Elastic Matrix Research Articles

A Zener-Stroh crack along the interface of a rigid elliptical inhomogeneity in an anisotropic elastic matrix

A Zener-Stroh crack along the interface of a rigid elliptical inhomogeneity in an anisotropic elastic matrix

Anisotropy cyclic plasticity constitutive modelling for Ni-based single-crystal superalloys based on Kelvin decomposition

Nickel-based single-crystal (SC) superalloys exhibited excellent exceptional mechanical properties at high temperatures due to the elimination of internal grain boundaries, contributed a strong orientation-dependent material response. The anisotropy of SC superalloys was modeled viscoplastically from a macroscopic viewpoint based on the Kelvin decomposition theory [1] which was a decomposition of the stress space according to the elastic matrix eigen-directions to control the viscoplastic flow by Kelvin stress decoupled from each other. Compared to the classical phenomenological macro model, the proposed model effectively captures the slip deformation mechanism of SC superalloys with the inherent ability to simulate anisotropic because of the two criterions framework controlled by Kelvin stress. Compared with others, the proposed model was able to simulate time-dependent inelastic deformation and cyclic deformation behavior under complex loading. The kinematic hardening and isotropic hardening models incorporated microscopic quantities, such as dislocation density and channel phase width, connecting the macroscopic mechanical response with the microscopic state to achieve multiscale constitutive modelling. The parameter identification and finite element implementation were conducted on a SC superalloy [2]. Simulation results demonstrated the accuracy of the proposed model in predicting deformation behavior under various orientations, rate-dependent effects, isothermal and non-isothermal cyclic deformation. Comparison with the classical anisotropic matrix macroscopic phenomenological approaches highlights the superior capability of the proposed model to simulate the orientation-dependent mechanical properties of single-crystal alloys.

New Insights in the Nanomechanical Study of Carbon-Containing Nanocomposite Materials Based on High-Density Polyethylene

The investigation of new composite materials possessing low weight but not at the expense of their mechanical performance is of great interest in terms of reducing energy consumption in many industrial applications. This study is focused on the nanomechanical characterization of high-density polyethylene (HDPE)-based composite specimens modified with equal loadings of graphene nanoplatelets (GNPs) and/or multiwall carbon nanotubes (MWCNTs). Quasi-static nanoindentation analysis revealed the impact of the carbon nanofillers on the receiving of nanocomposites with higher nanohardness and reduced modulus of elasticity, reaching values of 0.146 GPa and 3.57 GPa, respectively. The role of the indentation size effect in elastic polymer matrix was assessed by applying three distinct peak forces. Nanoscratch experiments depicted the tribological behavior of the composite samples and inferred the influence of the carbon nanofillers on the values of the coefficient of friction (COF). It seems that the incorporation of 4 wt% GNPs in the polymer structure improves the scratch resistance of the material, resulting in a higher value of the exerted lateral force and therefore leading to the detection of a higher coefficient of friction at scratch of 0.401. A considerable pile-up response of the scratched polymer specimens was observed by means of in-situ SPM imaging of the tested surface sample area. The sway of the carbon nanoparticles on the composite pile-up behavior and the effect of the pile-up on the measured friction coefficients have been explored.

Losartan-based nanocomposite hydrogel overcomes chemo-immunotherapy resistance by remodeling tumor mechanical microenvironment

Preclinical studies demonstrating high cure rates with PD1/PD-L1 combinations have led to numerous clinical trials, but emerging results are disappointing. These combined immunotherapies are commonly employed for patients with refractory tumors following prior treatment with cytotoxic agents. Here, we uncovered that the post-chemotherapy tumor presents a unique mechanical microenvironment characterized by an altered extracellular matrix (ECM) elasticity and increased stiffness, which facilitate the development of aggressive tumor phenotypes and confer resistance to checkpoint blocking therapy. As thus, we rationally designed an in situ nanocomposite hydrogel system, LOS&FeOX@Gel, which enabled effective and specific delivery of the therapeutic payloads (losartan [LOS] and oxaliplatin [OX]) into tumor. We demonstrate that sustained release of LOS effectively remodels the tumor mechanical microenvironment (TMM) by reducing ECM deposition and its associated “solid stress”, thereby augmenting the efficacy of OX and its immunological effects. Importantly, this hydrogel system greatly sensitized post-chemotherapy tumor to checkpoint blocking therapy, showing synergistic therapeutic effects against cancer metastasis. Our study provides mechanistic insights and preclinical rationale for modulating TMM as a potential neoadjuvant regimen for tumor to optimize the benefits of chemo-immunotherapy, which lays the groundwork for leveraging “mechanical-immunoengineering” strategies to combat refractory tumors.Graphical

Organic-Inorganic Coupling Strategy: Clamp Effect to Capture Mg2+ for Aqueous Magnesium Ion Capacitor.

