Superior Mechanical Properties Research Articles

Multiobjective optimization of carbon fiber–reinforced epoxy composite properties using nonparametric modeling

Carbon fiber–reinforced epoxy composites are widely used in the marine and aviation sectors due to their superior mechanical properties. As research into these materials progresses, the demand for materials with even more complex and superior properties has increased. Traditional trial-and-error methods are limited to optimizing single factors and are plagued by heavy workloads and prohibitive costs when applied to multifactor composite designs. Addressing these problems, this study introduces a nonparametric multiobjective optimization process for composite materials. This approach employs a Gaussian process (GP) to establish a multiobjective regression model and uses nondominated sorting genetic algorithm II (NSGA II) to determine the Pareto front. Pareto solutions were ranked in accordance with their similarity to ideal solutions and on the basis of predetermined preference weights. The results demonstrate variations in optimal outcomes contingent on the weight values assigned. The differences between the optimized results and experimental validations reached 12.9%, with the minimum deviation being 0.6%. The effectiveness of the proposed method was demonstrated. The strategy combines GP and NSGA II to extend design methods for small samples and materials with multiple attributes. This method enables the simultaneous optimization of multiple conflicting objectives, offering greater efficiency than addressing them individually.

Polyvinyl alcohol-based multifunctional hydrogel film: a novel strategy for food preservation packaging

Food spoilage leads to the annual huge wastage of food. There is a pressing need for safe, multifunctional food preservation packaging to curb this wastage and prevent contamination. In this study, we present a novel, cross-linked P-GL hydrogel film with a smooth surface microstructure, derived from polyvinyl alcohol (PVA), gallic acid (GA), and lysozyme (L). This hydrogel film serves as an exceptional packaging material for food preservation, displaying an ability to completely block UV light and efficiently impede the penetration of water vapor and O2. Remarkably, the P-GL hydrogel film exhibits a fracture strength of approximately 37.9 MPa, demonstrating superior water solubility, thermal stability, and mechanical properties. Also, this P-GL hydrogel film can effectively eliminate E. coli and S. aureus. The P-GL hydrogel film has proven to be successful in mitigating the spoilage of blueberries through coating and covering treatments, outperforming commercial plastic wrap. As a result, the shelf life of blueberries can be extended to 20 days. Our work provides innovative insights that could potentially drive the use of safe and multifunctional hydrogel films in the food preservation packaging industry.

Synergistic enhancement of dielectric strength and thermal conductivity in meta-aramid-based composite films via honeycomb cavities filling strategy

Owning superior dielectric and mechanical properties, poly (m-phenylene isophthalamide) (PMIA) fiber is an ideal insulation material for next-generation electric and electronic devices. However, its low thermal conductivity poses a risk of thermal breakdown. Moreover, PMIA films prepared using the unique protonation method exhibit a honeycomb-like structure with numerous air pockets, further reducing heat transfer efficiency. Herein, we propose a strategy of honeycomb cavities filling to synergistically improving the dielectric strength and thermal conductivity of PMIA-based composite films. To achieve a denser configuration, the nanodiamond (ND) fillers modified by polydopamine (PDA) are uniformly filled in the cavities within the PMIA skeleton, serving as thermally conductive reinforcements. In the 15 wt% composite film, the breakdown strength and thermal conductivity measure 334 kV/mm and 1.12 W/(m·K), respectively, which are 42.3% and 833% higher than that of the pure one. Furthermore, the underlying mechanisms are studied based on density functional theory and multi-physics simulations.

Effects of B2 ordered structure on the mechanical properties of TiZrHfCoNiCu high-entropy alloy

High-entropy alloys (HEAs) were once considered to be typical disordered solid solutions with various atoms randomly distributed in a lattice. Recent studies have found that owing to the chemical complexity of multiple primary elements, HEAs may also form ordered structures that directly influence their mechanical properties. In this study, B2-ordered and body-centered-cubic-disordered structures of TiZrHfCoNiCu HEAs were established using the special quasi-random structure method. The results of first principles calculations and ultrasonic wave velocity measurements indicated that the B2-ordered TiZrHfCoNiCu HEA exhibited superior phase stability, structural stability, and mechanical properties such as strength and hardness. Significantly, the results of this study revealed the physical mechanisms underlying the excellent mechanical properties of ordered HEAs and can guide their design and development accordingly.

