Shape Memory Alloy Layer Research Articles

Simulation of Self Tuning Shape Memory Alloy Based PZT Energy Harvester

Shape Memory Alloy (SMA) is tuned to match the frequency of excitation with the resonance frequency. Simulation is carried out numerically using COMSOL 5.3 software. This model consists of cantilevered beam without tip mass, PZT layer, Aluminium beam and SMA layer. Lead Zirconium titanate (PZT – 5A) is used as PZT layer for the conversion of energy. Harvesters power frequency response for different frequency ranges are carried out. The maximum output is obtained in excitation frequency with SMA and the results were compared without SMA material. The numerical simulation of the Frequency Response Functions (FRF) was compared with the analytical frequency response functions of the harvester. The maximum difference between the numerical and analytical results is 9.77 % in FRF’s and 1.85 % in resonance frequency. Materials used are Lead Zirconium titanate (PZT – 5A), SMA material and Aluminium beam which reaches the scopes of journal.

Study on removal of recast layer of NiTi shape memory alloy machined with magnetic field-assisted WEDM-ECM complex process

Study on removal of recast layer of NiTi shape memory alloy machined with magnetic field-assisted WEDM-ECM complex process

Passive Damping of Solar Array Vibrations Using Hyperelastic Shape Memory Alloy with Multilayered Viscous Lamina

A novel passive vibration-damping device is proposed and investigated for a large deployable solar array. One strategy for achieving high damping in a solar panel is using a yoke structure comprising a hyperelastic shape memory alloy and multiple viscous adhesive layers of acrylic tape. The effectiveness of the proposed system in achieving a high damping performance was demonstrated by conducting free vibration and low-level sine sweep tests using a solar array, and a 0.75-m-long flexible dummy structure was simulated. We also investigated the dependence of the damping performance of the proposed structure on the number of viscous lamina layers. Finally, the damping characteristics of the proposed system were assessed under predictable on-orbit temperature conditions.

Flexible magnetoelectric sensor and nonvolatile memory based on magnetization-graded Ni/FSMA/PMN-PT multiferroic heterostructure

Flexible multiferroic heterostructures are promising to unveil technological developments in wearable magnetic field sensing, nonvolatile memory, soft robotics, and portable energy harvesters. Here, we report an enhanced and a zero-biased magnetoelectric (ME) effect in flexible, cost-effective, and room temperature sensitive Ni/FSMA/PMN-PT magnetization-graded ME heterostructure. Flexible Ni foil with −q (piezomagnetic coefficient) and the ferromagnetic shape memory alloy (FSMA; Ni-Mn-In) layer with +q offers the desired q-grading. The temperature-dependent dielectric behavior shows an anomaly in the martensite transformation regime of the FSMA layer. The Ni/FSMA/PMN-PT ME heterostructure exhibits noteworthy ME output of ∼3.7 V/cm Oe, significantly higher than Ni/PMN-PT (∼1 V/cm Oe). The q-grading-induced bending moment impedes the asymmetry-related flexural strain and strengthens the ME interaction. The zero-bias ME output of ∼0.4 V/cm Oe is ascribed to the interaction between q-grading-induced transverse magnetization and AC magnetic field. Ni/Ni-Mn-In/PMN-PT ME heterostructure displays excellent magnetic field sensing parameters: correlation coefficient, sensitivity, inaccuracy, and hysteresis of 0.99916, ∼0.74 mV/Oe, 1.5% full-scale output (FSO), and 1.8% FSO, respectively. The reversible and repeatable nonvolatile switching of the ME coefficient obtained with positive and negative electric fields is useful for next-generation memory devices. The flexible ME heterostructure shows no degradation in performance up to 1500 bending cycles. Such Ni/FSMA/PMN-PT based ME heterostructures are propitious for multifunctional flexible magnetic field sensors and nonvolatile memory applications.

Actuation based on phase transformations in microlayered architectures

The influence of phase transformations on the actuation capacity of microlayered architectures based on shape memory alloys is presented based on models developed based on the analysis of the phase transformations in each layer and on their contribution to the stress in the fil-substrate architecture. The analysis of the phenomena associated with the martensitic transformation allows the selection of the alloy composition to obtain a tuneable actuation in the desired temperature range as well as the profile of this operation based on the type of substrate used and its geometry as well as the fabrication parameters. The prediction of a microactuation profile is described for bimorph architectures with a film consisting of one or more shape memory alloy layers

Nonlinear Dynamic Analysis of Axially Moving Laminated Shape Memory Alloy Beam with 1:3 Internal Resonance.

