Simple, robust hybrid test systems for non-linear structural dynamic research and development

Hybrid or real-time pseudo-dynamic tests couple virtual structures under dynamic loading with physical sub-structures or devices in a dynamic test rig. The use of sensors and actuators in a closed-loop feedback system maintains the dynamic equilibrium of the overall system comprising the physical test article and virtual modelled structure. Hybrid testing thus alleviates much of the time and cost associated with full-scale testing and enables tests that would be infeasible as full-scale complete structural tests. This research presents a simple, low-cost, robust hybrid test system, and outlines solutions to the major issues faced in developing any hybrid system. The overall approach is centred on the dSpaceTM real-time control system development tool. The major issues in developing a hybrid system are: minimal signal processing lag, optimised sensing resolution and bandwidth, and efficient model computation. All three affect the ability of the system to maintain dynamic equilibrium of the overall virtual-physical system, and thus provide an accurate test. The final system readily accommodates non-linear-multi-degree-of-freedom models and a 1kHz operating band-width