Smart Structures Research Articles

The mediating role of customer satisfaction for a sustainable e-banking performance

Information and communication technologies have created a revolution in the approach of companies and customers. Digitalisation has led to the adoption of Electronic Banking worldwide befitting not only the user but also the banking industry. In this study primary data was collected from 374 participants using stratified random sampling. Using Smart PLS3 (Christian M.Ringle, Germany) and Structure Equation Modelling fitness of the model and reliability were derived, and this study has revealed that customer satisfaction affects retention which is directly influenced by efficiency, quality of service and reliability. It has revealed that for retaining customers when the mediator used is customer satisfaction, there is a significant impact of reliability, efficiency and service quality. Through these researches E-banking’s four main components, that is, reliability of services, the quality of services rendered, satisfaction of customers and efficiency has been specified.

Open loop flutter control of optimally oriented smart variable stiffness plates under hygrothermal environment

The present study investigates the impact of hygrothermal effects on the free vibration and flutter characteristics of a smart variable stiffness composite laminate (VSCL). This research seeks to underscore the inherent advantages of VSCLs in contrast to conventional straight fibre constant stiffness composite laminates (CSCLs). Utilizing curvilinear fibres, VSCLs offer a heightened level of customization, culminating in notably enhanced structural performance. The Genetic Algorithm is employed to obtain optimal fibre paths for the variable stiffness laminates. Introducing an active fibre composite layer as an actuator atop the optimally oriented VSCL laminate enhances its capabilities. A parametric inquiry into the influence of hygrothermal loading on the smart structure's free vibration and flutter traits is undertaken. While hygrothermal loading imparts vulnerability to the laminate, the introduction of voltage to the active fibre composite layer counteracts this weakening effect, effectively augmenting stiffness and concurrently enhancing the flutter parameters (velocity, frequency) intrinsic to the plate structure.

Gas foamed scaffolds as smart 3D structures in skin tissue engineering

Globally, wound care is a major problem that poses big issues for national healthcare systems. Consequently, the development of wound dressings, systems applied over a wound to prevent complications and speed up recovery, is receiving increasing attention. Electrospun nanofibrous scaffolds gained great interest in the medical field due to their many advantages and beneficial characteristics. However, they are formed by of densely packed fiber layers, which render the available space between adjacent fibers minimal. In this study, nanometric fibers from pullulan polymeric blends were developed using cricket powder as novel component, due to its high chitin and chitosan content. Hydroxyapatite was also added due to its biocompatibility and capability to interact with the host tissues. The 2D mats based on electropsun fibers in membrane were converted to a 3D structure by gas foaming, involving NaBH4. The obtained 3D systems were characterized for their morphology and composition, and mechanical properties. The scaffolds biocompatibility was tested on normal human dermal fibroblasts and mesenchymal stem cells, and cell adhesion was assessed. TNF-α secretion was thereafter characterized to evaluate the anti-inflammatory effects of the scaffolds on macrophages, and their antioxidant activity was also investigated. Finally, an evaluation of the scaffolds’ safety and efficacy in vivo on a murine incisional and burn model was performed. The results obtained not only revealed greater structural and mechanical integrity of the gas-foamed scaffolds containing cricket powder, but also higher cytocompatibility towards different cell lines together with anti-inflammatory and antioxidant properties, thereby making them innovative tools to improve the process of wound healing.

