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Development and Validation of Experimental Modal Analysis with Fixture-Free Oblique Impact Testing based on Vector Projection Method.

Khoo, S.Y., Lian, Y.C., Ong, Z.C., Ismail, Z. and Noroozi, S., 2020. Development and Validation of Experimental Modal Analysis with Fixture-Free Oblique Impact Testing based on Vector Projection Method. Measurement Science and Technology, 32 (1), 015002.

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DOI: 10.1088/1361-6501/aba969

Abstract

Experimental modal analysis (EMA) with oblique excitation (i.e. oblique impact testing) is useful in improving the long testing time problem of conventional EMA with normal excitation (i.e. tri-axial normal impact testing), in order to extract all important dynamic characteristics of a 3D complex structure. In this study, a new methodology involving vector projection method is introduced to find the driving point frequency response function (FRF) in the oblique direction, without the need of special fixture with oblique-oriented impedance head. Hence, it presents a low cost and practical solution to scale the mode shape, as compared to the traditional approach. Moreover, the concurrent forces characteristic of the oblique excitation is used in the development of the theoretical relationship between the FRF with oblique excitation and normal excitation. This is important for the validation of the oblique impact testing result, such as the FRF and modal parameter estimations. Experimental results show that the oblique impact testing has reliable and effective results, as compared with the tri-axial normal impact testing in terms of the FRF correlation, natural frequency discrepancy, modal damping ratio error and modal assurance criterion (MAC) of the unit modal mass (UMM) mode shape.

Item Type:Article
ISSN:0957-0233
Uncontrolled Keywords:Concurrent Forces Effect; Oblique Frequency Response Function; Oblique Impact Testing; Oblique Driving Point Measurement; Tri-axial Normal Impact Testing; Vector Projection Method.
Group:Faculty of Science & Technology
ID Code:35009
Deposited By: Unnamed user with email symplectic@symplectic
Deposited On:04 Jan 2021 16:37
Last Modified:27 May 2021 07:56

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