Load-bearing Capability Research Articles

Improving contact damage resistance of spinel translucent ceramics through a multi-layer design

The brittle response of transparent spinel ceramics to contact damage is limiting their application as an alternative to glasses and single crystals. In this work, we explore a strategy to enhance the contact damage resistance of spinel ceramics by embedding alumina layers in a multi-layer architecture. Crack initiation upon Hertzian indentation was investigated in MgAl2O4 – Al2O3 laminates and compared to their corresponding monoliths. Contact stresses during loading were analyzed using finite element simulations by considering the elastic properties of the layers and contact non-linearities. Results were analyzed using Weibull statistics. It was found that the effect of in-plane residual stresses on crack formation in the laminate depends on the disposition of the compressive spinel layers, either at the surface or embedded in the structure. Embedding alumina between spinel layers increased the load-bearing capability before crack initiation by ~70% compared to spinel, offering a promising approach to enhance contact damage resistance.

Optimization and synthesis on the dynamics performance of the tensioning and relaxing wearable system in a novel knee exoskeleton using co-simulation

Abstract In this paper, a novel tensioning and relaxing wearable system is introduced to improve the wearing comfort and load-bearing capabilities of knee exoskeletons. The research prototype of the novel system, which features a distinctive overrunning clutch drive, is presented. Through co-simulation with ANSYS, MATLAB, and SOLIDWORKS software, a comprehensive multi-objective optimization is performed to enhance the dynamics performance of the prototype. Firstly, the wearing contact stiffness of the prototype and the mechanical parameters of the relevant materials are simulated and fitted based on the principle of functional equivalence. And then, its equivalent nonlinear circumferential stiffness model is obtained. Secondly, to enhance the wearing comfort of the exoskeleton, a novel comprehensive performance evaluation index, termed wearing comfort, is introduced. The index considers multiple factors such as the duration of vibration transition, the acceleration encountered during wear, and the average pressure applied. Finally, through the utilization of this indicator, the system’s dynamics performance is optimized via multi-platform co-simulation, and the simulation results validate the effectiveness of the research method and the proposed wearable comfort index. The theoretical basis for the subsequent research on the effectiveness of prototype weight-bearing is provided.

Axial hysterestic behavior of prestressed CFDST columns for lattice-type wind turbine towers

The escalating power outputs of wind turbines necessitate enhanced load-bearing capabilities in their support structures. A new type of prestressed concrete-filled double skin steel tubular (CFDST) lattice-type wind turbine tower has been proposed to replace the original steel-concrete hybrid tower. The corner columns of the tower are made of prestressed CFDST columns, with the prestressing steel strands situated within the hollow area. While numerous studies have researched the axial characteristics of concrete-filled steel tubular (CFST) columns, investigations into prestressed CFDST columns subjected to axial cyclic loading remain sparse. To address this research gap, this study carried out the experimental and finite element studies of eight prestressed CFDST columns under axial tensile, axial compressive, and tensile-compressive cyclic loads. Detailed analyses of failure modes, hysteresis curves, stiffness degradation, skeleton curves and ductility were conducted. The test results indicate that the prestressing enables the concrete to establish good contact with the steel tubes, thereby preventing the premature cracking. At a cost of approximately 6.8 % reduction in axial compressive load, the axial tensile load of the structure is enhanced by about 47.2 %. Furthermore, an advanced finite element (FE) model, refined based on the test, closely matched the experimental data, thereby validating its accuracy for subsequent mechanism and parameter investigation.

Ultimate strength assessment of randomly pitted stiffened panels considering stiffener corrosion

