This paper is concerned on the phase transformation mechanism of porous Shape Memory Alloys (SMAs). A unit-cell model is adopted to establish the constitutive relation for porous SMAs, the stress distributions, the phase distributions and the martensitic volume fractions for the model are then derived under both pure hydrostatic stress and uniaxial compression. Further, an example for the uniax...

Shape memory alloys (SMAs) offer a high power-to-weight ratio, large recovery strain, and low driving voltages, and have thus attracted considerable research attention. The difficulty of controlling SMA actuators arises from their highly nonlinear hysteresis and temperature dependence. This paper describes a combination of self-sensing and model-based control, where the model includes both the ...

The study of simple beams made of shape memory alloys (SMA) is very interesting for industrial and experimental reasons. In this paper, it is realised using strength of materials' approach: different kinematical and behavioural assumptions are successively used to solve circular and three supports bendings' problems. The kinematical ones consist in taking into account small or large displacemen...

A novel Shape Memory Alloy (SMA) actuator consisting of a number of thin NiTi bers woven in a counter rotating helical pattern around supporting disks is rst described. This structure can be viewed as a parallel mechanism used to accomplish a highly ee-cient transformation between force and displacement. The actuator overcomes the main mechanical drawback of shape memory alloys, that being limi...

In this paper we give a formal deenition of dissipative systems that is considerably more general than earlier deenitions. The measured output is irrelevant in this formulation. The key component of dissipation is an appropriate work rate. We also deene cyclo-dissipation and show how it can be used to obtain a suitable work rate. Using this idea, we propose a new work rate for the Preisach hyst...

the pseudo-elastic behavior of shape memory alloy (sma) truss and cantilever beam are investigated. brinson’s one-dimensional material model, which uses the twinned and detwinned martensite fractions separately as internal variables, is applied in the algorithm to establish the sma stress-strain characteristics. this material model also incorporates different young’s modulus for austenitic and ...

In the case of medical implants, foreign materials are preferential sites for bacterial adhesion and microbial contamination, which can lead to the development of prosthetic infections. Commercially biomedical TiNi shape memory alloys are the most commonly used materials for permanent implants in contact with bone and dental, and the prevention of infections of TiNi biomedical shape memory allo...

Shape memory alloy (SMA) thin films formed by sputter deposition have attracted considerable attention in the last decade. Current intensive research demonstrated that thin films' unique fine microstructure is responsible for superior shape memory characteristics in films, compared to that of bulk materials. Simultaneously, much effort has been taken in the development and fabrication of microd...

We have investigated the effect of pressure and thermal ageing on transformation behavior of Ni-%45.16Ti shape memory alloy. 70-320 MPa pressure was applied and annealed at 500 o C for 2 hour to see the effect of applied pressure on transformation temperature. It was observed that the starting and final temperature of austenit increased, the martensite start temperature almost remain constant a...

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...