Bending Response Research Articles

Fabrication of low-viscosity injectable mineralized hydrogel sensor with redox-activated hybrid nanoparticle structure for cancer detection

A redox-responsive low-viscosity, injectable hydrogel (LVI-gel) sensor with capabilities involving bimodal cancer detection via the incorporation of glutathione (GSH) and reactive oxygen species (ROS)-activated nanoparticles (PD-Cu2+) is proposed and made injectable with varying degrees of mineralization. The PD-Cu2+ complex, in the presence of overexpressed GSH and ROS, undergoes a structural change that causes a regain of fluorescence and a shift in conductivity, accompanied by the variations in the mechanical, and adhesive properties for cancer detection. The release of catechol moieties brought about by the structural change of the PD-Cu2+ complex influences the shift in hydrogen bonding, resulting in increased water uptake, further reducing viscosity (η decreases by 95.14 %) and increasing adhesiveness (360.28 % increase) in the presence of GSH 10 mM. The alterations in mechanical and electrical properties further affect the bending response via LCR (control: ΔR/R0 ∼ 0.55 and GSH 10 mM: ΔR/R0 ∼ 0.89), which was confirmed in vitro via wireless response with HeLa, PC-3, and B16F10 as cancer cells. The effect of Cu2+-catalyzed oxidation of GSH was observed in vivo from the immunohistochemical studies and the downregulation of transcription for GPx1/Rn18s. Additionally, increased superoxide dismutase (SOD2) and catalase (CAT) activity along with the downregulation of the oncogenic NFκβ and TNF gene are observed. Finally, the ex situ sensing activity was monitored by the shift in resistance and the wireless response, demonstrating the ease with which the sensor could diagnose.

Design Optimization of Printed Multi-Layered Electroactive Actuators Used for Steerable Guidewire in Micro-Invasive Surgery.

To treat cardiovascular diseases (i.e., a major cause of mortality after cancers), endovascular-technique-based guidewire has been employed for intra-arterial navigation. To date, most commercially available guidewires (e.g., Terumo, Abbott, Cordis, etc.) are non-steerable, which is poorly suited to the human arterial system with numerous bifurcations and angulations. To reach a target artery, surgeons frequently opt for several tools (guidewires with different size integrated into angulated catheters) that might provoke arterial complications such as perforation or dissection. Steerable guidewires would, therefore, be of high interest to reduce surgical morbidity and mortality for patients as well as to simplify procedure for surgeons, thereby saving time and health costs. Regarding these reasons, our research involves the development of a smart steerable guidewire using electroactive polymer (EAP) capable of bending when subjected to an input voltage. The actuation performance of the developed device is assessed through the curvature behavior (i.e., the displacement and the angle of the bending) of a cantilever beam structure, consisting of single- or multi-stack EAP printed on a substrate. Compared to the single-stack architecture, the multi-stack gives rise to a significant increase in curvature, even when subjected to a moderate control voltage. As suggested by the design framework, the intrinsic physical properties (dielectric, electrical, and mechanical) of the EAP layer, together with the nature and thickness of all materials (EAP and substrate), do have strong effect on the bending response of the device. The analyses propose a comprehensive guideline to optimize the actuator performance based on an adequate selection of the relevant materials and geometric parameters. An analytical model together with a finite element model (FEM) are investigated to validate the experimental tests. Finally, the design guideline leads to an innovative structure (composed of a 10-stack active layer screen-printed on a thin substrate) capable of generating a large range of bending angle (up to 190°) under an acceptable input level of 550 V, which perfectly matches the standard of medical tools used for cardiovascular surgery.

