Basic examination of two substructuring schemes for shake table tests
Basic examination of two substructuring schemes for shake table tests
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DOI：
10.1002/stc.2497
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发表时间：
2020-01
影响因子：
5.4
通讯作者：
R. Enokida
中科院分区：
文献类型：
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作者：
R. Enokida
本研究考察了振动台试验的两种基本子结构方案，其中振动台的动力受到试样的显著影响。混合仿真（HS）是子结构实验中常用的一种方法，它直接将数值子结构的输出作为物理子结构的输入信号。动态子结构系统（DSS）方案是在HS之后发展起来的，它使用前馈和反馈控制器来最小化由数值子结构和物理子结构输出产生的控制误差。在研究这两种方案之前，本研究介绍了将多自由度仿真系统划分为数值子结构和具有振动台的物理子结构的系统公式。然后，对子结构进行了HS和DSS的控制器设计。通过对一个线性三维立体仿真系统的子结构试验，对两种基本控制方法进行了数值验证。具有稳定性的DSS即使在纯时间延迟和表动态估计不准确的控制条件下也很强大，而这些因素会降低HS的性能。在考虑非线性特性的附加仿真中，DSS （HS）的性能主要受到非线性（表动态估计不准确）的影响。发现具有非线性特性的子结构的稳定性可以用Nyquist稳定性判据进行粗略的评定。这些具有/不具有非线性特性的仿真通过基本控制方法和实际条件下的稳定性分析，阐明了HS和DSS方案的性能。
This study examines two basic substructuring schemes for shake table tests where the dynamics of the table is significantly affected by a specimen. The hybrid simulation (HS) scheme, commonly adopted in substructuring experiments, directly uses the output of a numerical substructure as an input signal to a physical substructure. The dynamical substructuring system (DSS) scheme, developed long after HS, uses feedforward and feedback controllers to minimise the control error produced by the outputs of numerical and physical substructures. Before examining these two schemes, this study introduces a systematic formulation for dividing a multi‐degree‐of‐freedom emulate system into a numerical substructure and a physical substructure with a shake table. Then, controller designs for HS and DSS are discussed for the substructures. The two schemes with basic control approaches were numerically examined through substructuring tests for a linear 3DOF emulate system. DSS with stability was powerful even under a control condition with a pure time delay and inaccurate estimation of the table dynamics, whereas these factors degraded the HS performance. In additional simulations in which nonlinear characteristics were considered, the performance of DSS (HS) was degraded mainly by the nonlinear (inaccurate estimation of the table dynamics). It was found that the stability of substructures with nonlinear characteristics could be roughly assessed by the Nyquist stability criterion. These simulations with/without nonlinear characteristics clarified the performances of the HS and DSS schemes through basic control approaches and stability analysis under practical conditions.