Real-Time Hybrid Substructuring Using an Inertial Shaker Transfer System

Real-time hybrid substructuring (RTHS) is proposed as a cyber-physical method, combining both experimental and numerical testing, to capture the system-level dynamic interaction between numerical and physical substructures. With RTHS, a structural dynamic system can be partitioned into separate experimental and numerical components or substructures and interfaced together as a cyber-physical system similar to hardware-in-the-loop (HWIL) testing. The substructures that are well understood are simulated in real time using analytical or numerical models, while the substructures of particular interest, overly complex, or nonlinear are tested experimentally using physical specimens. In an RTHS test, the experimental and numerical substructures communicate together in real time by transferring displacement and force signals through a feedback loop using controlled actuation and sensing. In a typical RTHS configuration, a transfer system is used to impart numerically determined displacements onto the physical substructure, and force sensors are used to measure the resulting restoring forces. The measurements are feed back into the numerical model to determine the displacement response at the next integration time step. Depending on the structural system’s configuration, this traditional RTHS substructuring approach may not be desirable, and it may be required to apply forces or loads to the physical substructure through the transfer system and measure the specimen response (displacement or acceleration) for input to the numerical component. This might be the case for fluid–structure interaction problems or for physical testing of the bottom floor of a multistory building – as proposed here with use of an inertial shaker as the transfer system. In this study, an inertial shaker is utilized to transfer story shear force from the numerical substructure to the physical substructure.