Shape Memory Alloy Hybrid Composite Research Articles

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.

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.

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.

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.

Numerical analysis of mechanical performances of shape memory alloy hybrid composites

The effects of the content and position of SMA wires on the static properties of glass fiber reinforced epoxy (GF/epoxy) composite laminates prepared by vacuum-assisted resin infusion (VARI) process were investigated. According to the influence of different embedding content and position of SMA wire on mechanical performances of composite laminates, the optimal content and optimal position of SMA were found out. The static mechanical finite element models of GF/epoxy composite and shape memory alloy hybrid composites (SMAHCs) are established. The validity of the models is verified by comparing the simulation results with the experimental results. According to the finite element results, the influence of SMA embedding content and position on the mechanical performances of composites is described quantitatively.

Thermo-mechanical modeling and characterization of three-phase shape memory alloy hybrid composites

The thermo-mechanical properties of shape memory alloy hybrid composites (SMAHCs) are characterized, and their three-phase constitutive relationship in the form of a lamina embedded with shape memory alloy (SMA) wires is established by micromechanics. Considering large beam deflection, a theoretical bending model of SMAHC beams with different fiber volume fractions and arbitrary ply schemes is proposed. The Runge–Kutta method is employed to solve the nonlinear ordinary differential equations, and the quantitative relations of curvature, rotation and deflection under thermal load are obtained from the model by directly using the original three-phase material parameters without the need of the experimental measurement in single layer. The SMAHC beams with different fiber orientation, number of layers, and volume fraction of SMA are fabricated, and their thermo-mechanical behavior is experimentally evaluated. Good agreements between the theoretical predictions and experimental results demonstrate that the proposed model is capable of predicting the thermo-mechanical behavior of three-phase SMAHC beams. The generic model developed can be used as an analytical tool in design analysis and optimization of SMAHC structures for effective shape, tracking, and vibration control.

Experimental and numerical investigation on the low-velocity impact response of shape memory alloy hybrid composites

The impact response of shape memory alloy hybrid composite (SMAHC) prepared by vacuum-assisted resin infusion was investigated experimentally and numerically. The impact properties of shape memory alloy composites under three impact stages were characterized. A numerical simulation method is used to simulate the impact damage evolution process of SMAHCs. The experimental results are consistent with the numerical results, which further verified the effectiveness of the laminate against impact load after embedding SMA. The impact threshold energy value of impact damage of SMAHCs was found by numerical simulation. The results show that the impact failure of SMAHC laminates requires more energy than GF/epoxy composites due to the excellent energy absorption capacity of SMA.

Self-sensing-based deflection control of carbon fibre-reinforced polymer (CFRP)-based shape memory alloy hybrid composite beams

The fabrication of carbon fibre-reinforced polymer (CFRP)-based shape memory alloy hybrid composite (SMAHC) beams is highly challenging because conductive carbon fibres alter the electrical characteristics of the beams when driven by an electrical current. Here, we propose and fabricate a CFRP-based SMAHC beam with embedded SMA actuators using the electrical insulation methods. We firstly implemented a self-sensing-based deflection control of the CFRP-based SMAHC beam for unit-step and sinusoidal wave targets using its resistance as a feedback signal for estimating self-sensed deflection. The results reveal that the deflection was well controlled; however, the responses were slightly delayed. Therefore, in our future studies, we will concentrate on overcoming this response delay. Nevertheless, we found that the proposed SMAHC beam is highly feasible and can form the basis for future self-sensing-based controllable CFRP composite morphing structures.

Review on fabrication and mechanical characterization of shape memory alloy hybrid composites

Metals are replaced by composites in various structural applications as composite possesses unique properties such as low weight, high specific strength, and stiffness. However, there is a need to enhance mechanical properties of composite structure. Therefore, hybridization of composite is required that can improve mechanical properties in different testing conditions. One method of fabricating hybrid composite is by reinforcing the shape memory alloy (SMA) in composite laminates. In spite of various advantages offered by the SMA, there is always a challenge in an integration of SMA with the composite for the hybridization. Mainly, these challenges offered during the fabrication process due to their incompatibility of matrix fiber, lack of bonding between SMA and polymer matrix, location of SMA in the composite, and curing temperature of composites. Different methods have been proposed by various researchers for reinforcing SMA into composite. The current review emphasizes the fabrication process of SMA hybrid composite (SMAHC), fractographic study using scanning electron microscopy (SEM) to detect interfacial bonding of SMA and polymer matrix and also the effect of SMA reinforcement on mechanical properties such as tensile, flexural, and impact.

