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• Effects of hard/soft Al 2 RE phases on damage behaviors of Mg alloys have been uncovered by using a CPFEM model. • Microscale damage mechanisms have been found by DIC tests and Al 2 RE quantifications using TEM and 3D XCT. • Crystal plasticity model based on dislocation density proves crack initiation at Al 2 RE phases. • CPFEM predicts stiffer Al 2 RE having better damage resistance than soft ones matching SEM fracture analysis. The influence of hard Al 2 RE phases (Sc , Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) on the overall and local deformation as well as damage mechanism of Mg alloys has been studied by using a crystal plasticity model based on dislocation density with a brittle damage criterion. Microcracks that lead to swift damage initiation and propagation throughout the matrix have been predicted. It has been found that the hard Al 2 RE with higher elastic modulus enhances the damage resistance of the Mg matrix, which was confirmed by fracture SEM/EDS characterizations and phase-field damage simulation. This discovery provides valuable insights for designing Mg alloys with both high stiffness and enhanced damage resistance. [Display omitted] [ABSTRACT FROM AUTHOR]

Acoustically-triggered droplet vaporization (ADV) and tissue deformation are numerically analyzed by extending a numerical model for ADV process based on a level-set method, which considers multiple interfaces between bubble, droplet and ambient water regions, bubble compressibility and droplet-bubble phase change, to include nearby tissue deformation using a full Eulerian formulation. The tissue is assumed to be a viscoelastic neo-Hookean material to properly handle large deformation. The numerical results show that droplet vaporization causes greater tissue deformation than isothermal bubble growth under the same acoustic and initial size conditions. The computations of ADV near a deformable solid demonstrate various bubble-tissue interactions such as mushroom-shaped bubble formation near an elastic tissue, tissue compression due to high-speed liquid jet, and large tissue deformation and perforation caused by the non-spherical bubble re-expansion and bubble entrapment. The effects of droplet-tissue distance and elastic shear modulus on the tissue deformation and perforation are investigated. [ABSTRACT FROM AUTHOR]

• Mechanical behavior of ZrNiSn-based HH material examined at service temperatures. • Elastic–plastic responses and load-carrying capacities of the material changed with temperature. • Analysis of compression failure mechanism of ZrNiSn-based HH material based on microfractography observation. • Stress–strain relationship for the material over its operational temperature range was proposed. Half-Heusler (HH) compounds have emerged as promising candidates for high-temperature thermoelectric power generation; however, their mechanical properties in service environments have been scarcely reported. In this study, the temperature dependences of the mechanical responses and failure mechanisms of an n-type ZrNiSn-based HH compound (Zr 0.5 Hf 0.5 NiSn 0.985 Sb 0.015) were systematically evaluated through high-temperature compression tests and microfractographic characterization. The test results indicated that the elastic modulus and ultimate compressive strength of Zr 0.5 Hf 0.5 NiSn 0.985 Sb 0.015 decreased with increasing temperature. The stress–strain behavior of the material changed from linear (300, 500, and 700 K) to nonlinear (900 and 1100 K). Microfractography observations revealed that increasing the temperature reduced the strength of the grain boundary as well as aggravated oxidation and segregation on the fracture surface, which significantly impacted the macro-compressive behavior of Zr 0.5 Hf 0.5 NiSn 0.985 Sb 0.015 at elevated temperatures. Finally, a stress–strain relationship for the ZrNiSn-based HH was proposed to describe the change in the compressive response from linear to nonlinear with increasing temperature. The present study elucidates the load-carrying and failure mechanisms of Zr 0.5 Hf 0.5 NiSn 0.985 Sb 0.015 within its operational temperature range, providing valuable guidance for the mechanical design of HH thermoelectric devices over their entire service temperature range. [Display omitted] [ABSTRACT FROM AUTHOR]

• Improved metal-ceramic interphase bonding by all-fused ceramics synthesized in situ. • Dislocation coordination and specific growth orientations promote interfacial coherence. • Toughness phase enrichment at metal-ceramic interface improves fracture toughness. This work used the in-situ synthesis of molten-state nitride ceramic phase-reinforced Ni-based alloy coatings, aiming to improve the phase-interface bonding through the interdependent co-solidification between molten droplets. The XRD was used to analyze the physical phases of the composite coatings. The microstructure and phase-interface structure were characterized in detail by combining SEM, TEM, HRTEM, FFT, and SAED techniques. Microhardness tester and microforce microhardness tester were employed to measure the surface hardness and elastic modulus of the composite coatings. The fracture behavior of the composite coatings was characterized by observing the fracture morphology of the coatings using SEM combined with the EDS technique. It was found that the formation mechanisms of interfacial misfit dislocation assistance, lattice distortion, aggregation of stacking faults, and specific growth orientation between the γ-Ni matrix phase and each ceramic phase in NiCrBSi-TiCrN composite coatings improved the lattice matching between the two-phase interface, which resulted in the formation of atomically corresponding coherent lattice relations and stepped interfacial semi-coherent lattice relations, and enhanced the degree of phase-interface bonding. On this basis, the composite coatings with high Cr content further inhibited the expansion of interphase penetration cracks due to the existence of Cr-rich zones at the phase interface, thus exhibiting high fracture toughness. This work provides new opinions on the improvement of phase-interface bonding and composition design of Ni-based composite coatings. [Display omitted] [ABSTRACT FROM AUTHOR]

• After high-temperature annealing, the compressive strength of the NiTiNb scaffolds with 85.9 % porosity was more than doubled. • There was an element diffusion zone in several nanometers surrounding the β-Nb particle, where the substitution of Nb with Ti led to a higher Ni: Ti atomic ratio, lowering transformation temperatures. • The β-Nb particles can store dislocations and coordinate the deformation, while internal dislocations will be gradually entangled and act as reinforcement. Metallic scaffolds with lightweight, low elastic modulus, and high energy-absorbing capacity are widely utilized in industrial applications but usually require post-heat treatment to enhance their comprehensive mechanical properties. However, it is unclear how to utilize the impact of β -Nb on the surrounding matrix for NiTiNb ternary alloys to achieve strength-ductility-superelasticity enhancement. Here, we prepared rhomboidal dodecahedral NiTiNb porous scaffolds with a porosity of 85.9% by additive manufacturing. Subsequently, annealing treatment was employed to drastically reduce the phase transformation temperatures and expand the thermal hysteresis. Interestingly, the 850 °C annealed scaffold exhibited exceeding double compressive strength of the as-built sample, with a remarkable improvement in ductility and superelasticity. From the microstructure perspective, high-temperature annealing caused a further eutectic reaction of the unmelted Nb particles with the NiTi matrix and the transformation of mesh-like β -Nb into dispersedly distributed spherical β -Nb particles. The microstructure evolution after deformation indicated that stress-induced martensitic transformation occurred in the matrix away from the NiTi-Nb eutectic region whereas almost no martensite formed nearby β -Nb particles. Atom probe tomography characterization revealed an element diffusion zone in several nanometers surrounding the β -Nb particle, where the substitution of Nb with Ti led to a higher Ni: Ti atomic ratio, lowering transformation temperatures. Molecular dynamics simulations illustrated that β -Nb particles can not only entangle dislocations internally, acting as reinforcements but also hinder the twin growth, contributing to strain hardening. This work elucidates the influence of β -Nb particles on the deformation mechanism of the NiTi-Nb eutectic region through in-depth atomic-scale investigation, which can provide inspiration for the improvement of comprehensive mechanical properties of NiTiNb alloys. [Display omitted] [ABSTRACT FROM AUTHOR]

