Shape Memory Alloy Hybrid Research Articles

Mechanical properties and damage mechanism of SMAHC laminates

Abstract The combination of smart materials and composite materials to achieve lightweight and intelligent structures has been an important research direction in recent years. In this paper, a three-dimensional woven hybrid shape memory alloy (SMA actuator) is modularly implanted into a composite laminate to prepare a SMA hybrid composite (SMAHC) laminate. The orthogonal test was designed with the three variables of SMA actuator modular implantation position, SMA pre-strain and SMA number. According to the orthogonal test results and finite element results, the influence of the three variables on the stiffness before heating, the stiffness change rate after heating and the strength of SMAHC laminates was studied. According to the test index, the influence of the three variables on the results was further evaluated. The results show that the implantation position has the greatest influence on the mechanical properties of SMAHC laminates, followed by SMA pre-strain, and the number of SMA has the least influence. The location and form of damage of SMAHC laminates are further summarized, and the bending damage mechanism of SMAHC laminates is analyzed.

Enhanced interface adhesion in shape memory alloy hybrid composites via an elastomeric interface: An experimental and numerical investigation

Shape Memory Alloy Hybrid Composites (SMAHCs) hold great promise for different applications. However, the interface between SMAs and the matrix presents challenges due to large strains associated with the martensitic transformations (MTs). Although different strategies have been proven effective in increasing interfacial strength, debonding and its prevention remain unresolved. Therefore, to enable MTs in SMAHCs, this paper proposes a novel solution using a rubber-like elastomeric interface. Pull-out SMAHC specimens were tested at different embedding lengths with and without the elastomeric interface. Specimens with the elastomeric interface showed better performance and stress-strain transfer during MT up to SMA wire breakage. The behaviour of the interface was studied using finite element analysis. A fine-tuning method was proposed for the cohesive zone model parameters. Simulated pull-out tests matched experimental data, revealing the debonding mechanisms. However, results with the elastomer underscored the need to fully represent the underlying physics of the highly deformable interface.

Applications of Shape Memory Alloy Hybrid Composite for Ballistics: A Review

Shape Memory Alloys (SMAs) are remarkable in that they can regain their previous shape upon exposure to specific stimuli. This unique property has attracted a lot of attention for use in a spectrum of engineering applications.

Pull‐Out Testing of Electrochemically Etched NiTi Shape Memory Alloy Wires in Shape Memory Alloy Hybrid Composites

This study presents an experimental characterization of the interface strength of the shape memory alloy hybrid composite (SMAHC) consisting of the two‐way effect NiTi shape memory alloy (SMA) wire structured by electrochemical etching and the surrounding thermoset matrix. Mechanically induced, in situ thermally induced, and cyclic load‐increase pull‐out tests consistently reveal that SMAHC with structured SMA wires outperforms those with as‐delivered SMA wires by a substantial factor of 2.6–2.7 in interfacial strength — the critical factor governing the overall performance and functionality of the composite. Analyzing the force–displacement curves from mechanically induced pull‐out tests demonstrates that structuring the SMA wire surface leads to a significantly increased elastic energy to initiate a crack and achieve complete failure. SMA wires with structured surfaces continue transferring load even after the initial interfacial failure due to the presence of intact mechanical interlocking sites. The cyclic load‐increase pull‐out test confirms that SMA wires with structured surfaces exhibit a significantly higher load‐bearing capacity, withstanding more load levels and demonstrating greater force of the first failure. Furthermore, in thermally induced pull‐out tests with structured SMA wires, a re‐initiation of failure from the lower side follows an initial failure progression at the SMA wire entry point.

