Free Vibration Characteristics of FG-GRC Sandwich Shallow Shells with Porous Core in Thermal Environments

Background

The doubly-curved sandwich shells find widespread applications as light structural elements in most engineering applications such as large-span roofs, aircraft components and nuclear power plant domes. The free vibration behaviour of sandwich shells with a porous core and functionally graded graphene-reinforced composite (FG-GRC) face sheets are highly dependent on the shell curvature and porosity distribution across the shells when operating in thermal environments.

Purpose

A free vibration analysis of FG-GRC sandwich shallow shells with porous core under thermal environments is presented considering the influence of shell geometry, graphene grading and porosity distribution patterns.

Method

In the present work, a finite element (FE) based formulation in the framework of higher-order shear deformation theory (HSDT) is developed to investigate free vibration characteristics of sandwich shallow shells with FG-GRC face sheets and porous core. The temperature-dependent effective properties of the GRC laminate are evaluated employing the extended Halpin–Tsai model.

Results

The non-dimensional frequencies are studied based on the variations in crucial parameters such as porosity coefficient, porosity distribution, graphene grading pattern, core-to-face sheet thickness ratio, curvature ratio, geometrical characteristics, boundary conditions and thermal environments. The presented results are originally based on the developed higher-order FE formulation.

Conclusions

An increase in the porosity coefficient of the core results in an increase in the natural frequency of the sandwich shell for all types of porosity distributions considered. The natural frequencies are found to decrease with a rise in the curvature ratio and operating temperature.

Applications

The results of the present study will be useful in the safety evaluation, dynamic analysis and reliable design of the FG-GRC sandwich doubly-curved shells with porous core considering their widespread engineering applications.