• Creep samples exhibit a higher γʹ dissolution rate than thermal exposure. • Creep samples show Co depletion and Ti enrichment in deformation twins. • A linear model is proposed for Vickers hardness changes. • Dissecting the impacts of temperature and stress on microstructure. The study provided a systematic investigation into the creep behavior of a γʹ-strengthened Co-based single crystal superalloy Co-7Al-8W-1Ta-4Ti (at.%) under compressive creep conditions at 1000 °C and 137 MPa. Simultaneously, the microstructural changes during thermal exposure at 1000 °C were thoroughly examined. The microstructure analysis of the creep samples revealed the presence of γ/γʹ rafts, twins, stacking faults, and dislocation networks. Statistical analyses were conducted to assess the dimensions and volume fractions of γʹ, alongside Vickers hardness tests and nanoindentation experiments. Results show that γʹ dissolution in the creep samples with substantially higher dissolution rates compared to thermal exposure. Localized Co depletion and Ti enrichment in twin is observed in creep sample, potentially initiating localized phase transformations. Concurrently, lattice rotation occurred during creep, resulting in a progressive deviation of crystal orientation away from the [001] direction. Stacking faults transitioned from network-like structures to parallel configurations, and twins played a significant role in creep deformation, particularly in samples subjected to 382 h creep. The study also explored the evolution of Vickers hardness and the elastic modulus, introducing a systematic linear model to describe Vickers hardness changes during both thermal exposure and creep conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel (Ti,Zr)-Ni-based amorphous filler metal was designed. • TiAl/K4169 alloy hybrid joint was brazed with a rapid vacuum reaction procedure. • The relationship between microstructure and strength of joint was established. • The strengthening mechanism of the hybrid joint as strong as 322 MPa was analyzed. TiAl intermetallic could be used to replace Ni-based alloy in assemblies to generate excellent specific strength. A (Ti,Zr)-Ni-based amorphous filler metal Ti 21.25 Zr 25 Ni 25 Cu 18.75 (at.%) was designed using a cluster-plus-glue-atom model to successfully vacuum braze K4169 and TiAl bimetallic assemblies. At various brazing temperatures and holding time, the quantitative relationships between lattice distortion, grain boundary, dislocation density, and hardness, elastic modulus, shear strength of the joints were investigated. Meanwhile, the fracture mechanism of the joints was revealed. The brazed seam mainly consisted of solid diffusion reaction layers (Zones I and III) and filler metal residue zone (Zone II). When the brazing temperature increased to 1030 °C, grain refinement occurred in the brazed seam. Zone I was primarily composed of (Ni) ss[0-11] +TiNi [011] /(Cr,Fe,Ni) ss[0-11] /(Ti,Zr)Ni [0-1-1] +(Cr,Fe,Ni) ss[0-11]. The (Ti,Zr)(Ni,Cu) [001] and (Ti,Zr)(Ni,Cu) [101] intermetallic compound-based solid solutions were formed in Zone II. And the lattice distortion of (Ti,Zr)(Ni,Cu) [101] and (Ti,Zr)(Ni,Cu) [001] was 32.05% and 14.82%, respectively. As a result, the proportion of low angle grain boundaries (LAGBs) and deformed grains in Zone II rose to 38.6% and 38.7%. In Zones I and III, the proportion of LAGBs reduced to 8% and 3.4%, respectively. As the holding time increased, the long-range diffusion of Al in Zone II caused the (Ti,Zr)(Ni,Cu) [001] with cubic structure to transform into (Ti,Zr)(Ni,Cu,Al) [00-1] with hexagonal crystal system structure, where the lattice distortion was 4.42% and 10.49% for a and c. At 1030 °C/10 min, the average geometrically necessary dislocation densities (GNDs) in Zones I, II and III were 9.87 × 1014 m−2, 8.55 × 1014 m−2 and 11.4 × 1014 m−2, respectively. Therefore, the shear strength of joints reached 322 MPa due to the lattice distortion, dislocation strengthening and fine grain strengthening. Meanwhile, the plastic and brittle hard phases were generated in Zone II and displayed a mechanical interlocking structure that contributed to the performance of the joint. Both (Ti,Zr)(Ni,Cu) [001] and (Ti,Zr)(Ni,Cu) [101] in Zone II formed along different low-index cleavage planes during transgranular fracture. The cracks initiated in this region extended to the interface between Zones I and II and exhibited bimodal grain characteristics. [Display omitted] [ABSTRACT FROM AUTHOR]

• A uniform BCC TiZrHfNbTa RHEA without carbon contamination was prepared by the improved one-step electrochemical method. • Solid oxygen ion-conducting membrane containing graphite and tin (SOM@C/Sn) anode prevented the circulation of CO 3 2−. • Protecting the mixed precursor with the Nb 2 O 5 protective layers can effectively remove carbon contamination from the product. • The TiZrHfNbTa RHEA prepared by this method has a hardness and elastic modulus more suitable for artificial bones. Creating refractory high-entropy alloys (RHEAs) effectively without impurities is a momentous challenge. Conventional methods for the preparation of RHEAs have exacting requirements for raw material purity and energy consumption. Molten salt electrolytic oxides are applied to the preparation of HEAs by virtue of their low cost and high efficiency. However, the use of graphite anodes in electrolysis will result in the carbon contamination of the products due to the deposition of CO 3 2− at the cathode. Increasing the reaction temperature accelerates the deoxidation of the oxide, thus reducing the amount of carbide but not eliminating it. Switching HfH 2 instead of HfO 2 and using Nb 2 O 5 to shield the precursor can effectively remove carbon contamination. However, this leads to a complicated preparation process and energy waste. Herein, we use the solid oxygen ion-conducting membrane (SOM) containing graphite and Sn (named as SOM@C/Sn) anode to separate the carbon from the molten salt and prevent the circulation of CO 3 2−. The pure single-phase TiZrHfNbTa RHEA can be produced in only one-step with the SOM@C/Sn anode, which completely solves the problem of carbon contamination in the molten salt electrolysis preparation of HEAs. This work provides a feasible solution for the preparation of novel complex alloys such as carbon-free RHEAs in a low-cost short process. [ABSTRACT FROM AUTHOR]

