Based on nonlocal strain gradient theory approach, we have analyzed the nonlinear dynamic response and vibration of sandwich thick plates with functionally graded (FG) face sheets and FG porous core subjected to mechanical, thermal and blast loads on elastic foundations. Three types of porosity, including symmetric porosity distribution, non-symmetric porosity distribution, uniform porosity distribution have been considered of sandwich plate. The system of dynamic governing equations of motion

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... s obtained by utilizing Hamilton's principle and solved by Bubnov-Galerkin method for a case of simply supported sandwich plate. Numerical results are presented and verified with other studies. The influence of nonlocal and strain gradient parameters, materials and porosity volume fraction, geometrical characteristics and parameters of elastic foundations on fundamental frequencies and dynamic response of the sandwich plates are elucidated.