Abstract
A verified computational model of a complex structure is crucial for reliable vibro-acoustic simulations. Mass and stiffness matrices of such a computational model may be constructed correctly, provided all the design information is available. Since it is an unknown, the damping matrix is usually populated through mathematical models based on some assumptions. In the current study, it is proposed to use the identified non-proportional structural damping matrix in the computational model. Structural damping matrix can be identified using the complex frequency response functions obtained from experimental modal analysis data. No matter what type of a damping mechanism a structure has; proportional or non-proportional, the frequency response functions of the system can be measured. First, the calculation procedure for the non-proportional structural damping matrix is explained. The damping matrix of an analytical model is identified successfully using the proposed procedure. The same procedure is then applied through a case study. Computational model of a test vehicle is constructed. Next, the test vehicle is subjected to a modal test to measure the frequency response functions of the structure. Incompleteness of the measured data and the requirements of the procedure are discussed, as well. The described procedure can be used in any model updating framework.
Highlights
A multi degree of freedom (MDOF) structure is theoretically modelled in terms of mass, stiffness and damping matrices
The results showed that the structural damping matrix identified by the proposed method yields exactly correct values, when the calculated frequency response functions (FRFs) are employed without adding any noise
The complex FRFs obtained from the Experimental modal analysis (EMA) study are refined using digital signal processing techniques
Summary
A multi degree of freedom (MDOF) structure is theoretically modelled in terms of mass, stiffness and damping matrices. Another drawback of this method is that the updated system matrices are not symmetric and positive definite Another approach used in the model updating studies is to improve the correlation of computational and experimental data by making iterations subject to modal parameters. These techniques are commonly known as iterative methods. To cancel the imaginary part of the complex FRF does not necessarily mean the elimination of damping As it is proposed in the literature, an undamped computational model can be updated using NFRFs [14]. The proposed approach is applied both on a simple analytical model and on a complex geometry
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