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It is important for people to feel listened to in professional and personal communications, and yet they can feel unheard even when others have listened well. We propose that this feeling may arise because speakers conflate agreement with listening quality. In 11 studies (N = 3,396 adults), we held constant or manipulated a listener's objective listening behaviors, manipulating only after the conversation whether the listener agreed with the speaker. Across various topics, mediums (e.g., video, chat), and cues of objective listening quality, speakers consistently perceived disagreeing listeners as worse listeners. This effect persisted after controlling for other positive impressions of the listener (e.g., likability). This effect seemed to emerge because speakers believe their views are correct, leading them to infer that a disagreeing listener must not have been listening very well. Indeed, it may be prohibitively difficult for someone to simultaneously convey that they disagree and that they were listening. [ABSTRACT FROM AUTHOR]

Smart surfaces with responsive wettability are unstable, and depend upon continuous external stimuli, which limits their widespread application in switchable oil/water emulsions separations. In this study, a Ti‐based 3D porous structure (SLM‐3DTi) is printed using advanced selective laser melting (SLM) technology for the switchable separation of oil/water emulsion. With the assistance of the computer program, porous structure and re‐entrant texture can be easily designed and printed in one step. Without any continuous external stimulus, the wettability of SLM‐3DTi can be reversibly switched between underwater superoleophobicity and underoil superhydrophobicity simply by drying and washing cycles. The SLM‐3DTi achieves switchable surfactant‐stabilized oil‐in‐water emulsion (SSE(o/w)) and surfactants‐stabilized water‐in‐oil emulsion (SSE(w/o)) separation with purity above 99.8% at a flux of more than 2000 L m−2 h−1. In addition, the re‐entrant texture of the SLM‐3DTi surface is formed with the partially melting powder particles on the part contour, which has much stronger mechanical durability than any binder. Furthermore, SLM‐3DTi has excellent corrosion resistance due to the material properties of Ti. More importantly, based on the visualization analysis of the simulation, the mechanism of SLM‐3DTi emulsion separation is further elucidated. Therefore, SLM‐3DTi has broad practical application potential for high‐flux, high‐purity, and switchable oil/water emulsion separation. [ABSTRACT FROM AUTHOR]

As a novel lightweight metallic structure, metal rubber seals (MRS) can be used for sealing elements in extreme environments where traditional polymer rubber seals become ineffective. In the present work, a virtual fabrication technology (VFT) of MRS based on computer-aided simulation technology was developed to accurately reflect the random contact interface behavior between the disordered spiral network structure of MRS core and metal sheet. The mechanical properties (meso contact characteristics and macro structural response) of the complex structure were characterized by numerical analysis and compressive tests. The effect of the compression ratio and material porosity on contact pressure performances of sealing interface was analyzed in detail. It is found that the meso contact pressure of MRS is affected by the joint action of compression condition, inner core support and cladding failure. There is a turning point in a certain range, which allow the MRS prepared in this work has the relatively best contact characteristics when the porosity is 51.5% and the compression condition is 15%. The force-displacement curves obtained from simulation and experiment both exhibit an obvious nonlinearity and slow growth area, which confirm that the MRS constitutive model based on VFT can effectively characterize the multi-scale conformity of MRS specimens from meso-structure to macro-performance. [ABSTRACT FROM AUTHOR]

Titanium and its alloys are one of the mainstream materials for the manufacture of intervertebral cages. With the application on clinical, the problems of elastic modulus is relatively high, subsidence of adjacent vertebral implants and stress shielding after surgery have gradually exposed. In this paper, metal rubber made from titanium alloy wire was used to prepare cervical fusion cage (CFC), which was a porous material with buffering and vibration damping properties. The C5/C6 segment of the goat cervical vertebra was used as the research object. The shape parameters of the CFC were determined by combining the three-dimensional model data of the cervical vertebra and the structural characteristics of the natural intervertebral disc. The force of CFC under different working conditions were simulated and analyzed by finite element simulation. Then three kinds of metal rubber core (MRC) were prepared by medical titanium alloy wire (TC4), and their mechanical properties and fatigue strength were experimentally studied. With the increases of density, the mechanical properties of MRC improved. The variation range of the loss factor η under different amplitudes and frequencies were 20% and 16.3%, respectively. After one million vibrations, the wear rate was 0.131 g/MC; after five million vibrations, the wear rate was 0.158 g/MC, which was similar to the existing clinical prosthesis wear rate. The MRC has sufficient mechanical strength. Compared with the existing clinical prostheses, it has a longer service life and has broad application prospects. [ABSTRACT FROM AUTHOR]

