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In this paper, the acoustic noise reduction of aluminum honeycomb/carbon face sheet sandwich panel with Melamine Foam (MF) lining of variable thicknesses (25 mm & 50 mm) is numerically estimated and then experimentally verified using impedance tube based on transfer matrix method. The presence of carbon face sheets and MF lining can have a significant impact on the Transmission Loss (TL). The impedance tube can measure the TL for frequency range of 64 Hz–6.2 kHz. A conventional, two-microphone impedance tube, is connected to a sample holder downstream of the first microphone pair and a section downstream of the sample holder that accommodates a second pair of microphones. The Finite Element Analysis and experimental results are compared and found in good agreements. The TL levels for each layer of material is estimated prior to have TL for combined structure. Furthermore, the optimized insulation foam thickness of 50 mm is obtained based on required acoustic parameters.

Prediction of possible vibration responses for a composite structure via subscale modeling is discussed in this article. The analytical correlations for three-dimensional (3-D) subscale modeling for metallic structures cannot be directly used for composite structures. In such structures, change in thickness can alter the mechanical properties of a composite structure and its prototype; therefore, vibration characteristics can only be predicted via two-dimensional (2-D) subscale modeling. For this purpose, the 3-D analytical relations are customized for 2-D subscale modeling along with an additional parameter, i.e., rigidity factor (RF), avoiding violation of dimensional consistency of the structure. They are also validated experimentally for variable diameter glass fiber shell composite structure. Three different approaches were used to develop these empirical correlations, which were then compared to determine the best one, closely matching the experimental results. It is found that empirical relations obtained for the 2-D subscaling technique produces better results against their counterpart 3-D subscale correlations. The dynamic behavior of shell structure can be predicted within a 10 % error band. Moreover, it was found that the research can be applied to all the composite shell structures that are difficult to scale in the third dimension.