The Woodruff School

SUMMARY

Surface integrity is of great significance in grinding performance since grinding process is often used as a finishing step in manufacturing practice. For metallic materials, residual stresses near the surface strongly affects fatigue life, and corrosion resistance. For ceramic materials, the surface fracture damage induced by grinding process impacts the mechanical strength and surface finish of the component. The functionality of the component hinges upon these surface integrities. Because of this, understanding the surface integrity imparted by grinding is very important. The use of fluid is common in grinding process for lubrication and cooling purposes, however, the high cost and environmental impact of the conventional flood cooling is very undesirable. The minimum quantity lubrication (MQL) has been introduced in industry as a promising alternative to overcome these drawbacks. A comprehensive understanding of the MQL effect on the surface integrity, specifically residual stresses, is of great value to the implementation of MQL technique in industrial situation. In addition to the superior surface finish produced by grinding process, shaping hard and brittle materials is another area where grinding possesses incomparable capability compared to cutting processes. The understanding of surface damage and finish is key to the development of ceramic grinding technology. Grinding-induced residual stress prediction and the surface damage of ceramic grinding has been a topic of research since the 1970�s. Research efforts are in the forms of experimental findings, analytical modeling, finite element modeling, and various combinations. Although there has been significant research in the area, there are still opportunities for advancing predictive methods. The objectives of the current research are as follows: (1) develop a method of predicting residual stress based on an analytical description of the grinding process under MQL condition, (2) develop a method of predicting surface quality in ceramic grinding, and (3) validate the models with experimental data. The research will focus on predicting residual stresses in MQL grinding based on fundamental physics. Grinding process output parameters such as grinding forces and temperatures will be predicted as part of the overall modeling effort. These output parameters will serve as the basis for determining the loads which generate residual stresses. The research will also investigate the surface damage and finish in ceramic grinding. The crack system developed from indentation fracture mechanics approach will be utilized in evaluating the ductile-brittle mixed surface generation. The modeling techniques will be applied to a range of grinding conditions and materials.

SUBJECT:	Ph.D. Dissertation Defense

BY:	Yamin Shao

TIME:	Monday, April 20, 2015, 2:00 p.m.

PLACE:	MARC Building, 431

TITLE:	Predictive Modeling of Residual Stress in MQL Grinding and Surface Characteristics in Grinding of Ceramics

COMMITTEE:	Dr. Steven Liang, Chair (ME) Dr. Shreyes Melkote (ME) Dr. Steven Danyluk (ME) Dr. Roshan Vengazhiyil (ISyE) Dr. Ismail Lazoglu (Koc University) Dr. Beizhi Li (Donghua University)

SUMMARY Surface integrity is of great significance in grinding performance since grinding process is often used as a finishing step in manufacturing practice. For metallic materials, residual stresses near the surface strongly affects fatigue life, and corrosion resistance. For ceramic materials, the surface fracture damage induced by grinding process impacts the mechanical strength and surface finish of the component. The functionality of the component hinges upon these surface integrities. Because of this, understanding the surface integrity imparted by grinding is very important. The use of fluid is common in grinding process for lubrication and cooling purposes, however, the high cost and environmental impact of the conventional flood cooling is very undesirable. The minimum quantity lubrication (MQL) has been introduced in industry as a promising alternative to overcome these drawbacks. A comprehensive understanding of the MQL effect on the surface integrity, specifically residual stresses, is of great value to the implementation of MQL technique in industrial situation. In addition to the superior surface finish produced by grinding process, shaping hard and brittle materials is another area where grinding possesses incomparable capability compared to cutting processes. The understanding of surface damage and finish is key to the development of ceramic grinding technology. Grinding-induced residual stress prediction and the surface damage of ceramic grinding has been a topic of research since the 1970�s. Research efforts are in the forms of experimental findings, analytical modeling, finite element modeling, and various combinations. Although there has been significant research in the area, there are still opportunities for advancing predictive methods. The objectives of the current research are as follows: (1) develop a method of predicting residual stress based on an analytical description of the grinding process under MQL condition, (2) develop a method of predicting surface quality in ceramic grinding, and (3) validate the models with experimental data. The research will focus on predicting residual stresses in MQL grinding based on fundamental physics. Grinding process output parameters such as grinding forces and temperatures will be predicted as part of the overall modeling effort. These output parameters will serve as the basis for determining the loads which generate residual stresses. The research will also investigate the surface damage and finish in ceramic grinding. The crack system developed from indentation fracture mechanics approach will be utilized in evaluating the ductile-brittle mixed surface generation. The modeling techniques will be applied to a range of grinding conditions and materials.