Prof. Valentin L. Popov from Berlin University of Technology was invited to visit the State Key Laboratory of Tribology and give a presentation on Structural damping in oscillating contacts on 28 th September 2015. This presentation is dedicated to the active control of structural damping, a problem that is both important and not yet satisfactorily solved in many areas of engineering. Prof. Valentin L. Popov discussed how to control structural damping through frictional contacts - either using joints already present in the structure or contacts introduced for the specific purpose of damping control. Almost 30 teachers and graduate students were attracted to attend this activity.