Prof Huajiang Ouyang PhD

Friction-induced vibration (general nonlinear vibration, brake squeal and other brake noise, turning chatter):
Friction is everywhere. It is usually a source of energy dissipation, but sometimes can cause vibration. The latter includes brake squeal, squeaky hinges, machining chatter, etc. Friction also causes wear and heat conduction. Contact must be considered in friction-induced vibration. This remains a challenging and interesting research subject. TRW Automotive and Jaguar Land Rover are two sponsors of this research topic of mine.

Moving-load dynamic problems (vehicle-track-bridge dynamic interaction, spinning discs, turning chatter):
Most loads are fixed in space but some loads are in relative motion to the structures, for example, a train crosses a bridge and runs through a tunnel, a computer spins past a reader/writer head. Moving loads make a structure gain time-varying mass, stiffness and damping. Analysis of moving-load induced vibration is computationally intensive and its control is difficult. EPSRC has sponsored two project on mine on this topic.

Parametric and nonlinear vibration.
Friction-induced vibration and moving-load induced vibration all belong to parametric vibration. If the law of friction is of a nonsmooth Coulomb type, the vibration is highly nonlinear. Stick-slip vibration and loss of contact can also take place. This kind of vibration is numerically challenging.

Vibration control via eigenstructure assignment:
Vibration reduction (or magnification) can effectively be realised by assigning frequencies/mode to a structure/machine. Various work done includes: passive and active assignment of frequencies and modes, passive partial assignment, pole assignment for stabilising friction-induced vibration.

Vibration is often used as a way of identifying structural properties. A theoretical model can be corrected via model updating based on measure vibration data. Structural damage can be identified too. Of particular interest are identification of welded joints and bolted joints in assembled structures. These topics belong to challenging inverse dynamics.

Rotating machines are prone to vibration. Research is going on in passive and active assignment of frequencies and modes to rotating machines for vibration control.