Nonlinear dynamic analysis of opto-electro-thermo-elastic perovskite plates

AbstractPhotostrictive materials have attracted tremendous interest as the new generation of smart materials that can achieve a direct conversion from optical energy to mechanical energy. Understanding their nonlinear mechanical properties under light illumination is of paramount significance for their realistic optomechanical applications. This article proposes a novel opto-electro-thermo-elastic constitutive model that can consider the effects of photostriction, photothermal temperature, and electrostriction for metal halide perovskite crystals and investigates the nonlinear static and dynamic responses of the perovskite plates. The nonlinear governing equations are established based on the first-order shear deformation theory and von Kármán nonlinearity and are numerically solved by the differential quadrature method. A detailed parametric investigation is performed to analyze the effects of light and electricity on the nonlinear mechanical behaviors of perovskite plates. It is concluded that light illumination leads to the presence of optical stress and thermal stress in the perovskite plates, giving rise to increased static and dynamic deformations and stresses, as well as reduced postbuckling and free vibration characteristics. The research findings pave the way for the optomechanical applications of perovskite-based smart materials and structures.

Analysis of torsional buckling of a cylindrical sandwich shell with a magnetorheological fluid core layer

This study is an attempt to analyze the torsion buckling of a structure consisting of a cylindrical sandwich shell with two isotropic face sheets that surround a magnetorheological fluid (MRF) core layer. In this analysis, the simply supported boundary conditions were considered for the edges of the face sheets and the core layer. The components of displacement were calculated using the first-order shear deformation theory, and the governing equations were derived using Hamilton’s principle and were solved drawing upon the Galerkin method. The parameters of interest were magnetic field, buckling analysis, torsional buckling convergence, h/L ratio, ht/h ratio, and rt/L ratio. The equations obtained from MATLAB were verified using ABAQUS owing to the absence of any similar study in the existing literature. A good agreement was observed in terms of torsional buckling, indicating the robustness of the proposed structure. As smart sandwich structures are broadly used in robotics and aerospace, this structure can be a good choice thanks to its lightness (resulting from the thinness of the face sheets and hollowness) and strength and resistance (contributed by MRF core layer), which can be modified with the application of different magnetic fields.

Plant Biomimetic Principles of Multifunctional Soft Composite Development: A Synergistic Approach Enabling Shape Morphing and Mechanical Robustness.

Plant tissues are constructed as composite material systems of stiff cellulose microfibers reinforcing a soft matrix. Thus, they comprise smart and multifunctional structures that can change shape in response to external stimuli due to asymmetrical fiber alignment and possess robust mechanical properties. Herein, we demonstrate the biomimetics of the plant material system using silk fiber-reinforced alginate hydrogel matrix biocomposites. We fabricate single and bilamellar biocomposites with different fiber orientations. The mechanical behavior of the biocomposites is nonlinear, with large deformations, as in plant tissues. In general, the bilamellar system shows increased modulus, strain UTS, and toughness compared to the single-lamellar system for most of the tested orientations. Overall, the biocomposites present a wide range of elastic modulus values (3.0 ± 0.6-104.7 ± 11.3 MPa) and UTS values (0.23 ± 0.04-12.5 ± 2.0 MPa). The bilamellar biocomposites demonstrated shape-transforming abilities with diverse morphing modes, emulating different plant tissues and creating complex shape-morphing structures. These multifunctional biocomposites possess tunable and robust mechanical properties, controllable shape-morphing deformations, and the ability to self-controlled encapsulation, grip, and release objects. By harnessing biomimetic principles, these soft, smart, and multifunctional materials hold potential applications spanning from soft robotics, medicine, and tissue engineering to sensing and drug delivery.

What Is a Resilient Smart City? Blue–Green Infrastructure as a Strategic Feature of Smart Urban Form: Empirical Evidence with a Particular Focus on the Songdo IBD and Aspern Seestadt in Vienna

This study concerns the correlation of a smart city as an idea with urban form, with a particular focus on blue–green infrastructure. It aims to bridge the research gap on the physical structure of a smart city. It attempts to answer the following questions: (1) are there any patterns or rules in how a smart city’s urbanscape should be shaped? (2) Can green and recreational spaces contribute to a smart city’s smartness? If so, can a smart city be more resilient? To answer these questions, the author proposes the framework of a ‘smart urban form’ and a five-goal checklist to evaluate the blue–green infrastructure of a smart city. This checklist tool is based on the following five goals: morphology, ecology and environmental protection, accessibility, multifunctionality and activities, and identity and aesthetics, with specific factors for each goal. The paper presents a test of the tool on two existing smart city urban structures: the Songdo IBD, South Korea, and Aspern Seestadt, Vienna, Austria. This research is based on a combination of mixed methods: analysis of the literature, a multiple-case study, and observation. A correlation between the resilience of a smart city and its urban form, with an emphasis on blue–green infrastructure, was found.