[Display omitted] • A damage hysteresis dynamic model of tangled metal was proposed for analyzing the damage incurred by TMW under cycles. • The Damage hysteresis dynamic model was constructed from which the coupled relationship between micro-damage and macroscopic performance degradation in the TMW. This model provides insights into the dynamic damage and life prediction modeling of the TMW. • Based on the higher-order dry friction model that considers the internal structural characteristics and process parameters of TMW, this study further proposed a TMW damage hysteresis dynamic model that characterizes the evolution of internal damage in the TMW. Tangled metal wire (TMW) is a kind of porous hyperplastic high damping material, which can realize the vibration isolation of key equipment. However, the unclear mapping relationship between internal microscopic damage and overall macroscopic performance made it difficult to construct a damage hysteresis dynamic model. This limits the application and development of TMW vibration isolation. In this paper, a strategy to analyze the dynamic damage evolution of TMW was proposed. Firstly, a cross-scale relationship between internal damage in TMW and macroscopic performance degradation was established. Furthermore, a damage hysteresis dynamic model was constructed by considering the high-order dry friction (HDF). The complex spatial spiral structure and preparation process parameters were described by using the HDF. Then, the damage factors of each component force were built and analyzed: The damage factor of HDF could be used to characterize the damage evolution of the metal wire inside TMW and the cross-scale correlation between microscopic damage and macro performance degradation, whereas the degree of hysteresis characteristics of TMW could be characterized by the damage factor of hysteretic coulomb damper. Finally, the damage hysteresis dynamic model was evaluated through residual analysis, and it has high prediction accuracy in more than 80 % of the cycles R 2 > 0.7. This paper provided a new idea for the modeling of TMW life prediction. [ABSTRACT FROM AUTHOR]

Super-wetting materials are widely used to treat oil–water mixed sewage. However, there are still great challenges in manufacturing strong and durable super-wetting materials for the separation of complex emulsions. A method for the simple preparation of durable, low-cost, superhydrophobic, and superlipophilic 3D materials is reported in this paper. Superhydrophobic metal rubber, MR–C, was successfully prepared by depositing low-cost candle soot on a metal rubber workblank, and then stamping and dipping the soot-coated rubber workblank in a polydimethylsiloxane solution. MR–C effectively separated a variety of water-in-oil emulsions driven by gravity. In addition, because the 3D porous material acted as a protective layer, MR–C could still be used to efficiently separate emulsions even after the sample was subjected to a wear test under 500 N loads. After being immersed in a corrosive environment for a long time, the surface of the material maintained its stable superhydrophobic properties. The stable and efficient separation efficiency and strong mechanical durability ensure the reusability of MR–C in purification, and it shows great potential in oily wastewater treatment applications. [ABSTRACT FROM AUTHOR]

Metal rubber materials, formed by entangling single metal wires and also known as ESW-MR, have attracted widespread attention due to their unique non-linear load curves and excellent environmental adaptability. The mechanical behavior of these materials, which are created through the weaving or winding of pure metal wires, is influenced by the structural characteristics of semi-flexible fiber cross-linked fibers. This study delves deeply into the microstructure of ESW-MR, with the aim of establishing a numerical model that can accurately simulate and characterize its structure. A method based on arbitrarily defined baselines parametric equations in the global space was adopted, leading to the creation of a parametric model for a continuously wound wire with multiple spiral mechanisms. Finite element simulations based on explicit dynamics were conducted using LS-DYNA and could successfully simulate the cold stamping forming process of ESW-MR blanks. The model was validated through stamping and quasi-static tests, as well as computed tomography (CT) scan tests. The results demonstrate the model accuracy in describing the macroscopic and microscopic characteristics of the material, showing excellent agreement with the actual material. Furthermore, the study successfully extracted the micro-topological features of the material, providing additional quantitative information on the topological characteristics of ESW-MR. This work offers a valuable tool for the study and application of ESW-MR and presents a novel perspective for the numerical simulation of a wide range of entangled materials. It paves the way for gaining a deeper understanding of the microstructure and mechanical behavior of such materials. [ABSTRACT FROM AUTHOR]

As a new composite material with high strength, toughness, and heat resistance, the continuous fiber-reinforced polyaryl ether sulfone ketone (PPESK) thermoplastic resin matrix composite (CFRP) has a wide temperature range, which is attributed to the complex temperature sensitivity of the matrix. The failure evolution characteristics under different conditions are not clear yet, which significantly limits its development and application to high-precision equipment. In this work, in order to deeply explore the full three-dimensional (3D) multi-scale multi-physics damage evolution mechanism of the CFRP over a wide temperature range, macroscale cross-temperature stretching/bending experiments, computer tomography (CT) scanning, and microscale scanning electron microscopy (SEM) are performed to effectively capture the overall damage morphology and local fiber/matrix damage failure characteristics of the material. The results show that the reinforcement with continuous fibers increases the tensile strength of the CFRP by 14–45 times and its bending strength by 2–6 times compared to those of the PPESK matrix in the cross-temperature domain. Moreover, the main failure mechanism of the CFRP in the cross-temperature domain is matrix crushing and fiber fracture at room temperature and fiber fretting slip and matrix viscous flow at high temperatures. This further explains the deformation mechanism of the CFRP, which can maintain its stability at high temperatures (low elongation at break: 1%–1.2%). The unique trans -temperature regional energy evolution and continuous fiber reinforcement of the material matrix resin PPESK lay the synergic stability of the high temperature performance and damage morphology of the CFRP. In particular, a cell model is constructed to further reveal the damage evolution characteristics of the matrix, fiber, and interface of the CFRP at the micro-scale. Combined with the failure mode theory and the performance degradation mechanism of composite materials, the temperature influence factor is introduced to formulate a multi-scale full 3D temperature-dependent damage evolution constitutive model of the CFRP over a wide temperature range. The constitutive model of the CFRP is incorporated in finite element software, and the simulation results are compared with the experimental ones for validation. The results show that the model developed in this work can effectively characterize the complex mechanical damage morphology and progressive failure characteristics of the CFRP over a wide temperature range. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, a high-temperature fretting wear prediction model was established for metal rubber, which was then validated through experiments. Initially, a three-dimensional numerical model of metal rubber was reconstructed, and statistical distribution of contact points and types of curved wires inside the virtual component was achieved. Meanwhile, a high-temperature fretting wear evolution model for curved wires was constructed by introducing a temperature function f(T), considering material thermal expansion, softening, and oxidation. Subsequently, the model was incorporated into the macro model, establishing a cross-scale predictive model for wear from micro-coil elements to component wear. Experimental validation demonstrated good prediction performance of the model, with a maximum wear mass prediction error of 14.81% and prediction errors below 10% for 80,000 cycles. [ABSTRACT FROM AUTHOR]

