Thermal post-buckling and aeroelastic behaviour of shape memory alloy reinforced plates

Abstract

A novel concept is proposed: the use of shape memory alloy (SMA) to reduce panel thermal deflection and flutter responses. SMA has a unique ability to recover large pre-strains completely when the alloy is heated above the austenite finish temperature Af. The transformation austenite start temperature As for nitinol can be anywhere between -60 °F (-50 °C) and +340 °F (+170 °C) by varying the nickel content. During the recovery process, a large tensile recovery stress occurs if the SMA is restrained. The shape memory effect phenomenon is attributed to a change in crystal structure known as a reversible austenite to martensite phase transformation. This solid-solid phase transformation also gives a large increase in Young's modulus and yield stress. In this paper, a panel subject to the combined aerodynamic and thermal loading is investigated. A nonlinear finite element model based on the von Karman strain-displacement relation is utilized to study the effectiveness of an SMA-embedded panel on the flutter boundary, critical buckling temperature, post-buckling deflection and free vibration. The study is performed on an isotropic panel with embedded SMA. The aerodynamic model is based on the first-order quasi-steady piston theory. The dynamic pressure effect on the buckling and post-buckling behaviour of the panel is investigated by introducing the aerodynamic stiffness term, which changes the critical buckling temperature. Panels with SMA embedded in either the longer or shorter direction and either fully or partially embedded are investigated for post-buckling behaviour. Similarly, the influence of temperature elevation on the flutter boundary and vibration frequencies is investigated.

Aerospace applications of shape memory alloys

“…This behaviour is often secondary in other applications but can be very important in manipulating the dynamic response of a structure. In one study [40], it was shown that thermally-induced postbuckling deflection could be decreased by increasing the volume fraction of SMA fibres or the prestrain (detwinned strain) of the SMA. It also happened that the natural frequencies for each mode of vibration were decreased due to the added weight and reduced stiffness of the added SMA, thus changing the structural flutter response.…”

Analysis of SMA Hybrid Composite Structures in MSC.Nastran and ABAQUS

“…6 Several subsequent research efforts have investigated SMAHC laminates for a variety of applications. [7][8][9][10][11] The ECTE model has been used previously in a research code to analyze the static and dynamic response of beam and plate structures. 5,12,13 It is the objective of this study to demonstrate SMAHC structural analysis using the ECTE model within the framework of commercial finite element codes.…”

Macroscopic Mechanical Characterization of SMAs Fiber-Reinforced Hybrid Composite Under Uniaxial Loading

“…Recently, several theoretical and finite element models have been proposed to evaluate the effect of SMAs fiber when the composite structures subjected to various loading conditions (Ref [13][14][15][16][17][18][19][20]. For instance, Tawfik et al (Ref 13) utilized a nonlinear finite element model to study the effectiveness of a SMA-embedded isotropic panel on the critical buckling temperature, postbuckling deflection, free vibration, and flutter boundary.…”