A novel smart disinfection system using 3D-printed and electrically conductive composite hydrogel

AbstractSmart materials are ushering in the era of smart and adaptable products. Hydrogels are a distinct class of smart materials that can be 3D-printed to produce smart and active structures that can be used as sensors and actuators. The development and characterization of a 3D-printable and electrically conductive composite hydrogel, as well as its application in the development of a smart disinfection system, are discussed in this article. The developed composite hydrogel has a maximum electrical conductivity of 145 S.m−1, is stable up to 200 °C, and has a 3D printable rheology. Virtuous of its electrical conductivity, the composite hydrogel was used to create a smart disinfection system. Various disinfection systems have been adopted for the disinfection of contaminated surfaces; however, most of these systems require human evacuation from the surroundings due to the hazardous nature of the virucide. The proposed system is designed to disinfect contaminated surfaces on common-use equipment and is capable of real-time activation through user interaction. It employs a thermal disinfection process at 60 °C for 5 min and becomes ready for the next user once its temperature drops below 55 °C. This system consumes 1.64 Wh of energy per disinfection cycle and is suitable for scenarios with fewer than 60 user interactions in an 8-h work shift.

μ-Analysis and μ-Synthesis Control Methods in Smart Structure Disturbance Suppression with Reduced Order Control

In this study, we created an accurate model for a homogenous smart structure. After modeling multiplicative uncertainty, an ideal robust controller was designed using μ-synthesis and a reduced-order H-infinity Feedback Optimal Output (Hifoo) controller, leading to the creation of an improved uncertain plant. A powerful controller was built using a larger plant that included the nominal model and corresponding uncertainty. The designed controllers demonstrated robust and nominal performance when handling agitated plants. A comparison of the results was conducted. As an example of a general smart structure, the vibration of a collocated piezoelectric actuator and sensor was controlled using two different approaches with strong controller designs. This study presents a comprehensive simulation of the oscillation suppression problem for smart beams. They provide an analytical demonstration of how uncertainty is introduced into the model. The desired outcomes were achieved by utilizing Simulink and MATLAB (v. 8.0) programming tools.

Application of intelligent controller to speed up vibration attenuation of a sandwich smart structure subjected to external excitation

Intelligent controllers represent a class of advanced control systems designed to adapt, learn, and make decisions based on changing environments and dynamic conditions. These controllers leverage artificial intelligence and computational techniques to enhance traditional control methods, providing a level of adaptability and sophistication that is particularly valuable in complex and uncertain systems. In this work for the first time, the Proportional–integral–derivative (PID) controller the intelligent controller is used to speed up vibration attenuation of a sandwich smart structure subjected to external excitation. The sandwich smart structure is made of a composite core and sensor and actuator patches. Using shear deformation theory, Hamilton’s principle, and compatibility equations, the governing equations of the sandwich smart structure under external excitations are obtained. After that using numerical solver and time-dependent solution procedure, the equations are solved. After obtaining the datasets via mathematical modeling, this kind of dataset is used as the input and output data to train, validate, and test the machine learning method to use it with low computational cost. After that, using this kind of machine learning method, future researchers can use it to estimate a control vibration of the sandwich structure after mechanical excitation. The results suggest some applicable recommendations to speed up the vibration attenuation of a sandwich smart structure subjected to external excitation.