The rapid transport kinetics of divalent magnesium ions are crucial for achieving distinguished performance in aqueous magnesium-ion battery-based energy storage capacitors. However, the strong electrostatic interaction between Mg2+ with double charges and the host material significantly restricts Mg2+ diffusivity. In this study, a new composite material, EDA-Mn2O3, with double-energy storage mechanisms comprising an organic phase (ethylenediamine, EDA) and an inorganic phase (manganese sesquioxide) was successfully synthesized via an organic-inorganic coupling strategy. Inorganic-phase Mn2O3 serves as a scaffold structure, enabling the stable and reversible intercalation/deintercalation of magnesium ions. The organic phase EDA adsorbed onto the surface of Mn2O3 as an elastic matrix, works synergistically with Mn2O3, and utilizes bidentate chelating ligands to capture Mg2+. The robust coordination effect of terminal biprotonic amine in EDA enhances the structural diversity and specific capacity characteristics of the composite material, as further corroborated by density functional theory (DFT) calculations, ex situ XRD, XPS, and Raman spectroscopy. As expected, the EDA-Mn2O3 composite achieved an outstanding specific discharge capacity of 188.97 mAh/g at 0.1 A/g. Additionally, an aqueous magnesium ion capacitor with EDA-Mn2O3 serving as the cathode can reach 110.17 Wh/kg, which stands out among the aqueous magnesium ion capacitors that have been reported thus far. The abundant reversible redox sites are ensured by the strategic design concept based on the synergistic structure and composition advantages of organic and inorganic phases. This study aimed to explore the practical application value of organic-inorganic composite electrodes with double-energy storage mechanisms.

Elastic Fields Around Multiple Stiff Prestressed Arcs Located on a Circle

Abstract The plane strain problem of an isotropic elastic matrix subjected to uniform far-field load and containing multiple stiff prestressed arcs located on the same circle is considered. The boundary conditions for the arcs are described by those of either Gurtin–Murdoch or Steigmann–Ogden theories in which the arcs are endowed with their own elastic energies. The material parameters for each arc can in general be different. The problem is reduced to the system of real variables hypersingular boundary integral equations in terms of two scalar unknowns expressed via the components of the stress tensors of the arcs. The unknowns are approximated by the series of trigonometric functions that are multiplied by the square root weight functions to allow for automatic incorporation of the tip conditions. The coefficients in series are found from the system of linear algebraic equations that are solved using the collocation method. The expressions for the stress intensity factors are derived and numerical examples are presented to illustrate the influence of governing dimensionless parameters.

Enhancing Exosomal Delivery to Abdominal Aortic Aneurysms using Magnetically Responsive Chemotactic Nanomotors for Elastic Matrix Regenerative Repair.

Abdominal aortic aneurysms (AAAs) involve localized dilation of the abdominal aorta, with the reversal of this condition being significantly limited by the inherently poor and abnormal regenerative repair of the aortic elastic matrix. Mesenchymal stem cell exosomes (MSCEs) are promising regenerative tools; however, achieving precise targeting of AAA with MSCEs is challenging owing to the high blood flow in the arterial system. In this study, an engineered exosomal nanomotor is developed for magnetic and chemical propulsion. The results demonstrate that this nanomotor effectively enhances the delivery of MSCEs to the AAA through magnetic field navigation and catalase-induced chemotaxis. The nanomotor significantly enhances the elastic matrix repair, reduces oxidative stress, and activates the PI3K/Akt pathway, leading to aneurysm shrinkage and reversal. In addition, the nanomotor possesses magnetic resonance imaging capabilities. The use of this nanomotor offers a novel, targeted drug delivery system in a rat model of AAA and holds promise as a potential therapeutic option for this condition.