• Novel Ti-Mo-Sn shape memory alloys are developed for bio-implant applications. • The high-cost elements such as Nb, Zr, Ta and/or Hf are not used in this study. • A high elastic admissible strain of 1.56% is obtained in the designed Ti-Mo-Sn alloy. • Low elastic modulus and superelasticity are obtained in the designed Ti-Mo-Sn alloy. The demand for titanium alloys simultaneously having high elastic admissible strain and large recovery strain for bio-implant applications is increasing. Ni-free Ti-based shape memory alloys are promising candidates for obtaining the required multifunctional properties. In this study, a wide content range of (0–15)wt% of low-cost, toxicity-free, and high-biocompatible Sn element was added to the Ti-8Mo (wt%) alloy to study its effect on the superelastic recovery and mechanical properties of biomedical Ti-Mo-Sn alloys. By tailoring Sn content, desired multifunctional properties of high elastic admissible strain and room temperature superelasticity were achieved in the studied Ti-Mo-Sn alloys. It was found that the increase in Sn content stabilized the β phase and a single β phase was obtained at room temperature in Ti-8Mo-(13, 15)Sn alloys. The addition of Sn modified the lattice parameters of the α″ martensite and β phase and affected the lattice deformation stain of β → α″. The lattice deformation strain along the [011] β direction was found to be decreased by –0.26%/wt% Sn. The room temperature superelasticity with a recovery strain of 3.1% and an elastic admissible strain of 1% was obtained in the Ti-8Mo-13Sn alloy. As Sn content increased to 15 wt%, a high elastic admissible strain of 1.56% and a recovery strain of 2.0% were obtained. These Ti-Mo-Sn alloys with excellent multifunctional properties are promising candidates for bio-implant applications. [ABSTRACT FROM AUTHOR]

• A new method of fabricating porous Ta-Ti-Nb-Zr bioHEA scaffolds with DIW 3D printing technology was proposed. • DIW 3D printing can use irregular metal powders as the raw materials, and porous Ta-Ti-Nb-Zr bioHEA green scaffolds with a 3D interconnected structure are fabricated by extruding the ink at room temperature. • Through vacuum sintering at high temperature, the scaffolds have a small shrinkage and deformation and ease of control are beneficial to maintaining the morphology of the porous structures. • The porous bioHEA scaffolds with excellent biological properties and mechanical properties that can be adjusted across a wide range. Porous tantalum-titanium-niobium-zirconium (Ta-Ti-Nb-Zr) bio-high entropy alloy (bioHEA) scaffolds are fabricated using direct ink writing 3D printing technology in this study. A composite ink is prepared using four metal powders as raw materials: Ta, Ti, Nb and Zr. Ink extrusion is used to build 3D scaffolds with interconnected porous structures at room temperature, which are then sintered in a vacuum environment. The interdiffusion of metal elements yields porous bioHEA scaffolds with a body-centered cubic (BCC) structure. The fabricated scaffolds have uniform compositions with a significant alloying effect and good biocompatibility. The scaffolds have a compressive strength of 70.08-149.95 MPa and an elastic modulus of 0.18-0.64 GPa, indicating that the mechanical properties can be controlled over a wide range. The scaffolds have a compressive strength close to that of human cortical bone and thus meet the requirements for porous structure characteristics and biological and mechanical properties of orthopedic implants. [Display omitted] [ABSTRACT FROM AUTHOR]

• Aided by a spinodal decomposition and its induced microstructural transition from the nanoscale spongy-like to the plate-like in a titanium alloy, the Elinvar effect with constant elastic modulus was obtained over a wide temperature range of ∼500 K. • A continuous crystal ordering mechanism was proposed to explain the origin based on quantitative data. • This nanoscale microstructure transition via spinodal decomposition has also a great contribution to strength but weak damage to ductility. Temperature-independent elastic modulus is termed as Elinvar effect, which is available by tuning the continuous spin transition of ferromagnetic alloys via composition optimization and the first-order martensitic transformation of shape memory alloys via plastic deformation. However, these reversible mechanisms are restricted generally in a narrow temperature range of less than 300 K. Here reports, by tuning a spinodal decomposition in a Ti-Nb-based titanium alloy via aging treatment, both the Elinvar effect in a wide temperature range of about 500 K and a high strength-to-modulus ratio of about 1.5% can be obtained by a continuous and reversible crystal ordering mechanism. The results demonstrate that the alloy aged at 723 K for 4 h has a nanoscale plate-like modulated β+α" two-phase microstructure and its elastic modulus keeps almost constant from 100 to 600 K. Synchrotron and in-situ X-ray diffraction measurements reveal that the crystal ordering parameter of the α" phase increases linearly with temperature from 0.88 at 133 K to 0.97 at 523 K but its volume fraction keeps a constant of about 33.8%. This suggests that the continuous ordering of the α" phase toward the high modulus α phase induces a positive modulus-temperature relation to balance the negative relation of the elastically stable β phase. The aged alloy exhibits a high yield strength of 1200 MPa, good ductility of 16% and a high elastic admissible strain of 1.5%. Our results provide a novel strategy to extend the Elinvar temperature range and enhance the strength by tuning the crystal ordering of decomposition alloys. [ABSTRACT FROM AUTHOR]

• The mechanical properties of different kinds of thermoelectric generators (TEGs) and their optimization are reviewed. • The mechanical properties of thermoelectric materials affect the mechanical properties of TEGs. • The strength of joints between thermoelectric material and electrode affects the mechanical properties of TEGs. • Flexible substrates with excellent mechanical performance help to share the stress generated by the bending of flexible thermoelectric materials. To satisfy the requirements of practical applications, thermoelectric generators should be highly efficient and mechanically robust. Recently, progress in designing high-performance thermoelectric generators has been made. However, the mechanical properties of thermoelectric generators are still unsatisfactory. In this review, studies on the mechanical properties of thermoelectric generators are summarized. The mechanical properties of bulk thermoelectric generators will be first discussed. In this section, the mechanical properties of thermoelectric materials and the strategies for improving their mechanical properties are emphasized. Since the device's failure usually occurs at the interface between the thermoelectric materials and electrode, the joint strength of electrodes and thermoelectric materials will be overviewed. After that, the mechanical properties of the inorganic thin-film thermoelectric devices will be discussed. Since the figure of merit for the flexibility of thermoelectric materials depends on the film thickness, elastic modulus, and yield strength, the synthesis methods of thin-film thermoelectric materials will be reviewed. Finally, this review will be concluded with a discussion on flexible organic thermoelectric devices and flexible devices using bulk legs. [ABSTRACT FROM AUTHOR]