The remarkable properties of shape memory alloys (SMA) are attracting significant technological interest in many fields of science and engineering. In this paper, a nonlinear dynamic analytical model is developed for a laminated beam with a shape memory alloy layer. The model is derived based on Falk’s polynomial model for SMAs combined with Timoshenko beam theory. In addition, axial velocity, axial pressure, temperature, and complex boundary conditions are also parameters that have been taken into account in the creation of the SMA dynamical equation. The nonlinear vibration characteristics of SMA laminated beams under 1:3 internal resonance are studied. The multi-scale method is used to solve the discretized modal equation system, the characteristic equation of vibration modes coupled to each other in the case of internal resonance, as well as the time-history and phase diagrams of the common resonance amplitude in the system are obtained. The effects of axial velocity and initial conditions on the nonlinear internal resonance characteristics of the system were also studied.

Bending model for functionally graded porous shape memory alloy/poroelastic composite cantilever beams

A new model is developed for bending of functionally graded (FG) porous shape memory alloy (SMA)/poroelastic composite cantilever beams. The model generalizes the ZM model for dense SMAs to cases involving potentially high degrees of porosity. The accuracy of the proposed model is verified against experimental data as well as simulations involving finite element analysis (FEA) of porous architected SMAs with fully detailed geometries. Using the new model, a bending theory is derived for a porous composite cantilever beam reinforced with a FG porous (FGP) SMA layer. The derivation involves expressing the effective material parameters of the porous SMA as polynomial functions of porosity, which facilitates analytical treatment of the bending theory. Moreover, the theory accounts for the distribution of solid phases within a beam cross section as a function of applied load during a complete loading cycle. Results such as the load-deflection behavior of the beam, as well as the location of the neutral axis and distribution of axial stress as a function of the applied load are validated against FEA data. The validated theory is further utilized to investigate the influence of several parameters on the behavior of the composite beam, including the index gradient, temperature, and thickness of the SMA layer.

A perturbation analysis in nonlinear free vibration of a microbeam reinforced by shape memory alloy layer based on the modified couple stress theory

Numerous applications have been found in various microelectromechanical systems for shape memory alloys. This study analyzes the nonlinear free vibrations of a sandwiched microbeam, consisting of a shape memory alloy core and two elastic layers on either side. The behavior of the shape memory layer is modeled with the one-dimensional Brinson model. The equation of motion is derived from Hamilton’s principle and the modified couple stress theory for the Euler–Bernoulli beam and then truncated into a reduced-order model through Galerkin’s technique. An approximate analytical solution is obtained using the Lindstedt–Poincare method for different temperatures. The effects of temperature, material length scale parameter, aspect ratio, and maximum vibration amplitude on nonlinear normalized frequency have been investigated. The results have been compared with those of some previous studies and can provide a better understanding of the design of sandwiched microbeams, which have a shape memory alloy layer.

Nonlinear free vibration and damping analysis of a microbeam with pseudoelastic shape memory alloy layer based on the modified couple stress theory

The aim of this investigation is to evaluate the size effects on the nonlinear free vibration of the sandwich composite microbeam with an extensible shape memory alloy layer in the midplane. A one-dimensional constitutive model is considered to simulate the pseudoelastic behavior of the shape memory alloy layer. The governing equation of motion is derived using the Euler–Bernoulli beam theory together with the modified couple stress theory through the Hamilton’s principle. Midplane stretching and phase transformation of the shape memory alloy which are sources of nonlinearity were considered, and a numerical solution method is presented. A damped response of the sandwich composite microbeam is observed because of the hysteresis behavior of the extensible shape memory alloy layer in the midplane. Results are appraised by comparing with the available literature. The influence of material length scale, temperature, and initial velocity on the loss factor and other pivotal vibrational behavior is evaluated. Results show that increasing the material length scale to thickness ratio has a decreasing effect on damping capacity.

A Model for FGM/SMA Bilayer Beams Accounting for Asymmetric SMA Behavior

A new model is proposed for bilayer cantilever beams consisting of shape memory alloy (SMA) and functionally graded material (FGM) layers and subjected to loading at the tip. The model accounts for tensile-compressive SMA behavior through the use of an appropriate set of constitutive relations and considers the deformation of the beam within the frame of the Timoshenko beam theory. The derivation of the model proceeds by first determining the correct sequence in which different solid phase structures develop within the SMA layer as the load is applied, resulting in the formation of distinct solid phase regions. The boundaries separating these regions are then located and used in deriving appropriate moment and shear force equations throughout a complete loading-unloading cycle. The model is capable of tracking the deviation of the neutral surface with respect to the mid-plane and the distribution of martensite in the beam as the load varies. The nonlinear variation of stress and strain in a cross section of the beam is also considered. Results of beam deflection and neutral surface deviation are presented and validated against finite element simulations of a 3D model of a beam consisting of a Nitinol and CNT-reinforced layers.

