High Fatigue Resistance Research Articles

Biomass valorization toward sustainable asphalt pavements: Progress and prospects

To cope with the global climate crisis and assist in achieving the carbon neutrality, the use of biomass materials to fully or partially replace petroleum-based products and unrenewable resources is expected to become a widespread solution. Based on the analysis of the existing literature, this paper firstly classified biomass materials with potential application prospects in pavement engineering according to their application and summarized their respective preparation methods and characteristics. The pavement performance of asphalt mixtures with biomass materials was analyzed and summarized, and the economic and environmental benefits of bio-asphalt binder were evaluated. The analysis shows that pavement biomass materials with potential for practical application can be divided into three categories: bio-oil, bio-fiber, and bio-filler. Adding bio-oil to modify or extend the virgin asphalt binder can mostly improve the low temperature performance of asphalt binder. Adding styrene-butadienestyrene (SBS) or other preferable bio-components for composite modification will have a further improved effect. Most of the asphalt mixtures prepared by using bio-oil modified asphalt binders have improved the low temperature crack resistance and fatigue resistance of asphalt mixtures, but the high temperature stability and moisture resistance may decrease. As a rejuvenator, most bio-oils can restore the high and low temperature performance of aged asphalt and recycled asphalt mixture, and improve fatigue resistance. Adding bio-fiber could significantly improve the high temperature stability, low temperature crack resistance and moisture resistance of asphalt mixtures. Biochar as a bio-filler can slow down the asphalt aging process and some other bio-fillers can improve the high temperature stability and fatigue resistance of asphalt binders. Through calculation, it is found that the cost performance of bio-asphalt has the ability to surpass conventional asphalt and has economic benefits. The use of biomass materials for pavements not only reduces pollutants, but also reduces the dependence on petroleum-based products. It has significant environmental benefits and development potential.

Strong, tough, rapid-recovery, and fatigue-resistant hydrogels made of picot peptide fibres

Hydrogels are promising soft materials as tissue engineering scaffolds, stretchable sensors, and soft robotics. Yet, it remains challenging to develop synthetic hydrogels with mechanical stability and durability similar to those of the connective tissues. Many of the necessary mechanical properties, such as high strength, high toughness, rapid recovery, and high fatigue resistance, generally cannot be established together using conventional polymer networks. Here we present a type of hydrogels comprising hierarchical structures of picot fibres made of copper-bound self-assembling peptide strands with zipped flexible hidden length. The redundant hidden lengths allow the fibres to be extended to dissipate mechanical load without reducing network connectivity, making the hydrogels robust against damage. The hydrogels possess high strength, good toughness, high fatigue threshold, and rapid recovery, comparable to or even outperforming those of articular cartilage. Our study highlights the unique possibility of tailoring hydrogel network structures at the molecular level to improve their mechanical performance.

Modelling of major phases formation during solidification of Ferro-Silicon-Magnesium

Ductile cast iron, also known as nodular cast iron, is a graphite-rich cast iron with high impact and fatigue resistance, due to its nodular graphite inclusions. Ductile cast iron is produced by incorporating additives (often FeSi alloys) to the iron base metal at different production steps to obtain the desired graphite shape. A crucial step is the addition of Magnesium to promote the spheroidization of the graphite. The most common method is by adding crushed and sized Ferro-Silicon-Magnesium (FSM). The alloy composition, microstructure, and sizing are assumed to affect the key parameters of this reaction, namely, reactivity, recovery, and slag formation. Therefore, the study of the solidification of FSM is important to understand and predict its performance at the foundries. The present work aims at understanding and predicting numerically the formation of the major phases during the solidification process. Two approaches have been used: thermodynamic calculations through Thermo-Calc solver and phase field modelling using MICRESS. The models have been calibrated by comparison with advanced statistical characterization of the microstructure. The results indicate a competitive growth of the major phases and transformation of phases in solid state that can be emulated by the model.

Nacre-Inspired Bacterial Cellulose/Mica Nanopaper with Excellent Mechanical and Electrical Insulating Properties by Biosynthesis.

