This paper presents vibration analysis of FGM sandwich structure having intrinsic profile governed by refined higher order shear deformation theory(RHSDT) using isogeometric analysis (IGA). Functionally graded sandwich plates provide a wide range of application in aerospace, defence and aircraft industries due to their ability to distribute material properties to influence the thermo-mechanical properties as desired. In practical applications, these structures generally have holes and their response to loads are significantly affected due to cut-outs. IGA is primarily a NURBS based technique that is effective in solving higher order differential equation due to its inherent C1 continuity for single patch. Complex structures generally require multiple patches to accurately represent the geometry and hence there is loss of continuity at adjoining patch junctions. Therefore, patch coupling is desired to maintain continuity requirements throughout the domain. In this work, a novel strong coupling approach is provided that generates a well defined NURBS based model while achieving continuity for analysis of FGM plates. The methodology is validated by free vibration analysis of sandwich plate with present literature. The results are in good agreement with the analytical solution for different plate configuration and power law index. Numerical examples of rectangular and annular plates with holes are discussed with variable boundary conditions. Additionally, parametric studies are provided by varying the aspect ratio, porosity ratio and their influence on the natural frequency of the plate. REFERENCES [1] H. Nguyen-Xuan, L.V Tran, C.H Thai, S. Kulasegaram and S.P.A Bordas. Isogeometric analysis of functionally graded plates using a refined plate theory, Composites Part B: Engineering, 64:205-208, 2014. [2] C. L. Chan, C. Anitescu, and T. Rabczuk, Strong multipatch C1-coupling for isogeometric analysis on 2D and 3D domains, Computer Methods in Applied Mechanics and Engineering, 357:112599, 2019.