نوع مقاله : مقاله پژوهشی
دانشکده مهندسی مکانیک، دانشگاه صنعتی شریف
عنوان مقاله [English]
Magnetic shape memory alloys (MSMAs) are a new class of smart materials which are good candidates for energy harvester, actuator and sensor systems due to their special properties such as high reversible strain, high fatigue life and fast time response. In order to use these materials in mentioned systems, a returning mechanism is always needed to return the specimen to the initial situation. Common method in energy harvesters is applying a bias magnetic field, but in this paper, the function of returning mechanism is improved by applying a bias stress which works together with the bias field. For this purpose, the influence of exerting a compressive stress along the bias field direction on a single crystal of a magnetic shape memory alloy is addressed. This compressive stress can be caused by a pre-strain or a spring-based system. To achieve this aim, general equations of problem in 2-dimentional loading situation is derived by using existing thermodynamic-based models, and in simulation section, the effect of the biasing compressive stress on magneto-mechanical characteristics of material is investigated by altering this stress in different situations. After applying this stress, it is illustrated that the returning mechanism shows a better performance in the sense that the amount of magnetization variation of material, which influences output voltage, increases. It is also demonstrated that completely removing the bias field is impossible and the best function is in 0.24 tesla of magnetic field with 0.3 MPa compressive stress.