The exploration of extreme environments has become necessary for understanding and changing nature. However, the development of functional materials suitable for extreme conditions is still insufficient. Herein, a kind of nacre-inspired bacterial cellulose (BC)/synthetic mica (S-Mica) nanopaper with excellent mechanical and electrical insulating properties that has excellent tolerance to extreme conditions is reported. Benefited from the nacre-inspired structure and the 3D network of BC, the nanopaper exhibits excellent mechanical properties, including high tensile strength (375MPa), outstanding foldability, and bending fatigue resistance. In addition, S-Mica arranged in layers endows the nanopaper with remarkable dielectric strength (145.7 kVmm-1 ) and ultralong corona resistance life. Moreover, the nanopaper is highly resistant to alternating high and low temperatures, UV light, and atomic oxygen, making it an ideal candidate for extreme environment-resistant materials.

Designing Viscoelastic Gelatin-PEG Macroporous Hybrid Hydrogel with Anisotropic Morphology and Mechanical Properties for Tissue Engineering Application

The mechanical properties of scaffolds play a vital role in regulating key cellular processes in tissue development and regeneration in the field of tissue engineering. Recently, scaffolding material design strategies leverage viscoelasticity to guide stem cells toward specific tissue regeneration. Herein, we designed and developed a viscoelastic Gel-PEG hybrid hydrogel with anisotropic morphology and mechanical properties using a gelatin and functionalized PEG (as a crosslinker) under a benign condition for tissue engineering application. The chemical crosslinking/grafting reaction was mainly involved between epoxide groups of PEG and available functional groups of gelatin. FTIR spectra revealed the hybrid nature of Gel-PEG hydrogel. The hybrid hydrogel showed good swelling behavior (water content > 600%), high porosity and pore interconnectivity suitable for tissue engineering application. Simple unidirectional freezing followed by a freeze-drying technique allowed the creation of structurally stable 3D anisotropic macroporous architecture that showed tissue-like elasticity and was capable of withstanding high deformation (50% strain) without being damaged. The tensile and compressive modulus of Gel-PEG hybrid hydrogel were found to be 0.863 MPa and 0.330 MPa, respectively, which are within the range of normal human articular cartilage. In-depth mechanical characterizations showed that the Gel-PEG hybrid hydrogel possessed natural-tissue-like mechanics such as non-linear and J-shaped stress-strain curves, stress softening effect, high fatigue resistance and stress relaxation response. A month-long hydrolytic degradation test revealed that the hydrogel gradually degraded in a homogeneous manner over time but maintained its structural stability and anisotropic mechanics. Overall, all these interesting features provide a potential opportunity for Gel-PEG hybrid hydrogel as a scaffold in a wide range of tissue engineering applications.

A Flexible and Wearable Strain Sensor from Polypyrrole‐Doped Elastomers with Dual Functions in Motion Monitoring and Thermotherapy†

Comprehensive SummaryFlexible strain sensors are essential components of wearable electronic skins. Here we report a new kind of flexible strain sensor by filling conductive nanowires in elastomers featuring a concentration gradient. The fabrication method involves a fast photo‐induced copolymerization of acrylates in the presence of gradient deposited polypyrrole (PPy) nanowires, which is facile and cost‐effective in steadily doping PPy into elastomeric films. The combination of delicately selected polyacrylates as the matrix filled with entangled, nano‐sized PPy endows the sensor good stretchability, sensitive deformation‐electrical signal conversion and high fatigue resistance, which can be used repeatedly without scarifying the sensitivity of electrical signal. Besides, the lower side of the composite films exhibits high light absorption (> 98%) in a wide spectral range (250—2400 nm). Systematic characterizations of the sensors support that the excellent strain sensing and light‐heat conversion performances are essentially dependent on the gradient filling of PPy nanowires. Moreover, the applications of this flexible strain sensor for human motion monitoring and wearable thermotherapy are demonstrated, manifesting a promising option for wearable electronics and personalized healthcare.