On the nonlinear dynamics and flutter response of hybrid shape memory alloy composite beams

This study presents a theoretical and numerical investigation of the dynamic response of a hybrid SMA composite beam. Particular emphasis is given to the evaluation of the equivalent damping, the aeroelastic stability, and the possibility to tune the composite’s dynamics by means of pre-strain applied locally to the SMA layers. The model of the hybrid composite beam (HCB) accounts for both the material nonlinearity associated with the phase transformation of the SMA and the geometric nonlinearity (in the von Kármán sense) due to potentially large displacements. The nonlinear governing equations of the HCB are solved by the finite element method and the dynamic behavior of the HCB is assessed for different design parameters, such as thickness, position, and pre-strain level of the SMA layers. Results help understand the role played by the different design parameters in improving the dynamic characteristics of the HCB, with particular attention to effective damping. Furthermore, it is of particular interest to understand the aeroelastic stability of hybrid layered composites due to their widespread applications in aerospace engineering. A simplified model of the nonlinear flutter response of the HCB under supersonic flow conditions is presented and analyzed with particular emphasis on bifurcations and limit cycle oscillations.

Variable stiffness mechanism of flexible composite laminates implanted with modular SMAHC

In this study, a new flexible hybrid shape memory alloy composites (SMAHCs) with a polydimethylsiloxane (PDMS) matrix containing a shape memory alloy (SMA) of a hybrid Basalt/Kevlar fiber 3D woven composite is developed. The SMAHC is implanted into a glass fiber/PDMS composite laminate in a modular manner to study the stiffness of composite plates in response to temperature. The variable stiffness theory of the SMAHC is derived, and the influence of SMA parameters on the stiffness of the SMAHC is analyzed. A three-point bending test is performed to determine the stiffness of the composite plates at multiple temperature points in the form of Joule heat driving the composite plates. The stress and temperature distributions of the composite plate are analyzed in Abaqus under a temperature-displacement coupling setting. The results shows that the SMAHC stiffness is negatively correlated with SMA fiber diameter and positively correlated with SMA fiber volume fraction. With an increase in driving temperature, the stiffness of the composite plates tends to decrease. When the end temperature of the austenitic phase transformation is reached, the high-modulus austenitic SMA slightly increase the stiffness of the composite plate. The stiffness improvement is more significant when the SMAHC is placed in the middle area of the laminate and the SMA is located in the tension area. This study may provide a reference for the design of variable stiffness SMAHC for plate composite structures.

Experimentally characterization and theoretical modeling of the electro-thermomechanical coupling of unimorph Shape Memory Active Hybrid composites

Shape memory alloy hybrid composites (SMAHC) are a class of smart composites with the ability to change their shape in response to external stimuli, such as heat or electric current, due to the thermoelastic phase transition of embedded filaments of a shape memory alloy. In this work, a multiphyical electro-thermomechanical SMAHC model, capable of describing the dynamic shape adaptive behavior of SMAHC on various length scales under the influence of external loads and ambient temperatures, is developed and experimentally validated. Activation and deactivation experiments were performed systematically for different geometries and all material parameters needed for validation purposes were measured.

Nonlinear vibration of SMA hybrid composite beams actuated by embedded pre-stretched SMA wires with tension-bending coupling effect

Theoretical and numerical analyses for nonlinear vibrations of the shape memory alloy hybrid composite(SMAHC) beam actuated by the pre-stretched shape memory alloy(SMA) fibers with tension-bending coupling effect are presented in this paper. Under the sudden action of thermal temperature, a recovery force and moment are caused in the SMAHC beam due to the phase transition in the SMA fibers, exciting the nonlinear vibration of the SMAHC beam. The one-dimensional Brison constitutive model was adopted to express the influence of the phase transition temperature, initial volume fraction of martensite, and pre-strain on the phase transition in the shape memory alloy. On this basis, the constitutive law of the SMAHC beam is built by considering the tension-bending coupling effect and the phase transition in the SMAHC beam. The equation of motion for nonlinear vibration of the SMAHC beam with geometric nonlinearity and material nonlinearity is derived from the Hamilton principle and is discretized into matrix form using the Galerkin method. According to the algorithm of the NewMark-β method, numerical solutions are computed by developing Matlab program and are compared with the results from ABAQUS analysis. It shows that the frequencies and amplitudes of the theoretical calculations are very consistent with those obtained from ABAQUS analysis. In addition, both the theoretical study and ABAQUS simulation indicates that the high frequency for longitudinal vibration is not observed in the spectrum diagram of transverse vibration, while the low frequencies for transverse vibration are captured in the longitudinal vibration. With the established Matlab program, parametric study is carried out to investigate the effect of the temperature and the location of the SMA fibers on the vibration responses of the SMAHC beam. The results from this study indicate that the transverse vibration of SMAHC beams is characterized as one of low frequency, while the longitudinal vibration has the characteristics of high frequency. Especially in the case of nonlinear vibration, not only the vibration of high frequency but also the vibration of low frequency observed in the transverse vibration will occur in the longitudinal direction of the SMAHC beam. Furthermore, the double and triple fundamental frequencies of the transverse vibration are excited in the nonlinear vibration of the SMAHC beam. The results of this paper can provide a theoretical basis for the evaluation of the safety and stability of smart composite structures.

