Frequency Response Function Based Modal Updating of Aerospace Structures

Genç, Cem
This thesis explores finite element updating methods based on frequency response functions (FRFs), comparing classical modal approaches with newer techniques like Amplitude Residue (AR) or mostly called Response Function Method (RFM). It also uses FRF correlation functions such as Cross Signature Criterion (CSC) and Cross Signature Assurance Criterion (CSAC) for damping update of composites. Specifically, the thesis analyzes a Glass Fiber Reinforced Polymer (GFRP) composite beam, contributing to the limited literature on composite structures model updating. Additionally, Dynamic Mechanical Analysis (DMA) tests are utilized to determine the frequency-dependent damping behavior of the GFRP composite material. Integrating FRF-based updating techniques with DMA data enhances comprehension of structural dynamics and damping properties. The study also employs the Modal Strain Energy Method (MSEM) to forecast damping behavior, improving resilience and understanding of composite dynamics. Combining this approach with Response Surface Method (RSM) and Design of Experiments (DoE) facilitates a comprehensive study of damping characteristics of invdividual plies and laminate stack-ups. The influence of air damping on ply damping properties is also examined. Moreover, a concurrent investigation focuses on determining composite material characteristics through Multi-model Updating of Poisson's plates, ensuring uniqueness of material properties. In summary, the study confirms the effectiveness of FRF-based updating methods for composites, particularly those with specific damping properties. Validation underscores their importance and usefulness in real-world applications.
Citation Formats
C. Genç, “Frequency Response Function Based Modal Updating of Aerospace Structures,” Ph.D. - Doctoral Program, Middle East Technical University, 2024.