Stiffened panels are renowned for their exceptional load-bearing capabilities due to their high strength-to-weight ratio and are extensively utilized in ship and marine structures. Nevertheless, they are susceptible to failure under compression, particularly in marine environments where corrosion leads to material and structural degradation. Stiffener corrosion was not involved adequately in current studies, with an unclear synergistic effect of corrosion damage with structural configurations. This paper introduces a numerical modeling approach to develop finite element (FE) models of panels with random pitting corrosion, considering both corrosion on the plating and stiffeners. These FE models are validated against existing experiments and empirical formulae and employed to investigate the effect of random pitting damage on the ultimate strength of panels. The study examines the impact of various structural parameters, such as plate aspect ratio, plate slenderness ratio, stiffener slenderness ratio, and the height-to-thickness ratio of stiffener web, on ultimate strength under different levels of pitting damage. Additionally, the load-bearing behavior and failure modes of damaged panels are analyzed. An artificial neural network (ANN) is developed to predict the ultimate strength of pitted panels. The findings indicate that the ultimate strength of panels with stiffener corrosion in the form of random pitting corrosion leads to a more significant reduction by about 17.7% than that without stiffener corrosion, potentially altering the failure mode. The proposed ANN model accurately predicts the ultimate strength of pitted panels with and without stiffener corrosion, with a mean relative error of approximately 1.1% compared to FE analysis results.

Multiscale Fiber Remodeling in the Infarcted Left Ventricle using a Stress-Based Reorientation Law

The organization of myofibers and extra cellular matrix within the myocardium plays a significant role in defining cardiac function. When pathological events occur, such as myocardial infarction (MI), this organization can become disrupted, leading to degraded pumping performance. The current study proposes a multiscale finite element (FE) framework to determine realistic fiber distributions in the left ventricle (LV). This is achieved by implementing a stress-based fiber reorientation law, which seeks to align the fibers with local traction vectors, such that contractile force and load bearing capabilities are maximized. By utilizing the total stress (passive and active), both myofibers and collagen fibers are reoriented. Simulations are conducted to predict the baseline fiber configuration in a normal LV as well as the adverse fiber reorientation that occurs due to different size MIs. The baseline model successfully captures the transmural variation of helical fiber angles within the LV wall, as well as the transverse fiber angle variation from base to apex. In the models of MI, the patterns of fiber reorientation in the infarct, border zone, and remote regions closely align with previous experimental findings, with a significant increase in fibers oriented in a left-handed helical configuration and increased dispersion in the infarct region. Furthermore, the severity of fiber reorientation and impairment of pumping performance both showed a correlation with the size of the infarct. The proposed multiscale modeling framework allows for the effective prediction of adverse remodeling and offers the potential for assessing the effectiveness of therapeutic interventions in the future. Statement of SignificanceThe organization of muscle and collagen fibers within the heart plays a significant role in defining cardiac function. This organization can become disrupted after a heart attack, leading to degraded pumping performance. In the current study, we implemented a stress-based fiber reorientation law into a computer model of the heart, which seeks to realign the fibers such that contractile force and load bearing capabilities are maximized. The primary goal was to evaluate the effects of different sized heart attacks. We observed substantial fiber remodeling in the heart, which matched experimental observations. The proposed computational framework allows for the effective prediction of adverse remodeling and offers the potential for assessing the effectiveness of therapeutic interventions in the future.

Structural determinants of tendon multiscale mechanics and their sensitivity to mechanical stimulation during development in an embryonic chick model

There is an abrupt increase in the multiscale mechanical properties and load-bearing capabilities of tendon during development. While prior work has identified numerous changes that occur within the collagenous structure during this developmental period, the primary structural elements that give rise to this abrupt increase in mechanical functionality, and their mechanobiological sensitivity, remain unclear. To address this knowledge gap, we used a shear lag model along with ultrastructural imaging, biochemical/thermodynamic assays, and multiscale mechanical testing to investigate the dynamic structure-function relationships during late-stage embryonic chick development and to establish their sensitivity to mechanical stimulation. Mechanical testing and modeling suggested that the rapid increase in multiscale mechanics can be explained by increases in fibril length, intrafibrillar crosslinking, and fibril area fraction. To partially test this, we inhibited collagen crosslinking during development and observed a drastic reduction in multiscale mechanical behavior that was explained by a reduction in both fibril modulus and length. Using muscle paralysis to investigate mechanosensitivity, we observed a significantly impaired multiscale mechanical response despite minimal changes in fibril diameter and fibril area fraction. Additionally, the shear lag model found a trend toward lower fibril lengths with paralysis and experimental data found decreased crosslinking and fibril modulus values following flaccid paralysis. Together, these data suggest that both intrafibrillar crosslink formation and fibril elongation are critical to the formation of load-bearing capabilities in tenogenesis and are sensitive to mechanical loading. These findings provide critical insights into the biological and structural mechanisms that give rise to tensile load-bearing soft tissue. Statement of SignificanceDespite prior work investigating the structural and mechanical changes that occur during tendon development, there has not been a comprehensive analysis of how these simultaneous changes in structure and function are connected. In this study, we performed a comprehensive battery of mechanical and structural assessments of embryonic chick tendons and input these data into a shear lag model to estimate the individual importance of each structural change to the tendon mechanical properties. Additionally, we inhibited muscle activity in the embryos to evaluate the impact of mechanical stimulation on these evolving structure-function relationships during tendon development. These data provide insight into the primary structural elements that produce the tensile load-bearing capabilities of tendon, which will inform efforts to produce tissue engineered tendon replacements.