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AbstractThe simultaneous achievement of mechanical/thermal sensitivity and extreme environmental tolerance is an enormous challenge for hydrogel‐based sensors. Herein, the authors (DOI: 10.1002/inf2.12409) develop a novel skin‐inspired hydrogel–elastomer hybrid with a sandwich structure and strong interfacial bonding that combines high transmittance, temperature resistance, waterproofness, fatigue resistance and biocompatibility, which can be used for mechanical–thermal multimode sensing applications. image

Lightweight quasi-layered elastic fibrous porous ceramics with high compressive stress and low thermal conductivity

• An elastic fibrous porous ceramic (EFPCs) was successfully prepared using a simple filter press process. • The inter-layer gaps created by the quasi-layered structure and the well bonding between the layers are the keys to the elastic properties. • Compared with other elastic porous ceramics or fibrous aerogel, the as-prepared EFPCs have higher compressive stress, which endows it better shape-maintaining ability. • EFPCs have temperature-invariant elastic properties and low thermal conductivities. Fibrous porous ceramics are attractive for use as thermal insulation materials. However, the intrinsic brittleness of rigid materials has remained challenging and severely restricts their applications. Here, we demonstrated a facile method for fabricating elastic fibrous porous ceramics (EFPCs) with high compressive strength and low thermal conductivity through ordinary press filtration and subsequent heat treatment. The quasi-layered structure and the well-bonded bridging fibers between layers are the key points for the elasticity of EFPCs. The advanced EFPCs exhibited low density (∼0.126 g cm −3 ), high compressive stress (∼0.356 MPa), and low thermal conductivity (∼0.026 W m −1 K −1 ). Compared with rigid porous fibrous materials, the EFPCs had deformability and excellent shape recovery. In contrast to flexible materials, the EFPCs possessed high compressive stress, thus endowing them with good resistance to deformation. The emergence of this fascinating material may provide new insights for candidate materials in thermal insulation and other fields. In this paper, we demonstrated a facile method for fabricating elastic fibrous porous ceramics (EFPCs) with high compressive stress and low thermal conductivity by using silica fibers through ordinary press filtration method. The inter-layer gaps created by the quasi-layered structure and the well bonding between the layers are the keys to the elastic properties. Compared with traditional ceramics, the EFPCs possessed high compression ability up to 20% strain with ultimate stress as high as 0.356 MPa and high compression fatigue resistance of 200 cycles at 15% strain. The compressive test in the alcohol lamp flame and liquid nitrogen proved that the samples exhibited excellent temperature-invariant mechanical properties. The ideal combination of these properties may make EFPCs a strong competitor for thermal insulation and other applications in many areas

Ultrastrong and fatigue-resistant bioinspired conductive fibers via the in situ biosynthesis of bacterial cellulose

High-performance functional fibers play a critical role in various indispensable fields, including sensing, monitoring, and display. It is desirable yet challenging to develop conductive fibers with excellent mechanical properties for practical applications. Herein, inspired by the exquisite fascicle structure of skeletal muscle, we constructed a high-performance bacterial cellulose (BC)/carbon nanotube (CNT) conductive fiber through in situ biosynthesis and enhancement of structure and interaction. The biosynthesis strategy achieves the in situ entanglement of CNTs in the three-dimensional network of BC through the deposition of CNTs during the growth of BC. The structure enhancement through physical wet drawing and the interaction enhancement through chemical treatment facilitate orientation and bridging of components, respectively. Owing to the ingenious design, the obtained composite fibers integrate high strength (939 MPa), high stiffness (52.3 GPa), high fatigue resistance, and stable electrical performance, making them competitive for constructing fiber-based smart devices for practical applications.

Autonomous Healable Elastomers with High Elongation, Stiffness, and Fatigue Resistance

Although self-healing elastomers have been developed in a great breakthrough, it is still a challenge to develop one kind of material that can respond to the fracture instantly even though this characteristic plays an essential role in emergency circumstances. Herein, we adopt free radical polymerization to construct one polymer network equipped with two weak interactions (dipole-dipole interaction and hydrogen bonding). The elastomer we synthesized has a high self-healing efficiency (100%) and a very short healing time (3 min) in an air atmosphere, and it can also self-heal in seawater, showing an ideal healing efficiency of >80%. Additionally, on account of its high elongation (>1000%) and antifatigue capacity (no rupture after loading-unloading 2000 times), the elastomer can be utilized in a wide range of applications, including e-skin and soft robot fields.

