Dynamic Resonance of Curved Panels in Adverse Hygrothermal Environment

The present paper deals with the dynamic resonance of composite curved panels subjected to periodic dynamic loadings. The effects of various parameters of four-sided clamped composite curved panels at elevated temperatures and moisture concentrations on the principal instability regions are investigated by finite element method which is used to study the antisymmetric angle-ply square plates. The results show that instability of composite plates occurs for different parameters in adverse hygrothermal environment. The experimental and numerical investigation is also carried out for four-sided clamped boundary condition for vibration and buckling of curved panels in hygrothermal environment. 1. Introduction Structural elements under in-plane periodic forces may undergo unstable transverse vibrations, leading to parametric resonance, due to certain combination of the values of in-plane load parameters and natural frequency of transverse vibration. This instability may occur below the critical load of the structure under compressive loads over a range or ranges of excitation frequencies. Several means of combating parametric resonance such as damping and vibration isolation may be inadequate and sometimes dangerous with reverse results. A number of catastrophic incidents can be traced to parametric resonance. In contrast with the principal resonance, the parametric instability may arise not merely at a single excitation frequency but even for small excitation amplitudes and combination of frequencies. Thus, the parametric instability characteristics are of great technical importance for understanding the dynamic system under periodic loadings. The distinction between good and bad vibration regimes of a structure, subjected to in-plane periodic loading, can be made through an analysis of dynamic instability region (DIR) spectra. The calculation of these spectra is often provided in terms of natural frequencies and the static buckling loads. So, the calculation of these parameters with high precision is an integral part of dynamic instability analysis of composite plates and shells in adverse hygrothermal environment. A review of earlier works on vibration and stability of plates subjected to thermal loadings is given by Tauchert [1]. A recent review of parametric instability studies is carried out by Sahu and Datta [2] who studied the dynamic stability of laminated composite curved panels with cutouts subjected to in-plane static and periodic compressive loads. L.-W. Chen and Y. M. Chen [3] studied the free vibration of the laminated rectangular composite