Effect of Ti additions on the mechanical properties and thermal expansion properties of Ni9Cr9Co9Fe9Tix (x=1, 2, 3) high entropy alloy

The mechanical properties and thermal expansion properties of high entropy alloys (HEAs) are crucial for practical applications. However, there is a scarcity of research on how to optimize the relationship between the mechanical and thermal expansion properties, which currently restricts the application of HEAs as precision structural materials. To address this critical issue, the present study investigates the mechanical properties and thermal expansion properties of Ni9Cr9Co9Fe9Tix (x=1,2,3) HEAs fabricated via repeated arc melting and casting in a vacuum environment. The results show that Ni9Cr9Co9Fe9Tix HEAs exhibit a typical microstructure characteristic of dendritic and inter-dendritic phase, and a small amount of Ni3Ti phase is formed in the Ni9Cr9Co9Fe9Tix HEAs. The addition of Ti notably increases the tensile strength of Ni9Cr9Co9Fe9Tix HEAs, while the presence of the Ni3Ti phase contributes to a reduction in its thermal expansion coefficient. Notably, HEAs with higher Ti content demonstrate increased yield strength but diminished ductility. The primary mechanisms that strengthen the HEA are solid-solution strengthening, secondary phase hardening and dislocations strengthening of the FCC matrix. This study provides superior mechanical properties for HEAs structural components and reduces the thermal expansion coefficient of the matrix alloy, which also indicated the potential of this material for the design and development of HEAs for precision structural components.

Formation of High Hardness ZnO/Cu Nanocomposite by Thermal Oxidation from Cu-Zn Alloy Strips

Due to their superior thermal, electrical, and mechanical properties, brass and Cu-Zn alloys are widely used in a broad range of applications. In applications requiring greater durability, corrosion resistance, and wear resistance, however, the ZnO/Cu composite is preferable. Typically, ZnO/Cu composites are manufactured through powder metallurgy. In this article, brass strips are thermally oxidized in an oxygen atmosphere to produce ZnO/Cu composite strips. The optimal temperature and oxygen pressure are 600–650 °C and less than one atmosphere, respectively. The homogeneous distribution of nanoscale ZnO clusters in the Cu matrix can be attributed to the diffusion of both Zn and O in the matrix. In addition, the composite is substantially harder than brass, increasing from 70–90 HV to 200–240 HV. Therefore, thermal oxidation has been shown to be a simple and cost-effective process for producing ZnO/Cu composites with high hardness.

Superb Silk Hydrogels with High Adaptability, Bioactivity, and Versatility Enabled by Photo-Cross-Linking.

The exceptional biocompatibility and adaptability of hydrogels have garnered significant interest in the biomedical field for the fabrication of biomedical devices. However, conventional synthetic hydrogels still exhibit relatively weak and fragile properties. Drawing inspiration from the photosynthesis process, we developed a facile approach to achieve a harmonious combination of superior mechanical properties and efficient preparation of silk fibroin hydrogel through photo-cross-linking technology, accomplished within 60 s. The utilization of riboflavin and H2O2 enabled a sustainable cyclic photo-cross-linking reaction, facilitating the transformation from tyrosine to dityrosine and ultimately contributing to the formation of highly cross-linked hydrogels. These photo-cross-linking hydrogels exhibited excellent elasticity and restorability even after undergoing 1000 cycles of compression. Importantly, our findings presented that hydrogel-encapsulated adipose stem cells possess the ability to stimulate cell proliferation along with stem cell stemness. This was evidenced by the continuous high expression levels of OCT4 and SOX2 over 21 days. Additionally, the utilization of photo-cross-linking hydrogels can be extended to various material molding platforms, including microneedles, microcarriers, and bone screws. Consequently, this study offered a significant approach to fabricating biomedical hydrogels capable of facilitating real-time cell delivery, thereby introducing an innovative avenue for designing silk devices with exceptional machinability and adaptability in biomedical applications.

