多自由度实时子结构试验系统稳定性分析方法

实时子结构试验将数值模拟和物理试验相结合，充分发挥各自优点，为工程结构研究提供了一种新的试验手段。系统稳定性是保证实时子结构试验成功实现的前提，但现有研究成果主要针对单自由度结构，多自由度系统稳定性评价方法所需参数相对复杂、稳定性指标物理意义不够明确。该文结合振型叠加法和增益裕度概念发展了多自由度稳定性分析方法，通过试验验证了该方法的有效性。同时运用该方法就时滞补偿下实时子结构试验系统稳定性进行了评估，并阐述了时滞补偿对实时子结构试验系统稳定性的影响机理。研究结果表明该方法能准确评价多自由度子结构试验系统稳定性，时滞补偿对子结构稳定性可能产生有利也可能产生不利影响。

AN ANALYTICAL METHOD OF SYSTEM STABILITY FOR MDOF REAL-TIME SUBSTRUCTURING TESTING

Combing the advantages of numerical simulation with experimental testing, real-time dynamic substructure (RTDS) testing provides a new experimental method for the investigation of engineering structures. The premise of a successful RTDS testing is to ensure its stability. However, most researchers focused on the stability of RTDS testing in terms of single degree of freedom systems. For multi-degree of freedom (MDOF) systems, the parameters required in the stability analysis are often complex and the index of stability assessment has no specific physical meaning. This work developed an analytical method for MDOF RTDS system incorporating the mode superposition method and the concept of gain margin. The effectiveness of this method was verified experimentally. Meanwhile, the influencing mechanism of time delay compensation on the stability of MDOF RTDS system was uncovered. The analytical and experimental results show that the developed method can accurately evaluate the stability of MDOF RTDS system. Delay compensation can be beneficial as well as detrimental to the stability of RTDS system.