• Compacted colloidal nanoparticles resulted in millimeter-scale iron nanoglasses. • The nanoparticle size was used to control grain size in bulk nanoglasses. • Elastic modulus, hardness, plasticity, and strength of nanoglasses were measured. • Mechanical comparisons between nanoglass and bulk metallic glass are discussed. • Compressive plasticity of up to 5.0% in an iron nanoglass was achieved. Metallic nanoglasses are made of amorphous grains that are separated by lower-density amorphous boundaries, which have been proposed to enhance plasticity through the deflection of cracks and shear bands at interfaces. It has been difficult to experimentally control grain size and interfacial structure to understand their roles in plastic deformation. Here, we fabricate bulk nanoglasses via compaction and sintering of colloidally synthesized amorphous iron-boride nanoparticles. These nanoglasses have amorphous grains with diameters from 116 nm to 576 nm and were tested using nanoindentation and micropillar compressions. The nanoglass with a grain size of 576 nm shows the highest elastic modulus and hardness of 101 GPa and 7.4 GPa, respectively. Transmission electron microscopy reveals that nanocrystals form within the nanoglasses during compaction. Higher nanocrystal density correlates with higher nanoparticle crystallization enthalpy, an increase in plasticity, and a decrease in yield strength. Plastic strain of 5.0%, yield strength of 3.8 GPa, and ultimate compressive strength of 2.7–3.8 GPa were achieved. We show that the compaction of colloidal metallic glass nanoparticles results in robust bulk samples, with mechanical properties similar to that of other iron-based bulk metallic glasses. [ABSTRACT FROM AUTHOR]

• The tetrahedral and trigonal configurations and their nesting contribute to the structural flexibility of amorphous Si 2 BC 3 N. • The weakened tetrahedra containing coordinated Si and easily distorted trigona lead to the low elastic moduli and strengths. • The balance between tetrahedral and trigonal features could be the key to the structure-dependent mechanical properties tailoring. The atomic structural features and the mechanical properties of the Si 2 BC 3 N are investigated employing ab-initio calculations. The chemical bonding types and their proportion are clarified. The tetrahedral and trigonal configurations, together with their nesting, are identified, which contribute to the flexibility of structural characteristics. The Si-related coordination aggravates the inhomogeneous distribution of chemical bonding and weakens the tetrahedral units. The accompanying polyhedral distortion is quantitatively reflected by the bond length and its deviation of polyhedron units. The elastic moduli and the ideal strengths of Si 2 BC 3 N are found to be lower than SiC and Si 3 N 4 , as a result of the weakening effect of coordination Si on tetrahedral units and the existence of easily distorted trigona. The balance between tetrahedral and trigonal features through composition tailor is believed an effective way for the design of Si-B-C-N ceramics for structural applications. [ABSTRACT FROM AUTHOR]

• Multi-morphology graded Ti scaffolds with different porosities were designed and characterized systematically. • Hybridized gradients design enhances mechanical and biological performances of scaffolds simultaneously. • Higher strength, appropriate permeability and elastic modulus, and excellent cytocompatibility make PG50 an promising orthopedic implant. Porous Titanium scaffolds have attracted widespread attention as bone implants for avoiding the stress shielding effect and promoting bone-in-growth. In this study, multi-morphology graded scaffolds hybridized by Primitive and Gyroid structures with porosity of 50, 60, and 70% were designed (denoted as PG50, PG60, and PG70, respectively) and fabricated by selective laser melting. The simulation results showed that the maximum von–Mises stress of hybridized scaffolds increased from 504.22 to 884.24 MPa with porosity. The permeability and average pore size of multi-morphology PG50, PG60, and PG70 were in the range of 3.58 × 10–9–5.50 × 10–9 m2 and 568.1–758.4 μm, respectively. The microstructure of multi-morphology graded scaffolds consisted of a fully martensitic α′ phase. Tested permeabilities of PG50 and PG60 were 3.27 × 10–9 and 4.35 × 10–9 m2, respectively, which were within the range of human bone (0.01–12.1 × 10–9 m2). Elastic modulus and compressive yield strength of PG50 and PG60 ranged within 5.93–9.86 and 180.06–257.08 MPa, respectively. Therein, the PG50 not only exhibited a similar elastic modulus compared to human cortical bone (10.1 GPa) but also had higher strength (257.08 vs 131 MPa). The results of in vitro biocompatibility assay showed that PG50 and PG60 have better cytocompatibility than mono-morphology scaffolds with the same porosity. Taken together, PG50 is promising to be used for the restoration of bone defects due to its excellent mechanical properties, appropriate permeability, and good cytocompatibility. [ABSTRACT FROM AUTHOR]

• The dual-phase high-entropy ceramics (HECs) were first designed and fabricated using reaction-driven inter-diffusion processes among ZrB 2 , HfB 2 , NbB 2 , TaB 2 , and TiC. • The inhomogeneity of element distribution in boride and carbide phases was quantitatively investigated. • The novel diboride-carbide HECs showed outstanding mechanical properties as compared with other single-phase HEC samples. Fully dense dual-phase high-entropy ceramics (HECs) were fabricated by hot-pressing at 2000 °C for 1 h based on the in-situ reaction and solid solution processes among equimolar ZrB 2 , NbB 2 , HfB 2 , TaB 2 and 30–70 mol% TiC. The negligible porosity, fine grain size, and plate-like diboride grains are found by microstructure observation. The element distribution is not uniform in different phases: Ti and Nb are enriched in the diboride phase, while Zr, Hf, and Ta are preferentially dissolved into the carbide phase. The reactive sintering dual-phase HECs exhibit superior mechanical properties of hardness 28.4 ± 1.5 GPa, flexural strength 1017 ± 91 MPa, elastic modulus 565 GPa, and fracture toughness 4.7 ± 0.3 MPa m1/2, respectively, which surpass most of diboride and carbide high-entropy ceramics in the previous reports. [ABSTRACT FROM AUTHOR]

A study from the University of Pennsylvania explores the mechanical and clinical properties of customized orthodontic bracket systems using CAD/CAM and 3D printing technologies. The research compares these systems to traditional orthodontic brackets, highlighting potential advantages such as increased precision, reduced treatment time, and cost-efficiency. However, the study notes that the benefits and drawbacks of customized bracket systems depend on the material and manufacturing methods used, calling for further controlled investigations in the future. [Extracted from the article]

Researchers at Kalashnikov Izhevsk State Technical University conducted experimental studies on the surface roughness of non-metallic materials, such as leather, bone, wood, and plastic, after laser processing. They used parameters like depth of penetration, micro unevenness, and mean square deviation to assess the quality of the surface layer. The research proposed a regression model that relates material properties to micro unevenness, allowing for control of laser processing modes based on the modulus of elasticity of the material's surface. The study demonstrated the effectiveness of adjusting laser operating modes to ensure quality surfaces on non-metallic materials, leading to the production of various products like writing devices and gifts for newlyweds. [Extracted from the article]

A patent application by inventor Ganesh P. D. Kannan from Bangalore, India, has been made available online for a securement device designed to stabilize medical devices and tubing on a patient's body to prevent complications. The device includes a monolithic body with a cavity, a detachable lid, and an adhesive film for skin attachment. The patent application outlines the device's structure, method of use, and inclusion in a kit, emphasizing its potential benefits in medical settings. [Extracted from the article]