Experimental study on thermal insulation mortar with normal bearing capacity and its mesoscopic characteristics analysis

Low strength limits the application potential of thermal insulation concrete in high-temperature underground engineering. However, current research on enhancement methods for thermal insulation concrete is relatively limited, and there is a lack of appropriate evaluation indicators, which results in significant room for improvement in its overall performance. To address this issue, this paper develops a load-bearing and thermal insulation mortar (LBTIM) with both thermal insulation and load-bearing capabilities: based on M20 mortar, low-thermal-conductivity materials (aerogel, coal gangue, fly ash) and reinforcing materials (silica fume, basalt fiber, polypropylene fiber) were added. Orthogonal experiments with 6 factors at 5 levels and 6 factors at 3 levels were designed to investigate the thermal conductivity and uniaxial compressive strength of different material ratios. Subsequently, the "strength-to-thermal conductivity ratio" (RST) was defined, and an intensity-thermal conductivity scatter plot was drawn as an evaluation indicator. Based on the experimental results, the ratio of LBTIM was successfully developed and optimized, and its stability was verified through experimental replication. The optimal ratio of LBTIM was determined as follows: aerogel 0.26 %, silica fume 3.35 %, fly ash 7.06 %, coal gangue 30 %, basalt fiber 0.05 %, and polypropylene fiber 0.45 %. Experimental results showed that its thermal conductivity was approximately 0.8 W/m·K, and its uniaxial compressive strength reached 17 MPa. The strength-to-thermal conductivity ratio was improved by 60.7 % compared to M20 mortar. Furthermore, near-distance imaging and SEM tests revealed the mesoscopic mechanism of LBTIM: the high porosity and the formation of an effective porous shear-resistant structure in LBTIM significantly reduced internal air convection. Combined with the externally added porous materials, this effectively blocked the large heat flow channels within the mortar, thereby significantly reducing the thermal conductivity. Meanwhile, the internal porous shear-resistant structure and the reinforcing fiber materials jointly ensured the good load-bearing capacity and stability of LBTIM, providing an important reference solution for addressing the load-bearing and thermal insulation issues in high-temperature tunnels.

The application of novel shear deformation theory and nonlocal elasticity theory to study the mechanical response of composite nanoplates

The use of composite structures, which have many layers of materials, has become more prevalent in the field of engineering. One of the advantages of this approach is its ability to use the inherent strengths of the constituent materials, resulting in a substantial increase in their load-bearing capability. Hence, this research represents the pioneering investigation into the static bending and free vibration characteristics of composite nanoplates including several layers of materials, whereby the material layers are interconnected via intricate profiles characterized by square wave and sine waveforms. The purpose of this endeavor is to fully capitalize on the benefits of attending courses in order to enhance practical working efficiency. This study also incorporates the use of two innovative third-order shear deformation theories. Simultaneously, considering the negligible size impact facilitated by the nonlocal theory, the mathematical formulations and equilibrium equations are derived using the Hamilton principle. The issue has been addressed using a four-node element with six degrees of freedom per node. One novel aspect of this study is its consideration of the impact of initial shape imperfections in various manifestations. Additionally, the elastic foundation incorporates characteristics that exhibit spatial variation. This statement provides a somewhat more accurate depiction of the behavior shown by actual structures. The numerical findings have been meticulously computed and thoroughly examined. Notably, it is possible to determine the optimal number of wavelengths in the profile to enhance the load-bearing capability of the structure. The findings derived from this study have significant value in informing the design of operational frameworks in practical settings.

