This study proposes a frequency-based finite element updating method for an effective physics-based digital twin (DT). One approach to constructing a physics-based DT is to develop a mechanics-based mathematical model that accurately simulates the behavior of an actual structure. The proposed method utilizes finite element updating, adjusting model parameters to improve model accuracy. Unlike simple modal analysis, which focuses on vibration characteristics, this method recognizes that accurate dynamic transient-based vibration analysis requires considering the damping effect, as well as mass and stiffness, during the updating process. Moreover, a frequency-based analysis is employed instead of the computationally expensive time-based analysis for more efficient dynamic modeling. By transforming data into the frequency domain, the method efficiently represents dynamic behavior within relevant frequency ranges. We further enhance the computational efficiency using the model reduction technique. To validate the method’s accuracy and efficiency, we compare the analysis results and computation time using a numerical example of the control rod drive mechanism. The proposed method shows significantly reduced computation time, by a factor of 8.9 compared to conventional time-based methods, while preserving high accuracy. Therefore, the proposed method can effectively support the development of physics-based DTs.

In this paper, we propose a degree-of-freedom-based adaptive reduction method that ensures accuracy over a wide band. In the conventional dynamic condensation method, a single reduced model consisting of low-order modes is used throughout the analysis. This results in low accuracy in the high-frequency band because it does not reflect the characteristics of the frequencies. To address this issue, we implemented a reduced model for each frequency using a Taylor series. This method converts the transformation matrix into a frequency-independent form, which allows for a simple interpolation of the reduction model by updating the differences between frequencies. Numerical examples were adopted to examine the accuracy and efficiency of the proposed method.