Computational Modeling and Parametric Analysis of SMA Hybrid Composite Plates under Thermal Environment.

This paper presents a coupled thermoelastic finite element formulation for static and dynamic analysis of composite laminated plates with embedded active shape memory alloy (SMA) wires, which accounts for both the phase transformation and the nonlinearity effects of SMA wires. The equations of motion are obtained by using Hamilton's principle and first-order shear deformation theory (FSDT). Furthermore, based on Brinson's one-dimensional phase transformation constitutive law, a novel coupled thermoelastic finite element model that enables analysis of the SMA hybrid composite (SMAHC) plate is developed. The accuracy and efficiency of the developed computational model for analysis of SMAHC plates are reinforced by comparing theoretical predictions with data available from the literature. The results of the numerical examples also show the ability of the proposed model to predict the thermal-mechanical behavior of SMAHC plates in accordance with SMA's hysteresis behavior. In addition, based on the proposed model, the influence of temperature as well as SMA volume fraction, pre-strain value, boundary condition and layup sequence on the static bending and free vibration behavior of the SMAHC plates is investigated in detail. The results of parametric analysis show that the variations of both static deflection and natural frequency of the SMAHC plate over temperature exhibit a nonmonotonic behavior.

Finite Element Analysis of Flexural Behavior of Shape Memory Alloy Hybrid Composites Laminates

In this paper, experiments and finite element analysis methods were adopted to study the flexural performance of shape memory alloy hybrid composites (SMAHC). The effect of embedding content and position of shape memory alloy (SMA) wire on the flexural properties of composite laminates was analyzed, and the optimal content and position of SMA wire were obtained. The optimal number of SMA wires for SMAHC laminates (B-2) is four. Compared with GFRP laminates, the flexural modulus of B-2-4 laminates increases by 5.19%, while the strength decreases by 5.76% on average. The finite element model of the SMAHC laminate was established by using ABAQUS finite element analysis software, and the validity of the model was verified by the comparison between the simulation results and the experimental results. The microscopic morphology results show that the weak interface between the matrix and SMA has a certain influence on the flexural performance of SMAHC specimens.

Development of a shape memory alloy-based friction damper and its experimental characterization considering rate and temperature effects

A new hybrid shape memory alloy (SMA)-based damper was developed to address two major challenges for SMA-based seismic control devices: (i) insufficient force capacity for real-world application and (ii) relatively low energy dissipation capacity. The hybrid damper, named Superelastic Friction Damper (SFD), leverages the high tensile resistance and excellent self-centering capability of SMA cables and non-sacrificial energy dissipation of a frictional damping mechanism. In this paper, the components and basic working principle of the proposed damper are first described, and the advantages of the proposed damper compared to the existing SMA-based hybrid dampers are highlighted. Then, the fabrication of a prototype damper and its experimental testing are discussed. The mechanical response of the damper under repeated cyclic loading at various displacement amplitudes and loading rates is revealed. The effects of ambient temperature on the hysteretic behavior of the developed damper are explored. Results reveal that the proposed damper exhibits stable hysteretic behavior with negligible sensitivity to the loading rate and temperature. The damper provides an equivalent viscous damping of 12 %, accompanied by 89 % recovery of the peak damper displacement.

