Development and validation of experimental modal analysis with fixture-free oblique impact testing based on a vector projection method
Authors: Yee, K.S., Cheng, L.Y., Chao, O.Z., Ismail, Z. and Noroozi, S.
Journal: Measurement Science and Technology
Volume: 32
Issue: 1
eISSN: 1361-6501
ISSN: 0957-0233
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 test time problem of conventional EMA with normal excitation (i.e. triaxial normal impact testing), in order to extract all the important dynamic characteristics of a 3D complex structure. In this study, a new methodology involving a vector projection method is introduced to find the driving point frequency response function (FRF) in the oblique direction, without the need for a special fixture with an obliquely oriented impedance head. Hence, this presents a low cost and practical solution for scaling the mode shape, as compared to the traditional approach. Moreover, the concurrent forces characteristic of oblique excitation are used in the development of the theoretical relationship between FRFs with oblique excitation and those with normal excitation. This is important for the validation of the oblique impact testing result, such as the FRF and modal parameter estimations. The experimental results show that oblique impact testing has reliable and effective results, as compared with the triaxial normal impact testing, in terms of the FRF correlation, natural frequency discrepancy, modal damping ratio error and modal assurance criterion of the unit modal mass mode shape.
https://eprints.bournemouth.ac.uk/34415/
Source: Scopus
Development and Validation of Experimental Modal Analysis with Fixture-Free Oblique Impact Testing Based on Vector Projection Method
Authors: Khoo, S.Y., Lian, Y.C., Ong, Z.C., Ismail, Z. and Noroozi, S.
Journal: Measurement Science and Technology
Publisher: Institute of Physics Publishing
ISSN: 0957-0233
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.
https://eprints.bournemouth.ac.uk/34415/
Source: Manual
Development and Validation of Experimental Modal Analysis with Fixture-Free Oblique Impact Testing Based on Vector Projection Method
Authors: Khoo, S.Y., Lian, Y.C., Ong, Z.C., Ismail, Z. and Noroozi, S.
Journal: Measurement Science and Technology
Volume: 32
Issue: 1
ISSN: 0957-0233
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.
https://eprints.bournemouth.ac.uk/34415/
Source: BURO EPrints