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The integration of smart materials with metamaterials offers significant research value in additive manufacturing. This paper proposes a novel approach combining shape memory polymers (SMP) with zero Poisson’s ratio (ZPR) metamaterials to create better space-filling, lightweight, and high-energy absorbing materials. A cellular structure with three deformation processes was designed by adjusting the rib arm lengths of the ZPR lattice AuxHex, forming a 3D gradient structure. The cellular units were also prepared using the dual-nozzle fusion filament printing technique, and the energy absorption and shape recovery properties of various hierarchical gradient structures, compared to the uniform structure, were simulated and analyzed using the viscoelastic intrinsic model. The results indicate that all gradient structures exhibit superior energy absorption capabilities compared to uniform materials, with the energy absorption performance of the optimal gradient material being 44.32% higher than that of the nongradient material, and they also enhance the shape recovery performance to some extent. Furthermore, it was observed that when a lattice layer, which avoids internal rib contact throughout the compression process, is positioned in the middle layer, it harmonizes the deformation of the upper and lower layers, thereby improving overall stability. This configuration enhances both energy absorption and partial shape recovery performance, offering a novel approach for the design of smart material assemblies with graded metamaterial structures. This study provides a new perspective and methodology for the future design of supergradient smart material collections.

When one cuts himself, it is amazing to watch how quickly the body acts to mend the wound. Immediately, the body works to pull the skin around the cut back together. The concept of repair by bleeding of enclosed functional agents serves as the biomimetic inspiration of synthetic self repair systems. Such synthetic self repair systems are based on advancement in polymeric materials; the process of human thrombosis is the inspiration for the application of self healing fibres within the composite materials. Results based on flexural 3 point bend test on the prepared samples have shown that the doubled layer healed hollow fibre laminate subjected to a healing regime of 3 weeks has a healed strength increase of 27% compared to the damaged baseline laminate. These results gave us confidence that there is a great potential to adopt such self healing mechanism on actual composite parts like in aircraft's composite structures.

Smart materials can be defined as materials that sense and react to environmental conditions or stimuli. In recent years, a wide range of novel smart materials have been developed in biomaterials, sensors, actuators, etc. Their applications cover aerospace, automobile, telecommunications, etc. This paper presents some recent progresses in polymeric smart materials. Special emphasis is laid upon electroactive polymer (EAP), shape memory polymer (SMP) and their composites. For the electroactive polymer, an analysis of stability of dielectric elastomer using strain energy function is derived, and one type of electroactive polymer actuator is presented. For the shape memory polymer, a new method is developed to use infrared laser to actuate the SMP through the optical fiber embedded within the SMP. Electrically conductive nanocarbon powders are utilized as the fillers to improve the electrical conductivity of polymer. A series of fundamental investigations of electroactive SMP are performed and the shape recovery is demonstrated.

The field-induced soft smart materials are a kind of soft matter whose macroscopic properties (mechanical, or optical) can be significantly and actively controlled and manipulated by external fields such as magnetic field, electric field, temperature or light. In this paper, we briefly review the research and application progress of the field-induced soft smart materials in recent years and discuss the development problems and trend in this research area. In particular, we focus on three typical field-induced soft materials of smart materials: magnetorheological fluid, electrorheological fluid, and temperature and light sensitive polymer gel.

A review of some of the author's results in the area of inverse scattering is given. The following topics are discussed: (1) Property C and applications, (2) Stable inversion of fixed-energy 3D scattering data and its error estimate, (3) Inverse scattering with “incomplete” data, (4) Inverse scattering for inhomogeneous Schrödinger equation, (5) Krein's inverse scattering method, (6) Invertibility of the steps in Gel'fand–Levitan, Marchenko, and Krein inversion methods, (7) The Newton–Sabatier and Cox–Thompson procedures are not inversion methods, (8) Resonances: existence, location, perturbation theory, 9) Born inversion as an ill-posed problem, (10) Inverse obstacle scattering with fixed-frequency data, (11) Inverse scattering with data at a fixed energy and a fixed incident direction, (12) Creating materials with a desired refraction coefficient and wave-focusing properties.

Ferromagnetic shape memory alloy (FSMA) is one of the smart materials which finds increasing industrial applications. This paper deals with the effect of Mn substitution for Ga on martensitic and magnetic transformation temperature of polycrystalline Ni–Mn–Ga alloy prepared in argon atmosphere. The prepared alloy has been characterized by means of scanning electron microscopy (SEM), differential scanning calorimeter (DSC), and superconducting quantum interference device (SQUID). Magnetic property of alloy has been analyzed with vibrating sample magnetometer (VSM). From the VSM measurement, it is studied that the saturation magnetization of polycrystalline ferromagnetic shape memory occurs at high magnetic field. The main finding of this article is the raise in transformation temperature by 28 K/atom. As the working temperature is above room temperature, it seems to be a promising candidate for practical applications. The result reported here may help for further research in the field of polycrystalline Ni–Mn–Ga alloy.

