科研之友
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摘要
This paper presents a development of a computational framework for effective force testing (EFT). The framework is intended to facilitate accurate computational simulations of EFTs that allow for performance evaluation of experimental tests, stability assessment of force feedback controllers, and others. To properly capture critical issues in EFT such as control-structure interaction and oil-column resonance, the computational framework incorporates nonlinear dynamics of servo hydraulic actuators including power electronics of a converter, electromagnetics of a flapper nozzle, hydrodynamics of hydraulic fluid, and kinematics of an actuator piston. The computational framework is verified through comparative studies with three different effective force tests that were previously conducted at the Johns Hopkins University. The comparative studies demonstrate that the computational framework is able to accurately simulate experimental EFTs of an single-degree-of-freedom (SDOF) linear elastic structure, an SDOF nonlinear inelastic structure, and an multi-degrees-of-freedom (MDOF) test structure. Using the developed computational framework, an investigation of nonlinear dynamics of servo hydraulic actuators is performed. Simulation results showed that the influence of the nonlinear actuator dynamics becomes significant as the level of force increases. A compensation technique that uses only force and valve command to reduce the effects of valve nonlinearities is developed and investigated using the computational framework. It was shown that the nonlinear valve dynamics compensation technique is effective at improving peak responses of force and reducing undesirable effects. The examples shown in this paper demonstrate that the computational framework facilitates further developments and applications of effective force test methods for seismic performance assessment of structural systems.
- 出版日期2014-5
