3.2.2. Effect of Curvature

Two forms of doubly curved shell panels (SPH and HPR) with *a*/*b* = 1, *a*/*h* = 20,*Rx* = *Ry* = *R*,(0/90)5, *V*∗ *CNT* = 0.17 were considered, to study the effect of curvature on the non-dimensional frequencies ω. The results are shown in the Figure 3a,b. These figures indicate that at the small value of *R*/*a*, the SHP panels have a much higher non-dimensional frequency than HPR panels. The non-dimensional frequencies of the SHP panels decrease, while those of HPR panels increase with the increase of *R*/*a* ratio from one to a specific value. After this value, the non-dimensional frequencies of both SHP and HPR panels have approximate values and seem to be unchanged.

**Figure 3.** Effect of *R*/*a* ratio on the frequency parameter ω of FG-CNTRC shell panels. (*a*/*b* = 1, *a*/*h* = 20,*Rx* = *Ry* = *R*, (0/90)5, *V*<sup>∗</sup> *CNT* = 0.17): (**a**) SPH panel; (**b**) HPR panel.