Asymmetric two-dimensional poroelastic analysis of heterogeneous smart discs considering hygrothermal loading

The objective of this study is to examine through the finite element method the impacts of employing two-dimensional (2D) properties grading on the behaviors of piezoelectric sensors/actuators due to their significance. These structures are modeled as variable thickness discs and are assumed to be exposed to simultaneous asymmetric loading conditions (thermal, hygral, electrical, and mechanical loads). Results demonstrate that the 2D grading is superior compared to the conventional one-dimensional grading for reducing the von Mises stress. The reduction reached, for instance, 8.3% allowing further increase of loading and/or safety. Also, the change of the displacement is varied between −4.5% and 31% depending on the considered grading pattern, and thus can be controlled to a desired value which helps to improve the sensing and actuating functionality for certain requirements. The study also examines the effects of porosity, and the results are compared to nonporous discs. Reductions of the maximum compressive tangential stress and von Mises stress reached 79.75% and 33.6%, respectively at specific porosity distribution patterns and volume fractions. These findings have significant implications for the manufacturing of smart structures, enabling them to operate in severe working conditions with better sensing and actuating capabilities than previously possible.

Effect of Process Parameters in Additively Manufactured Sensors prepared via Material Extrusion Processes: Correlation among Electrical, Mechanical and Microstructure Properties

Fusion-based Material Extrusion (MEX) Additive Manufacturing (AM) processes have been extensively used for the fabrication of smart structures with embedded sensors, proving to have several benefits such as reduction in cost, manufacturing time, and assembly. A major issue negatively affecting 3D printed sensors is related to their poor electrical conductivity, as well as inconsistent electrical performance, which leads to electrical power losses amongst other issues. In the present paper, a set of process parameters (ironing, printing temperature, and infill overlap) has been analyzed by performing a Design of Experiment (DoE) factorial plan to minimize the electrical resistance. The best process parameters configuration involves a remarkable reduction of electrical resistance of 47.9%, as well as an improvement of mechanical properties of 31.9% (ultimate tensile strength), 25.8% (elongation at break) and 28.14% (flexural stress). The microstructure of the obtained results has also been analyzed by employing a high-resolution, X-ray Computed Tomography (X-Ray CT) system showing a reduction of intralayer voids of 19.5%. This work demonstrates a clear correlation between process parameters and the corresponding electrical properties, mechanical properties, and internal microstructure. In the present research, it has been shown that i) it is possible to significantly improve the overall 3D printed sensors performance by process parameter selection, and ii) small changes in the microstructure lead to remarkable improvements in electrical and mechanical performance.

Vibration characteristics of FG saturated porous annular plates integrated by piezoelectric patches on visco‐Pasternak foundation

AbstractThe vibrational behavior of a three‐layered annular plate is considered in the present study. The plate is composed of a functionally graded (FG) porous core which is saturated by fluid and two piezoelectric patches that are bonded to the core and are subjected to the electric field. The whole of the structure is also rested on visco‐Pasternak elastic foundation. The material properties of the FG porous core vary through the thickness direction based on different patterns which are called porosity distributions. Love‐Kirchhoff's hypothesis and Hamilton's principle is employed to extract the governing motion equations and boundary conditions and following it, they are solved by generalized differential quadrature method (GDQM) for various boundary conditions. After ensuring the validity of the results by comparing them with known data in the literature, the effect of the most important parameters on the results is considered. It is seen that the effect of the porosity coefficient on the natural frequencies is completely dependent on the pores’ distribution patterns. Also, increasing in externally applied voltage to the piezoelectric facesheets, leads the results to enhance. The outcomes of this work can help to design and create smart structures and systems such as sensors and actuators.

