Abstract This paper deals with the modelling and analysis of six degree of freedom random vibration test. It involves an advanced multi-input multi-output random vibration test system where three translational and three rotational motions can be controlled simultaneously. In this work, a mechanical model of the six degree of freedom vibration test system is established such that eight exciters are modelled as spring damper pairs and the shaker table is assumed to be rigid. The acceleration properties of the test article undergoing such six degree of freedom base vibrations are analyzed and the relationships among the absolute acceleration, relative acceleration and base acceleration are derived. In practical applications, typically there is no available angular acceleration sensor for high frequency measurements. Therefore, the three rotational accelerations are obtained from measured translational accelerations of three or more control sensors with a response coordinate transformation matrix. It is shown that the locations of the control points have a significant influence on the response spectral results, which is reflected in the condition number of the output coordinate transformation matrix. The general multi-input multi-output random vibration control method is applied to the 6-DOF random vibration test. A six degree of freedom random vibration test simulation is finally provided.

中文翻译：

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六自由度随机振动试验的简化建模与分析

摘要 本文研究了六自由度随机振动试验的建模与分析。它涉及先进的多输入多输出随机振动测试系统，可以同时控制三个平移和三个旋转运动。在这项工作中，建立了六自由度振动测试系统的力学模型，将八个激振器建模为弹簧阻尼器对，并假设振动台是刚性的。分析了受试件在这种六自由度基础振动下的加速度特性，推导出绝对加速度、相对加速度和基础加速度之间的关系。在实际应用中，通常没有用于高频测量的角加速度传感器。所以，这三个旋转加速度是从三个或更多控制传感器的测量平移加速度和响应坐标变换矩阵中获得的。结果表明，控制点的位置对响应谱结果有显着影响，这体现在输出坐标变换矩阵的条件数上。6自由度随机振动试验采用通用的多输入多输出随机振动控制方法。最后提供了六自由度随机振动试验模拟。这反映在输出坐标变换矩阵的条件数中。6自由度随机振动试验采用通用的多输入多输出随机振动控制方法。最后提供了六自由度随机振动试验模拟。这反映在输出坐标变换矩阵的条件数中。6自由度随机振动试验采用通用的多输入多输出随机振动控制方法。最后提供了六自由度随机振动试验模拟。