Arno Merkle - Ph.D. Candidate - Northwestern University

Research Interests

Nanotribology

We seek to identify the fundamental mechanisms of energy dissipation at sliding interfaces through theoretical and experimental methods. We are currently utilizing customized in situ TEM nanomanipulation stages to directly characterize single asperity sliding interfaces within the microscope. In this way, we can form specific structure-friction relationships by dynamically observing a sliding contact.

tri-bol-o-gy

n. from the greek tribos (to rub), the study of the mechanisms involved with bodies in contact and relative motion.

Why Tribology?

The phenomena associated with surfaces in contact and relative motion form the basis for tribological research. The importance of controlling friction and wear through structure, materials selection and lubrication was realized since the time of the construction of the pyramids, and was formulated and documented scientifically by Leonardo Da Vinci 200 years before Newton defined the laws of force and mechanics, making tribology one of the oldest fields of scientific study. Despite this, only a fragmented understanding of the fundamental mechanisms exists.

In the modern world, energy losses by friction have been estimated to represent an economic cost of $100 billion dollars annually in the U.S. alone, and up to 4% of developed countries’ GDPs (Jost Report). Up to $21,000,000,000 (1981 U.S. dollars) could realistically be saved through efficiency improvements resulting from tribological research (ASME report). A cost-benefit ratio for this type of research has been estimated to be 1:50 (Jost). This massive economic driving force plays a large role in the development of alternative fuels and energies, including the design of new materials with favorable friction and wear properties. Controlling friction on an industrial scale has traditionally relied on trial and error research. Moving away from this inefficient process, the ambitious goals of tribological research now aim to create computational models that quickly and accurately predict friction properties from contact conditions and basic principals of materials deformation. The fabrication of new materials with more favorable mechanical properties, particularly in the field of protective coatings, remains an active field of research.

The limits of improving tribological performance have long surpassed mechanical design entering an era of materials limitations, where structure, properties and processing of materials, understanding their limitations and exploiting their properties has become the center point. For this reason, tribology centers worldwide have branched out from mechanical engineering departments towards their physics, materials science and chemistry colleagues.

My research is supported by the NSF IGERT Virtual Tribology funding grant at Northwestern University.

Links

Resume: .pdf

HREM and Surface Structure Facility (NU)

IGERT Virtual Tribology (NU)

Fraunhofer Institut für Werkstoffmechanik (Freiburg)

Northwestern University

Timeline

2/2004 - present: Ph.D. research...

09/2003 - 2/2004: Graduate Research Fellowship (DAAD supported) to Freiburg, Germany (Fraunhofer Institut)

09/12/2003: Ph.D. candidacy qualifying examination (coursework completed)

09/2001: Begin Graduate Studies at Northwestern University's Materials Science Department (Research Assistant)

09/1997 - 05/2001: Undergraduate education at Gustavus Adolphus College (B.A. Physics, Music minor)

06-09/2000: Summer Research Experience for Undergraduates, University of Chicago

06-09/1999: Summer Research Internship at the Max Planck Institut für Metallforschung

Files & Publications

A predictive analytical friction model from basic theories of interfaces, contacts and dislocations, A.P. Merkle and L.D.
Marks. Submitted to Tribology Letters (2006).

Structure and Stability of Grain Boundaries in Molybdenum with Segregated Carbon Impurities, R.Janisch, T. Ochs, A. Merkle, C. Elsässer; Materials Research Society Symposium Proceedings 578 (2000).

Other:

Qualifying Exam Slides (.ppt)

DAAD Internship Research Slides (.pdf) (Boron Carbide DFT studies)