Fabricating a photochromic benzonitrile Schiff base into a low-cost reusable paper-based wearable sensor for naked-eye dosimetry of UV radiations

We report in this study a photochromic benzonitrile Schiff base, (E)-4-((2-hydroxy-4-methoxybenzylidene)amino)benzonitrile (HMBAB). The molecular design, synthesis, aggregation-induced emission (AIE) as well as the quantum chemical calculations were outlined. In particular, HMBAB would undergo a reversible tautomerism in response to UV exposure, exhibiting remarkable changes in both absorption and emission: the compound shows yellow color and green-yellow luminescence; after UV exposure, the changes into orange-red while the luminescence is dramatically quenched, accompanied by a large bathochromic-shift. In addition, the photochromic state can be fully recovered via thermal treatment. Such reversible dual-channel photochromism was investigated using UV–vis reflectance spectroscopy and colorimeter, wherein a gradient change with time and a high fatigue resistance in cycle use was recorded. The photochromism is quantified by well-established RGB and Lab color space, in which the color change can be accurately analyzed by the chromatic aberration (ΔE*Lab). Sensitivity test gives a two-stage linear relation between ΔE*Lab and UV intensity, by which a limit of detection (LOD) as low as 67 μW/cm2 is obtained. HMBAB was further fabricated into a paper-based wearable sensor, capable of being integrated into a chest card or a bracelet. It exhibits various degrees of color change in different sunlight environments, which can be readily observed by naked eyes, providing an early warning for high-dose UV radiations.

Conductive Hydrogel Patches with High Elasticity and Fatigue Resistance for Cardiac Microenvironment Remodeling.

Remodeling the conductive zone to assist normal myocardial contraction and relaxation during myocardial fibrosis has become the primary concern of myocardial infarction (MI) regeneration. Herein, we report an unbreakable and self-recoverable hyaluronic acid conductive cardiac patch for MI treatment, which can maintain structural integrity under mechanical load and integrate mechanical and electrical conduction and biological cues to restore cardiac electrical conduction and diastolic contraction function. Using the free carboxyl groups and aldehyde groups in the hydrogel system, excellent adhesion properties are achieved in the interface between the myocardial patch and the tissue, which can be closely integrated with the rabbit myocardial tissue, reducing the need for suture. Interestingly, the hydrogel patch exhibits sensitive conductivity (ΔR/R0 ≈ 2.5) for 100 cycles and mechanical stability for 500 continuous loading cycles without collapse, which allows the patch to withstand mechanical damage caused by sustained contraction and relaxation of the myocardial tissue. Moreover, considering the oxidative stress state caused by excessive ROS in the MI area, we incorporated Rg1 into the hydrogel to improve the abnormal myocardial microenvironment, which achieved more than 80% free radicalscavenging efficiency in the local infarcted region and promoted myocardial reconstruction. Overall, these Rg1-loaded conductive hydrogels with highly elastic fatigue resistance have great potential in restoring the abnormal electrical conduction pathway and promoting the myocardial microenvironment, thereby repairing the heart and improving the cardiac function.

L. KLEIN BRONZE 3444

Abstract L. Klein Bronze 3444 is a wrought copper-tin-lead-zinc-phosphorus alloy. The addition of tin increases its corrosion resistance and strength, while the addition of phosphorous increases wear resistance and stiffness. L. Klein Bronze 3444 combines high strength and fatigue resistance with high wear resistance, good machinability, and good corrosion resistance. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Cu-939. Producer or source: L. Klein SA.