Novel implant design for comminuted posterior wall acetabular fractures.

In recent years, the medical community has witnessed a notable increase in high-energy traumatic injuries, leading to a surge in complex fracture patterns that challenge existing treatment methodologies. Among these, the posterior approach to acetabular fractures stands out for offering direct visualization of the retro-acetabular surface, with current fixation methods relying on 3.5mm low-profile reconstruction plates and various other implants. Despite the effectiveness of these methods, there is a burgeoning demand for a singular, adaptable implant that not only streamlines the surgical process but also optimizes patient outcomes. In an innovative approach to address this need, three-dimensional (3D) models of the posterior acetabular wall were meticulously crafted using AutoCAD® software. The chosen material for the implant was 316L surgical steel for its durability and strength. The design of the implant featured a low-profile mesh structure, which was instrumental in facilitating osteosynthesis. This design allowed for the placement of screws of varying lengths in multiple directions, ensuring the initial reconstruction of the joint in an anatomical position without hindering the placement of the definitive implant. The primary objective was to secure the fixation and stabilization of the fracture by specifically targeting the smaller bone fragments. A comparative analysis was then conducted between this novel plate and a conventional 316L surgical steel, seven-hole, 3.5mm reconstruction plate through finite element analysis. The comparative analysis unveiled that both plates demonstrated comparable deformation capacities, with no significant differences in load-bearing capabilities observed. This finding suggests that the innovative plate can match the performance of traditional plates used in such surgeries. The finite element analysis revealed that the newly developed anatomical plate for posterior wall acetabular fractures meets the necessary physical and mechanical criteria for permanent implementation in patients with these fractures. This breakthrough represents a promising advancement that could simplify surgical procedures and potentially elevate patient outcomes. This study is classified as a Level II, diagnostic study.

Investigation on Flexural Behavior of HFRC with Partial Replacement of Nano Silica and Slag Cement

This investigation directs to understand the flexural behavior of Hybrid Fiber Reinforced Concrete (HFRC) with incorporation of Nano silica and Portland slag cement. The mechanical properties of Concrete for the grade M50 is enhanced by combining different fibers such as glass, polypropylene, and steel. Specifically, we explore the replacement of these fibers for the cement at ratios of 2%, 3%, 4%, 5% and 6%. Findings indicate that it significantly improved flexibility, as well as micromechanical support. To assess the performance of the HFRC, Specimens are cast to undergo compression, Flexure and Spilt tensile using hybrid materials with a water-cement ratio of 0.40 and made to undergo normal water curing for a period of 7, 14, and 28 days. Our comprehensive analysis reveals that the inclusion of 5% fibers along with 5% of Nano silica as a partial replacement to fine aggregate exhibits superior ductility and flexural strength compared to other fiber ratios. The addition of latex admixture enhances the flexural strength of HFRC. Comparing the flexural behavior of HFRC to conventional concrete under applied loads the remarkable load-bearing capabilities of HFRC beams under flexural conditions are highlighted furthermore emphasizing the advantages of this innovative material for use in construction applications. The results were tabulated and comparative results were presented.

Interface reinforced by polymer binder for expandable carbon fiber structural lithium-ion battery composites

Carbon fiber (CF) composite structural battery (SB) is a novel energy storage device that integrates electrochemical energy storage with mechanical load-bearing capability. Carbon fiber's inherent conjugated carbon network possesses excellent electronic conductivity, thus serving as a current collector for electrode active materials. The bonding between active materials and carbon fibers relies on their manufacturing processes, requiring optimization of their electrochemical performance and addressing the challenges of large-scale production. In this work, a LiFePO4/PEO-LiTFSI/CF composite cathode was fabricated using the direct coating method. Polyethylene oxide (PEO) acted as a binder to form a stable LiFePO4 (LFP) coating on the carbon fiber woven fabric, while multi-walled carbon nanotube (MWCNT) were employed to construct a conductive network. This significantly enhanced both the charge-discharge performance and interface stability of the composite cathode. This composite cathode achieved a first-cycle discharge-specific capacity of 133.21 mAh·g−1 at 0.1 C rate and retained 93.7 % of its capacity after 200 cycles at 1 C rate. Based on this composite cathode, multiple active material coatings were integrated onto a carbon fiber woven fabric to manufacture an expandable multi-cell structural battery. Its advantage lies in the ability of multiple battery cells to disperse stress under load, thus achieving a higher capacity retention rate under bending loads. The structural battery possesses a high degree of customizability, allowing for adjustment of the area, position, and quantity of active material coatings to meet the demands of practical conditions.

