Damping and induced damping of a lightweight sandwich panel with simple and complex attachments

• Published in: Journal of sound and vibration Vol. 322; no. 4-5; pp. 901 - 925
• Main Authors: CONLON, S. C, HAMBRIC, S. A
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier 22.05.2009
• Subjects: Acoustics; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Linear acoustics; Measurement and testing methods; Noise: its effects and control; Physics; Solid mechanics; Structural and continuum mechanics; Vibration, mechanical wave, dynamic stability (aeroelasticity, vibration control...); Steady-state conditions; Energy analysis; Transient response; Electronic equipment; Statistical analysis; Internal friction; Vibration; Internal noise; Sandwich structure; Vibration test; Substructure; Fastener; Experimental study; Noise control; Modeling; Wave transmission; Wide band; Honeycomb structure; Aerospace; Metal foam; Acoustic radiation; Lightweight material; Lumped parameter system; Structural acoustics
• ISSN: 0022-460X; 1095-8568
• DOI: 10.1016/j.jsv.2008.12.006

Accurately estimating a structure's broadband response is highly dependent on a proper characterization of the system's internal damping as well as induced (or effective) damping when coupled systems are considered. In many aerospace and related applications a primary or master structure is loaded with equipment or substructures. The effects of these attachments on the master structure are often poorly understood and frequently overlooked, but in many cases can dominate the master structure's response. In this work various measures of damping of a lightweight aerospace panel (aluminum sandwich honeycomb core panel) with simple (lumped mass) and complex (electronic equipment) attachments are investigated using experimental techniques and simple statistical energy analysis models. The panel's various measures of damping in steady-state conditions are defined and explored. The panels with simple and complex attachments are experimentally evaluated using power injection methods. The results show that at different frequencies the simple panel's response is controlled by internal and then acoustic radiation damping. The complex attachment's induced damping effects, however, can far exceed both the structure internal and acoustic radiation components. A range of complex attachment configurations are evaluated and general design assessment procedures developed for use by designers. Future work is planned to explore the systems transient response and derived parameters, as well as investigate the effects when the attachment mass varies over a greater range of values, a realistic condition applicable to many aerospace systems.