Belirli sıcaklık ve sürelerde kürlenen hibrid tabakalı kompozit plakalarının titreşim davranışlarının incelenmesi

Laminated composite plates are used most of industrial applications such as aviation, marine and automobiles industries. The laminate composite plates can be classified as anisotropic, isotropic, orthotropic etc. in terms of fiber orientation and plate mechanical behavior. Due to several parameters affected the mechanical behavior of laminated composited plates it is so much significant to foreseen the probable behaviors them. Especially vibration analysis has to be observed in the laboratory before full scale applications to save cost and time. There are many technics to determine the plate natural frequencies which are very important for understanding the vibration behaviors under dynamic loads. In this work natural frequencies were calculated by using the classical thin plate theory. Furthermore, to calculate the natural frequencies algebraically is required the rectangular composite plates’ used in the test [A], [D],[B] matrix elements. In this study, symmetrical laminated rectangle orthotropic that is being considered in plane tension; glass/epoxy, carbon/epoxy and carbon/epoxy hybrid composite plates with 4 different fiber directivity angle are investigated by means of their vibration behavior and their natural frequencies are studied with using Rayleigh–Ritz method algebraically and after that these results are compared with experimental modal analysis. Each laminate which is cured at 120 oC consist of 8 plies whose thickness is 0.25 mm has been performed vibration test by impact hammer testing method. By means of computer software obtained frequency response function is processed and acquired natural frequency for each mode. Investigations have concluded that the first six modes are enough for engineering applications. It is figured out that there is an average 5% deviation between algebraic results and experimental results. It is believed this deviation is the result of experimental conditions, classical lamination theory assumptions that is used to determine material properties and nonhomogeneous conditions of produced material. It is concluded that the natural frequencies by means of materials, for the same methods, carbon/epoxy’s natural frequency is approximately twice compared with glass-carbon/epoxy materials. Main reason of this statement is carbon fiber which is more rigid than glass produces a higher elastic matrix and this creates higher vibration frequencies. In order to see the effects of fiber support angles to the vibration behaviors, hybrid composite plates made of glass-carbon/epoxy are manufactured with 0o, 15o, 30o ve 45o degrees fabric fiber and their vibration behaviors are investigated. Because of using fiber as fabric material, there is not much change occurred and the biggest change seen with 30o degree support angle.