Towards high-strength electrolyte-supported solid oxide fuel cells

The functionality and structural reliability of electrolyte-supported solid oxide fuel cells depend crucially upon the load-bearing capability of the ceramic electrolyte. In this work, the effect of thickness on the mechanical strength of tape-casted 8 mol% yttria-stabilized zirconia electrolyte discs was investigated. Samples with 98 % relative density and 2–3 µm grain size fabricated with thicknesses between 75 µm and 360 µm were mechanically tested using an adapted biaxial bending test. Thin electrolytes with biaxial strength up to 1 GPa could be produced. The measured characteristic strengths ranged from σ0 = 940 MPa to σ0 = 520 MPa for thin and thick samples, respectively, yielding a common Weibull modulus of m = 6. A higher strength scaled with decreasing thickness, confirming the “size effect” as in many technical ceramics. The measured ionic conductivity was above 0.1 S/cm at 1000 °C, which is in good agreement with commercial or conventionally prepared electrolytes.

Experimental investigation on the shear performance of hybrid structures comprising textile reinforced concrete stay-in-place formwork and reinforced concrete

Recently, the application of textile-reinforced concrete (TRC) in thin-walled precast structures has gained significant attention. Among these innovations, the combination of TRC and reinforced concrete (RC) has emerged as an effective method for creating hybrid structural systems. This paper presents the experimental results analyzing the shear behavior of a hybrid deck slab structure consisting of TRC stay-in-place (SiP) formwork and RC components. Shear performance was evaluated using 3-point bending tests on four large-scale specimens with aspect ratios (a/d) varying from 1.6 to 2.3. The average load carried by the TRC SiP formwork prior to failure—due to textile reinforcement rupture—was approximately 26.3 kN, with compressive strains at the top edge ranging from 2.8 to 3.4 ‰, just below the concrete's ultimate strain. The findings demonstrate the versatility of TRC SiP-formwork, highlighting its adaptable cross-section and substantial load-bearing capabilities, making it particularly suitable for composite bridge deck applications. The specimens experienced both shear compression and diagonal shear failures. Moreover, the TRC SiP-formwork effectively mitigated transverse cracking at the interface, enhancing bond strength and improving overall structural performance

Design-manufacturing-performance of electromagnetic absorbing/load bearing three-dimensional honeycomb woven composites

Structural electromagnetic wave (EMW) absorbing composites play a critical role in both civilian and military applications. However, traditional sandwich honeycomb EMW absorbing composites have poor out-of-plane mechanical properties and load-bearing performance.This study introduces the development of a three-dimensional honeycomb woven composite (3DHWC) that integrates EMW absorption and load-bearing capabilities. A weaving loom was used to fabricate a three-dimensional honeycomb woven structure fabric (3DHSWF) with varying structural parameters. Subsequently, the composites were formed using carbon black (CB), multi-walled carbon nanotubes (MWCNTs), and carbonyl iron powder (CIP) as hybrid absorbers, epoxy resin as the matrix, combined with the vacuum-assisted resin transfer molding (VARTM) process. Testing confirmed the material’s excellent EMW absorption and mechanical properties, achieving a maximum reflection loss (RL) of −30.9 dB and an adequate EMW absorption bandwidth (EAB) of 14.58 GHz. The maximum bending load reached 5799.1 N, with no delamination observed in the samples. This material demonstrates outstanding EMW absorption performance and exhibits superior load-bearing capacity while maintaining structural integrity. Our research provides valuable insights into the design of honeycomb EMW absorbing composites, offering significant advancements in EMW absorption efficiency and bending mechanical properties.