Decreased flexural and buckling capacity of composite structures due to the development of fatigue cracks is a serious issue in a variety of fields. This paper discusses the buckling capacity and piezoelectric material enhancement of cracked column structures. A model of the rotational discontinuity at the crack location is used to develop analytical buckling solutions and the effect of crack location and intensity on the buckling capacity of the damaged columns is investigated. Small piezoelectric patches are employed to induce local moments to compensate for the decreased buckling capacity of column structures, using a mechanical model coupled with piezoelectric strain-voltage relations. The voltages required to enhance the buckling capacity are analytically determined and the general relationship between crack location and voltage developed. The primary advantage of the piezoelectric-based repair approach presented is the ability to use a single small patch, with different applied voltages, to repair cracks of a wide variety of depths, intensities and locations passive design solutions would require custom designs to restore the axial load capacity for each case.

Vibration analysis is carried out for compressively loaded and thermally loaded postbuckled functionally graded material (FGM) plates with piezoelectric fiber reinforced composite (PFRC) actuators. The temperature field is assumed to be uniformly distributed over the plate surface but it varies through the thickness. The electric field has a non-zero-valued component E_Z. Material properties of the substrate FGM layer are assumed to be graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. The material properties of both FGM and PFRC layers are assumed to be temperature-dependent. The formulations are based on a third order shear deformation plate theory and the general von Kármán-type equation that include thermo-piezoelectric effects. The numerical illustrations cover small- and large- amplitude vibration characteristics of postbuckled, mid-plane symmetric FGM plates with surface-bonded or embedded PFRC actuators under uniform and non-uniform temperature fields. The results for monolithic piezoelectric actuators, which is a special case in the present study, are compared with those of PFRC actuators. The results reveal that control voltage has a small effect on the vibration characteristics of the compressed postbuckled FGM plate with PFRC actuators but has a relatively large effect on the natural frequency of thermally postbuckled plates.

In this paper, by using the piezoelectric material, the active aeroelastic flutter characteristics and vibration control of supersonic sandwich panels with different honeycomb interlayers, resting on an elastic foundation, are studied. Classical beam theory along with the Winkler–Pasternak foundation model, and the quasi-steady first order supersonic piston theory are employed in the formulation of the structural theory and aerodynamic loading, respectively. Hamilton's principle in conjunction with the generalized Fourier expansions and Rayleigh–Ritz (RR) method are used to develop the dynamical model of the structural systems in the state–space domain. The aeroelastic flutter bounds are obtained via the p-method. The classical Runge–Kutta integration algorithm is then used to calculate the open-loop aeroelastic response of the system under different loading excitations. Finally, two classical control strategies, including direct proportional feedback and linear-quadratic regulator (LQR) optimal control scheme, are used to actively suppress the closed loop system response, while increasing the flutter aerodynamic pressure.

A thermal buckling analysis is presented for simply-supported rectangular symmetric cross-ply laminated composite plates that are integrated with surface-mounted piezoelectric actuators and subjected to the combined action of thermal load and constant applied actuator voltage. The material properties of the composite and piezoelectric layers are assumed to be functions of temperature. Derivations of the equations are based on the classical laminated plate theory, using the von-Karman nonlinear kinematic relations. The Ritz method is adopted to obtain closed-form solutions for the critical buckling temperature. Numerical examples are presented to verify the proposed method. The effects of the applied actuator voltage, plate geometry and stacking sequence of laminates are investigated.

In this study, the effects of micro-structural parameters such as particle volume fraction, size and random distribution of Al 6061/SiC particulate metal-matrix composite (MMC) beams on free vibration response and the active vibration control are investigated. For this purpose, numerical particle-reinforced MMC (PRMMC) beam specimens were modeled with 3D finite elements, and the cubic-shaped reinforcing SiC particles were randomly distributed in Al 6061 metal matrix similar to an actual micro-structure. The particle size and especially volume fraction play an important role on the natural frequencies of the smart PRMMCs although they have no effect on the mode shapes. The random particle distribution has minor effect on the natural frequencies of the smart PRMMCs. With the increase of the feedback control gain, both the vibration amplitude and the suppression time are reduced reasonably. Increasing the particle volume fraction induces an important reduction in the damping time and the vibration amplitude for both the controlled and uncontrolled damped vibrations. Finally, increasing the particle size decreases the vibration suppression capacity and increases the vibration amplitude and time slightly. Random particle distribution had no obvious effect on the uncontrolled and controlled vibrations.

The current investigation examines the vibrational properties of porous truncated conical structures made from a composite material consisting of polyvinylidene fluoride (PVDF) reinforced with Terfenol-D particles. The effective properties of the magneto-electro-elastic composite were determined using the Eshelby–Mori–Tanaka model. The governing equation of the system is obtained by applying the principles of minimal potential energy and Hamilton’s principle to the first-order shear deformation theory. The equations are solved utilizing the generalized differential quadrature technique. This study aims to examine the interconnections among the volume percentage, vertex angle, shell length, boundary conditions, and porosity of Terfenol-D. Moreover, to validate the results, a comprehensive analysis was performed by comparing them with the existing body of literature, resulting in a favorable and accurate agreement. The results demonstrate a consistent decrease in the linear natural frequency as the vertex angle gradually increases. The findings derived from this study have the potential to serve as a reference point for future analyses.

