Arnaud Duval

Finite Element analysis of a shape memory alloy actuator for a micropump

Abstract This paper deals with a Finite Element (FE) behavior analysis of a shape memory alloy actuator for a micropump. It is composed of two membranes of NiTi shape memory alloy (SMA) in a martensitic state at room temperature. They have an initial flat shape and are bonded together with an intermediate spacer. The thermal loading allows the actuator to move up and down in the membrane normal direction. A detailed analysis of sensibility to material and geometric parameters of the SMA actuator is undertaken by FE method. The actuation capability and reliability are studied in order to lead to optimal parameters set providing a higher stroke (deflection) with a low heating temperature. The shape memory effect exhibited by these membranes is simulated by means of the phenomenological constitutive law based on Chemisky–Duval model [1] , [2] , and implemented in the Abaqus® FE code. The obtained numerical results were detailed proving the ability of the proposed modeling to reproduce the actuator behavior under thermal loading. This analysis showed that it is possible to provide a large stroke for a minimal geometry of the actuator.

Numerical tool for SMA material simulation: application to composite structure design

Composite materials based on shape memory alloys (SMA) have received growing attention over these last few years. In this paper, two particular morphologies of composites are studied. The first one is an SMA/elastomer composite in which a snake-like wire NiTi SMA is embedded into an elastomer ribbon. The second one is a commercial Ni47Ti44Nb9 which presents elastic–plastic inclusions in an NiTi SMA matrix. In both cases, the design of such composites required the development of an SMA design tool, based on a macroscopic 3D constitutive law for NiTi alloys. Two different strategies are then applied to compute these composite behaviors. For the SMA/elastomer composite, the macroscopic behavior law is implemented in commercial FEM software, and for the Ni47Ti44Nb9 a scale transition approach based on the Mori–Tanaka scheme is developed. In both cases, simulations are compared to experimental data.

Numerical Tool Based on Finite Element Method for SMA Structures Design

A macroscopic model for SMA materials is proposed. Thermodynamics considerations, strain mecanisms and numerical implementation in a commercial code are presented here. This numerical tool is used to design structures, such elastomer/SMA composites ribbons, and by adding scale transition schemes, this model is able to predict the behavior of allied SMA, like commercial Ni47 Ti44 Nb9 . Simulations in these two cases are compared to experimental datas.Copyright