Modeling and analysis of bending and torsional coupling vibration response of multi-piece wet friction clutch

Modeling and analysis of bending and torsional coupling vibration response of multi-piece wet friction clutch

Effect of bi-directional material gradation on thermo-mechanical bending response of metal-ceramic FGM sandwich plates using inverse trigonometric shear deformation theory

PurposeThe purpose of this study is to investigate the bending analysis of metal (Ti-6Al-4V)-ceramic (ZrO2) functionally graded material (FGM) sandwich plate with material property gradation along length and thickness direction under thermo-mechanical loading using inverse trigonometric shear deformation theory (ITSDT). FGM sandwich plate with a ceramic core and continuous variation of material properties has been modelled using Voigt’s micro-mechanical model following the power law distribution method. The impact of bi-directional gradation of material properties over the bending response of FGM plate under thermo-mechanical loading has been investigated in this work.Design/methodology/approachIn this study, gradation of material properties for FGM plates is considered along length and thickness directions using Voigt’s micromechanical model following the power law distribution method. This type of FGM is called bi-directional FGMs (BDFGM). Mechanical and thermal properties of BDFGM sandwich plates are considered temperature-dependent in the present study. ITSDT is a non-polynomial shear deformation theory which requires a smaller number of field variables for modelling of displacement function in comparison to poly-nominal shear deformation theories which lead to a reduction in the complexity of the problem. In the present study, ITSDT has been utilized to obtain the governing equations for thermo-mechanical bending of simply supported uni-directional FGM (UDFGM) and BDFGM sandwich plates. Analytical solution for bending analysis of rectangular UDFGM and BDFGM sandwich plates has been carried out using Hamilton’s principle.FindingsThe bending response of the BDFGM sandwich plate under thermo-mechanical loading has been analysed and discussed. The present study shows that centre deflection, normal stress and shear stress are significantly influenced by temperature-dependent material properties, bi-directional gradation exponents along length and thickness directions, geometrical parameters, sandwich plate layer thickness, etc. The present investigation also reveals that bi-directional FGM sandwich plates can be designed to obtain thermo-mechanical bending response with an appropriate selection of gradation exponents along length and thickness direction. Non-dimensional centre deflection of BDFGM sandwich plates decreases with increasing gradation exponents in length and thickness directions. However, the non-dimensional centre deflection of BDFGM sandwich plates increases with increasing temperature differences.Originality/valueFor the first time, the FGM sandwich plate with the bi-directional gradation of material properties has been considered to investigate the bending response under thermo-mechanical loading. In the literature, various polynomial shear deformation theories like first-order shear deformation theory (FSDT), third-order shear deformation theory (TSDT) and higher-order shear deformation theory (HSDT) have been utilized to obtain the governing equation for bending response under thermo-mechanical loading; however, non-polynomial shear deformation theory like ITSDT has been used for the first time to obtain the governing equation to investigate the bending response of BDFGM. The impact of bi-directional gradation and temperature-dependent material properties over centre deflection, normal stress and shear stress has been analysed and discussed.

A finite element for nonlinear three-dimensional Kirchhoff rods

This paper presents the formulation of a finite element method for nonlinear Kirchhoff rods (i.e. without transverse shear strain) in the general three-dimensional setting defined by a Cosserat director treatment of the cross sections attached to the rod's axis. The new element is based on a G1 interpolation of the rod's geometry in terms of Hermite shape functions of the rod's axis (including its tangent defining the tangential director), while the transversal directors defining the different bending and torsional responses of the rod consider a Lagrangian interpolation of the section directors. This direct interpolation of the directors, as opposed of underlying rotation vectors, assures the objectivity of the proposed formulation. In fact, the invariance properties of the resulting finite element are analyzed in detail, assuring the correct resolution of the local fundamental equilibrium relations between forces and moments, hence avoiding the so-called “self-straining” associated to separate treatments of the rod's geometry and its kinematics. Several representative numerical simulations are presented illustrating these properties as well as the appropriateness of the proposed formulation for the analysis of thin rods undergoing large finite deformations in the three-dimensional range.

Transient bending analysis of the graphene nanoplatelets reinforced sandwich concrete building structure validated by machine learning algorithm

This paper demonstrates a thorough examination of the bending behavior of sandwich concrete building structures that are reinforced with graphene nanoplatelets (GPLs). The analysis is confirmed using a machine learning technique. Sandwich structures have notable benefits in terms of strength, longevity, and thermal insulation, making them well-suited for many building applications. Integrating GPLs into the concrete matrix improves the mechanical characteristics and performance of these structures, especially in terms of bending behavior. This study utilizes a machine learning technique to verify the characterization of the temporary bending behavior of a concrete building structure reinforced with graphene nanoplatelets. The approach utilizes a dataset consisting of simulated bending data to create a prediction model that can reliably estimate the temporary bending response of the reinforced structure under different loading situations. The machine learning algorithm’s effectiveness and dependability in optimizing the design and performance of graphene nanoplatelets reinforced sandwich concrete building structures are demonstrated through validation against simulated results. This provides engineers and designers with a powerful tool. This study enhances the comprehension and use of machine learning approaches in analyzing and designing sophisticated structural materials and systems.