A Mathematical Model for Non-Linear Structural Analysis Reinforced Beams of Composite Materials

The beams are frequently utilized in construction as well as in the fabrication of vehicles like as trains, ships, and airplanes. Depending on the necessary working circumstances, several materials may have been utilized in the production of these beams, from high fatigue resistance, high corrosion resistance, strong earthquake resistance, and other aspects. As a result, composite beams made of glass or carbon fibers are increasingly commonly employed. This is a result of its strong collapse resistance, light weight, and strong fatigue stress resistance. In order to compare the models' resistance to deformations, stresses, and strains that they are exposed to during loading, this article focuses on constructing a variety of models using a variety of composite materials and shapes. The outcomes demonstrate a rise in the rate of deformation. against beams with linear shapes in those with non-linear shapes. Additionally, the findings demonstrate an increase in stresses and strains in regions with curves (i.e., areas that are nonlinear).

Environment‐tolerant ionic hydrogel–elastomer hybrids with robust interfaces, high transparence, and biocompatibility for a mechanical–thermal multimode sensor

AbstractThe human skin, an important sensory organ, responds sensitively to external stimuli under various harsh conditions. However, the simultaneous achievement of mechanical/thermal sensitivity and extreme environmental tolerance remains an enormous challenge for skin‐like hydrogel‐based sensors. In this study, a novel skin‐inspired hydrogel–elastomer hybrid with a sandwich structure and strong interfacial bonding for mechanical–thermal multimode sensing applications is developed. An inner‐layered ionic hydrogel with a semi‐interpenetrating network is prepared using sodium carboxymethyl cellulose (CMC) as a nanofiller, lithium chloride (LiCl) as an ionic transport conductor, and polyacrylamide (PAM) as a polymer matrix. The outer‐layered polydimethylsiloxane (PDMS) elastomers fully encapsulating the hydrogel endow the hybrids with improved mechanical properties, intrinsic waterproofness, and long‐term water retention (>98%). The silane modification of the hydrogels and elastomers imparts the hybrids with enhanced interfacial bonding strength and integrity. The hybrids exhibit a high transmittance (~91.2%), fatigue resistance, and biocompatibility. The multifunctional sensors assembled from the hybrids realize real‐time temperature (temperature coefficient of resistance, approximately −1.1% °C−1) responsiveness, wide‐range strain sensing capability (gauge factor, ~3.8) over a wide temperature range (from −20°C to 60°C), and underwater information transmission. Notably, the dual‐parameter sensor can recognize the superimposed signals of temperature and strain. The designed prototype sensor arrays can detect the magnitude and spatial distribution of forces and temperatures. The comprehensive performance of the sensor prepared via a facile method is superior to that of most similar sensors previously reported. Finally, this study develops a new material platform for monitoring human health in extreme environments.image

Promoted Comprehensive Properties of Polyisoprene Rubber with Extremely High Fatigue Resistance Enabled by Oligopeptide Aggregates

Promoted Comprehensive Properties of Polyisoprene Rubber with Extremely High Fatigue Resistance Enabled by Oligopeptide Aggregates

Biomedical core–shell micro-nanocrystalline Ti6Al4V5Cu alloy with high fatigue properties

Fatigue strength is one of the most important indicators used to evaluate titanium alloy orthopedic implants. Sufficient fatigue strength can enhance the reliability of orthopedic implants. It is well known that grain refinement is beneficial to enhancing material strength but against fatigue resistance. This work has fabricated a triple-phase core–shell micro-nanostructure in a biomedical Ti6Al4V5Cu alloy with the ultrafine grained α phase stabilized by the nanoscale conjugated β/Ti2Cu shells, of which results in a high fatigue resistance. The results show that the average grain size of the α, β, and Ti2Cu phases are 585 nm, 421 nm and 135 nm, respectively. The soft β phases in the conjugated β/Ti2Cu shells can produce a plastic zone at the crack tip to hinder the propagation of fatigue cracks. The fatigue strength of the core–shell structured Ti6Al4V5Cu alloy is 750 MPa under the experimental condition of R = -1 andNf = 107, which is 36.3 % higher than the widely used Ti6Al4V alloy. The mechanisms for improving the fatigue properties have also been discussed. These are of great significance for the development of a new generation of high fatigue strength titanium alloys.

