Experimental Validation of the EBF3PanelOpt Vibro-acoustic Analysis of Panels with Straight and Curvilinear sti[|#11#|]ffeners

The vibro-acoustic experiments are performed at Structural Acoustics Loads and Transmission (SALT) facility of Langley Research Center to measure the sound radiation from and transmission loss (TL) of two panels with straight and curvilinear stiffeners, respectively. The focus of the work addressed in this article is to validate the Vibro-acoustic analysis methods implemented in a multi-objective design optimization framework, EBF3PanelOpt. The stiffened test panels with six stiffeners have been designed using EBF3PanelOpt for turbulent boundary layer (TBL) excitation. To build the confidence in finite element models, free vibration tests of the manufactured stiffened panels are also performed. The excited experimental mode shape and eigen frequencies match quite well with the finite element analysis results for the free vibration test. A medium density fiberboard and aluminum frame is used to clamp the stiffened panels in the SALT transmission loss window. Due to strong coupling of the stiffened test panels with the frame, a finite element model of the stiffened panels with frame is developed. To capture the effect of the bolted joints in the test setup, bush elements with optimal values of rotational and translational stiffnesses are used. Measurements are also performed to estimate the damping in the stiffened panels with the rame. The numerical prediction of sound radiation from and TL of stiffened panels is in fair agreement with the measured values for both the panels.