Real-time dynamic substructuring
Real-time dynamic substructuring (or hybrid testing) is an experimental technique for experimentally testing the dynamic behaviour of components within the context of the structure they operate in.
A physical test of the component and a numerical model of the remainder of the structure are run together in real-time. To capture the interactions between these substructures, interface forces and displacements are passed between them.
A key challenge is to remove the effects of the dynamics associated with interface actuators, used to impose displacements on the experimental substructure.
The Group has devices control techniques to minimise these deleterious effects and refine the accuracy of the method. As well as developing the technique, it is used for testing vibration suppression devices including a helicopter lag-damper.
Wind-tunnel "flight" testing
The Group is developing a novel ‘manoeuvre rig’ for dynamic testing of aircraft models in a wind-tunnel.
The rig allows testing of such models in up to five degrees-of-freedom. It consists of a pivoted arm that supports the aircraft model via a gimbal at one end and an aerodynamic compensator at the other
This compensator is used to minimise the dynamic effects of the arm such that the model behaves, in principle, as if it were in free motion but with the effective thrust provided by the arm.
The resulting ‘physical simulation’ allows for the observation of aircraft behaviour, including the influence of nonlinear and time- dependent aerodynamics that can be responsible for the onset of upset/departure.
The motion data can also be used for parameter estimation allowing the development of more refined numerical models of the aircraft dynamics and for assessing aircraft control strategies.
In addition to validating new theoretical insights made by the Group, there is also development of new experimental testing methods. These techniques include developing real-time dynamic substructuring (or hybrid testing), a method for testing part of a structure experimentally and the remainder numerically and novel modal testing methods.