Study of aluminum honeycomb sandwich composite structure for increased specific damping

Joshi, Aditi S. M.S.M.E., Purdue University, May 2014. Study of Aluminum Honeycomb Sandwich Composite Structure for Increased Specific Damping. Major Professors: Dr. Douglas E. Adams and Dr. J. Stuart Bolton, School of Mechanical Engineering The aluminum honeycomb sandwich composite structure is commonly used in the aerospace and automotive applications where high strength to weight ratio is desirable. However the poor performance of the aluminum honeycomb sandwich composite structure in terms of the vibration damping and the sound transmission makes their applications limited. Studying the effect of different structural modifications on the damping has become an interesting area of research in past few decades. The present study addresses the effect of adding a mass on the composite beam at various locations on the damping loss factors for the modes of vibration present in the frequency range of interest. The experimental results are validated by comparing with a finite element analytical model. Also, another modification of drilling holes on one of the face sheets of the beam is studied. The holes drilled on the beam surface create a cellular resonator effect which has an impact on the damping loss factors of the beam. The concept of creating the cellular resonators is studied in detail using thermography testing with acoustic excitation. Finally, a correlation between the increase in the damping loss factors and increase in the temperature of the beam after excitation is obtained, supporting the effectiveness of the modification.