Adaptive pitch control of full-scale ship composite propeller using shape memory alloy to enhance propulsive efficiency in off-design conditions

In this study, we investigate the use of shape memory alloy for adaptive control of twist of the propeller blade for a full-scale marine composite propeller of actual blade geometry, to offset the reduction in its hydrodynamic efficiency in off-design conditions. A full-scale ship propeller of 4.2 m diameter, made of graphite–epoxy laminate integrated with Nitinol fibre–reinforced hybrid composite (shape memory alloy hybrid composite) patches, is considered. The shape memory alloy hybrid composite patches are placed such that the recovery stress induced on heating the pre-strained shape memory alloy fibres embedded in martensite phase to the austenite phase causes twisting deformation in the propeller blade. The open water performance is estimated from the flow solution obtained using the finite volume method considering viscous flow and fluid structure interaction, while the deformation analysis is performed using the finite element method based on the first-order shear deformation theory, considering the nonlinearity due to large deformation. It is shown for the first time for a ship propeller of actual size and shape that the heating of the shape memory alloy fibres generates sufficient twist in the propeller to cause appreciable improvement (up to 6.3%) in its hydrodynamic efficiency in off-design conditions with lower advance ratios, thereby enhancing its fuel efficiency.

Analysis of the Impact Dynamics of Shape Memory Alloy Hybrid Composites for Advanced Applications.

In this work, the behaviour of thermoplastic composites and Shape Memory Alloy Hybrid Composites (SMAHCs) for aeronautical applications is analysed and compared by means of findings from numerical analyses and experimental tests. At first, experimental tests are performed by using a drop tower facility on both carbon fibre reinforced plastic samples and Carbon Fibre Reinforced Plastic (CFRP) samples hybridized with shape memory alloy materials. The materials properties and the different lower velocity impacts behaviours are simulated and validated by means of numerical models discretized in LS-Dyna explicit solver. For both configurations, the deformation mechanism for low intensity impacts, the absorbed energy, and the effect of rebounding upon the velocity change, and hence the amount of force, are investigated. Then, a configuration is prepared to withstand higher-energy impacts. Finally, the numerical analysis is extended for an innovative layup adapted on an aeronautical structure, which is subjected to the bird-strike phenomenon at 180 m/s and with an impacting mass of 1.8 kg according to the airworthiness requirements. In this study, SMAHCs are used to improve the composite impact response and energy absorption thanks to the superelastic effect.

The Low Velocity Impact Response of Shape Memory Alloy Hybrid Polymer Composites.

Polymer composites are sensitive to impact loading due to their low impact resistance. Shape memory alloy (SMA) wires have been used to improve the impact resistance of the polymer composite materials because of their unique superelasticity performance. In this study, a new SMA hybrid basalt fiber-reinforced polymer composite embedded with two perpendicular layers of superelastic SMA wires is designed and the low-velocity impact behavior is experimental investigated. For contrast, the conventional polymer composite without SMA wires is also tested as the reference laminate. The tests are carried out at three different impact energy levels (30, 60 and 90 J). Moreover, to find out indications for manufacturing of SMA hybrid composites with high impact resistance, four different SMA wires embedded modes are investigated. Visual inspection and scanning electron microscope methods are adopted to identify the damage modes of the impacted samples. Results show that the impact resistance of the hybrid laminates is improved due to the hybridization of SMA wires. The most effective impact resistance of the SMA hybrid composites can be obtained by incorporating the SMA wires with one layer between the front two plies and another layer between the bottom two plies into the composite structure.

Natural Frequency Analysis of Composite Skew Plates with Embedded Shape Memory Alloys in Thermal Environment

In this study, free vibration analysis of laminated composite skew plates with embeddedshape memory alloys under thermal loads is presented. The plates are assumed to be made of NiTi/Graphite/Epoxy with temperature-dependent properties. The thermo-mechanical behavior of shape memory alloywires is predicted by employing one-dimensional Brinson’s model. The governing equations are derivedbased on first-order shear deformation theory and solved using generalized differential quadraturetechnique as an efficient and accurate numerical tool. Some examples are provided to show the accuracyand efficiency of the applied numerical method by comparing the present results with those availablein the literature. A parametric study is carried out to demonstrate the influence of skew angle, pre-strainand volume fraction of shape memory alloys, temperature, and stacking sequence of layers on the naturalfrequencies of the structure. Results represent that shape memory alloys can change the vibrationalcharacteristics of shape memory alloy hybrid composite skew plates by a considerable amount. Thenumerical results also reveal that the effect of shape memory alloy wires on natural frequencies ofcomposite plates with simply supported boundaries is higher than those with clamped boundaries.

Mechanical characterization of pseudoelastic shape memory alloy hybrid composites

Shape memory alloys (SMAs) are embedded in fiber reinforced plastic (FRP) composites material to achieve properties like higher toughness, shape morphing, variable stiffness etc. Pseudoelastic SMAs are mostly used in improving the energy absorbing capability of composites subjected to impact loading. Pseudoelastic SMA material has the property of absorbing higher strain energy without failure as compared to other engineering materials. Embedding SMA in FRP composites may affect its in-plane properties. This paper deals with study on SMA hybrid GFRP (Glass Fiber Reinforced Plastic) composites to find out the effect of embedding SMA in composites on the mechanical properties such as longitudinal tensile and compressive strength, transverse tensile strength and compressive strength and in-plane shear strength. Experimental results show that longitudinal compressive strength of shape memory alloy hybrid composites (SMAHCs) increases by approximately 30% over pristine composites. There is a marginal change in values of longitudinal tensile strength and in-plane shear strength in SMAHCs as compared to pristine composites whereas there is reduction observed in transverse tensile and compressive strength in SMA hybrid GFRP composites as compared to pristine GFRP composites.