Thermal Buckling and Vibration Analysis of SMA Hybrid Composite Sandwich Beams

This work studies the buckling and free vibration behavior of Shape Memory Alloy Hybrid Composite (SMAHC) sandwich beams under a thermal environment. The sandwich beams consist of layers reinforced with SMAs and a FGM core, and they are simply supported at both ends. The higher order theory is combined with the Minimum Potential Energy principle or Hamilton principle to derive the governing equations of the thermal buckling and thermal vibration problems, respectively. The material properties of the beam are assumed as temperature-independent (TID) or temperature-dependent (TD). In the last case, two different types of thermal distribution are considered, namely a uniform and a linear distribution. The results based on the proposed formulation are verified against the reference literature, with a very good matching. A parametric study checks for the influence of different effective parameters such as thickness-to-length ratios, volume fraction powers, initial strain, volume fraction of SMA wires, and temperature distribution on the overall mechanical response of the selected structural member, with useful insights from a design standpoint.

Processing of hybrid shape memory alloy coupled with P(VDF-TrFE) piezoelectric polymer composite for energy harvesting application

Small-scale energy harvesting to power self-powered electronic devices is tremendously increasing. In this context, the ability to combine thermal and mechanical energy harvesting using smart materials deserves more attention for further study. We have presented the feasibility of using P(VDF-TrFE) piezoelectric polymer coupled with NiTi shape memory alloy (SMA) to harvest both mechanical and thermal energy in simple scalable devices. A novel hybrid composite consisting of SMA, and P(VDF-TrFE) has been developed without any complex composites or patterned structures, which couples the piezoelectric effect of the poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) and the shape memory effects of NiTi SMA. We have also fabricated a multi-layer SMA/PEN/P(VDF-TrFE) device using epoxy as an interface and bonding layer. During bending, the P(VDF-TrFE) device with an active area of 3.68 cm2 generated an output voltage of 8 V and an output power of 6.25 µW. When coupled with NiTi SMA to create a hybrid composite thermoelectric material, the device can convert the phase change associated with SMA, and thus thermal energy is converted to mechanical energy and finally into electrical energy. The SMA/P(VDF-TrFE) hybrid composite produced an output voltage of ∼2 V for one cyclic heating and cooling of the device. This is a promising approach for the further development of coupled hybrid energy harvester devices for the powering of small-scale electronic devices such as sensors, MEMS, or biomedical devices.

Thermomechanical characterization of functionally stabilized nickel-titanium-copper shape memory alloy

Shape memory alloy hybrid composites have promise in realizing the 21st century goal of morphing structures. There is considerable work to be done in the development of characterization and modeling techniques for these materials. The proposed characterization methodology adapts existing standards to include previously omitted factors required for the numerical modelling of shape memory alloys and their integration into end-use applications. A nickel-titanium-copper (NiTiCu) shape memory alloy is characterized using these methods and then numerically modelled. Samples’ mechanical behaviour is shown to stabilize after 43 cycles of mechanical loading. Thermomechanical properties measured before and after stabilization are shown to vary inconsistently by up to 72%, demonstrating the need for stabilization for accurate thermomechanical characterizations and consistency in end-use applications. Physical experiments are numerically replicated in Abaqus\\Standard using the measured properties. Sufficient correlation is shown for the design of shape memory alloy hybrid composites. The result of this work is a comprehensive thermomechanical characterization approach for shape memory alloys which can be used to develop morphing SMA hybrid composite structures.

