A Homogenized Free Energy Model for Hysteresis in Thin-film Shape Memory Alloys
نویسندگان
چکیده
Thin-film shape memory alloys (SMAs) have become excellent candidates for microactuator fabrication in MEMS due to their capability to achieve very high work densities, produce large deformations, and generate high stresses. In general, the material behavior of SMAs is nonlinear and hysteretic. To achieve the full potential of SMA actuators, it is necessary to develop models that characterize the nonlinearities and hysteresis inherent to the constituent materials. We develop a model that quantifies the nonlinearities and hysteresis inherent to SMAs. The model is based on free energy principles combined with stochastic homogenization techniques. The fully thermomechanical model predicts rate-dependent, polycrystalline SMA behavior, and it accommodates heat transfer issues pertinent to thin-film SMAs. We illustrate aspects of the model through comparison with thin-film SMA superelastic and shape memory effect hysteresis data.
منابع مشابه
A Free Energy Model for Thin-film Shape Memory Alloys
Thin-film shape memory alloys (SMAs) have become excellent candidates for microactuator fabrication in MEMS. We develop a material model based on a combination of free energy principles in combination with stochastic homogenization techniques. In the first step of the development, we construct free energies and develop phase fraction and thermal evolution laws for homogeneous, single-crystal SM...
متن کاملExperimental Hysteresis Identification and Micro-position Control of a Shape-Memory-Alloy Rod Actuator
In order to exhaustively exploit the high-level capabilities of shape memory alloys (SMAs), they must be applied in control systems applications. However, because of their hysteretic inherent, dilatory response, and nonlinear behavior, scientists are thwarted in their attempt to design controllers for actuators of such kind. The current study aims at developing a micro-position control system ...
متن کاملA 3d Micro-Plane Model for Shape Memory Alloys
are compared with the experimental results. In these test results the shape memory alloys behavior as: super elasticity under various temperatures, loading rate effects, asymmetry in tension and pressure, various loops of loading and unloading, hydrostatic pressure effects, different proportional tension-shear biaxial loading and unloading, and also deviation from normality due to non-proportio...
متن کاملHysteresis and phase transitions for 1D and 3D models in shape memory alloys
By means of the Ginzburg-Landau theory of phase transitions, we study a non-isothermal model to characterize the austenite-martensite transition in shape memory alloys. In the first part of this paper, the onedimensional model proposed in [3] is modified by varying the expression of the free energy. In this way, the description of the phenomenon of hysteresis, typical of these materials, is imp...
متن کاملNonlinear Thermo-Mechanical Behaviour Analysis of Activated Composites With Shape Memory Alloy Fibres
General thermo-mechanical behavior of composites reinforced by shape memory alloy fibers is predicted using a three-dimensional analytical micromechanical method to consider the effect of fibers activation. Composite due to the micromechanical method can be exposed to general normal and shear mechanical and thermal loading which cause to activate the shape memory alloy fibers within polymeric m...
متن کامل