Abstract

In the last two decades, the Out-of-Autoclave (OOA) manufacturing process has been mainly established to replace the conventional autoclave curing technology due to the notable techno-economic features. The principal idea of OOA processing is to facilitate fabrication of composites with the same required material performance as autoclave-cure systems, whereas utilizing more economical and light-weight equipment. The present research work aims at application of an unconventional approach to efficiently and effectively identify the viscoelastic material properties (storage and loss moduli) of composite laminates fabricated using OOA manufacturing process. First, the in-plane viscoelastic parameters of a highly directional OOA prepreg system (a high-modulus carbon/epoxy composite material) are identified experimentally using the dynamic mechanical analysis (DMA). DMA testing is performed on unidirectional sample coupons with different thicknesses and using two distinct DMA clamp configurations. To assess the accuracy of the measured properties, a finite element (FE) model based on the first-order shear deformation theory is developed and programmed in the MATLAB environment using DMA test data to evaluate the fundamental damping factors and the first three resonance frequencies of unidirectional laminated beam and plate components. Subsequently, a modal experimental test has been conducted to evaluate the modal characteristics of the fabricated unidirectional beams as well as thin to moderately thick plates clamped at one end (CFFF) in response to an impact excitation. It has been demonstrated that a good agreement exists between modal experimental test results and those obtained from the FE model on the basis of measured material properties using the DMA three-point bending clamp configuration. Using the FE model, the effect of fiber orientation on the fundamental damping factor in a unidirectional beam under CFFF boundary condition has subsequently been investigated and then assessed experimentally for selective fiber orientations. Finally, the developed FE model has been utilized to investigate the effect of lamination sequence, number of layers, structural geometry and boundary conditions of square laminated plates on the natural frequency and loss factor associated with the fundamental mode of flexural free vibration. The optimal values have also been identified, considering unidirectional, cross-ply, and angle-ply square laminates under combined clamped and free boundary conditions.