• Metal wire and cotton fibers are combined through ingenious weaving methods. • The combination of macroscopic and microscopic fibers makes SWCM have excellent durability and efficient emulsion separation performance. • For the first time, an emulsion separation simulation model has been established via computational fluid dynamics (CFD) to understand the SWCM emulsion separation mechanism. • The separation efficiency of the SWCM is above 99.98% only by gravity drive. Superhydrophobic materials have been extensively investigated for their ability to separate oil/water mixtures, but their fragile durability has limited further development in this field. In this study, a durable superhydrophobic wire-cotton-based material (SWCM) was prepared by weaving metal wire and cotton fiber and modifying it with a mixed poly(vinyl phenol) (PVPh)/1,3-phenylene bisoxazoline (PBO) solution, which exhibits both macro-frame and micro-aperture. The SWCM demonstrates remarkable separation efficiency (greater than99.98 %) for a variety of water-in-oil emulsions using only gravity drive. More importantly, computational fluid dynamics (CFD) simulations were conducted to investigate the separation mechanism of SWCM, revealing dynamic trajectory and volume changes of water droplets in real-time. Moreover, the micro-aperture, protected by the macro-frame, can withstand hundreds of impacts and abrasions and still maintain reliable separation efficiency. Under the encapsulation of micro-apertures, the macro-frame exhibits excellent corrosion resistance and can maintain stable superhydrophobicity even after long-term immersion in different harsh solutions. Due to its excellent durability, the SWCM can maintain a long service life in oil–water separation in complex environments. Therefore, the presented SWCM has great potential in the development of durable and efficient materials for emulsion separation. [ABSTRACT FROM AUTHOR]

Superhydrophilic and underwater superoleophobic metal rubber was prepared by simple and economic alkali etching method. The modified metal rubber could efficiently and rapidly separate the oil-water mixture. More importantly, it could not only separate the mixture of water with common oils (gasoline, diesel, engine oil, and kerosene) in mechanical systems but also had excellent durability. Metal rubber (MR) with excellent mechanical properties and porosity is often used as a filter material in mechanical systems. Oil filtration involves not only the recycling of contaminated oil, but more importantly, it ensures normal functioning of the hydraulic system and lubrication system. Here, one-step etching method was employed to fabricate the superhydrophilic and underwater superoleophobic MR. The modified MR could efficiently and quickly separate oil-water mixtures, especially oil-water mixtures of several oils (gasoline, diesel, engine oil, kerosene) commonly used in machinery, driven by gravity. Furthermore, the modified MR demonstrate the excellent durability and maintain the high efficiency after multiple oil-water separations. Significantly, the modified MR also showed good thermal resistance and corrosion resistance. This research has provided MR with a new functionality. This opens a new avenue for MR to be used for separation of oil-water mixture, thereby expanding greatly its application in filtration. [ABSTRACT FROM AUTHOR]

Metal rubber (MR) using steel wires is increasingly desired, particularly for the practical process of industrial production. However, realizing multifunctionality of MR during its service remains challenging. In this work, for the first time, we present a simple chemical etching method and a straightforward modification to render an MR surface made of stainless steel wires superhydrophobic while strengthening its corrosion resistance. Creation of a lotus-like hierarchical structure was performed by a two-step chemical etching process. The superhydrophobic MR with a water contact angle of about 152° and a sliding angle of about 5° can be used for effective and rapid oil/water separation. And the water repellency property of the superhydrophobic MR still remains even after 10 abrasion cycles with sandpaper (400 cW), indicating excellent mechanical durability. Additionally, the corrosion resistance of the superhydrophobic MR is much higher than that of raw MR, which will broaden its practical applications. This study expands the potential applications of functional MR, which might be a breakthrough for traditional MR-making industries. [ABSTRACT FROM AUTHOR]

