A nonlinear shell finite element formulation for shape memory alloy applications Edoardo Artioli (Roma Tor Vergata) In the last decades, the development of efficient computational models for the nonlinear analysis of structures made of shape memory alloys (SMA) has been one of the most important research activities. The shape memory alloys (SMA) represent one of the most interesting smart mater...

The purpose of this paper is to explain the thermodynamical and shape memory behaviour in comparison with structural parameters for Zr-based intermetallics a new class of potential shape memory alloys (SMA) for high-temperature applications [I]. Electrical resistivity, structural, shape memory and calorimetric measurements were carried out for the Zr2CuNi Zr,CuCo quasibinary cross-section. It w...

This paper describes a method for improving the speed of actuators based on shape memory alloys (SMA) by increasing the rate at which an SMA element can safely be heated. The method consists of measuring the electrical resistance of an SMA element, calculating a maximum safe heating current as a function of measured resistance, and ensuring that the actual heating current does not exceed this m...

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....

Components made of alloys with a magnetic shape memory (MSMA) are not commonly used in industrial systems or prototype solutions. The reasons behind this include the cost and implementation difficulties attached to MSMA alloys synthesis technology. The article presents the results of a prototype actuator in which the active element is a rod made of Ni-Mn-Ga alloy and with dimensions of 2x1x20 m...

Shape-memory alloys are known to have two unique characteristics: a shape-memory effect and superelasticity. The shape-memory effect is the ability of the alloys to revert to their initial shape upon being heated until they enter their phase transformation temperature. Superelasticity is where the alloys exhibit comparatively large recoverable strain. Different families of shape-memory alloys h...

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...

Irregularities in bridge pier stiffness concentrate the ductility demand on short piers; while not operating on the longer and more flexible ones. The existence of non-uniform, ductility demand distribution in bridges significantly influences seismic response. As such, this paper proposes a new approach for balancing the ductility demand in irregular bridges by utilizing shape memory alloys (SM...

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....

Shape memory alloys (SMAs) can produce large strains when deformed (e.g., up to 8%). Heating results in a phase transformation and associated recovery of all the accumdated strain. This strain recovery can occur against large forces, resulting in their use as actuators. Thus an SMA element can integrate both sensory and actuation fitnctions, by inhercEtly s e x k g a c h m ~ c ia temperature an...