An improved sound transmission loss (STL) experimental technique based on the sound pressure method (SPM) and acoustic box method is proposed to investigate the temperature influence on the STL of the ribbed carbon fiber reinforced plastics aircraft panel. SPM principle is given. The measurement procedure of the improved STL technique is presented and its reliability is verified. STL variable characteristics of the panel within −40°C–40°C were measured. Results showed that temperature had a significant effect on the panel’s STL. The overall STL varied nonlinearly with temperature, whereas STL exhibited a fluctuation or monotony trend at a single center frequency. Temperature variation caused changes of STL peak/dip frequencies and redistribution of stiffness-controlled, resonance-controlled, coincidence-controlled, and damping-controlled regions. The causes of the aforementioned are given. This study reveals the relationship between temperature, thermomechanical parameters and STL. The findings have applications in the design, measurement, analysis, and theoretical development of composite structure acoustics.

A rapid prediction technique of sound transmission loss (STL) is proposed to investigate the acoustic characteristics of the aerospace vehicle composite panel based on the equivalent method and the hybrid finite element method-boundary element method (FE-BEM). The composite panel is equivalent to a single anisotropic plate using the classical laminate theory, and then its STL within a wide frequency band is predicted by the FE-BEM method. To verify the applicability of the equivalent method, modal tests and numerical analyses of the panel are carried out. To verify the correctness of the predicted conclusions, FE-BEM results are compared with FE-SEA results and experimental results. Results show that I) the equivalent method is correct to simulate the natural characteristics of symmetrical laminates, which are consistent with the experimental results; II) it's effective for the panel's STL prediction via introducing the equivalent structure into the FE-BEM STL prediction model, and III) the FE-BEM method is superior to the FE-SEA method. The proposed method has application in acoustic characteristics analysis and design of manned spacecraft.