Machine learning-aided risk-based inspection strategy for hydrogen technologies

Although technically challenging, effective, safe, and economical transport is crucial for enabling a widespread rollout of hydrogen technologies. A promising option to transport large amounts of hydrogen lies in employing retrofitted natural gas pipelines. Nevertheless, H2-rich environments tend to degrade pipeline steels, reducing their load-bearing capability and accelerating crack propagation. Regular inspection and maintenance activities can preserve the pipelines’ integrity and guarantee safe operations. The risk-based inspection (RBI) approach is based on estimating the risk for each component item. It focuses most inspection activities on high-risk components to reduce costs while maximizing the plant’s safety and availability. However, the RBI standards do not consider hydrogen-induced degradations and cannot be adopted for industrial equipment operating in H2 environments. This study proposes a novel ad-hoc methodology for the risk-based inspection planning of hydrogen handling equipment. A machine-learning model to predict the fatigue crack growth in gaseous hydrogen environments is developed and integrated with the conventional RBI approach. The proposed methodology is validated on three pipelines transporting hydrogen and natural gas in different concentrations. The results show how similar operating conditions can determine different degradation rates depending on the environment and highlight how hydrogen-enhanced fatigue can reduce the pipelines’ lifetime.

Proposing novel body-centered cubic lattice core sandwich panels as satellite structure

In the present paper, a comparative study on the load-bearing as well as shielding performance against hypervelocity impact of space debris of sandwich panels with body-centered cubic lattice core is performed numerically in order to evaluate their eligibility to be utilized as the satellite structure. To this end, four types of body-centered cubic lattice structures, with similar areal densities which are assumed to be made of 5A06 aluminum alloy, including BCC, BCCz (BCC reinforced in Z direction), and also BCCz-I and BCCz-II were considered. Whipple shield structure of same material and areal density was also investigated in order to justify the necessity of lattice structures application, especially in protection field. The present study simulates hypervelocity impact of a spherical projectile with 2 mm diameter, represented the space debris, collides with the structures at the velocity range of 2–6 km/s. Current numerical simulation process accuracy and efficiency were verified through comparing its obtained data based on simulating a problem had been investigated at a valid experimental study to the data proposed by the mentioned research. BCCz-II structure which is newly proposed at this study provided outstanding shielding and load-bearing capabilities in comparison to other structures. Furthermore, the detailed effects of projectile impact location and a middle structure placed plate on the protection performance were investigated and the mentioned items were found to have crucial impact on the structure shielding performance.

Identifying the evolution of through cracks in iron-reinforced hollow slabs under the influence of a standard fire temperature mode

The object of this study is the fire resistance of reinforced concrete hollow slabs at the onset of the limit state of loss of integrity. The problem of accurate modeling of the formation and development of cracks in concrete was investigated. The paper reports an analysis of the results of the stress-strain state of a reinforced concrete hollow slab during fire exposure for devising a method for evaluating the fire resistance of such structures upon the onset of the limit state of loss of integrity. According to EN 1992-1-2, the determination of fire resistance of structures is provided by calculation methods, however, there is no such procedure for reinforced concrete hollow slabs. Many scientific works offer refined methods for evaluating only the loss of load-bearing and heat-insulating capabilities, leaving aside the issue of loss of integrity. Thus, this can lead to a biased evaluation of reinforced concrete hollow floor slabs according to the criterion of the limit state of loss of integrity, which in turn can put under a threat to the fire safety of buildings, which threatens the life and health of people. According to the results of the calculation, a parameter has been determined, according to which the onset of the limit state of fire resistance, in particular, the loss of integrity, was established. Summarizing the damage distributions, it was assumed that in the case of reaching the critical plastic deformation of 2.5e-3 in concrete finite elements, they are excluded from the general set of finite elements. Thus, in the case of the formation of through cracks, the removal of finite elements is taken as a parameter to identify the onset of the limit state of loss of integrity. According to the results of the computational experiment, it was established that through cracks in a fragment of a reinforced concrete hollow slab are formed in 44 min. According to the results of the research, the method of evaluating the fire resistance of such structures based on the onset of the limit state of loss of integrity has been substantiated. Such a method could be applied during design, which provides an opportunity to determine the limit of fire resistance in reinforced concrete hollow slabs