The impact head, tip leakage vortex, and pressure pulsation during start-up can cause vibration and noise in the pump, and affect its hydraulic performance. The linear speed start-up method cannot solve the impact head and vibration problems. Therefore, in this study, a mixed-flow pump was investigated to explore the influence of different speed start-up schemes on the flow field and to optimize them. The rated speed was set to 1634 r/min, and numerical simulations of different start-up schemes were carried out using the standard k-ε model. Furthermore, the turbulent kinetic energy distribution of the inlet and outlet sections of the mixed-flow pump during different start-up schemes was provided. In addition, the normalized helicity and blade surface pressure for different start-up schemes were compared. Finally, an evaluation function was proposed to evaluate the stability of the flow field during start-up. The results showed that the evaluation function had four factors related to speed and acceleration during start-up. Factors α and γ were obtained based on the acceleration and speed at 0.2 s and 0.42 s during start-up, respectively. Factor β was affected by the time taken to reach the rated speed. Parameter δ was determined by the acceleration of the period before reaching the rated speed. Based on the evaluation function, a theoretical scientific selection of speed start-up scheme is proposed to improve the stability of the flow field in the pump during start-up. • A new evaluation system of pump start-up scheme results is proposed to find the most suitable speed start-up scheme. • This evaluation system considers more comprehensive factors and the weight distribution of internal evaluation factors is reasonable. • The relationship between the change of evaluation factors and the change of flow field parameters is found. • It is found that compared with the traditional speed start-up scheme, the segmented linear start-up scheme is more stable. [ABSTRACT FROM AUTHOR]

The entangled metal wire/silicone rubber continuous interpenetrated phase composite (EMW-SRC) is a high-performance damping material with silicone rubber as matrix and metal wire turns as the reinforcement skeleton. EMW-SRC has good damping characteristics and significant load-bearing stiffness. This work first characterizes the fine interface morphology and macroscopic mechanical characteristics of the EMW-SRC and adopts a computer-aided preparation technology to accurately reconstruct the complex structure of the spatially random distribution of the entangled metal wire material. It develops a finite element model of the EMW-SRC with high-quality structured mesh based on the domain mesh superposition method cohesive cells to share and embed the surface nodes at the interface. Moreover, the composite interface bonding performance between metal wire and silicone rubber is investigated, the interfacial bonding parameters are determined, and the reliability of the mesh model is assessed by comparing the results of a single wire pull-out test and simulation analysis. Based on this, quasi-static compression test and simulation of the material are further performed, with the simulation results matching well with the experimental ones. The mesoscale simulation results show that the metal wire inside the EMW-SRC can overcome the silicone rubber restriction on micro-slip during the load-bearing process. The metal wire micro-element is subjected to torsional load. Under a compression displacement of 0.7 mm, the composite interface bonding remains intact without damage. In conclusion, the developed model can provide a prior guidance on the preparation and use conditions of the proposed material and offers an effective way to investigate the fine-mechanics of such materials with high damping and high load-bearing characteristics. [ABSTRACT FROM AUTHOR]

In this study, a porous structure for a porous liquid storage medium is generated, and the homogenization theory based on displacement boundary conditions is used to predict the effective mechanical properties. The relationship between the porous material's macroscopic mechanical properties and microstructure is next analyzed. In order to establish the relationship between the microstructure of porous materials and their macroscopic mechanical properties, assuming that the pores grow along the z direction, a method is proposed to generate 3D open-cell porous materials based on six design parameters (i.e., the number of pores, porosity, irregularity of pore distribution, the randomness of pore growth in the x and y directions, and randomness of pore size). Since the porosity of oil-bearing materials ranges from 20 to 30%, the porosity of the RVE (Representative Volume Element) was kept under control at about 25%, and the effect of the six design factors on the mechanical properties of the RVE was investigated. Utilizing SLA 3D printing technology, specimens were produced, and compression tests were used to show how useful the results of the numerical analysis were. The results demonstrated that after the number of RVE pores reaches 9, the numerical results have good repeatability. The irregularity of the initial pore distribution has little effect on the effective mechanical properties of the RVE. At the same time, the increase in the randomness of pore growth and the randomness of pore size increases the degree of weakening of the mechanical properties in the z-direction, while reducing the degree of weakening in the x and y directions, but the latter has a smaller impact. Furthermore, there is a superimposition effect of design parameters on the RVE. [ABSTRACT FROM AUTHOR]

[Display omitted] • A high-order nonlinear friction (HNF) model was proposed for the first time according to the inclination angle and contact form of the spatial distribution of metal wires in MR. • The HNF hysteresis dynamic model was constructed from which the NHF was the influence factor to adapt to the change of process parameters of metal rubber. • The probability function of three contact forms was constructed from the estimated parameters. And the transferred probability of three contact forms was analyzed under a harmonic excitation with 10 Hz. Metal rubber (MR) is a kind of porous and highly elastic pure metal damping material, but its strong nonlinear hysteresis characteristics are the main factors limiting its engineering application. In this paper, a high-order nonlinear friction (HNF) model was proposed for the first time according to the inclination angle and contact form of the spatial distribution of metal wires in MR. At the same time, combined with nonlinear elastic restoring force, nonlinear damping force, and coulomb hysteresis friction force, a general hysteresis dynamic model of MR was constructed. In order to verify the accuracy of the model, three kinds of MR with different densities were prepared and tested. The results show that the HNF hysteresis dynamic model has a very high prediction accuracy ( R 2 = 0.9999) and a high signal-to-noise ratio (SNR > 700). The hysteresis curve of the HNF hysteresis dynamic model was highly consistent with the experimental hysteresis curve, while the accuracy and versatility of the traditional dynamic model decreased with the change of density. It is because the HNF term includes the influence factors that can characterize the contact form of the metal wire inside MR and the material properties. These influence factors will be adjusted in real-time to reduce the error of the model according to the changes in the preparation process parameters or material properties. Therefore, the HNF hysteresis dynamic model could effectively demonstrate the nonlinear hysteresis characteristics of MR and had the adaptive ability to change process parameters. This paper provided a new theoretical model for the dynamic system of MR materials with a complex network structure. [ABSTRACT FROM AUTHOR]

