Hybrid simulation with multiple actuators: A state-of-the-art review

This paper reviews the conceptual and technical advances in multi-actuator dynamic loading in modern structural testing. In particular, a focus is given to the developments and challenges in multi-axial hybrid simulation (maHS) and multi-axial real-time hybrid simulation (maRTHS), where a specimen is subjected to multi-directional dynamic loading by interacting with a numerical simulation of its surrounding structural subsystems and components. This review introduces the general framework for maHS and maRTHS, describing substructuring techniques, loading equipment, and nonlinear kinematics. In particular, the process of dynamic compensation for multi-actuator loading assemblies in maRTHS is explored. Different compensation architectures in the task (Cartesian) and joint (actuator) spaces are covered, and each alternative is assessed on its own merits for the dynamic synchronization of multi-actuator loading platforms. Finally, current challenges in maHS and maRTHS testing are identified, with recommendations for future research endeavors for the scientific community.