Vibration and buckling of composite twisted Panels subjected to hygrothermal loading

Abstract

The twisted composite cantilever have significant applications in aeronautical and aerospace industry civil, naval and other high-performance engineering applications due to their light weight, high-specific strength and stiffness, excellent thermal characteristics, ease in fabrication and other important specialties These structural members are often exposed to various service loads during their entire service life. The presence of temperature and moisture concentration in the environment may greatly reduce the stiffness and strength of the structures and may affect some design parameter such as vibration and stability characteristics of the structures. To avoid these typical problems caused by vibrations and stability, it is important to find out natural frequency, static stability of the composite laminated twisted cantilever panels under hygrothermal conditions. Therefore the vibration and stability behavior of laminated composite twisted panels subjected to hygrothermal conditions are studied in the present investigation. A simple laminated model is developed for the vibration and stability analysis of laminated composite pre-twisted cantilever panel subjected to hygrothermal conditions. A computer program based on FEM in MATLAB environment is developed to perform all necessary computations. Here an eight noded isoparametric quadratic shell element with five degrees of freedom per node is used based on FSDT theory with hygrothermal loading. Element elastic stiffness matrices, mass matrices, geometric stiffness matrix due to hygrothermal loads and load vectors are derived using the principle of minimum potential energy. The influences of various parameters such as angle of twist, aspect ratio, ply-orientation, geometry and number of layers of laminate are studied on the vibration and buckling characteristics of laminated pre twisted cantilever panels for different temperatures and moisture concentrations.