In this study, a porous structure for a porous liquid storage medium is generated, and the homogenization theory based on displacement boundary conditions is used to predict the effective mechanical properties. The relationship between the porous material's macroscopic mechanical properties and microstructure is next analyzed. In order to establish the relationship between the microstructure of porous materials and their macroscopic mechanical properties, assuming that the pores grow along the z direction, a method is proposed to generate 3D open-cell porous materials based on six design parameters (i.e., the number of pores, porosity, irregularity of pore distribution, the randomness of pore growth in the x and y directions, and randomness of pore size). Since the porosity of oil-bearing materials ranges from 20 to 30%, the porosity of the RVE (Representative Volume Element) was kept under control at about 25%, and the effect of the six design factors on the mechanical properties of the RVE was investigated. Utilizing SLA 3D printing technology, specimens were produced, and compression tests were used to show how useful the results of the numerical analysis were. The results demonstrated that after the number of RVE pores reaches 9, the numerical results have good repeatability. The irregularity of the initial pore distribution has little effect on the effective mechanical properties of the RVE. At the same time, the increase in the randomness of pore growth and the randomness of pore size increases the degree of weakening of the mechanical properties in the z-direction, while reducing the degree of weakening in the x and y directions, but the latter has a smaller impact. Furthermore, there is a superimposition effect of design parameters on the RVE. [ABSTRACT FROM AUTHOR]

Across a pilot study and three preregistered experiments (N = 4128), we demonstrated that people knowingly shared conspiracy theories to advance social motives (e.g., to receive "likes"). In addition to accuracy, people seemed to value social engagement (e.g., "likes" and reactions). Importantly, people not only expected most conspiracy theories to generate greater social engagement than factual news, but they were also more willing to share conspiracy theories when they expected such theories, compared to factual news, to generate sufficiently greater levels of social engagement. In an interactive, multi-round, content-sharing paradigm, we found that people were very sensitive to the social feedback they received. When they received greater social feedback for sharing conspiracy theories than factual news, participants were significantly more likely to share conspiracy theories, even when they knew these theories to be false. Our findings advance our understanding of why and when individuals are likely to share conspiracy theories and identify important prescriptions for curbing the spread of conspiracy theories. • People share conspiracy theories to generate social engagement. • Positive social feedback promotes the spread of conspiracy theories. • People readily share conspiracy theories that they know to be untrue. • In contrast to the theory of the Marketplace of Ideas, subtle forces can significantly and persistently promote the spread of conspiracy theories. [ABSTRACT FROM AUTHOR]

Metal rubber (MR) is a porous material which possesses macroscopic damping properties through the dry friction between the internal helical metal wires. Due to its complex topological structure, the research on the fretting wear of MR is rarely reported in the literature. In the present work, a double-body wear model of metal filaments is constructed by the master-slave composite method. The friction and wear conditions of the dynamic and static metal wires inside the MR are analyzed under different contact angles, loads, and vibration amplitudes. The results indicate that the wear area and volume of the dynamic wire under each working condition are significantly larger than those of the static wire, while the case for the wear depth is the opposite. After wear, the wires exhibit an obvious stress concentration phenomenon, which is distributed along the wire wear contour area, and the wear profile has a high sensitivity to the contact angle. In order to further investigate the difference in the wear degree of the static and dynamic wires inside the MR, the fretting amplitude is introduced to describe the wear scar area of the dynamic wire, the special wear scar area is reorganized regularly, and the wear volume of the wire is approximated by the regional combination, deriving and constructing a fretting wear evolution model suitable for MR wires. This evolution model can simultaneously predict the wear degree of dynamic and static wires, and its prediction accuracy is high. The prediction accuracy under each working condition is basically less than 10%; thus, the proposed model can be effectively applied to the fretting wear prediction of MR ultra-fine wire contact pairs. This work provides theoretical guidance for the life prediction and other aspects of MR materials. • The differences between single body wear model and double body wear model are compared. • A fretting wear evolution model suitable for MR wires was constructed by introducing the fretting amplitude. • A local wear phenomenon will occur in the spatial sequence of the MR during the working process was indicated. [ABSTRACT FROM AUTHOR]

