In great harmony with the green energy, energy harvesting from ambient vibration has been attracted so many researchers towards saving our environment in near future, since last decade. However, linear energy harvesters suffer from narrow operating bandwidth and make them highly inefficient in various vibration environments. Moreover, brittleness and high rigidity of piezoelectric-ceramic materials make them unfavorable to employ for practical applications. In this paper, in order to improve the capability of the piezoelectric energy harvester (PEH) in capturing energy from broader and more complex excitations, magnetoelastic structure [1] with geometric nonlinearity is presented. Furthermore, to remove the brittleness of the piezoelectric-ceramics and reduce the stress concentration in layer, functionally graded piezoelectric materials (FGPMs) are introduced which are a promising solution to increase the durability of piezoelectric devices [2]. Although the behavior of FGPM in sensors and actuators was studied considerably, functionally graded piezoelectric energy harvester (FGPEH) has not been received much investigation yet. As investigated in Ref. [3] ceramic-polymer composites are new class of materials which have the high electromechanical coupling coefficients while having flexibility, low density and high strength.

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