The use of shape memory alloys (SMAs) in engineering applications has increased the interest of the accuracy analysis of their thermomechanical description. This work presents an uncertainty analysis related to experimental tensile tests conducted with shape memory alloy wires. Experimental data are compared with numerical simulations obtained from a constitutive model with internal constraints employed to describe the thermomechanical behavior of SMAs. The idea is to evaluate if the numerical simulations are within the uncertainty range of the experimental data. Parametric analysis is also developed showing the most sensitive constitutive parameters that contribute to the uncertainty. This analysis provides the contribution of each parameter establishing the accuracy of the constitutive equations.

In this paper, we present an efficient finite element framework for modeling the finite deformations of slender magneto-active elastomers (MAE) under applied magnetic fields or currents. For the convenience of numerical modeling, magnetic field is defined at fixed spatial coordinates in the background space rather than in the elastic MAEs using material coordinates. The magnetic field will vary with free or localized currents while the spatial distribution of the magnetic field will evolve with the motion or deformation of the MAE materials, which is actuated by the surface or body forces induced by external magnetic fields or equivalent currents. A staggered strategy and a Riks method are introduced to solve the strongly coupled governing equations of the magnetic field and displacement field using finite element method. The mesh distortion along the interfaces between MAE domain and free-space domain is resolved by considering concurrent deformation of the mesh in these two domains. A few 2D numerical examples demonstrate the validity and efficiency of the developed model for simulating large deformation of MAE with non-uniform spatial magnetic field under different actuation sources such as free currents, magnetization or external magnetic field. This framework offers a new solution strategy for modeling mechano-magneto problems of MAEs and will help rational design and analysis of MAE-based actuators and soft robotics in the future.

Soft dielectric elastomers (SDEs) represent a category of intelligent electroactive materials utilized in electro-mechanical actuation technology. The dynamic performance of these materials during actuation is notably affected by intrinsic factors like crosslinks, entanglements and the limited extensibility of polymer chains. In this paper, we provide a theoretical framework for modeling the dynamic behavior of a balloon actuator made up of soft dielectric elastomer. To account for the inherent characteristics of polymer chain networks, we employ a physics-based nonaffine material model proposed by Davidson and Goulbourne. The governing equation for dynamic motion is established using Euler–Lagrange’s equation of motion for conservative systems. The reported dynamic modeling framework is then utilized to explore the transient response, stability, periodicity and resonance properties of a dielectric elastomer balloon (DEB) actuator for varying levels of polymer chain crosslinks, entanglements and finite extensibility parameters. To assess the periodicity and stability of the nonlinear vibrations exhibited by the DEB actuator, we present Poincaré maps and phase-plane plots. The results demonstrate that changes in the density of polymer chain entanglements lead to transitions between quasi-periodic and aperiodic vibrations. These findings represent an essential initial step toward the design and production of intelligent soft actuators with diverse applications in future technologies.

Shape memory alloys (SMAs), known for their unique superelastic effect, exhibit superior mechanical properties compared to traditional materials. In this study, the reproducing kernel particle method (RKPM) is applied to investigate the superelastic effect of the SMAs. A segmented linearization RKPM model is developed to establish the stress–strain relationship for the superelastic effect, and relevant formulas of superelasticity for the SMAs are derived. Finally, the applicability and accuracy of the RKPM in analyzing the superelastic effect of the SMAs are demonstrated through numerical examples.

Today, in the medical field, innovative technological advancements support healthcare systems and improve patients’ lives. 4D printing is one of the innovative technologies that creates notable innovations in the medical field. For the COVID-19 pandemic, this technology proves to be useful in the manufacturing of smart medical parts, which helps treat infected patients. As compared to 3D printing, 4D printing adds time as an additional element in the manufactured part. 4D printing uses smart materials with the same printing processes as being used in 3D printing technology, but here the part printed with smart materials change their shape with time or by the change of environmental temperature, which further creates innovation for patient treatments. 4D printing manufactures a given part, layer by layer, by taking input of a virtual (CAD) model and uses smart material. This paper studies the capability of smart materials and their advancements when used in 4D printing. We have diagrammatically presented the significant parts of 4D printing technology. This paper identifies 11 significant applications of 4D printing and then studies which one provides innovative solutions during the COVID-19 pandemic.

An analytical-numerical method is proposed to analyze the surface waves in multi-layered piezoelectric cylinders. In this present method, the cylinder is divided into layer elements with three-nodal-lines along the wall thickness. The Hamilton principle is used to develop approximate dynamic equilibrium equations. The dispersion relationship for multi-layered cylinder is defined and deduced from the Rayleigh quotient and the orthogonal condition of the eigenvalues. The method of Fourier transform combined with the modal analysis is used to determine the displacement response and electronic potential to mechanical and electromechanical loads. Numerical examples are presented for calculating the frequency and group velocity dispersion behaviors, as well as electronic potential distribution in multi-layered piezoelectric cylinder.