• A micro spring element with adaptive deformation (MSEAD) is constructed to characterize the actual load of the micro-elements of the turns in the space randomly distributed. • The spatial distribution law and friction motion form of micro-turns in FMR-MR are deeply explored and introduced as an important parameter in the constitutive relation. • With the concept of combined probability distribution (CPD), a constitutive model based on FMR microscopic and macroscopic parameters is constructed to reflect the disordered grid interpenetrating structure (DGIS) of materials. In this study, the disordered grid interpenetrating structure (DGIS) of wire turns in flexible microporous metal rubber (FMP-MR) for vibration and noise reduction is investigated, and an effective constitutive model is developed to dynamically capture the nonlinear mechanical behavior of FMP-MR. In this model, a micro spring element with adaptive deformation (MSEAD) model with random spatial distribution is employed, based on the phenomena of irregular overlapping and interlacing of material turns. The spatial distribution of micro springs and the evolution of the contact area morphology in FMP-MR are taken into consideration and introduced as key variables in model development. The concept of combined probability distribution (CPD) of micro spring pairs between wire turns in FMP-MR is proposed to characterize the random combination mode of material turns. Eventually, based on the micro-patterns of wire turns in FMP-MR, a constitutive model including macroscopic parameters, such as shape, density, wire diameter, helix pitch, and wire elastic modulus, and microstructure parameters, such as spatial distribution of wire turns, contact shape, and friction coefficient is developed for the first time. By analyzing and discussing the fitting degree of quasi-static compression experimental results and the model constitutive curves, the validity of the proposed constitutive model is quantitatively confirmed by residual analysis. According to the results, the FMP-MR constitutive model based on DGIS can effectively reflect the nonlinear mechanical behavior and complex micro-contact friction phenomena of the material. [ABSTRACT FROM AUTHOR]

This work is devoted to investigate the mechanical properties of entangled metallic wire material-silicone rubber composites (EMWM-SRC) sandwich structures. The core material involves the infiltration of silicone rubber (SR) into the pores of entangled metallic wire material (EMWM) through vacuum compression. Low-velocity impact tests were conducted to compare dynamic responses and energy absorption characteristics. Additionally, visual observation and computerized tomography scans were employed to characterize the damage mechanisms. It was observed that the sandwich structures did not perforate at 40–100 J impact energies, demonstrating outstanding energy absorption (97.5 %). Further explorations were conducted to explore the influence of EMWM density, wire diameter, and facesheet thickness. The results revealed that an increase in matrix density and wire diameter enhances the sandwich structure's impacts resistance but was accompanied by a decrease in energy absorption capacity. Notably, the energy absorption efficiency of the proposed sandwich structures consistently remains at a high level (88 %). Furthermore, facesheet thickness was identified as a significant factor affecting the sandwich structure. Finally, the superiority of the EMWM-SRC sandwich structure in enhancing impact resistance was validated by comparing it with individual EMWM and SR sandwich structures. These findings of this work offer valuable guidance for designing novel sandwich structures with excellent impact resistance. [Display omitted] • The low-velocity impact behaviour of EMWM-SRC sandwich structures were highlighted. • The proposed structure exhibited an enhanced impact resistance. • The density of EMWM-SRC core showed a positive effect on impact resistance. • The failure mechanism of the EMWM-SRC sandwich structure was assessed. [ABSTRACT FROM AUTHOR]

In this study, a laminated composite damping structure (LCDS) with metal rubber (MR) as matrix and silicone rubber (SR) as reinforcement has been designed. The embedded interlocking structure formed by the multi-material interface of the LCDS can effectively incorporate the high damping characteristics of traditional polymer damping materials and significantly enhance the adjustable stiffness of the damping structure. Based on the periodic cyclic vibration excitation, dynamic tests on different laminated structures were designed, and the damping performance and fatigue characteristics under periodic vibration excitation of the LCDS, based on MR and SR, were explored in depth. The experimental results exhibited that, compared to single-compound damping structures, the LCDS with SR as reinforcement and MR as matrix has excellent stiffness and damping characteristics. The incorporation of the silicon-based reinforcement can significantly improve the performance of the entire structure under cyclic fatigue vibration. In particular, the effects of material preparation and operating parameters on the composite structure are discussed. The effects of MR matrix density, operating frequency, amplitude, and preload on the stiffness and damping properties of the MR- and SR-based LCDS were investigated by the single factor controlled variable method. The results demonstrated that the vibration frequency has little effect on the LCDS damping performance. By increasing the density of the MR matrix or increasing the structural preload, the energy dissipation characteristics and damping properties of the LCDS can be effectively improved. With the increase in vibration excitation amplitude, the energy consumption of the LCDS increases, and the average dynamic stiffness changes at different rates, resulting in the loss factor decreasing first and then increasing. In this study, a damping structure suitable for narrow areas has been designed, which overcomes the temperature intolerance and low stiffness phenomena of traditional polymer rubber materials, and provides effective guidance for the design of damping materials with controllable high damping and stiffness. [ABSTRACT FROM AUTHOR]