Vibratory Response Characteristics of High-Frequency Shape Memory Alloy Actuators

Abstract This paper presents a shape memory alloy actuator design using a bimorph structure capable of high-speed actuation and low power consumption. Two active layers of shape memory alloy wires are separated by a passive layer of thermoplastic polyurethane. This structure results in a bending actuator when current is alternated between the two active shape memory alloy layers. Actuators of lengths 20, 25, 30, 35, and 40 mm were tested at peak current input of 110, 120, 130, and 140 mA. The 40-mm actuator was shown to have a natural frequency of 11.4 Hz with a bending displacement of 26.4 mm perpendicular to the neutral position and a power input of 0.78 W (140 mA peak current input). A relationship between the input current and the resulting vibratory characteristics was found. As the current increases, the natural frequency decreases and the damping ratio increases. The experimental results are compared with a finite element method (FEM) vibration analysis and an Euler–Bernoulli cantilever beam equations.

Modeling the behavior of bilayer shape memory alloy/functionally graded material beams considering asymmetric shape memory alloy response

A new model is proposed to describe the response of laminated composite beams consisting of one shape memory alloy layer and one functionally graded material layer. The model accounts for asymmetry in tension and compression of the shape memory alloy behavior and successfully describes the dependence of the position of the neutral surface on phase transformation within the shape memory alloy and on the load direction. Moreover, the model is capable of describing the response of the composite beam to both loading and unloading cases. In particular, the derivation of the equations governing the behavior of the beam during unloading is presented for the first time. The effect of the functionally graded material gradient index and of temperature on the neutral axis deviation and on the overall behavior of the beam is also discussed. The results obtained using the model are shown to fit three-dimensional finite element simulations of the same beam.

Bending model for a laminated composite cantilever beam with multiple embedded shape memory alloy layers presenting tensile-compressive asymmetry

A new model is proposed for a composite laminated beam comprising multiple alternating shape memory alloy (SMA) and elastic layers. The model fully considers asymmetry in SMA behavior, which is found to significantly influence the behavior of the laminates. Moreover, the equations governing the response of the SMA-reinforced beams are derived for a complete loading-unloading cycle considering a Timoshenko beam deformation model combined with well-established constitutive relations for SMAs. The derivation procedure involves first identifying the solid phase structure of the beam for a given applied load, followed by integration of the stress and strain in a cross section to obtain moment and shear force equations. The influence of temperature, as well as of layer thickness and material properties on the bending response of the beam is investigated. The results obtained using the proposed model are found to agree with finite element simulations.

Post-buckling analysis of non-uniformly heated functionally graded cylindrical shells enhanced by shape memory alloys using classical lamination theory

Thermal post-buckling analysis of functionally graded cylindrical shells enhanced by shape memory alloys under uniform and non-uniform heating is presented in this article. Nonlinear equilibrium equations are derived based on the classical lamination theory and von-Karman nonlinear kinematic relations and post-buckling field is investigated using Galerkin method. For temperature dependency of material properties, a numerical solution is applied to solve the nonlinear equilibrium equation using finite difference method to solve the nonlinear heat conduction equation and layered model to evaluate the thermal stress of hybrid cylindrical shells. A closed-form solution is also presented for temperature independency of material properties. Brinson model is adopted to describe the thermo-mechanical behavior of shape memory alloys. Numerical results are presented for evaluating the effects of shape memory alloy layer and functionally graded material cylindrical shells properties on suppressing of the post-buckling path of hybrid cylindrical shells.

Delamination analysis in bimaterials consisting of shape memory alloy and elastoplastic layers

Bimetallic shape memory alloy composites, consisting of an active layer of shape memory alloy and a metallic elastoplastic passive layer, are used for designing the sensors and actuators. Delamination analysis in SMA/elastoplastic bimaterial composites is numerically investigated in this study due to the important effects of interface cracks on failure and load bearing response of such composites. It is known that homogeneous elastoplastic material and shape memory alloy show different path-dependent behaviors for prediction of energy release rate near the crack tip. Therefore, evaluation of J-integral for an interface crack between SMA and elastoplastic layers remains a highly complex issue in fracture analysis of such bimaterials. Presuming small-scale phase transformation and yielding zones, path dependency of J-integral for this composite is investigated for a range of mixed-mode loading conditions, and the elastoplastic material properties including the Young’s modulus, hardening slope and yield stress. In addition, the maximum transformation strain within the framework of J2 plasticity for the elastoplastic material and the thermo-mechanical coupling model of Boyd and Lagoudas for the shape memory alloy are studied. Finally, the influence of mixed-mode loading rates on the crack tip fields is comprehensively assessed.