Low-velocity impact behavior of foam-based sandwich composite reinforced with warp-knitted spacer fabric; numerical and experimental study

The aim of this research is to investigate experimentally and numerically the low-velocity impact behavior of foam-based composites reinforced with warp-knitted spacer fabric (WKSF). To prepare different foam-based composites, the structural parameters of WKSFs including cell size, position, and Z-fiber height were considered. A drop weight impact test with an initial energy of 5J was carried out to examine the low-velocity impact behavior of composites, followed by experimental analyses of Mises, shear, and normal stress on various composite components. Thereafter, the impact behavior of the composites was simulated using ABAQUS/CAE software. The comparison between experimental and numerical results showed a maximum error of 9.79% in predicting the acceleration of impactor. In addition, the results revealed significant stress disparities among samples. Stress analysis showed complex patterns across samples, emphasizing structural parameter influence on stress tolerance and load-bearing capabilities. Notably, Z-fibers displayed substantial stress tolerance, while the matrix predominantly undergoes shear stress. Consequently, the ideal structure for low-velocity impact applications includes small cell size, high thickness, and non-facing hexagonal cells.

Energy-efficient dynamic 3D metasurfaces via spatiotemporal jamming interleaved assemblies for tactile interfaces

Inspired by the natural shape-morphing abilities of biological organisms, we introduce a strategy for creating energy-efficient dynamic 3D metasurfaces through spatiotemporal jamming of interleaved assemblies. Our approach, diverging from traditional shape-morphing techniques reliant on continuous energy inputs, utilizes strategically jammed, paper-based interleaved assemblies. By rapidly altering their stiffness at various spatial points and temporal phases during the relaxation of the soft substrate through jamming, we enable the formation of refreshable, intricate 3D shapes with a desirable load-bearing capability. This process, which does not require ongoing energy consumption, ensures energy-efficient and lasting shape displays. Our theoretical model, linking buckling deformation to residual pre-strain, underpins the inverse design process for an array of interleaved assemblies, facilitating the creation of diverse 3D configurations. This metasurface holds notable potential for tactile displays, particularly for the visually impaired, heralding possibilities in visual impaired education, haptic feedback, and virtual/augmented reality applications.

Electrophoretic deposition of polyvinyl alcohol, C-H NRs along with moringa on an SS substrate for orthopedic implant applications.

Metals are commonly used in bone implants due to their durability and load-bearing capabilities, yet they often suffer from biofilm growth and corrosion. To overcome these challenges, implants with enhanced biocompatibility, bioactivity, and antimicrobial properties are preferred. Stainless steel (SS) implants are widely favored in orthopedics for their mechanical strength and cost-effectiveness. To address the issues related to SS implants, we developed composite coatings using synthetic biopolymer polyvinyl alcohol (PVA), calcium hydrate (C-H) nanorods for improved bioactivity and antibacterial properties, and Moringa oleifera to enhance osteogenic induction. These coatings were deposited on 316L SS through electrophoretic deposition (EPD), providing protection against body fluids and enhancing the corrosion resistance of the SS. X-ray diffraction (XRD) confirmed the presence of the desired tobermorite crystal structure, while scanning electron microscopy (SEM) revealed nanorod-like C-H structures, a film thickness of 29 microns, and a hedgehog-like morphology in the composite particles. The coated sample demonstrated a contact angle of 64°, optimal for protein attachment and cellular uptake. Additionally, the coating exhibited strong adhesion with less than 5% damage observed in cross-cut hatch testing and appropriate surface roughness for protein attachment. Differential Scanning Calorimetry (DSC) and thermogravimetric analysis (TGA) assessed the thermal response of the materials. The coating also showed antibacterial activity against both Gram-negative and Gram-positive bacteria. Furthermore, the sample exhibited rapid bioactivity by forming a hydroxyapatite (HA) layer within 24 hours, with 35.4% degradability within 24 hours and 44.5% within 48 hours. These findings confirm that the composite film enhances the biocompatibility, bioactivity, and antibacterial properties of SS orthopedic implants in a cost-effective manner.