• A hierarchical multi-scale approach is presented that bridging nano to micro scale to study the elastic and fracture parameters of nanofibrous network with random and aligned distribution of nanofibers. • At the atomistic scale, molecular dynamics simulations on freestanding pristine and silver-doped polylactic acid nanofibers are used to determine the energy release rate, elastic modulus, and Poisson's ratio which serve to inform PD at microscale. • At the microscale, peridynamics is used to assess crack propagation and fracture toughness for Mode I and Mode II in both aligned and randomly oriented fibrous networks. • The framework allows the investigation of the effects of fibre orientation and surface treatment on the elastic and fracture properties of the nanofibrous network. • A good agreement with the available experimental data confirms the applicability of the proposed method. Polylactic acid (PLA) nanofibrous networks have gained substantial interest across various engineering and scientific disciplines, such as tissue engineering, drug delivery, and filtration, due to their unique and multifunctional attributes, including biodegradability, tuneable mechanical properties, and surface functionality. However, predicting their mechanical behaviour remains challenging due to their structural complexity, multiscale features, and variability in material properties. This study presents a hierarchical approach to investigate the fracture phenomena in both aligned and randomly oriented nanofibrous networks by integrating atomistic modelling and non-local continuum mechanics, peridynamics. At the nanoscale, all-atom molecular dynamics simulations are employed to apply tensile loads to freestanding pristine and silver-doped PLA nanofibres, where key mechanical properties such as Young's modulus, Poisson's ratio, and critical energy release rate are determined using innovative approaches. A new method is introduced to seamlessly transfer data from molecular dynamics to peridynamics by ensuring the convergence of the tensile response of a single fiber in both frameworks. This nano to micro coupling technique is then utilised to examine the Young's modulus, fracture toughness of mode I and II, and crack propagation in PLA nanofibrous networks. The proposed framework can also incorporate the effects of surface coating and fiber arrangements on the measured properties. The current research paves the way for the development of stronger and more durable eco-friendly nanofibrous networks with optimised performance. [Display omitted] [ABSTRACT FROM AUTHOR]

The determination of surface elastic moduli is discussed in the context of a recently proposed strongly anisotropic surface elasticity model. The aim of the model was to describe deformations of solids with thin elastic coatings associated with so-called hyperbolic metasurfaces. These metasurfaces can exhibit a quite unusual behaviour and concurrently a very promising wave propagation behaviour. In the model of strongly anisotropic surface elasticity, strain energy as a function of the first and second deformation gradients has been introduced in addition to the constitutive relations in the bulk. In order to obtain values of surface elastic moduli, we compare dispersion relations for anti-plane surface waves obtained using the two-dimensional (2D) model and three-dimensional (3D) straightforward calculations for microstructured coatings of finite thickness. We show that with derived effective surface moduli, the 2D model can correctly describe the wave propagation. [ABSTRACT FROM AUTHOR]

Recent technologies permit to build materials which have elastic spatially varying modulus which can also imitate solutions adopted in Nature to optimize some structures. It has been shown that for example the stress concentration due to a hole in an infinite plate can be cancelled with a radially varying modulus making it similar to load-bearing bones which seem to resist structural failures even in the presence of blood vessel holes (foramina). Here, we attempt to study the classical problem of a sharp wedge (which includes the important case of a crack) looking for stresses varying as power law of the distance from the notch tip, σ ∼ r α , with a modulus varying as E ∼ r β . In the inhomogeneous case the order of singularity of the LEFM case decreases if β > 0 , as confirmed by FEM investigations. Hence, we can remove stress singularities, which suggests an interesting alternative to the "rounding" of the notch. More in general, since for many materials it has been found that both strength and modulus are power laws of the density, using the so called strength-modulus exponent ratio we can obtain optimal design by keeping the asymptotic stress constantly equal to the strength. The present investigation paves the way for a new optimization strategy in the problems which eliminates size-scale effects due to singular stress fields, with potentially very wide applications. [ABSTRACT FROM AUTHOR]

Researchers from Khulna University conducted a molecular dynamics study on the mechanical stability of Ti4C3 MXene for Lithium-ion batteries. The study found that Ti4C3 MXene exhibited superior tensile strength and elasticity modulus along zigzag directions, with armchair orientation showing a higher fracture strain. Elevated temperature decreased both fracture strength and strain, while point vacancy significantly affected the elastic modulus. The research provides valuable insights for further experimental studies and potential applications of Ti4C3 MXene in LIBs. [Extracted from the article]

A patent application has been submitted for a "Ligature Resistant Flexible Swinging Door" that aims to address the issue of suicide attempts in medical facilities, prisons, and schools. The door hardware system allows for privacy and security while reducing ligature anchor points. The door panel is made of a flexible polymeric material and is designed to pivot in two directions. The invention aims to provide a safe opening solution that enhances wellness and reduces the risk of self-harm. The patent application provides detailed technical specifications and claims for the door assembly. [Extracted from the article]

A study conducted by researchers at Xinjiang University in Urumqi, China, examined the mechanical properties of cortical bone using nanoindentation. The study found that the elastic modulus and hardness of cortical bone varied significantly across different anatomical regions and bearing surfaces. The anterior and medial sides had significantly greater elastic modulus and hardness compared to the posterior and lateral sides. Additionally, the elastic modulus was higher in the axial direction compared to the radial direction, and there was a positive correlation between elastic modulus and hardness. The study concluded that the stresses in the axial direction of cortical bone exceeded those in the radial direction. This research provides new insights into the mechanical behavior of cortical bone and was supported by the National Natural Science Foundation of China. [Extracted from the article]

Researchers from Hebei University of Technology in Tianjin, China, have conducted a study on the use of strontium-doped biological coatings on Ti-15zr alloys for dental implants. The researchers modified the Ti-15Zr alloy using sandblast acid-etching and loaded Sr ions onto the surface using the hydrothermal method. The results showed that the Sr ions attached to the material's surface in the form of granular SrTiO3. The study found that the modified coatings had superior hydrophilic and hemolytic properties compared to the unmodified alloy, and the higher the concentration of Sr, the better the cell proliferation effect. [Extracted from the article]

Researchers at Northeastern University in Shenyang, China have discovered a potential biomedical application for the alloy Ti-13Nb-13Zr-7Ag (TNZ-7Ag). This alloy has a low elastic modulus and excellent antibacterial properties, making it suitable for use in biomedical titanium alloys. The researchers used a pre-deformation and aging treatment to enhance the antibacterial performance of TNZ-7Ag, resulting in an alloy with both low elastic modulus and strong antibacterial properties. This study demonstrates the effectiveness of pre-deformation as a strategy for developing novel biomedical titanium alloys. [Extracted from the article]

A recent study conducted by researchers at Hatay Mustafa Kemal University in Turkey examined the effects of acidic beverages on the physical and mechanical properties of tooth-colored fluoride-releasing dental materials. The study evaluated the nanohardness, elastic modulus, and surface roughness of three different restorative materials after immersion in distilled water, cola, and orange juice for one week. The results showed that the acidic beverages had a negative impact on the nanohardness, elastic modulus, and surface roughness of the restorative materials. This research provides valuable insights into the potential effects of acidic beverages on dental materials. [Extracted from the article]

