چكيده به لاتين
Abstract:
The main aim of this thesis is to employ an extension of two-variable Refined Plate Theory (RPT2) to determine Sound Transmission Loss (STL) through laminated composite plates which are used as aerospace structures in contrast to external excitation. It should be noted that the RPT2 known as a second type of Refined Plate Theory which includes the extension term in displacement field. To achieve this goal, Firstly, the lateral displacements are expanded by taking account three parts, including shear, bending and extension terms to provide an analytical model based on two-variable Refined Plate Theory without considering the effect of the shear correction coefficients in governing equations. Secondly, Vibro-acoustic analysis is administered by incorporating the laminated composite plate equation besides the acoustic wave equation, simultaneously. Hence, the power transmission through the laminated composite plate is specified as a result of oblique plane sound wave. Consequently, in order to illustrate the accuracy of the present formulation (RPT2) the obtained STL is compared with those of previous literature. However, the application of present study (RPT2) is clarified in the acoustical designs due to presenting more precise results in comparison with Classical Plate Theory. As a result, the parameters including various incident angle, deviation angle, external Mach number of the upstream flow, type of composite material are considred in the numerical result to designate which one are able to improve the behavior of STL. This research also contains lateral displacement amplitudes of plate in a band of plate thickness for some frequencies and critical plate thickness in each frequency. Additionally, some configuration related to stress distribution have been presented.
Keywords:
Sound Transmission Loss, Two Variable Refined Plate Theory, laminated composite Plate