Linear static, geometric nonlinear static and buckling analyses of sandwich composite beams based on higher-order refined zigzag theory

This study aims at developing finite element formulations based on higher-order refined zigzag theory (HRZT) to analyze sandwich composite beams under linear static bending, geometric nonlinearity and buckling. In HRZT, the higher-order terms associated with average shear strain and rotation due to zigzag are added based on refined zigzag theory (RZT). In linear static bending analysis, both C0 and C1 elements are developed. For the C0 element, an extra node is used in order to eliminate shear locking. For geometric nonlinear static analysis, the two-node C0 element is developed to solve the bending response with lateral loading and buckling response. The numerical results are compared with those calculated by 2D exact solutions, analytical solutions of HRZT and 2D models using commercial software. Various beam theories such as first-order shear deformation theory (FSDT), higher-order shear deformation theory (HSDT), RZT, and other types of higher-order zigzag theory are also introduced for comparisons. Through comprehensive comparisons with existing works on FEM or zigzag theories, the HRZT beam elements developed in this study exhibit superior accuracy and are free from shear locking in linear static analysis. Furthermore, the study also demonstrates that these elements achieve high accuracy in geometric nonlinear analysis and buckling analysis.

3D Textile Reinforced Cement (TRC) composites with integrated synthetic microfibres: Evaluation of mechanical response and crack formation in bending

This study explores the integration of short synthetic microfibres into 3D Textile Reinforced Cement (3D TRC) composites to achieve enhanced flexural capacity and improved crack control. The homogeneous distribution of microfibres within 3D TRCs was a challenge unaddressed in the current state of the art. The influence of the added microfibres on the bending behaviour and crack formation of the 3D TRCs was evaluated, along with the effect of crucial parameters such as the microfibre type (PP/PVA), length (3 mm/6 mm/8 mm) and content (0.5 %/0.7 %/1.0 %). Microfibre-enhanced 3D TRCs demonstrated a higher ultimate load and post-cracking stiffness, as well as more and narrower cracks.

Compressive, bending and shear properties of reinforced concrete beams containing sawdust ash as partial replacement of cement

150x600 mm for the bending test and 150x150x450 mm for the shear test) specimens were used for this investigation. The concrete cube and RC beam specimens had SDA as a partial cement replacement within the range of 0%–10% by weight of cement at 2.5% intervals. 120 RC beam specimens were cast, followed by curing and testing at 28, 60, 90, and 180 days. Using the 4-point loading method, the bending and shear responses of the beams and associated parameters, like the formation and growth of cracks, were determined during the testing. The impact of SDA replacement on the characteristics of fresh and hardened concrete was also assessed using 105 cube specimens cast, cured, and tested at 7, 14, 21, 28, 60, 90, and 180 days. A concrete mix ratio of 1:1.3:2.4 and a constant water/binder ratio of 0.50 at optimum 5% SDA replacement produced (25 N/mm2 ) the required compressive strength. The results show that workability decreases as the SDA percentage increases. Generally, the values of concrete’s densities containing SDA in the mix were in the range of standard weight applications. At 28 days, samples up to 5% recorded a higher compressive, bending, and shear strength development rate than the control mix. The results show that cement partially replaced with up to 5% SDA can produce RC that meets the requirements for concrete for structural application.