A patent has been issued for an elastomeric orthodontic bracket by Solventum Intellectual Properties Company. The invention relates to orthodontics and the use of brackets to reposition teeth. The patent describes a new design for orthodontic brackets that includes an inner elastomeric body adjacent to the outer bracket body, which helps maintain the axis of rotation and disperses forces from an arch member. The invention also includes a dental appliance with separate polymeric shell portions for each tooth. The patent provides detailed claims and methods for making the orthodontic appliance. [Extracted from the article]

A patent application titled "Fusion Cage" has been published online by the US Patent and Trademark Office. The inventors, LIU, Hao; MA, Xuewei; SUN, Lu; XU, Kai; ZHANG, Jing, filed the application on February 18, 2024. The patent application describes a fusion cage that aims to address the technical issues of existing fusion cages by configuring lattice structures with different specifications on different end surfaces. The fusion cage also includes features such as an instrument groove, inclined surface reinforcement ribs, and a bone graft chamber. The patent application provides detailed descriptions and claims for the fusion cage design. [Extracted from the article]

A new study conducted by researchers from the Bandung Institute of Technology in Indonesia explores the influence of bite force and implant elastic modulus on mandibular reconstruction using particulate cancellous bone marrow (PCBM) grafts. The study utilized a finite element model to simulate the healing process over a 12-week period. The findings suggest that lower bite force and larger implant elastic modulus contribute to faster healing and the development of bone graft elastic modulus and mandible equivalent stiffness. The study provides insights into mandibular reconstruction mechanobiology and offers a framework for post-operative planning, failure prevention, and implant design. [Extracted from the article]

Researchers at Nanjing Tech University in China have developed a new model for simulating soft tissue deformation in virtual surgery, specifically focusing on pulmonary hamartomas surgery. The model combines cellular neural networks (CellNN) with physical modeling methods to accurately represent the varying densities and softness of different tissues. By introducing the elastic modulus into the model, the researchers were able to simulate energy transfer and deformation in non-uniform soft tissues. Experimental results showed that the proposed model outperformed existing models in terms of real-time performance, accuracy, and realistic representation of tissue heterogeneity. This research has been peer-reviewed and published in Biomedical Signal Processing and Control. [Extracted from the article]

The mechanical properties of hydrogels are significantly influenced by synthesis parameters. Although the mapping from the space of synthesis parameters to the space of properties has been investigated experimentally, a quantitative theoretical framework is still lacking. In this work, the effect of synthesis parameters on the hyperelastic behaviors of hydrogels was experimentally studied. Subsequently, we conducted theoretical analysis by combining the constitutive model and polymer physics to quantify the correlation between synthesis parameters (the initial water content, current water content, and degree of cross-linking) and hyperelasticity (the elastic modulus, degree of entanglement, and stress-stretch ratio curve) of hydrogels. The internal relation between critical polymer content for entanglement and both the initial water content and degree of cross-linking arises from the scaling laws. By analyzing the critical polymer content for entanglement and comparing it with the current polymer content, hydrogels are categorized as either cross-linking-dominated or entanglement-dominated. The current study indicates that a low degree of cross-linking, i.e., a long-chain structure, is an important prerequisite for plenty of entanglements. Hydrogels with low cross-linking are highly entangled, whether they possess high initial water content/low current water content or low initial water content/high current water content. This work paves the way for the systematic design of synthesis parameters, thereby guiding the modulation and optimization of the overall mechanical properties and the application of hydrogels. [ABSTRACT FROM AUTHOR]

• This paper proposes a novel lattice-surfaced PEEK cage to provide tailored mechanical performance, better stress absorption and deformation resistance. • The compression modulus and elastic limit can be tailored by adjusting the lattice-surfaced area without sacrificing the energy absorption efficiency. • Multiple point-plane stress transfer mechanism is found for lattice-surfaced PEEK cage, which plays an important role in stress absorption and deformation resistance. • The high-strength PEEK shows a characteristic radial morphology and a more ordered double-stranded orthorhombic structure. Porous structure design on the contact surface is crucial to promote the osseointegration of the intervertebral cage while preventing subsidence and displacement. However, the stress response will undergo significant changes for the current random porous cages, which can directly affect the mechanical properties and long-term usability. Here, this paper proposed a newly designed polyetheretherketone (PEEK) cage with the triply periodic minimal surface (TPMS)-structured lattice surfaces to provide tailored 3D microporosity and studied the mechanical performance, stress/strain responses, and microstructure changes in depth. The lattice-surfaced PEEK cage mainly exhibits a multiple-point-plane stress transfer mechanism. The compression modulus and elastic limit can be adjusted by controlling the area of the Diamond TPMS surface while the energy absorption efficiency remains stable. The microstructure of high-strength PEEK is featured by the radial pattern morphology. Meanwhile, the double-stranded orthorhombic phase is more ordered, and the benzene plane subunit and lattice volume become more expanded. [Display omitted] [ABSTRACT FROM AUTHOR]

• Synthesis of Al-V alloys from high-energy ball milling and spark plasma sintering. • Al-V alloys with far-from-equilibrium microstructure: V solubility 6 orders of magnitude higher than equilibrium value. • Elastic modulus of Al-V alloys is much higher than that of any commercial Al alloy. • Effect of spark plasma sintering temperature on the microstructure, hardness and elastic modulus of Al-V alloys. Al- x V alloys (x = 2 at.%, 5 at.%, 10 at.%) with nanocrystalline structure and high solid solubility of V were produced in powder form by high-energy ball milling (HEBM). The alloy powders were consolidated by spark plasma sintering (SPS) employing a wide range of temperatures ranging from 200 to 400 °C. The microstructure and solid solubility of V in Al were investigated using X-ray diffraction analysis, scanning electron microscope and transmission electron microscope. The microstructure was influenced by the SPS temperature and V content of the alloy. The alloys exhibited high solid solubility of V―six orders of magnitude higher than that in equilibrium state and grain size < 50 nm at all the SPS temperatures. The formation of Al 3 V intermetallic was detected at 400 °C. Formation of a V-lean phase and bimodal grain size was observed during SPS, which increased with the increase in SPS temperature. The hardness and elastic modulus, measured using nanoindentation, were significantly higher than commercial alloys. For example, Al-V alloy produced by SPS at 200 °C exhibited a hardness of 5.21 GPa along with elastic modulus of 96.21 GPa. The evolution of the microstructure and hardness with SPS temperatures has been discussed. [ABSTRACT FROM AUTHOR]

