Identification of Suitable Excitation Nodes for Assembled Structures using Modal Participation Factors

Abstract

Accurate excitation point selection is essential in experimental modal analysis (EMA) to ensure sufficient excitation of structural vibration modes and the acquisition of quality Frequency Response Functions (FRFs). However, excitation nodes are commonly selected based on geometric accessibility and engineering judgement, which may result in incomplete dynamic characteristics. This study presents a systematic methodology for identifying suitable excitation nodes for a simplified aircraft structure. FE modal analysis is first performed using MSC NASTRAN SOL103 to obtain the eigenvalues and eigenvectors of the structure. The extracted modal parameters are subsequently used to calculate the Modal Participation Factors (MPFs) and effective modal masses for all candidate excitation nodes. Based on the obtained MPFs, excitation nodes are ranked according to their capability to excite multiple structural modes within the investigated frequency range. The effectiveness of the selected excitation locations is then validated using driving point FRF analysis through MSC NASTRAN SOL111. The results show that nodes with large MPF and effective modal mass values produce significantly stronger FRF amplitudes and clearer resonance peaks across multiple vibration modes. The strong agreement between the MPF based excitation ranking and the corresponding FRF responses demonstrates the effectiveness of the proposed methodology for EMA and structural dynamic investigations.