Thermo-electro-mechanical effects on nonlinear dynamics of smart dielectric elastomer minimum energy structures

Minimum energy structures made up of smart electro-active polymers (SEAPs) have attracted significant attention in the field of soft robotics and actuators due to their exceptional property of undergoing large deformations when subjected to electric fields. In general, temperature also plays a crucial role in modeling of SEAPs because it affects the mechanical, electrical, and thermal properties of the polymer. These properties, in turn, determine the performance of smart polymer-based devices. Motivated by these ongoing advancements, this study investigates the effects of temperature on the nonlinear dynamic behavior of a smart dielectric elastomer-based minimum energy structure (SDEMES) actuator. The governing dynamic equation of the actuator is derived using the standard Euler–Lagrange’s equation. Through the utilization of time-evolution diagrams, Poincaré plots, and phase portraits, the study comprehensively evaluates the effects of temperature on the stability, periodicity, and resonant behavior of the actuator. The results highlight the significant influence of temperature on the stiffness of the elastomer within the SDEMES actuator, directly impacting its actuation performance. The frequency response of the actuator demonstrates a distinct increase in resonant frequency as the temperature rises. These findings shed light on the crucial role of temperature in shaping the stiffness and nonlinear dynamic behavior of smart dielectric elastomer minimum energy structures.

Piezoelectric impedance-based high-accuracy damage identification using sparsity conscious multi-objective optimization inverse analysis

Two elements are essential in structural health monitoring utilizing dynamic responses: response measurement with high-frequency contents, i.e., small characteristic wavelengths, that can adequately reflect damage features, and effective inverse identification analysis that is however oftentimes under-determined. The advancement of smart structure integration has led to active interrogation through frequency-sweeping piezoelectric impedance measurement at high frequency range. In this research we develop a multi-objective optimization formulation for the identification of damage location and severity utilizing piezoelectric impedance. While one optimization objective is to match the response measurement with finite element model prediction in the damage parametric space, the other is the number of locations of damage, i.e., the sparsity of damage index as the solution vector, since damage usually occurs within a small number of locations. This multi-objective formulation fits well the under-determined nature of damage identification, as it naturally provides multiple solutions as basis for further elucidation. The challenge remaining is how to find a small solution set that can include the actual damage scenario. Here we develop a novel inverse identification framework utilizing the intelligent swarm optimizer which possesses flexibility for enhancement. We first embed a sparsity enforcement process into the population generation of the optimizer, which yields a solution repository intrinsically possessing sparsity. We then apply reinforcement learning so the agents can adaptively opt for local strategies with the aim of enriching the searching patterns to diversify the solutions. Through the incorporation of a Q-table, searching toward more promising directions will be rewarded. Our case analyses employing experimental data indicate that this sparsity-conscious multi-objective particle swarm optimization technique can lead to a small solution set which generally encompasses the true damage scenario. This effectively solves the structural damage identification problem with piezoelectric impedance measurement.

A new framework for optimizing energy harvesting from smart composites integrated with piezoelectric patches utilizing lamination parameters

Amongst various structures, 2D panels are widely used in many industries and in each application, there are many ambient vibrations which can be converted into electrical energy. The very efficient method to utilize can be using piezoelectric patches which are stuffiest enough for various applications like energy harvesting. This study presents a novel approach for investigating energy harvesting in smart structures using composite panels integrated with piezoelectric patches. The panels are chosen to symmetry-balanced laminated composites, and modal and harmonic analysis conducted using the Rayleigh-Ritz method. To compute the kinetic and potential energy components of the piezoelectric patches at a local level, piecewise Heaviside functions are employed, and these energy components are integrated into the equations of motion together with those of the host composite plate. The results of the numerical method are validated by a commercial finite element software (FEM) COMSOL and there is a good match between FEM and this paper results. By subjecting the laminated composite with piezoelectric patches to forced vibration while varying the lamination parameter, the power output is optimized. The findings emphasize the substantial impact of the lamination parameter on power output, indicating that modifications can result in significant power output increase.

