System-Level Vibration Testing of Physical Hardware Components Using Real-Time Hybrid Substructuring

Real-time hybrid substructuring (RTHS) is a relatively new method of vibration testing for characterizing the system-level performance of physical hardware components. With RTHS, a dynamic system is partitioned into physical and numerical substructures and interfaced together in real-time similar to hardware-in-the-loop testing. This paper presents an overview of RTHS including the challenges posed by its real-time constraints and the application to system-level testing of physical vibration control devices and mechanical equipment. Two laboratory RTHS experiments performed at the University of Connecticut Structures Research Laboratory are used to demonstrate the benefit of RTHS. The first test examines the connected control method using viscous damper hardware as the physical substructure coupled to adjacent base isolation systems as the numerical substructure. The second test involves a multi-stage isolation system comprised of an operating mechanical component on isolators as the physical substructure coupled to an intermediate mass on similar isolators as the numerical substructure. In these RTHS tests, feedforward inverse compensation combined with feedback is used to compensate the frequency-dependent dynamics of the multi-actuator system. Experimental results demonstrate that RTHS accurately captures the system-level behavior of the coupled system and allows for repeatable tests of various conditions and potential system improvements to be efficiently examined.