Finite element simulation for design optimisation of shape memory alloy spring actuators

Abstract

PurposeThe purpose of this paper is the optimisation of shape memory alloy (SMA) spring actuators. The purpose of these actuators is to control active endoscopes. The objective for such endoscopes is to minimize one patient pain during operation.Design/methodology/approachA range of recently published (1990‐2002) works, which aim to provide models for SMA actuators, do not focus on the simulation and on the design of such actuators. SMAs have two main characteristics, namely the phase change and non‐linear behaviour in each phase. The proposed model is based on a mixed approach combining an Euler‐Bernoulli beam model and a bi‐dimensional finite element model. It allows the modelling of plastic behaviour and drives the phase evolution in the beam cross‐section.FindingsThe physical properties of SMAs are described and modelled. A new beam model and a numerical algorithm are proposed. Preliminary results demonstrate the performance of our method on two problems and lead to determine the actuator capability. The resulting actuator model is then integrated into an optimisation process based on genetic algorithms. The overall approach provides a design tool for SMA spring actuator subjected to design constraints.Research limitations/implicationsThe proposed method is only validated for our practical purposes. However, we believe that the optimisation methodology may have other implications in structure design.Originality/valueThis paper provides an optimisation approach that is valuable for scientists and engineers in engineering computations.

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