Effect of Variation of Fibre Orientation on the Natural Frequency of a CFRP Conical Sandwich Structure

Process variability exists in the fabrication of any Carbon Fibre Reinforced Plastic (CFRP) structure which may affect the design parameters resulting in underestimating or overestimating the performance. One such variability occurs while laying the prepreg as the fibre orientation of each ply depends on parameters like prepreg sector, layup details, and the profile on which it is being laid. Truncated conical structure induces inherent variation in fibre orientation due to its geometry. The effect of variability in fibre orientation resulted during fabrication, on the natural frequency of a CFRP truncated conical sandwich structure is studied and presented in this paper. The variation of fibre angle is accounted in the Finite element (FE) model of the truncated conical shell by dividing each ply into different sectors and strips. Each strip will be having a constant and non-identical fibre orientation with respect to the generator (which is assumed to be at the centre of the sector). This variation of fibre angle for each ply causes changes in the layup angle for each strip and its ply properties. The equivalent material properties variation with respect to the designed configuration, i.e. having constant fibre orientation throughout the ply is also highlighted.