Functionally varied negative-stiffness metamaterial core sandwich structures with three-phase bending deformation

Abstract This paper introduces a novel class of negative-stiffness (NS) core sandwich composite structures that exhibit unique mechanical performance, including shape recovery, superelasticity, and energy absorption (EA) in bending and shear mode. The core of these structures consists of a periodic cellular arrangement of double-curved beams that undergo consecutive local snap-buckling transitions between multiple equilibrium states, enabling the structures to change shape reversibly between their initial and deformed configurations. To characterize the force-displacement relationship of the core, a comprehensive analysis was conducted using a combination of 3D printed models and finite-element simulations. The metamaterial core with gradient-thickness negative-stiffness beams were examined under uniform compression, demonstrating that the snap-through behavior of the curved beams was intricately controlled by the beam thickness in each row. The numerical simulations accurately predicted the deformation characteristics of the graded cellular core, supporting the design of a metamaterial core with functionally varied beam thickness for nonuniform transverse loading. This led to spatially controlled NS core material with specific EA of around 50 J kg−1 and an apparent core shear strength of 0.1 MPa, all mainly within the reusable elastic regime. The resulting sandwich structures efficiently mitigated the localized effect from concentrated compressive forces and achieved complete snap-through buckling in all curve beams. Three-point bending response revealed three distinct phases of flexural deformation: the local facial bending phase, the sequential core-snapping superelastic phase, and the global bending phase.

Achieving gradual failure under bending by the layering design of 3D printed continuous fiber reinforced composites

A variety of methods have emerged to tailor the mechanical properties of 3D-printed continuous fiber-reinforced thermoplastic composites (CFRTCs) through geometry design or manufacturing parameters. However, the potential to achieve customized failure behavior is not exploited. In this study, the effect of different layer orders on load bearing and failure of 3D-printed CFRTCs is investigated. Carbon fiber-reinforced polyamide composites with six layer orders were prepared and the mechanical response in 4-point bending was investigated. We show that the failure behavior ranges from catastrophic to pseudo-ductile, and we distinguished four typical stress-strain responses. We found that the location and the thickness of matrix-only layers strongly influence the failure. For the latter, we present a linear relationship to the ductility index which shows that toughness can be increased with thicker matrix layers. Our results facilitate the design of CFRTCs with customizable failure behavior, thus contributing to safer applications.

Dampened Transient Actuation of Hydrogels Autonomously Controlled by pH-Responsive Bicontinuous Nanospheres.

The fabrication of a soft actuator with a dampened actuation response is presented. This was achieved via the incorporation into an actuating hydrogel of urease-loaded pH-responsive bicontinuous nanospheres (BCNs), whose membrane was able to regulate the permeability and thus conversion of fuel urea into ammonia. The dampened response of these nanoreactors to the enzymatically induced pH change was translated to a pH-responsive soft actuator. In hydrogels composed of a pH-responsive and nonresponsive layer, the transient pH gradient yielded an asymmetric swelling behavior, which induced a bending response. The transient actuation profile could be controlled by varying the external fuel concentrations. Furthermore, we showed that the spatial organization of the BCNs within the actuator had a great influence on the actuation response. Embedding the urease-loaded nanoreactors within the active, pH-responsive layer resulted in a reduced response due to local substrate conversion in comparison to embedding them within the passive layer of the bilayer hydrogel. Finally, we were able to induce transient actuation in a hydrogel comprising two identical active layers by the immobilization of the BCNs within one specific layer. Upon addition of urea, a local pH gradient was generated, which caused accelerated swelling in the BCN layer and transient bending of the device before the pH gradient was attenuated over time.

Reliability and sensitivity analyses of porous functionally graded graphene platelet reinforced composite plate

The performance of composite is seriously influenced by numerous uncertain factors, in which the uncertainty analysis plays a vital role in composite materials analysis by providing a comprehensive understanding of uncertain factors and their influence on design and performance. In this study, uncertain behaviors of porous functionally graded graphene platelets reinforced composite (FG-GPLRC) plates are first investigated for assessing the safety under bending deformation. The mechanical model for static analysis of the porous FG-GPLRC plate is formulated by Reddy’s higher-order shear deformation theory, and the bending responses are derived by Hamilton’s principle and the Navier method. Material properties and loads are deemed as random variables, and the performance function is determined by the Tsai-Wu criterion. The univariate dimension reduction method and maximum entropy method are employed to estimate the reliability of porous FG-GPLRC plates with diverse distribution patterns. Additionally, the analytical sensitivities of failure probability with respect to material parameters are derived. The analysis results illustrate that the existence of uncertain factors significantly influences the performance and reliability of composites, and the structural reliability can be improved by adding appropriate pores and graphene platelets at the edge layer of the composite plate.

