The PhD defence and trial lecture will be streamed. The chair of the defence will moderate the disputation.
Ex auditorio questions: the chair of the defence will invite the audience physically present in the auditorium to ask ex auditorio questions.
→ Live streaming of trial lecture and disputation
→ Request for thesis copy (available until the disputation starts)
Trial lecture
Time and place: August 22, 2024; 10:15 AM, - Lille Fysiske auditorium (V232) - Fysikkbygningen
Title: "Viscoelastic contact formation and rupture"
Main research findings
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Friction is one of the oldest and most complex problems in physics, with research tracing back to Leonardo da Vinci in the 15th century. A central, unresolved question in friction is why static friction increases over time and how this affects sliding friction. In my PhD thesis, I have used molecular dynamics simulations to observe that surface diffusion causes particles to accumulate around the contact points between two surfaces. This increases the actual contact area and hence the frictional force over time when the surfaces are stationary relative to each other. When a surface begins to slide, parts of the surfaces remain in contact, with the contact time inversely proportional to the speed. By combining these two phenomena, we can explain why friction decreases with speed. These findings have significant implications for all friction systems with considerable surface diffusion, including geological processes like landslides and earthquakes. The observed mechanism is fundamentally different from traditional theories, as the increase in static friction is driven by internal forces rather than external influences. This makes contact aging possible even without an applied force. The new insight into friction dynamics enhances our ability to understand and predict friction behavior in various natural and industrial processes.
Adjudication Committee
- Professor Martin H. Müser, Universität des Saarlandes, Germany
- Associate Professor Ramin Aghababaei, Aarhus University, Denmark
- Associate Professor Maria Vetleseter Bøe, University of Oslo, Norway
Supervisors
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Professor Anders Malthe-Sørenssen, Department of Physics, University of Oslo, Norway
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Dr. Henrik Andersen Sveinsson, Department of Physics, University of Oslo, Norway
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Professor Francois Renard, Department of Geosciences, University of Oslo, Norway
Chair of defence
Professor Susanne Friederike Viefers, Department of Physics, University of Oslo, Norway
Candidate contact information
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https://www.linkedin.com/in/even-marius-nordhagen-a44248135/
Contact information to Department: ekspedisjon@fys.uio.no