Nanosilica-Reinforced Poly(dimethylsiloxane) Stretchable Transparent Electrodes and Multifunctional Applications.

Soft and stretchable transparent electrodes still face many challenges, requiring a balance between stretchability, conductivity, transparency, and stability. In this paper, poly(dimethylsiloxane) (PDMS) elastomer is selected, and amphoteric nonionic surfactants (Triton X-100) are introduced to improve the interfacial bonding between nanosilica (SiO2) and the elastic matrix. At the same time, a fluorosilane-modified glass template is used to induce nanosilica enrichment on the membrane surface. Based on the dual effects of nanoenhancement and surface regulation, a PDMS transparent nanocomposite membrane with good stretchability, surface hydrophilicity, and easy in situ polymerization of polydopamine can be obtained. Silver nanowires (AgNWs) and poly(3,4-ethylenedioxythiophene)/polystyrenesulfonate (PEDOT:PSS) conductive polymers can be assembled layer by layer on the surface of the nanocomposite membrane by simple spin coating and heat treatment. The transmittance of the soft and stretchable composite membrane can reach 63% in the visible light range, and the strength and elongation at break increase to 2.30 MPa and 150%, respectively. The sheet resistance of the stretchable transparent dry electrode is as low as about 6 Ω/sq. After being placed in the air for 3 months, the resistance increment is less than 5%, showing good environmental stability. The stretchable transparent electrode prepared based on the material-structure-preparation integrated method has brilliant application potential in wearable thermal management, electrochromism, strain sensing, and electromagnetic shielding.

Designing spongy-bone-like cellular materials: Matched topology and anisotropy

Bone is a natural material with properties such as high specific stiffness and strength. These exceptional mechanical properties are attributed to the meso-scale structure and elastic anisotropy of spongy bone. Replicating the topological traits and mechanical properties of spongy bone presents a novel opportunity to develop high-performance cellular materials. To achieve this, we propose an innovative framework for designing biomimetic cellular materials that match the trabecular structure and elastic anisotropy of spongy bone. This framework introduces a forward-flow design process that utilizes gradient-based feature tuning on a low-dimensional feature vector, transforming the complex inverse design problem into an efficient iterative process. A key innovation in our approach is the use of a pre-trained generative model, SliceGAN, to reconstruct 3D unit cells from 2D micro-CT images. This significantly reduces the cost and time associated with traditional layer-by-layer CT scans typically required for 3D training data. Numerical homogenization is then used to determine the effective elastic stiffness matrix, and a Fourier neural operator is trained to predict these matrices efficiently, greatly enhancing the computational efficiency of the design process. Using this framework, we successfully designed unit cells with topological traits and elastic anisotropy that closely approximate those of natural spongy bone. This opens new avenues for developing spongy-bone-mimetic cellular materials with exceptional mechanical properties. Moreover, the framework's versatility allows it to be extended to the design of other bio-inspired cellular materials.

Integration of deformable matrix and lithiophilic sites for stable and stretchable lithium metal batteries

In response to the growing interest in wearable devices, the demand for next-generation wearable devices that can endure various mechanical deformations such as folding and stretching is also increasing. As a result, the development of stretchable batteries, capable of operating under diverse conditions, is regarded as crucial for the advancement of these future wearable technologies. Many current studies on stretchable batteries suffer from limited energy density and complicated fabrication procedures. Thus, the development of batteries that meet both high stretchability and energy density remains challenging due to these factors. Herein, we propose a stretchable and lithiophilic matrix as a host for lithium (Li) metal anodes to realize stretchable Li metal batteries (LMBs), which consists of a polymer matrix embedded with silver nanoparticles (AgNPs). The lithiophilic AgNPs are incorporated both on the surface and within the elastic fiber matrix, providing facile Li nucleation kinetics and an electron-conductive network. Surface AgNPs serve as a primary electron pathway and offer numerous nucleation seeds to facilitate uniform Li electrodeposition. Meanwhile, AgNPs embedded in the matrix provide a sturdy conductive network even under mechanical deformation. Consequently, the structure-forming factors of stretchable lithiophilic Ag-incorporated matrix (SLiM) electrode contribute to enhanced electrochemical properties as a versatile Li metal host. As a proof of concept, the designed all-stretchable LMB with the SLiM electrode demonstrates minimal degradation of electrochemical performance in deformable conditions and confirms the feasibility of an LMB in stretchable application. This work provides insight into stretchable LMBs aimed at both highly deformable and high-energy-density wearable devices.

