Dynamic stability of composite shells subjected to hygrothermal enviornment

摘要: Structural components subjected to in plane periodic loads may undergo instability due certain combinations of natural frequency and load parameters which is called parametric resonance. Composite structural are often various environmental during their service life. The presence temperature moisture concentration significantly reduce the stiffness strength structures affect some design parameter such as vibration stability characteristics structures. To avoid typical problems caused by vibrations stability, it important determine frequency, critical buckling excitation composite laminated structures, under hygrothermal conditions. Therefore vibration, dynamic behavior shells loadings studied present investigation. A simple model developed for analysis computer program based on FEM MATLAB environment perform all necessary computations. An eight-node isoparametric element employed with five degrees freedom per node. Element elastic matrices, mass geometric matrix mechanical vectors derived using principle minimum potential energy. They evaluated Gauss quadrature numerical integration technique. Quantitative results presented show effects curvature, ply-orientation, degree orthotropy, geometry number layers laminate different temperatures concentrations.