Dr. Steven Liang

 

   Contact Information

     MARC, Room 458
     steven.liang@me.gatech.edu
     T: 404-894-8164

 

Morris M. Bryan, Jr. Professorship in Mechanical Engineering for Advanced Manufacturing Systems

Education

Ph.D., University of California, Berkeley, 1987
M.S., Michigan State University, 1984
B.S., National Cheng-Kung University, Taiwan, 1980

Research Areas and Descriptors

Manufacturing and Automation and Mechatronics; Modeling, monitoring, and control of advanced manufacturing processes and equipment.

Background

Dr. Liang began at Tech in 1990 as an Assistant Professor. Prior, he was an Assistant Professor at Oklahoma State University. He was named to the Bryan Professorship in 2005. He was President of Walsin-Lihwa Corporation in 2008-2010.

Research

Dr. Liang's research interests focus on precision manufacturing processes in the context of modeling, monitoring, control, and optimization.  Specifically, his work has been devoted to physics-based analysis and predictive modeling of metal machining and additive manufacturing, with emphasis on materials-driven processing.  It addresses the materials microstructural response to process-induced thermal-mechanical strain, stress, and heat distributions germane to part properties and performance, thus rendering a deeper insight into the manufacturing process physics as well as a scientific foundation to support process planning and optimization for effectiveness and productivity.

In the field of precision machining, Dr. Liang’s research has centered on predictive modeling of shear straining, thermal kinematics, and material constitutives to apprehend the coupling of thermal and mechanical loadings and the related materials behavior evolutions.  The study has shed lights on the effects of machining and grinding parameters, tool geometries, and lubrication condition on the dynamics of velocity, deformation, stress, and temperature profiles.  It has examined the microstructural aspects of recrystallization, grain growth, texture variation, and phase field change in machining, thus offering a better understanding of the fundamental mechanisms that govern the machined part performance of tolerance, strength, modulus, hardness, and endurance, in addition to process effectiveness attributes of machinability, tool efficiency, and environmental compatibility.

In the field of metal additive manufacturing, Dr. Liang’s work has developed physics-based analytical modeling flanked by computational mechanics of materials to quantify the thermodynamics, heat-transfer, and materials thermo-physical behaviors in powder bed and powder feed processes.  Aiming at a scientific scope and engineering applicability far beyond experimentation and finite element iteration numerics, closed-form analytical solutions have been established by integrating semi-infinite medium solutions with boundary heat transfers for temperature and thermal stress distributions.  The corresponding build residual stress, microstructure, distortion, porosity, and mechanical properties are expressed as explicit functions of process parameters and powder properties, factoring in the effects of scan strategy and powder size statistical distributions.

Much of Dr. Liang’s studies have bonded together materials science and mechanical manufacturing engineering to provide clearer linkages between the manufacturing process condition, material microstructures, and the part properties and functionalities.  Dr. Liang’s research program has been sponsored largely by federal agencies, national laboratories, along with industry sectors of aerospace, automotive, and energy to provide fundamental science and engineering with tangible application relevance.

Associated Photos

Full-field infrared digital thermography in wet machining

Temperature gradients in Ti64 additive manufacturing

Thermal conductivity profile in Ti64 additive manufacturing

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Georgia Institute of Technology
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Phone: 404-894-2000