Mechanosensitive Differentiation of Human iPS Cell-Derived Podocytes.

Stem cell fate decisions, including proliferation, differentiation, morphological changes, and viability, are impacted by microenvironmental cues such as physical and biochemical signals. However, the specific impact of matrix elasticity on kidney cell development and function remains less understood due to the lack of models that can closely recapitulate human kidney biology. An established protocol to differentiate podocytes from human-induced pluripotent stem (iPS) cells provides a promising avenue to elucidate the role of matrix elasticity in kidney tissue development and lineage determination. In this study, we synthesized polyacrylamide hydrogels with different stiffnesses and investigated their ability to promote podocyte differentiation and biomolecular characteristics. We found that 3 kPa and 10 kPa hydrogels significantly support the adhesion, differentiation, and viability of podocytes. Differentiating podocytes on a more compliant (0.7 kPa) hydrogel resulted in significant cell loss and detachment. Further investigation of the mechanosensitive proteins yes-associated protein (YAP) and synaptopodin revealed nuanced molecular distinctions in cellular responses to matrix elasticity that may otherwise be overlooked if morphology and cell spreading alone were used as the primary metric for selecting matrices for podocyte differentiation. Specifically, hydrogels with kidney-like rigidities outperformed traditional tissue culture plates at modulating the molecular-level expression of active mechanosensitive proteins critical for podocyte health and function. These findings could guide the development of physiologically relevant platforms for kidney tissue engineering, disease modeling, and mechanistic studies of organ physiology and pathophysiology. Such advances are critical for realizing the full potential of in vitro platforms in accurately predicting human biological responses.

A coated hypotrochoidal compressible liquid inclusion neutral to a hydrostatic stress field after relaxation by interface slip and diffusion

We study the steady-state response of a three-phase composite composed of an internal hypotrochoidal compressible liquid inclusion, an intermediate isotropic elastic coating and an outer isotropic elastic matrix with simultaneous interface slip and diffusion occurring on the solid–solid interface when the matrix is subjected to a uniform hydrostatic stress field. We design a neutral coated hypotrochoidal liquid inclusion that does not disturb the prescribed uniform hydrostatic stress field in the surrounding matrix. The neutrality is achieved when the plane-strain bulk modulus or the compressibility of the elastic matrix is determined by solving a system of simultaneous linear algebraic equations for given geometric and material parameters of the coated liquid inclusion.

Magnetic-field-controllable elasticity of helical spring magnets composed of magnetic-particle-polymer composites

Abstract We experimentally demonstrated the ability to control the spring constant of helical mechanical springs using a magnetic field. These springs were composed of magnetic nanoparticles embedded within an elastic polymer matrix. The composite material, in its gel form, was injected into a 3D-printed mold featuring a helical-spring-shaped cavity. An external magnetic field applied perpendicular to the coil axis of the spring allows the aligmment of the magnetic nanoparticle assemblies (chain axis) in the field direction. This alignment process determines the preferred magnetization orientation of the particle assembly chain, thereby balancing the magnetic force between the magnetic anisotropy field and the Zeeman field under a given external field. When the spring is subjected to compression or stretching loads under an externally applied magnetic field, these two magnetic fields modify the effective spring constant of the magnetic helical spring by ~ 31 %, incresing it from 8.7 N/m (under no field) to 11.5 N/m at 300 mT. Analytical modeling using a simplified rod geometry aptly explains the experimental results, demonstrating that the spring constant linearly increases with the field strength up to 300 mT. Such composite magnetic helical springs could be utilized as active vibration absorbers or isolators due to their field-controllable elasticity.