• Entangled metallic porous material–silicone rubber interpenetrating phase composites. • Damping materials with both high stiffness and energy consumption. • Interfacial friction enhances mechanical properties. • Attractive fatigue resistance characteristics. High stiffness and superior energy consumption have consistently been primary research focuses in the field of damping materials. Hence, this work presented an innovative interpenetrating phase composite (IPC) crafted from wound elastic entangled metallic porous material and silicone rubber. The proposed composite effectively integrates the unique properties of the original materials, showcasing a seamless blend. Dynamic experimental tests were conducted to analyze the dynamic compression mechanical behavior of the composites, revealing that the composites exhibit excellent energy consumption capabilities and elevated stiffness characteristics. The improvement in both stiffness and damping characteristics is attributed to the addition of silicone rubber, which solidifies the structure of the composites. The introduction of interfacial friction results from maintaining compression, sliding, and other frictional interactions among the original spiral coils. Notably, the composites also display exceptional fatigue resistance. Overall, this work demonstrates the potential to concurrently achieve enhanced stiffness and superior energy consumption through the use of entangled metallic porous material and silicone rubber. [ABSTRACT FROM AUTHOR]

• A framework-reinforced orderly-woven superhydrophobic metal spiral coil-carbon fibers composite with a durable, uniform micro-structure was prepared. • An emulsion separation model has been established via CFD, which revealed the dynamic trajectory and volume change of water droplets in real-time. • The prepared metal–carbon composites still showed reliable separation purity and stable flux for several industrial lubricating oil emulsions in harsh environments. The primary barrier to the widespread use of super-wetting materials is the surface's limited resistance to physical damage, which leads to poor mechanical qualities. In this study, framework-reinforced orderly-woven superhydrophobic metal spiral coil-carbon fibers composites (SMSC-CFsC) with a durable uniform micro-structure were prepared by nested carbon fibers into metal spiral coils cleverly and woven them into a three-dimensional porous material innovatively. The separation purity of the prepared metal–carbon composites on several commonly used industrial lubricating oil emulsions was better than 99.90 % and the flux was greater than 1000 L/m2h. More significantly, computational fluid dynamics was used to establish a simulation model for emulsion separation that revealed the real-time dynamic motion trajectory and volume changes of water droplets. Additionally, even after high-temperature, compression, wear, and corrosion experiments, it still showed dependable separation purity and stable flux. As a result, it has been demonstrated that the proposed metal–carbon composite has a long oil–water separation service life in harsh environments and has great potential for developing efficient and durable emulsion separation materials. [ABSTRACT FROM AUTHOR]

The interaction between adjacent asperities is a typical characteristic of the grinding process and plays an important role in the material removal mechanism. Therefore, in order to systematically investigate the formation mechanism of the subsurface damage, a precision grinding contact model between the diamond particle and optical glass with adjacent asperities is proposed in our research. The initiation and propagation mechanism of median/lateral cracks under residual stress, the propagation rules of the stress waves on the subsurface, and the interaction between the subsurface damage under stress superposition effect are fully investigated by a theoretical analysis and finite element simulation. The simulation results of the precision grinding model are verified by experiments, which show that the proposed numerical analysis model is reasonable and the finite element analysis process is feasible. [ABSTRACT FROM AUTHOR]

In this study, epoxy resin (EP) composites were prepared by using molybdenum disulfide (MoS2) and helical carbon nanotubes (H-CNTs) as the antifriction and reinforcing phases, respectively. The effects of MoS2 and H-CNTs on the friction coefficient, wear amount, hardness, and elastic modulus of the composites were investigated. The tribological properties of the composites were tested using the UMT-3MT friction testing machine, non-contact three-dimensional surface profilometers, and nanoindenters. The analytical results showed that the friction coefficient of the composites initially decreased and then increased with the increase in the MoS2 content. The friction coefficient was the smallest when the MoS2 content in the EP was 6%, and the wear amount increased gradually. With the increasing content of H-CNTs, the friction coefficient of the composite material did not change significantly, although the wear amount decreased gradually. When the MoS2 and H-CNTs contents were 6% and 4%, respectively, the composite exhibited the minimum friction coefficient and a small amount of wear. Moreover, the addition of H-CNTs significantly enhanced the hardness and elastic modulus of the composites, which could be applied as materials in high-temperature and high-pressure environments where lubricants and greases do not work. [ABSTRACT FROM AUTHOR]

Interpenetrating phase composites (IPCs) with porous metal materials as the matrix and polymer materials as the reinforcement, which have a broad application prospect, have both the high strength of metal materials and the high energy absorption capacity of polymer materials. Entangled metallic wire materials are a new type of porous material with damping characteristics, which is an excellent choice for use as the matrix of IPCs. In the present work, a novel entangled metallic wire material–silicone rubber IPC is developed through the vacuum infiltration method with the entangled wire material as the matrix and silicone rubber as the reinforcing element. The mechanical properties (loss factor and tangent modulus) of the as-synthesized composites are characterized through compression tests. More specifically, the effects of key experimental parameters (strain) and material properties (matrix density, wire diameter, and anisotropy) on the mechanical properties of the composites are analyzed in detail. It is found that with the introduction of interfacial friction, the loss factor of the composites becomes higher than those of the pure entangled metallic wire material and silicone rubber; in particular, the tangent modulus is significantly enhanced. The complex structural characteristics of the proposed composite enable the loss factor and tangent modulus to exhibit a nonlinear relationship with the density over a range of displacement values. Moreover, the smaller the wire diameter is, the greater the loss factor of the composites is, while the tangent modulus exhibits the opposite trend. The unique wire contact form and preparation process endow the composites with nonlinear properties in the molding direction as well as pronounced anisotropy characteristics. A novel interpenetrating phase composite is proposed. The composite quasistatic curve is nonlinear with excellent mechanical properties. The improved energy consumption properties are due to the interfacial friction. The increase in wire density greatly improves the elastic modulus of the composite. The composite is anisotropic with a better bearing capacity in the molding direction. [ABSTRACT FROM AUTHOR]

