Estimation of Rotational Frequency Response Function of Structures

在本研究中，提出了一种使用刚性t块测量旋转频响的方法。去年进行了一项使用梁结构的可行性研究。以下是今年的学习内容。研究了随机噪声对旋转频响测量的影响。提出了一种提高精度的估计方法。本文还研究了一种考虑t型块弹性振动的改进方法，该方法扩大了适用频率范围。通过这些研究，适用的频率范围扩大到1,000 Hz，而最初覆盖的范围可达500 Hz。将所提出的频响估计方法应用于某汽车副车架结构。通过将估计的频响与有限元预测结果进行比较，验证了该方法的有效性。利用旋转频响对副车架进行结构动力学修正。验证了该模型对实际产业结构的适用性。本文介绍了考虑转动自由度的试验模态分析流程。实验结果表明，实验模态分析在该方案下更具有实用性和可预测性。

In this study, a measurement method of rotational FRF using a rigid T-block was presented. A feasibility study using a beam structure was conducted last year. The followings are the contents of this year study.1. Improvement of accuracy and expansion of applicabilityEffect of random noise on rotational FRF measurement is investigated. The estimation approach in order to improve the accuracy is presented. The advanced approach is also examined, in which the elastic vibration of the T-block is considered to expand the applicable frequency range. By these investigations the applicable frequency range is expanded up to 1,000 Hz whereas the range is originally covered up to 500 Hz.2. Application to an industrial structureThe presented FRF estimation method is applied to an automobile sub-frame structure. The validity is confirmed by comparing estimated FRF with the FEM prediction. Structural Dynamics Modification is carried out to the sub-frame by using the rotational FRFs. Applicability to the real industrial structure is confirmed.3. Summary of the StudyThe flow of the experimental modal analysis in which the rotational DOFs are taken into account is presented. It is shown that the experimental modal analysis becomes more useful and predictable in the presented scheme.