Performance comparison of viscoelastic materials typically used for acoustical damping of aircraft fuselage structures.

Abstract

Vibration tests were performed to compare typical viscoelastic damping materials attached to two distinct representative aircraft fuselage structures. The fuselage structures were a 19×20‐in2 Al ribbed panel and a 20×21‐in2 carbon composite ribbed panel. A shaker was used to excite each panel with and without viscoelastic material treatment. Each test structure along with the shaker was situated in an environmental chamber to collect measurements at low temperatures of −20, −30, and −40 °C. A laser vibrometer was used to collect velocity measurements at 15–26 random locations on the surface of the panels. The parameters that were compared included input mobility, damping loss factor (DLF), and space averaged squared velocity. The DLF values that were obtained using the decay rate, power input, and half‐power bandwidth methods were presented as averages in 1/3 octave frequency bandwidths (from 100 to 2500 Hz). The space and frequency averaged squared velocity was used to quantitatively categorize the viscoelastic damping materials. The effect of viscoelastic damping material coverage was also evaluated by comparing measurements collected at 50% and 80% coverages. The results of this experimental study are being utilized in finite element modeling, optimization of viscoelastic material treatment, and development of alternatives to viscoelastic damping. [Work supported by the MTI Polyfab Inc.]