In this paper, we apply mesoscale numerical modeling to predict the effective elastic properties of conductive carbon-black/ultra-high-molecular-weight-polyethylene nanocomposites. The models are based on X-ray microcomputed tomography images. The images show that for the considered range of carbon additive weight fractions, the conductive carbon black (CB) particles are distributed around the ultra-high-molecular-weight-polyethylene (UHMWPE) granules forming a carbon-containing layer of a thickness on the order of 1–2 μ m. Finite element models of representative volume elements (RVE), incorporating the CB-containing layer, are developed. The RVEs are generated based on the size and shape statistics extracted from processed microcomputed tomography images with further incorporation of the CB-containing layer by a custom image processing code. The layer is modeled analytically as a 2-phase composite consisting of spherical CB inclusions distributed in the UHMWPE matrix. Elastic moduli predicted in the models are compared to experimental data. Results show that the numerical simulations predict effective elastic moduli within the confidence intervals of the experimental measurements up to 7.5 wt % of CB inclusions. [ABSTRACT FROM AUTHOR]

When subjected to repeated dynamic impacts at identical load level, a metallic monolithic beam/plate may reach a stable state wherein measurable deformation ceases (i.e., shakedown in elastic state) after undergoing a sequence of elastoplastic deformations, which has been termed as "pseudo-shakedown" (P-S) (Jones, 1973; Shen and Jones, 1992). While the response of a single beam/plate under repeated low-velocity impacts has been thoroughly studied, its dynamic behavior under high-velocity impacts, such as explosive or alternating impulsive loads, is difficult to measure experimentally, due mainly to high costs and setup challenges. In the current study, the method of metallic foam projectile impact was employed to produce repeated impulsive loadings on a fully-clamped elastoplastic monolithic plate made of L907A (a Chinese standard shipbuilding steel). Its dynamic responses, including mid-point deflection versus time histories, final deflections, and deformation modes after each impact, were systematically measured. The phenomenon of dynamic shakedown was observed. To further explore this phenomenon, the method of finite elements (FE) was employed to simulate the repeated impulsive impact test, and its prediction accuracy was validated against experimental results. Unlike an elastoplastic (e.g., steel) monolithic plate subjected to repeated low-velocity impacts, which exhibits zero plastic energy dissipation in the P-S (pseudo-shakedown) state, the same plate under repeated high-velocity impacts shows a small level of plastic energy dissipation in the P-S state, mainly due to more extreme loading conditions. The initial impact momentum, yield strength, and tangent modulus of the material the plate is made of significantly affect both the stable deflection in the P-S state and the number of impacts needed to reach it, while the elastic modulus has limited influence. A modified dimensionless impulse loading number, accounting for the strain-hardening effect, is proposed. An approximately linear relationship between stable deflection in the P-S state and impulsive loading is found in dimensionless form. [ABSTRACT FROM AUTHOR]

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

The contact between a rigid Hertzian indenter and an adhesive broad-band viscoelastic substrate is considered. The material behavior is described by a modified power law model, which is characterized by only four parameters, the glassy and rubbery elastic moduli, a characteristic exponent n and a timescale τ 0. The maximum adherence force that can be reached while unloading the rigid indenter from a relaxed viscoelastic half-space is studied by means of a numerical implementation based on the boundary element method, as a function of the unloading velocity, preload and by varying the broadness of the viscoelastic material spectrum. Through a comprehensive numerical analysis we have determined the minimum contact radius that is needed to achieve the maximum amplification of the pull-off force at a specified unloading rate and for different material exponents n. The numerical results are then compared with the prediction of Persson and Brener viscoelastic crack propagation theory, providing excellent agreement. However, comparison against experimental tests for a glass lens indenting a PDMS substrate shows data can be fitted with the linear theory only up to an unloading rate of about 100 μ m/s showing the fracture process zone rate-dependent contribution to the energy enhancement is of the same order of the bulk dissipation contribution. Hence, the limitations of the current numerical and theoretical models for viscoelastic adhesion are discussed in light of the most recent literature results. [Display omitted] • Numerical, theoretical and experimental investigations on viscoelastic adhesion enhancement. • Maximum amplification is constrained by preload and unloading rate. • Closed form results for the effective surface energy in broad-band spectrum viscoelastic materials. • Bulk and fracture process zone contribution to the effective surface energy. • Experiments show limitations of classical linear theories. [ABSTRACT FROM AUTHOR]

Important physical observations in rupture dynamics such as static fault friction, short-slip, self-healing, and the supershear phenomenon in cracks are studied. A continuum model of rupture dynamics is developed using the field dislocation mechanics (FDM) theory. The energy density function in our model encodes accepted and simple physical facts related to rocks and granular materials under compression. We work within a 2-dimensional ansatz of FDM where the rupture front is allowed to move only in a horizontal fault layer sandwiched between elastic blocks. Damage via the degradation of elastic modulus is allowed to occur only in the fault layer, characterized by the amount of plastic slip. The theory dictates the evolution equation of the plastic shear strain to be a Hamilton–Jacobi (H-J) equation, resulting in the representation of a propagating rupture front. A Central-Upwind scheme is used to solve the H-J equation. The rupture propagation is fully coupled to elastodynamics in the whole domain, and our simulations recover static friction laws as emergent features of our continuum model, without putting in by hand any such discontinuous criteria in the formulation. Estimates of material parameters of cohesion and friction angle are deduced. Short-slip and slip-weakening (crack-like) behaviors are also reproduced as a function of the degree of damage behind the rupture front. The long-time behavior of a moving rupture front is probed, and it is deduced that equilibrium profiles under no shear stress are not traveling wave profiles under non-zero shear load in our model. However, it is shown that a traveling wave structure is likely attained in the limit of long times. Finally, a crack-like damage front is driven by an initial impact loading, and it is observed in our numerical simulations that an upper bound to the crack speed is the dilatational wave speed of the material unless the material is put under pre-stressed conditions, in which case supersonic motion can be obtained. Without pre-stress, intersonic (supershear) motion is recovered under appropriate conditions. [ABSTRACT FROM AUTHOR]

• A self-spinning liquid crystal elastomer tube system is innovatively developed. • The tube system always evolves into the stationary state under vertical light. • The system undergoes periodic self-spinning due to the combined action of gravity and constant light intensity. • The frequency of self-spinning can be modulated by system parameters. Self-oscillating motion have the capacity to autonomously converting ambient power into repetitive motion without requiring an additional control unit, and designing more self-oscillating can broaden their utilization in energy extraction, robotic systems, and sensors. However, cyclic self-oscillating motions often cause structural instability and increase friction. To address these challenges, we creatively developed a zero-energy-mode self-spinning liquid crystal elastomer (LCE) tube-mass system under constant light intensity. By proposing a nonlinear dynamic model and using fourth-order Runge-Kutta method, the computational findings suggest that the LCE tube stays stationary when exposed to vertical light while develops into a zero-energy-mode self-spinning state under non-vertical light. The self-spinning state is self-sustained through harvesting ambient light energy, helping counteract the damping loss. In addition, the self-spinning frequency is controllable by tuning the light angle, contraction coefficient, light intensity, elastic modulus, radius, and damping coefficient. The translational damping has no impact on the self-spinning frequency, and the elastic modulus does not affect the X-axis displacement of the free end. The proposed self-spinning LCE tube system, differing from numerous existing self-oscillating systems, offers advantages like zero-energy-mode motion, structural simplicity, and controllability across multiple parameters, promising expanded design opportunities for applications such as motors, soft robotics, energy collectors, micro-machines, and beyond. [ABSTRACT FROM AUTHOR]