Bending theory for laminated composite cantilever beams with multiple embedded shape memory alloy layers

In this article, a new analytical model is proposed for laminated composite cantilever beams consisting of multiple alternating superelastic shape memory alloy and elastic layers. The model is based on the Zaki–Moumni model for shape memory alloys combined with Timoshenko’s beam theory. The Zaki–Moumni model accounts for solid phase transformation as well as detwinning and reorientation of martensite under multiaxial thermomechanical loading conditions. Mathematical formulas are first derived to characterize the evolution of the solid phase structure within the beam with a prescribed load at the tip during loading and unloading. Analytical moment–curvature and shear force–shear strain relations are then obtained following the strength of materials approach. The present work is the first to fully develop the nonlinear expressions of the axial stress in terms of the distance from the neutral plane and to allow the description of the phase distribution in both the longitudinal and the transverse directions in the beam as the load evolves. The proposed model is validated against finite element analysis and high-accuracy numerical solutions. The influence of temperature and the number of shape memory alloy layers on the superelastic behavior of the laminate is also investigated.

Investigation of shape memory alloy embedded wind turbine blades for the passive control of vibrations

This paper investigates hybridized architectures of large wind turbine blade material with the aim to passively suppress uncontrolled vibration. The laminate composite layup of the blade was hybridized by embedding shape memory alloy (SMA) layers, in areas which are recognized as having a major role in the dissipation of energy. The embedded SMA thin sheet was laser patterned in order to improve the interface adhesion and to tailor the flexural stiffness requirement. The response of the blade with new architecture has been investigated in the time domain, to find an optimal composite layup in which the smallest amount of SMA is used while system damping is being maximized.

Electromechanical analytical model of shape memory alloy based tunable cantilevered piezoelectric energy harvester

The resonant frequency of electromechanical energy harvester should be tuned to ambient frequency so as to maximize the harvester power. In this paper, it is proposed to tune the natural frequency of the energy harvester by varying the martensite volume fraction (0–1) of shape memory alloy (SMA). It is found that the shifting of natural frequency is around 8–10% for first three modes of vibration. This paper presents the exact analytical solution for composite cantilevered energy harvester composed of piezoelectric energy harvester layer, substructure layer and SMA layer using the assumption of Euler–Bernoulli beam. The beam base displacement in transverse direction with small angular rotation is due to base excitation. The electromechanical coupled equations of response are derived and then reduced to harmonic behavior. The expressions for frequency response of voltage output, current output and power output are obtained. Finally, a parametric case study of composite cantilevered energy harvester with shape memory alloy and important behavior of the electromechanical coupled system for short circuit and open circuit behaviors are studied in detail.

Nanoscaled superelastic behavior of shape memory alloy/metallic glass multilayered films

Abstract The mechanical properties of multilayered films with alternate layers of shape memory alloy (SMA) and metallic glass (MG) were studied. Specifically, TiNi SMA and ZrCuAlNi MG were deposited alternately on the Si substrate using magnetron sputtering. The as-deposited multilayered film was amorphous. The annealing temperature was chosen judiciously to crystalize TiNi layer while ZrCuAlNi layer remained amorphous. The superelastic behavior of SMA/MG multilayered film was characterized using nanoindentation tests. The stress required to induce martensitic transformation of TiNi layer increased as the thickness of TiNi layer decreased. Also, the multilayered SMA/MG films were found to have the better deformation recovery after indentation unloading which could be due to the synergy effects of superelasticity from SMA layers and high elastic strain limit from MG layers.

Generalized differential quadrature nonlinear buckling analysis of smart SMA/FG laminated beam resting on nonlinear elastic medium under thermal loading

ABSTRACTThe nonlinear thermal buckling analysis of functionally graded (FG) beam integrated with shape memory alloy (SMA) layer(s), with different lay-up configurations and supported on a nonlinear elastic foundation, has been investigated. The FG layer is graded through the beam thickness direction and thermomechanical properties are assumed to be temperature dependent. The Brinson one-dimensional constitutive law are used to model the characteristics of SMA. The von Kármán strain–displacement fields with the Timoshenko beam theory are applied to the Hamilton’s principle to derive the set of nonlinear equilibrium equations. Generalized differential quadrature method along with direct iterative scheme is utilized to discretize and solve the nonlinear equilibrium equations. The accuracy of proposed model is compared and validated with previous research in literature. The detailed parametric study has been performed to investigate the influence of geometrical, material, and some other key parameters on the nonlinear thermal buckling solutions. The results show that selecting the proper lay-up is of great importance because the type of SMA/FG lay-up can considerably affect the nonlinear buckling solutions. Moreover, adequate application of SMA layers in a proper lay-up configuration significantly postpones the thermal buckling temperature of the beam.