Vibro-acoustic performance of sandwich beams

This study investigates the vibro-acoustic performance of sandwich beams comprising carbon-fiber face sheets with a 45 degree orientation and foam core. The research focuses on three sandwich beams, sharing the same face-sheet and core material while varying in core thickness. The main purpose is to understand the interplay between core thickness, hole position combinations, and hole diameters and evaluate their effects on dynamic response and sound radiation characteristics. The specimens were tested through a Laser Doppler Vibrometer for natural frequency measurement. Subsequently, modal analysis was conducted using Ansys software to obtain natural frequencies and mode shapes. For an extensive exploration, three distinct hole position combinations, each with five different hole diameters (ranging from 10 percent to 50 percent of the relevant core), were selected. Experimental tests were specifically focused on a chosen hole position combination to identify natural frequencies. Following this numerical analysis computed, harmonic response analysis was performed for all combinations, and the obtained data were employed in harmonic acoustic analysis. Sound radiation and sound pressure levels were then computed for all cases. Results reveal a notable increase in sound pressure levels across the domain with increasing core thickness, particularly at the first three natural frequencies for the original specimens (without holes). Interestingly, a nonlinear behavior is observed for the peak mode with the highest amplitude, unveiling a complex interplay involving core thickness and hole position on sound pressure levels. The study revealed that variations in hole positions significantly influenced sound pressure levels. Different hole positions, demonstrated distinct impacts on the distribution and concentration of sound pressure levels, emphasizing the role of geometric arrangement in shaping the vibro-acoustic performance of the structures.