Static Response of Functionally Graded Porous Circular Plates via Finite Element Method

The main purpose of this paper is to investigate the axisymmetric bending response of functionally graded porous (FGP) circular plates. The material properties are changed continuously in the thickness direction of the plate. Three distinct porosity distributions uniform, symmetric and monolithic are employed. The effect of porosity on the axisymmetric bending analysis of circular plates is examined parametrically. In this study, clamped and roller supports which commonly serve to achieve ideal boundary conditions in numerous engineering applications are used. The finite element method is employed for numerical analysis. The principal of the potential energy is used to obtain the governing equations. To generate the model of the FGP circular plates, an eight-node quadratic quadrilateral element with two degrees of freedom on each node is utilized. The results of this study are confirmed by the existing published literature. A good agreement between the results of the presented model and the previous literature has been observed. The results of the present study show that plate deflection increases with the increase of the porosity coefficient and the ratio of radius to thickness of circular plates. By increasing the porosity coefficient, the displacement values of the plates made of uniform porosity distribution is effected more than those of other porosity distributions.

Numerical-analytical investigation on bending performance of laminated beams in modular steel buildings

It is well-known that the laminated channel beams can significantly strengthen the combination of adjacent beam components and further enhance the structural integrity of modular steel buildings. In present study, the superimposed bending performance of laminated channel beams was comprehensively investigated using the numerical and analytical methods. Firstly, FE models were developed and validated by the experimental data. Then, a series of numerical parametric studies combining the orthogonal and univariate analysis were successively conducted to identify the sensitivity of design parameters including interfacial bolt number (n), interfacial friction (f), layer height ratio (β), load type (p) and boundary condition (b), and further clarify the influence of key parameters on the cooperative bending properties. Finally, the analytical procedure was proposed to evaluate the equivalent bending stiffness of laminated channel beams. The results showed that the effect degrees of design factors on EIe and Pu were as follows: n > β > f > b > p and p > b > β > f > n, respectively. n and β were selected as the key design parameters for the modular laminated beams. The bending responses were nonlinearly promoted by n, while the linear regularity was observed for β. The influencing mechanism of n indicated that the bolt connections induced the additional internal forces, which caused the transferring of neutral axes and the superimposition effect of laminated beams. Quantifying the neutral axis deviations, the analytical models were developed and reasonably assessed the superimposed bending stiffness of laminated beams in modular steel buildings.

Anisotropic plates with architected tendon network

We synthesize geometrically tailorable anisotropic plates by combining button shaped fish-scale like features on soft substrates, then lacing them with high-stiffness strings. This creates a new type of biomimetic architectured structure with multiple broken symmetries. First, the tendons and substrate together break the symmetry of the bending response between the concave and convex curvature. Next, the weave pattern of the tendons further breaks symmetry along the two directors of plates. The anisotropy is clearly evident in 3-point bending experiments. Motivated by these experiments and the need for design, we formulate an analytical energy-based model to quantify the anisotropic elasticity. The derived architecture-property relationships can be used to design architected tendon plates with desirable properties.

Mechanical Analysis of the Quasi-Static and Dynamic Composite Action in PV Modules with Viscoelastic Encapsulant.

The mechanical analysis of photovoltaics and building integrated photovoltaics is a key step for their optimal design and certification, and requires careful consideration, alongside solar power, durability and functionality issues. The solar cells are encapsulated in thin interlayers that are usually composed of a viscoelastic Ethylene-Vinyl Acetate compound, and protected by thin glass and/or plastic layers. This paper investigates the out-of-plane bending response of a full-scale commercial PV module and focuses attention on the shear bonding efficiency of the thin encapsulant for quasi-static and dynamic mechanical considerations. The parametric analytical analysis, carried out in this study for a laminated glass plate, highlights the possible consequences of the viscoelastic shear coupling on the cross-section load-bearing demand in the covers. As a direct effect of severe operational conditions (i.e., ageing, non-uniform/cyclic thermal gradients, humidity, extreme mechanical/thermal loads, etc.) the shear rigidity and adhesion of these films can suffer from repeated/progressive modification and even degradation, and thus induce major stress and deflection effects in the out-of-plane mechanical response of the PV module components. The minimum shear bond efficiency required to prevent mechanical issues is calculated for various configurations of technical interest. Accordingly, it is shown how the quasi-static and dynamic mechanical performance of the system modifies as a function of a more rigid or weak shear coupling.

