In this paper, a modular microactuator based on shape memory alloy (SMA) actuation to drive the joints of a microgripper is described. Its design is a combination of two SMA actuators installed on the links of a special mechanism : one of them drives the rotation of the joint and the other one produces the necessary force to manipulate objects. An accurate model of the thermo-mechanical behavio...

Shape memory alloy (SMA) structures are usually analyzed numerically; there are very few closed-form solutions in the literature. In this paper, we study the pure torsion of SMA bars with circular cross sections. First, a three-dimensional phenomenological macroscopic constitutive model for polycrystalline SMAs is reduced to the one-dimensional pure shear case and then a closed-form solution fo...

UNLABELLED Nickel-titanium shape memory alloy (NiTi-SMA) implants might allow modulating fracture healing, changing their stiffness through alteration of both elastic modulus and cross-sectional shape by employing the shape memory effect (SME). HYPOTHESES a novel NiTi-SMA plate stabilizes tibia osteotomies in rabbits. After noninvasive electromagnetic induction heating the alloy exhibits the ...

Based on the experimental results and the finite element analysis, a constitutive model is proposed for two phase shape memory alloys by introducing a compensative volumetric strain into a constrained relationship between the two phases, accounting for the reduced constraint due to the growth of martensite band. The pseudoelasticity of NiTi shape memory alloy micro-tube, subjected to pure tensi...

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 eecient 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...

The paper presents the design strategies for two typical configurations of intelligent systems, using as active elements the Shape Memory Alloy (SMA) cantilever strip and the SMA helical spring. Based on the advantages and unique properties of shape memory alloys the authors defined the operating mode, the mechanical considerations and the design assumptions for these two examples. It also incl...

A thermomechanical boundary value problem and constitutive model are presented for a shape memory alloy (SMA) wire under uniaxial loading. The intent is to develop a one-dimensional continuum model of an SMA element that includes all the relevant thermomechanical couplings and is suitable for inclusion in finite element analyses. Thermodynamic relations are derived from phenomenological conside...

in this paper the design of a biped robot actuated with shape memory alloy (sma) springs with minimum degrees of freedom is presented. sma springs are a class of smart materials that are known for their high power to mass and volume ratios. it was shown that utilizing spring type of smas have many advantages as large deformation, smooth motion, silent and clean movement compared to ordinary typ...

This paper describes the objectives of this project, which are to design artificial limbs that are lightweight, compact and dexterous, that mimic human anatomy and maintain a high lifting capability. The key to satisfying these objectives is the use of Shape Memory Alloy (SMA) artificial muscles as actuators. A general methodology to find the placement of SMA wires to achieve desired ranges of ...

Brinson’s one-dimensional constitutive modeling for shape memory alloy (SMA) is extended to consider the asymmetric tensile and compressive behavior as well as the torsional behavior. The incremental finite element method using linear Timoshenko beam elements is formulated by the total Lagrangian approach for the superelastic, large deformation analysis of SMA helical springs. The NiTi helical ...