This article focuses on dynamic stability of smart sandwich beams resting on Winkler elastic foundation subjected to harmonic axial loads. To increase the dynamic buckling load and the stability region of the beam, an electro-rheological layer is adhered as a core. The finite element method is employed to derive a three layer smart sandwich beam element. By inspecting dynamic response of the beam in different load amplitudes, critical dynamic loads are calculated. Parametric study is done to investigate effects of various parameters such as beam geometry, foundation stiffness, static load, applied voltage and properties of core layer on critical dynamic loads and stability regions of the beam. This study indicates that by applying electric field to the electro-rheological core, dynamic critical load and consequently, dynamic stability of the beam increase efficiently. Furthermore, the elastic foundation reduces the unstable region and increases the critical dynamic load of the smart beam. Proper use of these parameters makes the beam less sensitive to axial harmonic loading by relocating the instability region.

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