A numerical study on bending behavior of sandwich beam with novel auxetic honeycomb core

To further improve the load-bearing capability and anti-impact properties of the auxetic structure, a novel enhanced auxetic honeycomb core (NEH) was introduced, and the bending resistance and crashworthiness of this sandwich beam (NEH-SWB) were analyzed through numerical simulation. First, bending tests on sandwich beams under different loading situations revealed that NEH-SWB was more susceptible to impact damage in three-point bending situations than those under four-point bending, and the influence of structural parameters were more pronounced. In addition, the impact of load position and structural parameters on the bending response and deformation pattern of NEH-SWB were investigated. NEH-SWB exhibited superior bending resistance when the punch was located in the S position. Furthermore, increasing the panel thickness and altering the panel thickness configuration both contributed to improving the flexural resistance of NEH-SWBs. At a certain mass, the configuration with T f / T b > 1 exhibited better bending resistance. Meanwhile, increasing both the cell angle (θ) and wall thickness-to-length ratio (t/l) enhanced load-carrying capability and energy absorption of NEH-SWB. Subsequently, further analysis showed that NEH had better bending performance compared to cell structures with reentrant (RH), star-shaped (SSH), and reentrant-star (RSH) honeycombs. Finally, the complex proportion assessment method was employed to examine the significance of structural parameters regarding the flexural behavior of the NEH-SWB. It was concluded that increasing the t/l value could be the best solution to enhance the bending performance of the NEH-SWB.

An Improved Winkler Foundation Modulus for a Beam in a Full Space

The Winkler foundation modulus is key to evaluating the response of underground structures using the elastic foundation beam model. In this paper, an improved formula of the Winkler foundation modulus for a beam embedded in a full space is proposed to overcome the limitation of inconsistent assumptions in previous studies. To achieve this goal, the bending responses of the beam are obtained using the elastic foundation beam model and three-dimensional elastic continuum model, respectively, wherein a consistent assumption is proposed that tangential interactions at the beam–ground interface are ignored in the two models. In addition, as deformation of the site is an important source of the underground structure response, the beam is applied to standard soil displacement of the free field on the Winkler foundation to improve the accuracy of the Winkler modulus obtained by fitting solutions based on the concentrated force on the beam. The formula for the Winkler foundation is obtained by equating the first zero of the bending moment in the two models. The Winkler foundation modulus is verified by comparing the results with numerical solutions and previous studies.

Effects of Temperature and Layer Thickness on the Static and Dynamic Behaviors of Biocomposite Materials with Interleaved Viscoelastic Layers

This study investigated the influence of temperature variations on the mechanical and dynamic behaviors of biobased composites incorporating a passive control layer. These composites, which include an external layer made up of Flax/polylactic acid (PLA) and an internal layer of rubber, were manufactured using 3D printing technique. To better understand their mechanical characteristics, bending tests were carried out on samples of Flax/PLA with and without a rubber coating at temperatures ranging from [Formula: see text]C to [Formula: see text]C. To evaluate the bending response of the materials under several temperatures settings, three-point bending tests were also conducted on the materials with different viscoelastic layer thicknesses. Additionally, resonance vibration studies were carried out at various temperatures to explore dynamic characteristics like frequencies and damping factors. The analysis of the data revealed the consequences of incorporating a functional rubber layer under diverse circumstances. The results demonstrated that increasing temperatures negatively impacts the mechanical and dynamic characteristics degradation of the composite with the viscoelastic layer. The main objective of this work is that under various thermal settings, passive control layers in biocomposites can display modified mechanical and dynamic behaviors. This understanding of how these biobased composites perform in different environments offers significant context for their possible applications.