Smart actuators, such as shape memory alloy (SMA) and magnetostrictive actuators, exhibit saturation nonlinearity and hysteresis that may be symmetric or asymmetric. The Prandtl–Ishlinskii model employing classical play operators has been used to describe the hysteresis properties of smart actuators that are symmetric in nature. In this study, the application of a generalized play operator capa...

Pseudoelasticity and the shape memory e ect (SME) due to martensitic transformation and reorientation of polycrystalline shape memory alloy (SMA) materials are modelled using a free energy function and a dissipation potential. Three di erent cases are considered, based on the number of internal state variables in the free energy: (1) Austenite plus a variable number of martensite variants; (2) ...

A novel Shape Memory Alloy (SMA) actuator consisting of several thin NiTi bers woven in a counter rotating helical pattern around supporting disks is rst described. This structure accomplishes a highly e cient transformation between force and displacement overcoming the main mechanical drawback of shape memory alloys, that being limited strain. Time domain open loop experiments were then conduc...

Actual endoscopes and boroscopes, widely used in industry and in minimal invasive surgery, have considerable limitations, mainly due to their low number of degrees of freedom and their manual operation. Two different solutions for the electrical actuation of articulated endoscopes are presented in this paper. The technical constraints for this kind of application are very limited space for the ...

Although medical applications for shape memory alloys (SMA) now dominate in today’s market, there are many applications in the industrial sector which have reached large volume production that far surpass the material usage in the medical fields. In the early growth of shape memory alloy technology the most important applications were for fasteners and couplings, mainly in the military sector. ...

The seismic performance of hybrid braces composed of steel and shape memory alloy (SMA) was investigated in this paper. Six types of hybrid braces were used, constituted by SMA content of 0, 20, 40, 60, 80, and 100%. A nonlinear dynamic analysis was performed under El Centro earthquake records, with the maximum acceleration of 0.6g and 0.9g. Our results showed that the seismic performance, i.e....

Innovative Technology To improve steering precision in needles as well as hollow, flexible cannula, researchers at the University of Maryland have introduced discrete actuators along the length of the probing device. The probe (needle or cannula) can be bent in the required direction in real-time, allowing more areas of the body tissues to be targeted with greater accuracy. A shape memory alloy...

Shape memory alloys have been widely proposed as actuators, in fields such as robotics, biomimetics and microsystems: in particular spring actuators are the most widely used, due to their simplicity of fabrication. The aim of this paper is to provide a general model and the techniques for fabricating SMA spring actuators. All the steps of the design process are described: a mechanical model to ...