Multiscale Simulation Based on the Generalized Method of Cells for Shape Memory Alloy Hybrid Composites

Multiscale Simulation Based on the Generalized Method of Cells for Shape Memory Alloy Hybrid Composites

Impact Behavior of Shape Memory Alloy Hybrid Composites under Different Temperatures

Impact Behavior of Shape Memory Alloy Hybrid Composites under Different Temperatures

Vari-stiffness characteristics of a 3D SMA hybrid basalt woven composite

Shape Memory Alloy Hybrid Composite (SMAHC) obtained by weaving shape memory alloy into composite materials is an intelligent composite material with broad application prospects. 3D woven composites can provide stronger delamination resistance, and taking SMA as warp to manufacture SMAHC is conducive to reducing bending and giving full play to the performance of SMA. In this study, SMA was woven into 3D woven as stuffer warp, and orthogonal experimental design was carried out using amount of SMA, pre-strain of the SMA and the fabric structure as three independent variables to investigate how to maximize the stiffness control effect of the material. A finite element Representative volume element (RVE) model was established to predict local responses. Water transfer print (WTP) and digital imagination correlation (DIC) technique were used to exclude temperature disturbances and monitor the strain field changes during the tensioning process. The results show that SMA has a greater effect on the surrounding yarn than expected. The influence of three factors on the composite structure is also discussed in detail and weaving suggestions for 3D SMAHC are put forward.

Influence of shape memory alloy on seismic behaviour of hollow-section concrete columns

The influence of shape memory alloy (SMA) reinforcement on the non-linear static and dynamic responses of hollow-section concrete columns to earthquakes was investigated. The seismic performance of concrete columns reinforced with steel and with a mix of SMA and steel was compared by assessing their ductility ratios, dissipated energies, strain recovery capacities and collapse drifts. The influence of near- and far-field ground motions on the static and dynamic responses of the test columns was also investigated. To verify the results, the columns were subjected to a near-field ground motion related to an existing earthquake and the relative displacement response history was compared with experimental results. Compared with the steel-reinforced column, it was found that the use of the hybrid SMA–steel reinforcement was more effective at recovering strains and reduced the residual deflections. On the other hand, the steel-reinforced column had a greater ductility ratio and energy dissipation capacity. It is therefore important to find an optimal combination length for the two types of reinforcement in a concrete column. The results indicated that the optimum reinforcement configuration involves replacing steel with SMA at 15–20% of column height, which includes the probable plastic hinge length.

Experimental study on the low-velocity impact failure mechanism of foam core sandwich panels with shape memory alloy hybrid face-sheets

Abstract Superelastic shape memory alloy (SMA) as an advanced smart material has been used to improve the impact performance of fiber-reinforced composites in recent decades. Due to the low impact toughness of the thin composite face-sheet and the poor strength of the foam core, sandwich panels are sensitive to the transverse loading. SMA fibers were embedded into the composite laminated to improve the impact resistance of the traditional foam core sandwich panel in this work. Five new types of SMA hybrid panels were prepared, and the testing panels with penetration failure were observed at the impact energy of 50 J. The impact mechanical responses and the damage morphology were analyzed, and the impact failure mechanism was also revealed. Results show that all sandwich panels were failed, the fiber breakage occurred at the impact region in the traditional panels, while part plies of the rear face-sheets split-off in the SMA hybrid panels. The impact performance of the SMA hybrid panels is improved when compared with the traditional panel, the reduction of the delamination area by 48.15% and the increase of the load-bearing threshold by 32.75% are acquired for the hybrid sandwich panel with two layers of SMA fibers in the rear face-sheet.

A Comprehensive Review on Applicability of Shape Memory Alloy Hybrid Composite Beam in Vibration Control

Smart materials are used to construct smart structures, which can perform both sensing and actuation functions. Shape Memory Alloys are a kind of smart materials which can undergo solid-to-solid phase transformation and can recover completely when heated to a specific temperature. The Hybrid Composites that embedded with SMAs showing better results in vibration control. The trend in the aeronautical, mechanical and civil design requires lighter, stronger, and more flexible structures. However, light weight structures can be more easily influenced by unwanted vibrations, which may lead to the performance reduction, sometimes the system may even fail due to resonance, etc. This paper focuses on research work carried till now in the area of SMA hybrid composites and its applicability in vibration control.