Performance of a freight platform equipped with automated handling units. Analysis thought an optimization model

Automation should help the freight platforms to be more competitive and sustainable. The automatic handling units (AHUs) allow to speed up the freight handling operations by eliminating time wasters, increasing safety, and also allowing for a reduction in traditional labour; but they require continuous monitoring and intelligent management entrusted to specialized personnel. The use of AHUs is also seen positively from an energy and environmental sustainability point of view.The paper focuses on a smart organizational and functional structure of a freight platform equipped with automated handling vehicles. The study proposes the mathematical formulation of an optimization model that aims to minimize the operating times of handling goods in a logistics platform through the introduction of fully automatic vehicles that replace traditional systems. So, this article concerns the scientific lock of automatic and optimized fleet management of AHU. It is a question of proposing a routing of this kind of smart vehicle fleet without blockages that allow regularly submitted missions to be carried out.

A state-of-the-art review of 4D printing techniques, stimuli activated materials and future perspectives

In recent years, 4DP has gained significant interest in the field of AM, functional prototyping, soft robotics, biomaterials, pharmaceutical, and textiles. 4DP is an AM technique that integrates 3DP with stimuli-responsive materials. When exposed to various external stimuli, such as temperature, light, pH, magnetic field, electricity, and moisture; the structures formed by 4DP technique are space time dependent and can change their shape and/or properties over the period of time. Herein, this overview presents stimuli activated smart materials used in 4DP, 4DP techniques and practical applications of 4D printed smart structures. This overview also elucidates challenges and future perspectives in terms of, synthetization of different polymers, multi material printing, sustainability, pre-programming knowledge, and latent applications of 4D printed structures.

Employing finite element analysis for assessing the condition monitoring of sandwich beams

In engineering and transportation, beams are frequently utilized as structural elements for both static and dynamic loads. This paper focuses on a smart structure method that incorporates ANSYS software for modeling and simulation. Piezoelectric transducers are employed for actuation and sensing throughout the structure. The governing equation of a finite element that converts the mechanical energy of the structure into the electric energy of the piezoelectric material is derived using Hamilton's principle. Debonding of piezoelectric sensors/actuators is caused by structural alterations in sandwich beams, and this leads to a notable fluctuation in both static and dynamic responses. It has been shown that Finite Element Modeling with ANSYS software yields accurate numerical solutions over a broad range of related parameters. The results are displayed and vibration modes are animated by utilizing the graphical post processing capabilities. It has been observed that the material and structural alterations are what cause the increase in natural frequencies. With an input of 1 V, the load is adjusted between 0 and 5000 Hz for every material configuration.

Design and Development of IoT based Smart System for Monitoring Laboratory Environment

This study was conducted to address the critical issue of the poor safety management system in laboratories, through the design of a smart laboratory management facility based on the Internet of Things (IoT). In this design, three major safety parameters-fire, temperature and carbon (ii) oxide (CO) levels were monitored by appropriate sensors, which transmit data to the microcontroller (Arduino) for interpretation. The Arduino microprocessor processed the data received from the sensor(s), makes decisions based on the predefined algorithms. Based on the decisions made by the Arduino, the microprocessor sends instructions to a relay module triggered the necessary actions to be taken by the output hardware devices-fire extinguisher, air conditioning system and exhaust fan unit. The temperature monitoring system was designed at an operational range of 18°C to 25°C, the CO control unit was designed to maintain the CO concentration inside the laboratory at a level not exceeding 4 parts per million (ppm), as approved by the World Health Organization; while fire control unit was designed to detect the presence of smoke of naked fire inside the building. In the event that any of these parameters breach safety thresholds, the smart structure's safety system will trigger the appropriate responses. The designed structure was built in compliance with international safety standards. Results obtained through the testing and evaluation of the system revealed that the smart system had overall performance efficiency of 91% and false output of 9%. The system's failure rate of 9% can be reduced by employing advanced sensors and adjusting the delay rate. The findings of this study revealed that IoT and automation can successfully monitor and protect the working environment inside laboratories.