Improved model for real-time substructuring testing system

Real-time substructuring (RTS) is a hybrid technique meant for evaluation of dynamic response of large structures. The critical component of the structure is experimentally tested, while the remaining components are modelled numerically. This paper discusses about various issues associated with the simulation of RTS. An improved model based on Simulink module of MATLAB is proposed to create the actual experimental conditions. Detailed model of electro servohydraulic actuator based on fluid power engineering is used to emulate the nonlinear behaviour of the actuator. As the response of the actuator is a function of specimen, the actuator model involves boundary conditions of the experimental setup. Such detailed model is then simplified to develop a transfer function for the actuator. Feedforward compensator with modified inverse dynamics is employed to compensate for actuator dynamics. Time integration is carried out by using Rosenbrock-W method, to solve the dynamic equations of motion of the numerical substructure. The dynamic response of a linear single degree of freedom (SDOF) system, nonlinear SDOF system and linear multi degree of freedom (MDOF) system to El-Centro earthquake is evaluated by using the proposed RTS model. The evaluated responses are compared with those obtained from the numerical analysis of full structure without substructuring using Operator Splitting Method (OSM). Upon comparison, the proposed model is found to be suitable for evaluation of the dynamic response of a structure.

► Improved model is developed for simulation of real-time substructuring.
► Actuator model based on fluid power engineering captures dynamics of actuator accurately.
► Modified feedforward compensator provides both phase and magnitude compensation.
► Dynamic response of a linear and a nonlinear SDOF system was evaluated using the proposed model.
► The simulation results were found to match well with those obtained from full structure.