In this work, the natural frequencies and mode shapes of a number of cantilever glass fiber reinforced polymer composites (GFRPCs) and carbon fiber reinforced polymer composites (CFRPCs) are numerically obtained using the commercial finite element analysis software (ANSYS). The laminates under study include 8 ply cantilevered plates having a plate aspect ratio of 2 and fiber volume fractions of 0.3, 0.4, 0.5, and 0.6. The finite element analysis procedure is described. The natural frequencies and mode shapes calculated using ANSYS are first validated with the results obtained from previous literature. The agreement between the two results is found to be excellent. The effect of change in the matrix material, hybridization, and laminate stacking sequence on the natural frequencies and mode shapes are also investigated. It is found that hybridization and orientation of the outermost layer has more significant influence on the natural frequencies of the laminated composite plates compared to fiber volume fraction and change in the matrix material.
Ti 2 AlC x ceramic was produced by reactive hot pressing (RHP) of Ti:Al:C powder mixtures with a molar ratio of 2:1:1-.5 at 10-20 MPa, 1200-1300 • C for 60 min. Xray diffraction analysis confirmed the Ti 2 AlC with TiC, Ti 3 Al as minor phases in samples produced at 10-20 MPa, 1200 • C. The samples RHPed at 10 MPa, 1300 • C exhibited ≥95 vol.% Ti 2 AlC with TiC as a minor phase. The density of samples increased from 3.69 to 4.04 g/cm 3 at 10 MPa, 1200 • C, whereas an increase of pressure to 20 MPa resulted from 3.84 to 4.07 g/cm 3 (2:1:1 to 2:1:.5). The samples made at 10 MPa, 1300 • C exhibited a density from 3.95 to 4.07 g/cm 3 . Reaction and densification were studied for 2Ti-Al-.67C composition at 10 MPa, 700-1300 • C for 5 min showed the formation of Ti-Al intermetallic and TiC phases up to 900 • C with Ti, Al, and carbon. The appearance of the Ti 2 AlC phase was ≥1000 • C; further, as the temperature increased, Ti 2 AlC peak intensity was raised, and other phase intensities were reduced. The sample made at 700 • C showed a density of 2.87 g/cm 3 , whereas at 1300 • C it exhibited 3.98 g/cm 3 ; further, soaking for 60 min resulted in a density of 4.07 g/cm 3 . Microhardness and flexural strength of Ti 2 AlC 0.8 sample were 5.81 ± .21 GPa and 445 ± 35 MPa.
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