دانلود رایگان مقاله تاثیر طبیعت بر رفتار هسته ای صوتی ارتعاشی سازه ساندویچ هوافضا

Abstract

This paper presents the study of influence of core geometry on vibration and acoustic response characteristics of sandwich panels which are used as aerospace structures. Sandwich panels considered in this research work are: (a) Honeycomb core, (b) Truss and Z core, (c) Foam core. The present study has found that (i) For a honeycomb core sandwich panel in due consideration to space constraint, the better acoustic comfort can be achieved by reducing the core height and increasing the face sheet thickness. (ii) It is demonstrated that, for a honeycomb core sandwich panel, vibration and acoustic response is not sensitive to the cell size. (iii) It is observed that, triangular core gives better acoustic comfort for the truss core sandwich panel compared to other type of core. (iv) For foam core sandwich panels, it is observed that sandwich panel with carbon-epoxy (high stiffness) face sheet radiates less sound in the lower frequency range (0–100 Hz). While the sandwich panel with Titanium (high density) face sheet radiates less sound at the higher frequencies. In order to reduce the preprocessing time and computational effort throughout the analysis in the present study, equivalent 2D elastic properties are calculated and used to find out the vibration and acoustic response characteristics.

5. Conclusion Numerical analysis of vibro acoustic behavior of sandwich panels with various cores has been carried out. In order to reduce the preprocessing time and computational effort through out the analysis in the present study, equivalent 2D elastic properties are calculated and used to find out the vibration and acoustic response characteristics. Accuracy of the result is ensured by the validation studies on natural frequency and sound response evaluation. The free vibration characteristics comparison of 3D FEM model and 2D FEM model has very good agreement in its results. The below mentioned scrutinies are made with respect to vibration and sound response characteristics of sandwich panels: • In honeycomb core sandwich panel the effect of face sheet thickness on vibration and sound radiation characteristics are significant. • Reduced sound power level can be achieved in lower core height honeycomb core sandwich panel. • One can select cell size as the parameter to reduce the weight with out affecting the sound and vibration characteristics. • The triangular core sandwich panel will be suitable among the different core topologies of truss core sandwich panel for better acoustic comfort due to the increased transverse shear stiffness and reduced radiation modes in the frequency range considered in this research work. • The effect of high density (Titanium) and high stiffness (Epoxy carbon) face sheet material and common aerospace material Aluminium is studied on foam core sandwich panels. From the results, epoxy carbon face sheet radiates less sound in the region up to 100 Hz and Titanium radiates less sound in higher frequencies compare to aluminium foam core sandwich panel. • For the wide range of frequencies, foam core with titanium as face sheet material can be used for less radiation of sound. The distinct results obtained in the present work using 2D FEM model can be used in the design of aerospace structures where acoustic comfort is required.