Research on diffusion wear mechanism of WC tool cutting Al2024 based on MD

Al2024 belongs to a typical Al-Cu-Mg series alloy. It has the advantages of high-strength, low-specific gravity, stress resistance, corrosion resistance, good heat resistance, and high fatigue resistance. It is widely used in aerospace, automobiles, ships, chemicals, and other fields. Aluminum alloys play a pivotal role in industry and manufacturing. Cemented carbide tools are often used in the processing of aluminum alloys, and diffusion wear is prone to occur during the processing. It is of great significance to study the diffusion phenomenon of WC tools in the process of cutting aluminum alloys for improving tool life and workpiece surface machining accuracy. In this paper, based on the molecular dynamics (MD) simulation method, the WC tool and the Al2024 model were established, the Morse potential parameters between the tool and the workpiece atoms were calculated, and the diffusion wear mechanism of the WC tool in the process of cutting Al2024 was studied. Through the displacement nephogram in the tool-worker X direction, it is found that the workpiece atoms have a tendency to diffuse to the tool. Using the mean square displacement (MSD) method, the diffusion velocities of Al, Cu, and Mg atoms in the workpiece were obtained. The results show that the activation energy of atomic vacancies at the grain boundary is smaller than that at the lattice, and the Al, Cu, and Mg atoms at the grain boundary of the workpiece are more likely to diffuse, and the diffusion rate of Mg atoms is the fastest. The total energy of single atoms in the cutting process was analyzed, and it was found that the energy required for Al, Cu, and Mg elements at the grain boundary of the workpiece to diffuse into the WC tool and the energy required for the Mg and Al elements at the workpiece lattice to diffuse into the WC tool were satisfied.

Soft, strong, tough, and durable protein-based fiber hydrogels

Load-bearing soft tissues normally show J-shaped stress-strain behaviors with high compliance at low strains yet high strength at high strains. They have high water content but are still tough and durable. By contrast, naturally derived hydrogels are weak and brittle. Although hydrogels prepared from synthetic polymers can be strong and tough, they do not have the desired bioactivity for emerging biomedical applications. Here, we present a thermomechanical approach to replicate the combinational properties of soft tissues in protein-based photocrosslinkable hydrogels. As a demonstration, we create a gelatin methacryloyl fiber hydrogel with soft tissue-like mechanical properties, such as low Young's modulus (0.1 to 0.3 MPa), high strength (1.1 ± 0.2 MPa), high toughness (9,100 ± 2,200 J/m3), and high fatigue resistance (2,300 ± 500 J/m2). This hydrogel also resembles the biochemical and architectural properties of native extracellular matrix, which enables a fast formation of 3D interconnected cell meshwork inside hydrogels. The fiber architecture also regulates cellular mechanoresponse and supports cell remodeling inside hydrogels. The integration of tissue-like mechanical properties and bioactivity is highly desirable for the next-generation biomaterials and could advance emerging fields such as tissue engineering and regenerative medicine.

Photo‐ and pH‐Responsive Hybrid Colloidal Particles

AbstractMaterials that respond to environmental changes in a predictable manner are called “smart”. Here, smart dual‐responsive hybrid colloidal particles were prepared using the interface‐mediated reversible addition–fragmentation chain‐transfer (RAFT) polymerization method. The structure and morphology of the prepared poly(methacrylated‐spiropyran) (p(MMASP)) colloids were characterized by FTIR, 1H‐NMR and GPC spectroscopies, and SEM. The molecular weight and polydispersity were determined as 7877 g mol−1 and 1.16, respectively. Heterocyclic ring cleavage of the spiropyran (SP) pendant group enables the pH‐ and light‐responsive behavior with a reversible conversion between the hydrophobic and hydrophilic states. The isomerization from SP to merocyanine (MC) form proceeds in 7 min, while the reverse action takes 9 min. The pronounced photochromic effect and high fatigue resistance make these colloids suitable for smart applications.