Cause and consequence of occasional computational delay in real-time hybrid simulation

To investigate the cause and consequence of computational delay in the experiments, the calculation time of sliding isolator tests was analyzed and the real-time performance was evaluated. The results show that the computational delay occasionally appears at some integration steps, thus destroying the real-time performance of the tests. The computational delay is caused by the slow convergence speed of errors in iterative calculations by introducing the implicit integration algorithm into the tests. The computational delay has contingency and randomness, affecting the load rate of the test specimen and making the command displacement signal present S-shaped curves. The signal commands the actuator to switch from deceleration to acceleration in a short time interval, so that the actuator needs to overcome the huge inertial force, resulting in an obvious actuator response delay. By using the explicit integration algorithm and simplifying the numerical model, the calculation time of real-time hybrid simulation can be greatly reduced, thus avoiding the computational delay and ensuring the real-time performance of the tests. © 2021, Editorial Department of Journal of Southeast University. All right reserved.