Enhancing the plasticity of HfZrTiCr x alloys by forming single phase solid solutions via reducing Cr content

ABSTRACT The solid solution design strategy bolsters the comprehensive mechanical properties of high/medium entropy alloys (H/MEAs), yet its utilisation within hexagonal close-packed (HCP) H/MEAs remains notably limited. Here, exploring the impact of reduced Cr content (x = 0.3, 0.1, and 0) from the HfZrTiCr0.5 prototype alloy, our study successfully obtained a novel HCP single phase MEA and investigated the relationship between microstructure and mechanical properties. Decreasing Cr content led to the diminishing presence of the Laves phase, culminating in a single HCP phase solid solution at x = 0.1. The Laves phase, arising from negative enthalpy between Cr and other elements and lower atomic radius of Cr, acted as crack initiation sites, resulting in brittle fracture (x = 0.5) alloy and limited plasticity strain of 3.5% (x = 0.3). Conversely, the HfZrTiCr0.1 alloy exhibited impressive combined yield strength (1360 MPa) and plasticity strain (14.5%), attributed to prominent solid solution strengthening and enhanced dislocation movement within the solid solution structure. These findings offer insights into manipulating Cr content to form HCP solid solution structures, potentially broadening solid solution alloy design strategies for superior mechanical properties in HCP H/MEAs.

A novel high-Cr CoNi-based superalloy with superior high-temperature microstructural stability, oxidation resistance and mechanical properties

A novel high-Cr CoNi-based superalloy with superior high-temperature microstructural stability, oxidation resistance and mechanical properties

Advancements in 3D printing materials: A comparative analysis of performance and applications

3D printing has rapidly evolved and matured in recent years, with a key factor being the improvement in printing materials. This paper compares the performance and applications of various 3D printing materials, including plastics, metals, ceramics, and biomaterials. Plastics remain the most widely used material due to their low cost and ease of printing, while metals are gaining popularity due to their superior mechanical properties. However, recent advancements in ceramic and biomaterials have opened up new possibilities for 3D printing in industries such as aerospace, healthcare, and electronics. The comparative analysis provides insights into the strengths and limitations of each material, and how they can be optimized for specific applications. With continuous developments in 3D printing technology and materials, the potential for this technology to revolutionize manufacturing and other industries is promising.

In-Plane Compressive Responses of Non-Homogenous Re-Entrant Honeycombs Fabricated by Fused Deposition Modelling Manufactured

Auxetic structures, with re-entrant (inverted hexagonal or bow tie) unit cells, have received considerable interest due to their negative Poisson’s ratio property that results in superior mechanical properties. This study proposes a simple method to create non-homogeneous re-entrant honeycombs by modifying the size of chevron crosslinks. The various structural designs were conceived by changing the geometrical dimensions of the crosslinks, namely the length (lcl) and the thickness (tcl), while maintaining the parameters of the re-entrant cell walls. The influence of the design parameters of chevron crosslinks on the mechanical behaviour of additively manufactured re-entrant honeycombs was investigated experimentally and numerically. The structures were fabricated using the Fused Deposition Modelling (FDM) technique from polylactic acid (PLA) plastic. In-plane quasi-static compression tests were conducted to extract the elastic, plastic, and densification properties of the structures. Furthermore, a Finite Element (FE) model was developed via LS-DYNA R11.0 software, validated experimentally, and was then used to obtain a deeper insight into the deformation behaviour and auxetic performance of various designs. The obtained results revealed that the mechanical performance of re-entrant honeycombs can only be tuned by controlling the geometrical configuration of chevron crosslinks.

