基于联合振动试验系统的正弦加随机振动研究

提出联合振动试验系统，将液压振动台与电动台有效结合，并实现较大量级的正弦加随机振动。用液压台施加低频正弦激励，用电动台施加宽频随机激励，将正弦信号与随机信号有效分离，并分别用功率谱及频谱控制。设置弹性、阻尼单元，用以模拟台面至工件的传递特性，通过调整弹簧刚度及阻尼大小，使台面至工件及电动台的传递特性一致，以保护电动台。利用有限元软件Nastran仿真控制效果，将刚度、阻尼合理匹配后，电动台能较好跟踪工件运动。通过功率谱均衡方法有效控制随机振动试验，并在电动台输出端获得与目标谱较一致的功率谱。工件呈现出要求的正弦加随机振动，从而证明该系统的有效性。

Sine on random vibration based on combined vibration test system

In order to increase the range of vibration frequencies, a novel combination of the hydraulic vibration table and the electrodynamic shaker is proposed. The joint test system has been used in sine on random vibration test. The sine signals and random signals are provided by the hydraulic and electrodynamic shaker respectively, and the control algorithms are spectrum equalization and power spectral density (PSD) equalization. The variable spring-damp elements are set to simulate the transfer properties from the table to the electrodynamic shaker. Based on the simulation results by the MSC (Nastran) software, it is indicates that the dynamic characteristics of electrodynamic vibration shaker is closely related to the low frequency part of test article. The random and sine signals separated can use the control algorithm to continuously update the drive signals, and the control accuracy of the reproduced PSD at the control point is quite satisfactory.