The invention relates to devices that produce displacements and/or forces (defined as actuators), when a magnetic field source(s) is (are) placed in such a way that the resulting magnetic field is of suitable strength and orientation in relation to the actuating element made from a Magneto-Mechanical Adaptive (MMA) material, so as to produce the desired displacement of the MMA element; or to devices that dampen mechanical vibrations by absorbing the vibration energy into an MMA element and/or by converting the vibration energy into electric power in the device and/or senses displacement, velocity or acceleration. The electric energy can be dissipated to heat or led out from the device. In the latter case, the device works as a power generator. The principle of using the devices as sensors is also described. The MMA material here is defined as a material whose dimensions change when a magnetic field or stress is applied to it, based on twin boundary or austenite-martensite phase boundary motion or magnetostriction.