Design and additive manufacturing of bionic hybrid structure inspired by cuttlebone to achieve superior mechanical properties and shape memory function

Abstract Lightweight porous materials with high load-bearing, damage tolerance and energy absorption as well as intelligence of shape recovery after material deformation are beneficial and critical for many applications, e.g., aerospace, automobiles, electronics, etc. Cuttlebone produced in the cuttlefish has evolved vertical walls with the optimal corrugation gradient, enabling stress homogenization, significant load bearing, and damage tolerance to protect the organism from high external pressures in the deep sea. This work illustrated that the complex hybrid wave shape in cuttlebone walls, becoming more tortuous from bottom to top, creates a lightweight, load-bearing structure with progressive failure. By mimicking the cuttlebone, a novel bionic hybrid structure (BHS) was proposed, and as a comparison, a regular corrugated structure (RCS) and a straight wall structure (SWS) were designed. Three types of designed structures have been successfully manufactured by laser powder bed fusion with NiTi powder. The LPBF-processed BHS exhibited a total porosity of 0.042% and a good dimensional accuracy with a peak deviation of 17.4 μm. Microstructural analysis indicated that the LPBF-processed BHS had a strong (001) crystallographic orientation and an average size of 9.85 μm. Mechanical analysis revealed the LPBF-processed BHS could withstand over 25 000 times its weight without significant deformation and had the highest specific energy absorption value (5.32 J/g) due to the absence of stress concentration and progressive wall failure during compression. Cyclic compression testing showed that LPBF-processed BHS possessed superior viscoelastic and elasticity energy dissipation capacity. Importantly, the uniform reversible phase transition from martensite to austenite in the walls enables the structure to largely recover its pre-deformation shape when heated (over 99% recovery rate). These design strategies can serve as valuable references for the development of intelligent components that possess high mechanical efficiency and shape memory capabilities.

Advanced fabrication and characterization of AMMT nano clay reinforced tri-functional epoxy nanocomposites for superior thermal and mechanical properties

Advanced fabrication and characterization of AMMT nano clay reinforced tri-functional epoxy nanocomposites for superior thermal and mechanical properties

A Simple and Efficient Magnesium Hydroxide Modification Strategy for Flame-Retardancy Epoxy Resin

Magnesium hydroxide, as a green inorganic flame-retardancy additive, has been widely used in polymer flame retardancy. However, magnesium hydroxide is difficult to disperse with epoxy resin (EP), and its flame-retardancy performance is poor, so it is difficult to use in flame-retardant epoxy resin. In this study, an efficient magnesium hydroxide-based flame retardant (MH@PPAC) was prepared by surface modification of 2-(diphenyl phosphine) benzoic acid (PPAC) using a simple method. The effect of MH@PPAC on the flame-retardancy properties for epoxy resins was investigated, and the flame-retardancy mechanism was studied. The results show that 5 wt% MH@PPAC can increase the limiting oxygen index for EP from 24.1% to 38.9%, achieving a V-0 rating. At the same time, compared to EP, the peak heat release rate, peak smoke production rate, total smoke production rate, and peak CO generation rate for EP/5 wt% MH@PPAC composite material decreased by 53%, 45%, 51.85%, and 53.13% respectively. The cooperative effect for PPAC and MH promotes the formation of a continuous and dense char layer during the combustion process for the EP-blend material, significantly reducing the exchange for heat and combustible gases, and effectively hindering the combustion process. Additionally, the surface modification of PPAC enhances the dispersion of MH in the EP matrix, endowing EP with superior mechanical properties that meet practical application requirements, thereby expanding the application scope for flame-retardant EP-blend materials.

Toward Multiscale, Multimaterial 3D Printing.

Biological materials and organisms possess the fundamental ability to self-organize, through which different components are assembled from the molecular level up to hierarchical structures with superior mechanical properties and multifunctionalities. These complex composites inspire material scientists to design new engineered materials by integrating multiple ingredients and structures over a wide range. Additive manufacturing, also known as 3D printing, has advantages with respect to fabricating multiscale, and multi-material structures. The need for multifunctional materials is driving 3D printing techniques toward arbitrary 3D architectures with the next level of complexity. In this paper, we aim to highlight key features of those 3D printing techniques that can produce either multiscale or multimaterial structures, including innovations in printing methods, materials processing approaches, and hardware improvements. Several issues and challenges related to current methods are discussed. Ultimately, we also provide our perspective on how to realize the combination of multiscale and multimaterial capabilities in 3D printing processes and future directions based on emerging research. This article is protected by copyright. All rights reserved.