CT-Based method for determining the elastic properties of an inhomogeneous medium element

The determination of mechanical parameters is one of the relevant directions in the calculation of inhomogeneous media elements. The need to build numerical models is primarily due to the development of modern approaches to the reconstruction of materials of various composite structures. The use of computational models in clinical practice also makes it possible to study the strength characteristics of objects of biological origin, the features of which include the uniqueness of the material structural distribution. The most widespread approaches in this case are based on the use of image data. Within the framework of this work, a method for constructing an elasticity matrix based on digital twin data is presented. During the work, images with a given material structure are constructed, as well as data extraction from CT scans of full-scale samples. The averaging of mechanical parameters was performed on the basis of the finite element method for the area of square or cubic geometry defining the unit cell. The calculations performed by the proposed method showed the convergence of the method with the analytical calculation data on the example of solving test problems, and also determined the qualitative correspondence of the results to the features of the structural distribution of the material in full-scale samples. The presented homogenization method makes it possible to determine the elastic characteristics of a medium element, taking into account the inhomogeneous properties of the forming material.

Microwave Radiation Assisted Construction of Fused Deposition Modeling 3D Printing Flexible Sensors

AbstractWith the rapid development of the internet of things, the simple preparation of sensors has become a challenge. The present work presents the simple preparation of flexible sensors by using the fused deposition modeling (FDM) 3D printing combined with the microwave radiation‐assisted treatment of the thermoplastic polyurethane (TPU) with carbon nanotubes (CNTs) as conductive fillers to create the flexible sensors. The as‐prepared TPU/CNT composites exhibit the 7.27 MPa tensile strength and 401% elongation at break, similar to those of the pure TPU. After 200 tensile cycles, the TPU/CNT composites can still stably convert pressure into electrical signals, which can be used as flexible sensors with high sensitivity (0.879 kPa−1). In addition, shoe insoles and finger cover with sensing performance are fabricated through the FDM 3D printing technology, demonstrating the potential of the sensors to monitor human gait, finger straightening, and bending movements. The as‐proposed method involves the embedding CNTs as conductive fillers on the surface of TPU to form the TPU/CNT composite conductive layers on the surface of TPU, which is beneficial for maintaining the elasticity of the polymer matrix. The challenges in preparing stable, low‐cost, and scalable flexible sensors and highlights of the advantages of 3D printing technology in manufacturing flexible piezoresistive sensors are also deeply discussed.

Two-Stage Distributed Robust Optimization Scheduling Considering Demand Response and Direct Purchase of Electricity by Large Consumers

The integration of large-scale wind power into power systems has exacerbated the challenges associated with peak load regulation. Concurrently, the ongoing advancement of electricity marketization reforms highlights the need to assess the impact of direct electricity procurement by large consumers on enhancing the flexibility of power systems. In this context, this paper introduces a Distributed Robust Optimal Scheduling (DROS) model, which addresses the uncertainties of wind power generation and direct electricity purchases by large consumers. Firstly, to mitigate the effects of wind power uncertainty on the power system, a first-order Markov chain model with interval characteristics is introduced. This approach effectively captures the temporal and variability aspects of wind power prediction errors. Secondly, building upon the day-ahead scenarios generated by the Markov chain, the model then formulates a data-driven optimization framework that spans from day-ahead to intra-day scheduling. In the day-ahead phase, the model leverages the price elasticity of the demand matrix to guide consumer behavior, with the primary objective of maximizing the total revenue of the wind farm. A robust scheduling strategy is developed, yielding an hourly scheduling plan for the day-ahead phase. This plan dynamically adjusts tariffs in the intra-day phase based on deviations in wind power output, thereby encouraging flexible user responses to the inherent uncertainty in wind power generation. Ultimately, the efficacy of the proposed DROS method is validated through extensive numerical simulations, demonstrating its potential to enhance the robustness and flexibility of power systems in the presence of significant wind power integration and market-driven direct electricity purchases.

A crack in a confocal elliptical inhomogeneity embedded in an infinite matrix subjected to uniform heat flux

We derive a series-form analytical solution to the thermoelastic problem of an insulated and traction-free crack in a confocal elliptical isotropic elastic inhomogeneity embedded in an infinite isotropic elastic matrix subjected to uniform remote heat flux. Using complex variable techniques such as conformal mapping, analytic continuation and Laurent series expansions, the original thermoelastic problem is reduced to an infinite system of linear algebraic equations, the solution of which will yield the mode I and mode II stress intensity factors at the crack tip. An exact closed-form solution is derived when the inhomogeneity and the matrix have identical shear moduli. Detailed numerical results are presented to demonstrate the series-form and closed-form solutions with an emphasis on the particular case of a vanishingly thin inhomogeneity.

Maneuvering the mineralization of self-assembled peptide nanofibers for designing mechanically-stiffened self-healable composites toward bone-mimetic ECM.