A study conducted at the University of Jena in Germany investigated the mechanical characteristics of resin composites and their suitability for restoring endodontically treated teeth (ETT). The study involved 38 premolars with occlusal access cavities that were directly restored using different resin composites and adhesives. The results showed that the tested resin composites and adhesives exhibited reliable mechanical characteristics and appeared to be suitable for the direct restoration of ETT. This research provides valuable insights for dental professionals and patients seeking information on the restoration of endodontically treated teeth. [Extracted from the article]

A preprint abstract from biorxiv.org discusses the relationship between the viscoelastic properties of breast cancer spheroids and their metastatic potential. The study used a microfluidic constriction to impose controlled, dynamic compression on the spheroids and monitored the relaxation of the deformation. The results showed that benign spheroids had higher bulk elastic modulus and viscosity compared to malignant spheroids. The differences in viscoelastic properties were found to be linked to cytoskeletal organization and cell-cell adhesion strength. This research has not yet undergone peer review. [Extracted from the article]

Tunnel excavation was a typical three-dimensional space problem. As a two-dimensional numerical method, the combined finite-discrete element method did not demonstrate the spatial effect during the tunnel excavation simulation. A new excavation path for the combined finite-discrete element method was proposed based on the spatial evolution characteristics. Then, the tunnel excavation simulation was carried out under different excavation paths (linear softening curve, exponential softening curve, power softening curve, and new softening curve). The results showed that the advantages of the exponential softening curve and power softening curve were inherited by the new softening curve. The new softening curve demonstrated the spatial effect during the tunnel excavation simulation. Moreover, both the maximum softening rate and peak value of model kinetic energy occurred near the intermediate moment, which was an advantage over other softening curves. The discussion indicated that both the softening rate and elastic modulus range should be considered when determining new softening curve parameters. And the optimal total softening steps can be estimated by the proposed equation with an error tolerance. Finally, the new softening curve was well applied in the numerical analysis of tunnel excavation and support design. [ABSTRACT FROM AUTHOR]

As undertaking various key functions, helical chiral structures are widely presented in nature. Herein, we develop a general theoretical framework to guide the formation of helical chiral structures through self-assembly of micro/nano-fibers driven by adhesion. By analyzing the spiral contact geometric characteristics of multiple fibers and extending the JKR theory, an analytical model for adhesive contact between helical interfaces is proposed. Further, the complete configuration space of self-assembled fibers depending on the adhesion work, elastic modulus, aspect ratio, and initial helix angle is theoretically obtained. A diversity of helical configurations that far beyond existing experimental findings are predicted, which stems from the existence of multiple energy minimum points on the configuration-energy map. This work reveals the mechanism of adhesion-driven helical chiral structures, and provides theoretical foundation for guiding high-efficient fabrication of helical chiral structures through self-assembly method, which could promote the wide application of chiral structures in fields such as optics, catalysis and drug screening. [ABSTRACT FROM AUTHOR]

The Boeing Company has been issued a patent for composite parts that facilitate ultrasonic imaging of layer boundaries. Composite parts, such as Carbon Fiber Reinforced Polymer (CFRP) parts, are initially laid-up in multiple layers that form an unhardened laminate. The patent describes a method and apparatus that utilize internal pores or particles at the boundary between layers to alter the acoustic impedance of the composite part, allowing for high-contrast imaging of the boundary via ultrasound. This technology could enhance the imaging of internal composition in composite parts, providing designers with a more effective technique for quality control. [Extracted from the article]

Obtaining complete rock cores is exceptionally challenging in certain extreme environments, such as deep earth and deep space; consequently, it is difficult to obtain the macro strengths of rock, which are the key indexes for engineering design, via standard rock mechanical tests. This research indicates that by determining and leveraging the mechanical properties of grains and grain-to-grain interfaces, the rock macro strength can be effectively estimated. Nanoindentation tests were first conducted to determine the elastic modulus of the mineral grains and their interfaces. Subsequently, symmetrical and anti-symmetrical four-point bending tests were executed to establish the statistical law governing interfacial tensile and shear fracture toughnesses. Furthermore, by employing the Dugdale–Barenblatt model and considering the oblique angular distribution of interfacial cracks, the corresponding tensile strength, shear strength, and friction parameter were derived. These meso‑mechanical parameters were then inputted into the 3D Finite-Discrete Element Method to estimate rock macro strength. And the numerical results were then compared with the results of standard uniaxial compression, direct tension, Brazilian splitting, and direct shear tests. The consistency observed between the predictions and experimental results attests to the validity of the proposed method. [ABSTRACT FROM AUTHOR]

Liquid crystal elastomers (LCEs) are a class of smart elastomers exhibiting unusual mechanical behavior, including large energy dissipation and soft elasticity under uniaxial tensile loading. LCEs are composed of liquid crystal molecules, called mesogens, linked by a network of polymer chains. During deformation, the mesogens orient in the direction of the loading, leading to soft elasticity, which is an increase in strain at constant stress. The combination of mesogen rotation and intrinsic polymer viscoelasticity leads to a nonlinear viscoelastic soft elastic behavior. The aim of this paper is to investigate the coupling between the viscoelastic mechanisms and soft elasticity in main chain LCEs. We propose a rheological model in which the mesogen rotation during deformation is represented by a reversible slider while viscoelastic relaxation mechanisms are modeled as series of Maxwell elements coupled or decoupled with mesogen rotation. Fitting this model to experimental data demonstrate that the coupling between polymer chain viscoelasticity and mesogen rotation is partial, i.e. the long-time relaxation mechanisms are coupled and the short-time relaxation mechanisms are decoupled from mesogen rotation. Furthermore, we show that the viscosity of mesogen rotation is not necessary to properly predict the elastic modulus during the soft elasticity but it is needed to properly predict the initiation of the phenomenon. [ABSTRACT FROM AUTHOR]

In this paper a practical numerical method for calculating the settlement response of piles embedded in multilayered soils is presented. Finite beam elements are used for the discretization of piles. The soil mass, which is considered as a semi-infinite or finite medium with each layer being elastic, homogeneous and isotropic, is modeled with the boundary element method and the Steinbrenner's approximation. In addition, the critical case in which the elastic modulus is decreasing with depth is appropriately treated by considering the soil as a half space inhomogeneous medium. The present formulation, besides yielding fully adequate results for design purposes when compared with other approaches, presents a more practical problem modeling and data preparation. Results of numerical examples considering single piles and pile groups are compared with those of other formulations in order to demonstrate the efficiency and accuracy of the proposed formulations. [ABSTRACT FROM AUTHOR]