Strain-invariant stretchable radio-frequency electronics.

Wireless modules that provide telecommunications and power-harvesting capabilities enabled by radio-frequency (RF) electronics are vital components of skin-interfaced stretchable electronics1-7. However, recent studies on stretchable RF components have demonstrated that substantial changes in electrical properties, such as a shift in the antenna resonance frequency, occur even under relatively low elastic strains8-15. Such changes lead directly to greatly reduced wireless signal strength or power-transfer efficiency in stretchable systems, particularly in physically dynamic environments such as the surface of the skin. Here we present strain-invariant stretchable RF electronics capable of completely maintaining the original RF properties under various elastic strains using a 'dielectro-elastic' material as the substrate. Dielectro-elastic materials have physically tunable dielectric properties that effectively avert frequency shifts arising in interfacing RF electronics. Compared with conventional stretchable substrate materials, our material has superior electrical, mechanical and thermal properties that are suitable for high-performance stretchable RF electronics. In this paper, we describe the materials, fabrication and design strategies that serve as the foundation for enabling the strain-invariant behaviour of key RF components based on experimental and computational studies. Finally, we present a set of skin-interfaced wireless healthcare monitors based on strain-invariant stretchable RF electronics with a wireless operational distance of up to 30 m under strain.

Composite patch with negative Poisson's ratio mimicking cardiac mechanical properties: Design, experiment and simulation

Developing patches that effectively merge intrinsic deformation characteristics of cardiac with superior tunable mechanical properties remains a crucial biomedical pursuit. Currently used traditional block-shaped or mesh patches, typically incorporating a positive Poisson's ratio, often fall short of matching the deformation characteristics of cardiac tissue satisfactorily, thus often diminishing their repairing capability. By introducing auxeticity into the cardiac patches, this study is trying to present a beneficial approach to address these shortcomings of the traditional patches. The patches, featuring the auxetic effect, offer unparalleled conformity to the cardiac complex mechanical challenges. Initially, scaffolds demonstrating the auxetic effect were designed by merging chiral rotation and concave angle units, followed by integrating scaffolds with a composite hydrogel through thermally triggering, ensuring excellent biocompatibility closely mirroring heart tissue. Tensile tests revealed that auxetic patches possessed superior elasticity and strain capacity exceeding cardiac tissue's physiological activity. Notably, Model III showed an equivalent modulus ratio and Poisson's ratio closely toward cardiac tissue, underscoring its outstanding mechanical potential as cardiac patches. Cyclic tensile loading tests demonstrated that Model III withstood continuous heartbeats, showcasing outstanding cyclic loading and recovery capabilities. Numerical simulations further elucidated the deformation and failure mechanisms of these patches, leading to an exploration of influence on mechanical properties with alternative design parameters, which enabled the customization of mechanical strength and Poisson's ratio. Therefore, this research presents substantial potential for designing cardiac auxetic patches that can emulate the deformation properties of cardiac tissue and possess adjustable mechanical parameters.

Implantable patch of oxidized nanofibrillated cellulose and lysozyme amyloid nanofibrils for the regeneration of infarcted myocardium tissue and local delivery of RNA-loaded nanoparticles.

Biopolymeric implantable patches are popular scaffolds for myocardial regeneration applications. Besides being biocompatible, they can be tailored to have required properties and functionalities for this application. Recently, fibrillar biobased nanostructures proved to be valuable in the development of functional biomaterials for tissue regeneration applications. Here, periodate-oxidized nanofibrillated cellulose (OxNFC) was blended with lysozyme amyloid nanofibrils (LNFs) to prepare a self-crosslinkable patch for myocardial implantation. The OxNFC:LNFs patch showed superior wet mechanical properties (60MPa for Young's modulus, and 1.5MPa for tensile stress at tensile strength), antioxidant activity (70% scavenging activity under 24h), and bioresorbability ratio (80% under 91 d), when compared to the patches composed solely of NFC or OxNFC. These improvements are achieved while preserving the morphology, required thermal stability for sterilization, and biocompatibility towards rat cardiomyoblast (H9c2) cells. Additionally, both OxNFC and OxNFC:LNFs patches reveal the ability to act as efficient vehicles to deliver spermine (Sp) modified acetalated dextran nanoparticles (Sp-AcDEX NPs), loaded with small interfering RNA (siRNA), with 80% of delivery after 5 d. This study highlights the value of simply blending OxNFC and LNFs, synergistically combining their key properties and functionalities, resulting in a biopolymeric patch that comprises valuable characteristics for myocardial regeneration applications. This article is protected by copyright. All rights reserved.

