Seminar & Colloquium
[세미나: 4월 2일(화), 오전 10시 30분] Prof. George M. Pharr, Texas A&M University
Title
PROGRESS IN THE DEVELOPMENT OF HIGH STRAIN RATE NANOINDENTATION TESTING
Speaker
Prof. George M. Pharr, Department of Materials Science and Engineering, Texas A&M University
* Education
- 1975. B.S., Mechanical Engineering & Materials Science, Rice University
- 1977. M.S., Materials Science and Engineering, Stanford University
- 1979, Ph.D., Materials Science and Engineering, Stanford University
- 1979 ~ 1980 Postdoctoral, Engineering Department, Cambridge University
* Experience
- 1975 Research Assistant, Los Alamos Scientific Laboratory, Los Alamos, NM
- 1975 ~ 1979 Research Assistant, Department of Materials Science, Stanford University
- 1976 ~ 1979 Metallurgical Consultant, Failure Analysis Associates, Palo Alto, CA
- 1979 ~ 1980 Postdoctoral Research Associate, Cambridge University, Cambridge, England
- 1980 ~ 1998 Professor of Materials Science, Rice University[Assistant Professor (1980-1985);
Associate Professor (1985-1991)]
- 1981 ~ 1986 Consultant, Sandia National Laboratories, Albuquerque, NM
- 1987 ~ 1993 Consultant, Kalium Chemicals, Chicago, IL
- 1987 ~ 1992 Affiliate, Los Alamos National Laboratory
- 1987 ~ 1988 Visiting Scientist, IBM Thomas J. Watson Research Center, Yorktown Heights, NY (sabbatical)
- 1989 ~ 1994 Master, Wiess College, Rice University
- 1994 ~ 1996 Visiting Scientist, Oak Ridge National Laboratory, Oak Ridge, TN (sabbatical)
- 1998 ~ 2016 Professor of Materials Science and Engineering, The University of Tennessee
- 1998 ~ 2016 UT/ORNL Collaborating Scientist and Joint Faculty, Oak Ridge National Laboratory
- 2002 ~ 2005 Adjunct Professor, Department of Biomedical Engineering, The University of Memphis
- 2006 ~ 2011 Head, Department of Materials Science & Engineering, The University of Tennessee
- 2006 ~ 2009 Deputy Director, Joint Institute for Advanced Materials, The University of Tennessee
- 2007 Consultant, Howrey, LLP, Palo Alto, CA
- 2008 Consultant, Fish and Richardson, PC, Redwood City, CA
- 2008 ~ 2009 Consultant, McKenna, Long and Aldridge, Washington DC
- 2009 ~ 2016 Director, Joint Institute for Advanced Materials, The University of Tennessee
- 2009 ~ 2010 Visiting Scientist, Karlsruhe Institute of Technology, Karlsruhe, Germany (sabbatical)
- 2014 Visiting Professor, University of Hong Kong, Department of Mechanical Engineering
- 2017 ~ present Professor of Materials Science and Engineering, Texas A&M University
| Date | Tuesday April 2nd , 2024
| Time | 10:30 ~
| Venue | 33동 125호(WCU 다목적실)
[Abstract]
Over the past four years, we have developed new hardware, software and testing methods to conduct nanoindentation testing at very high strain rates. To date, indentation strain rates as high as 105/s have been achieved during the initial stages of indentation contact with a Berkovich indenter. At the heart of the new testing system is a laser interferometer that measures indenter displacements with sub-nanometer resolution at data acquisition rates of 1.25 MHz. High data rates are essential since the loading of the indenter usually lasts no longer than a few hundred microseconds. The new testing system also incorporates a very high stiffness hexapod for precise sample positioning and alignment, and various hardware modifications that provide for the measurement of indentation load at speeds commensurate with the displacement measurements. Various testing methods have been explored, including impact tests in which the indenter is accelerated to velocities up to 0.3 m/s before contacting the specimen, and step load tests in which the indenter starts in contact with the specimen and is then step loaded to a high value in a relatively short period of time. Results demonstrating the capabilities and limitations of the system are presented and discussed based on experiments conducted in fused silica as a model hard material, and tungsten, aluminum and molybdenum as softer model metallic systems. Special attention is given to methods for analyzing high rate nanoindentation data to extract hardness and strain rate sensitivity as a function of indentation strain rate.
| Host | 최인석 교수(02-880-1712)