Amin Jafari  Amir Hossein Kazemian  Hossein Rahmani

10.1007/s12221-024-00503-w

Anisotropic composite Modal analysis COMSOL software Curvature radius Natural frequencies

This study involves the fabrication of aluminum plates reinforced with layers of glass composite (E-glass/epoxy) with varying curvatures. Subsequently, modal analysis was conducted on these plates with the objective of determining the natural frequencies and corresponding mode shapes for the first five modes. A comparative analysis was carried out by comparing the results with curved plates made of pure aluminum and pure glass composite materials of identical dimensions. For this purpose, the first-order shear deformation theory was applied to derive the vibration equation governing the behavior of the curved plates, which was subsequently utilized for numerical modeling using the COMSOL software. A comparative analysis was undertaken between the experimental and numerical outcomes, revealing a satisfactory agreement between the two sets of data. Through an examination of the frequency spectrum, mode shapes, and the influence of curvature on natural frequencies under free boundary conditions, it was established that the material composition of the structure, boundary conditions, and panel curvature radius exert a significant effect on the natural frequencies and corresponding mode shapes. Specifically, the natural frequencies of aluminum plates reinforced with glass/epoxy composite material, across all curvature radii and with the same thickness, were found to be higher than those of pure aluminum as well as curved plates made solely from glass composite material. Additionally, an increase in the curvature radius for each mode was found to correspond to a decrease in the associated frequency value. For instance, the mode with the highest frequency of 759.84 Hz was identified as the fifth mode with a curvature radius of 60 mm, while the lowest frequency of 32.8 Hz was observed in the first mode of a flat plate with an infinite curvature radius. Among plates of specific dimensions and curvature radii, the flat plate with an infinite curvature radius exhibited the lowest natural frequency. Moreover, it became evident that as the number of modes increased, the frequency values for each curvature radius exhibited an upward trend. Furthermore, it was noted that changes in curvature had a lesser effect on the first natural frequency compared to the other modes, regardless of the boundary conditions. By examining the frequency spectrum, mode shapes, and the influence of curvature on the natural frequencies under free boundary conditions, it was established that the boundary conditions and curvature of the panel significantly affected the natural frequencies and corresponding mode shapes. Specifically, an increase in the curvature radius for each mode corresponded to a decrease in the associated frequency value. The mode with the highest frequency was identified as the fifth mode with a curvature radius of 60 mm, exhibiting a frequency of 759.84 Hz. Conversely, the mode with the lowest frequency was observed as the first mode with a curvature radius of 100 mm, presenting a frequency of 59.78 Hz. Among the plates encompassing distinct dimensions and curvature radii, the planar plate with an infinite curvature radius demonstrated the lowest natural frequency value. Furthermore, it was evident that as the mode number increased, the frequency value for each curvature radius also exhibited an upward trend. Additionally, it was noted that alterations in curvature had a lesser impact on the first natural frequency compared to the other modes, irrespective of the boundary conditions.