Experimental Study on Coconut Fibre Reinforced Self Compaction Concrete

Self-Compacting Concrete (SCC) has revolutionized the construction industry with its superior flowability, workability, and ability to consolidate under its own weight without the need for mechanical vibration. However, the brittleness and cracking susceptibility of traditional SCC remain significant concerns, especially in applications requiring enhanced durability and structural integrity. To address these challenges, the incorporation of natural fibres such as coconut fibres into SCC has emerged as a promising solution. Coconut Fibre Reinforced Self-Compacting Concrete (CFRSCC) is an innovative material that combines the advantages of SCC with the mechanical benefits of coconut fibres. Coconut fibres are abundant, renewable, and environmentally friendly, making them a sustainable choice for reinforcement. The addition of these fibres improves the tensile strength, ductility, and crack resistance of SCC, thus enhancing its overall performance. This study compares the properties of CFRSCC with traditional SCC, focusing on key parameters such as compressive strength, tensile strength, flexural strength, and durability. The results indicate that CFRSCC exhibits superior mechanical properties, including increased tensile and flexural strength due to the bridging effect of the fibres, which helps to arrest crack propagation and improve post-cracking behavior. Furthermore, the enhanced ductility of CFRSCC contributes to greater energy absorption and deformation capacity, making it more resilient under dynamic and impact loads. In terms of sustainability, CFRSCC leverages agricultural waste products, thereby reducing the reliance on synthetic fibres and contributing to waste management and environmental conservation. The utilization of coconut fibres also offers economic benefits, particularly in regions where coconut production is prevalent, by providing a value-added use for by-products that would otherwise be discarded. In conclusion, CFRSCC presents a superior alternative to traditional SCC by addressing its limitations and offering enhanced mechanical performance, sustainability, and economic advantages. This innovative material holds significant potential for a wide range of construction applications, promoting more durable, resilient, and eco-friendly infrastructure development.

Novel nano magnesium oxide modified hybrid emulsion for antimicrobial coating

Purpose The purpose of this paper is to develop an inorganic-organic hybrid emulsion polymer using grafted hyperbranched alkyd modified with nanometal oxide and to study the performance of the developed hybrid emulsion in paint formulation with respect to antimicrobial and other properties. Design/methodology/approach A novel hybrid emulsion polymer was synthesized by grafting of vinyl acetate (VAM), vinyl ester of versatic acid (VeoVa 10) monomers onto hyperbranched alkyd resin and incorporation of nano magnesium oxide (MgO) into the hybrid resin matrix during dispersion of resin in water. Subsequently, paint was prepared by using this hybrid emulsion followed by a performance study. Findings The performance of nano MgO modified into VAM and VeoVa 10 grafted hyperbranched alkyd resulted in unique properties of coating especially antimicrobial activity. Research limitations/implications In the present study, soya fatty acid, polyol and di basic acid have been used to prepare hyperbranched alkyd by condensation polymerization. Monomers like VAM and VeoVa 10 used for grafting onto hyperbranched alkyd and nano MgO have been incorporated into hybrid resin matrix during emulsification of hybrid resin in water. Practical implications Grafting of VAM and VeoVa 10 onto hyperbranched alkyd along with in situ incorporation of nano MgO in resin matrix is an effective technique to achieve excellent coating properties. Originality/value Nano MgO modified VAM and VeoVa 10 grafted hyperbranched alkyd-based hybrid emulsion can be used as binder in water-based metal primer, direct to metal (DTM) coating as well as topcoat application. The developed system has antimicrobial properties as well as superior mechanical properties.