This work investigates the design of a vibration-powered generator with one rod (unimorph) of iron–gallium (galfenol) and compares it with its two-rod (bimorph) counterpart. Galfenol is a promising magnetostrictive material that combines high magnetic susceptibility and desirable mechanical properties and therefore very suitable for harvesting the vibration energy that involves bending stresses. In this study, an energy-based magnetoelastic model, so-called Armstrong model, is employed to predict the behavior of galfenol under multiaxial stresses. The Armstrong model of galfenol is implemented into a static 3D finite element model of the energy harvester by which the performances of the devices are predicted and experimentally observed. Copyright © 2012 John Wiley & Sons, Ltd.