FREE-VIBRATION OF FIBER-COMPOSITE THIN SHELLS IN A HOT ENVIRONMENT

Results are presented of parametric studies to assess the effects of v arious parameters on the free vibration behavior (natural frequencies) of [+/-theta](2) angle-ply fiber composite thin shells in a hot envir onment. These results were obtained by using a three-dimensional finit e element structural analysis computer code. The fiber composite shell is assumed to be cylindrical and made from T300 graphite fibers embed ded in an intermediate-modulus high-strength matrix (IMHS). The residu al stresses induced into the laminated structure during the curing are taken into account. The following parameters are investigated: the le ngth and the thickness of the shell, the fiber orientations, the fiber volume fraction, the temperature profile through the thickness of the laminate and the different ply thicknesses. Results obtained indicate that: the fiber orientations and the length of the laminated shell ha d significant effect on the natural frequencies. The fiber volume frac tion, the laminate thickness and the temperature profile through the s hell thickness had a weak effect on the natural frequencies. Finally, the laminates with different ply thicknesses had insignificant influen ce on the behavior of the vibrated laminated shell.