relationships with a broad range of faculty members and gained cross-disciplinary experiences in manufacturing science, mechanics of materials, computer control and mathematics.

Awards

Old Gold Fellowship, University of Iowa, Summer 2014

NSF Summer Institute Fellowship for Additive Manufacturing, Summer 2013

Poster Award Honorable Mention, "Laser peening and surface enhancement of wind turbine components," 2013 Annual Iowa Wind Energy Association (IWEA) Wind Conference, Des Moines, Iowa, USA, March 25-27, 2013.

Poster Award Honorable Mention, "Laser assisted machining and hardening of wind turbine components," 2013 Annual Iowa Wind Energy Association (IWEA) Wind Conference, Des Moines, Iowa, USA, March 25-27, 2013.

ASME Best Paper Award

I received the Best Paper Award at ASME/MSEC2011 (the 6th ASME 2011 International Manufacturing Science and Engineering Conference) in Corvallis, Oregon, for the paper entitled "Dislocation density-based grain refinement modeling of orthogonal cutting of commercially pure titanium". It was selected out of more than 200 papers.

Purdue Summer Research Grant

I have been awarded a 2011 Summer Research Grant for my thesis research support from Purdue Univeristy.

Lambert Teaching Fellowship

I have been awarded Lambert Teaching Fellowship from Purdue University.