Extracellular matrix (ECM) elasticity remains a crucial parameter to determine cell-material interactions (viz. adhesion, growth, and differentiation), cellular communication, and migration that are essential to tissue repair and regeneration. Supramolecular peptide hydrogels with their 3-dimensional porous network and tuneable mechanical properties have emerged as an excellent class of ECM-mimetic biomaterials with relevant dynamic attributes and bioactivity. Here, we demonstrate the design of minimalist amyloid-inspired peptide amphiphiles, CnPA (n = 6, 8, 10, 12) with tuneable peptide nanostructures that are efficiently biomineralized and cross-linked using bioactive silicates. Such hydrogel composites, CnBG exhibit excellent mechanical attributes and possess excellent self-healing abilities and collagen-like strain-stiffening ability as desired for bone ECM mimetic scaffold. The composites exhibited the formation of a hydroxyapatite mineral phase upon incubation in a simulated body fluid that rendered mechanical stiffness akin to the hydroxyapatite-bridged collagen fibers to match the bone tissue elasticity eventually. In a nutshell, peptide nanostructure-guided temporal effects and mechanical attributes demonstrate C8BG to be an optimal composite. Finally, such constructs feature the potential for adhesion, proliferation of U2OS cells, high alkaline phosphatase activity, and osteoconductivity.

Stress–strain hysteresis during hydrostatic loading of porous rocks

A micro-mechanical model is proposed to predict the stress–strain hysteresis during the cyclic hydrostatic loading of fluid-saturated rocks under drained or undrained conditions. A spherical pore is surrounded by a multi-cracked shell where local deviatoric stress develops despite the remote hydrostatic loading. The effective properties of the material composing the shell are constructed assuming an isotropic distribution of cracks with no interaction, and the overall properties thanks to the spherical assemblage approach. The fluid pressure in drained and undrained conditions is assumed to be uniform throughout the assemblage. A new analytical solution is proposed, assuming all cracks are closed and slipping either forwardly or reversely. It is shown with numerical simulations for drained conditions that this assumption is indeed respected for sufficiently small values of the crack friction angle. However, for reasonable values, the closed cracks during the unloading phase could slip in either direction: reversely close to the pore and still forwardly away from the pore. Moreover, at critical radii, the slip could occur in either direction depending on the crack orientation. A similar micro-structural response is observed for undrained conditions, although the remote confining stress required to close the cracks is much larger. The model’s predictions compare favourably with recent experimental data on dry sandstones and carbonates, which were presented in a study on the influence of strain amplitude on the transition between static and dynamic properties. The crack density and matrix elasticity modulus are sufficient fitting parameters to accurately predict the hysteresis loops, especially for porosity levels above 10%.

Optimizing sustainable energy integration: A novel approach using concentrated solar plant and hybrid power supply

This study pioneers sustainable energy solutions amidst escalating demand and fossil fuel depletion. Its primary novelty lies in proposing an integrated energy system, encompassing a concentrated solar plant, thermal energy system, and hybrid power supply within the solar energy domain. This integration substantially enhances overall system performance. The architectural design integrates various energy conversion components, including wind turbines, energy storage devices, and electric heaters, fostering synergistic collaboration. The optimization of energy usage is a key focus, utilizing heating and electricity costs as pivotal signals for participation in an Integrated Demand Response program (IRD). The demand response model, encompassing both thermal and electric loads, incorporates a sophisticated price elasticity matrix. Addressing challenges associated with renewable energy intermittency, phased carbon emissions, and the advantages of demand response, this study introduces an advanced system operation optimization model to effectively curtail operational costs. In the realm of methodology, this research breaks new ground by proposing an enhanced optimization algorithm that ingeniously combines the Whale Optimization Algorithm (WOA) with the Wavelet Transform (WT). This novel amalgamation significantly enhances the algorithm's search capabilities, providing superior performance in tackling the complexities inherent in the optimization problem. The proposed model undergoes rigorous evaluation in a comprehensive study featuring diverse energy sources and multiple scenarios. The outcomes of this evaluation distinctly showcase substantial reductions in overall operational costs compared to conventional approaches. This multifaceted contribution positions the study at the forefront of endeavors to revolutionize energy systems for enhanced sustainability and efficiency.