Background: Migraine is a common disabling neurological disorder with severe physical and psychological damage, but there is a lack of convenient and effective non-invasive early prediction methods. This study aimed to develop a new series of non-invasive prediction models for migraine with external validation. Methods: A total of 188 and 94 subjects were included in the training and validation sets, respectively. A standardized professional questionnaire was used to collect the subjects' 9-item traditional Chinese medicine constitution (TCMC) scores, Pittsburgh Sleep Quality Index (PSQI) score, Zung's Self-rating Anxiety Scale and Self-rating Depression Scale scores. Logistic regression was used to analyze the risk predictors of migraine, and a series of prediction models for migraine were developed. Receiver operating characteristic (ROC) curve and calibration curve were used to assess the discrimination and calibration of the models. The predictive performance of the models were further validated using external datasets and subgroup analyses were conducted. Results: PSQI score and Qi-depression score were significantly and positively associated with the risk of migraine, with the area of the ROC curves (AUCs) predicting migraine of 0.83 (95% CI:0.77–0.89) and 0.76 (95% CI:0.68–0.84), respectively. Eight non-invasive predictive models for migraine containing one to eight variables were developed using logistic regression, with AUCs ranging from 0.83 (95% CI: 0.77–0.89) to 0.92 (95% CI: 0.89–0.96) for the training set and from 0.76 (95% CI: 0.66–0.85) to 0.83 (95% CI: 0.75–0.91) for the validation set. Subgroup analyses showed that the AUCs of the eight prediction models for predicting migraine in the training and validation sets of different gender and age subgroups ranged from 0.80 (95% CI: 0.63–0.97) to 0.95 (95% CI: 0.91–1.00) and 0.73 (95% CI: 0.64–0.84) to 0.93 (95% CI: 0.82–1.00), respectively. Conclusions: This study developed and validated a series of convenient and novel non-invasive prediction models for migraine, which have good predictive ability for migraine in Chinese adults of different genders and ages. It is of great significance for the early prevention, screening, and diagnosis of migraine. [ABSTRACT FROM AUTHOR]

The high-efficiency and broadband acoustic reduction performance in a miniaturized free-flow structure remains challenging in acoustic engineering applications due to the contradiction of ventilation and acoustic reduction performance. Traditional acoustic absorbers can sufficiently attenuate acoustic wave, but meanwhile, block fluid flow due to the longitudinal nature of acoustic waves that can transmit among any small holes. Although different types of ventilated metamaterial absorbers (VMAs) with proper reduction and ventilation performance have been demonstrated recently, their insufficiencies lie in small open-area ratios, not efficient-enough reduction performance, bulky structure, and narrow working band. To further solve existing defects, a ventilated broadband absorber with the miniaturized metamaterial structure has been proposed. The designed absorber consists of miniaturized Archimedean spiral units, which can be easily stacked to achieve broadband and ventilated performance. This work opens up possibilities for practical acoustic applications where both noise control and ventilation are required, especially in a small space. [ABSTRACT FROM AUTHOR]

Compare to the ICP (Iterative Closet Points) registration method and its variants, the registration method based on GMM (Gaussian Mixture Models) is less sensitive to initial position, noise and outliers. For efficiency in a large-scale point sets alignment, the algorithm involved with FGT (Fast Gaussian Transformation) was proposed. However, due to its accuracy degeneration, the application of fast implementation is limited in large-scale point registration. Thus a modified GMM method is established to improve its accuracy and efficiency in point sets registration. To improve the precision and robustness of point density, noise and outliers, the corresponding weight matrix consisted of bidirectional gauss distance is proposed in this study. Instead of FGT (Fast Gaussian Transformation), the IFGT (Improved Fast Gaussian Transformation) and an adaptive adjustment based on axis-angle is proposed to further improve its efficiency and robustness about initial position simultaneously. We test capabilities of methods in classical model and symmetric and featureless manufacture parts. Compared to state-of-the-art methods in experiment, the result demonstrated applicability of proposed method in real life. [ABSTRACT FROM AUTHOR]

In recent years, the incidence rate of lumbar diseases has been progressively increasing. The conventional lumbar fusion cages used in existing lumbar interbody fusion surgery are not able to take into account the multiple characteristics of cushioning, vibration reduction, support, cell adhesion, and bone tissue growth. Therefore, in this work, based on the CT data of a lumbar intervertebral disc plain scan, a combined symmetric lumbar fusion cage structure was innovatively designed. The core was made of lightweight TC4 medical titanium alloy flexible microporous metal rubber (LTA-FMP MR), and the outer frame was made of cobalt–chromium–molybdenum alloy. Its comprehensive biomechanical performance was comprehensively evaluated through finite element simulation, static and dynamic mechanics, and impact resistance tests. The three-dimensional model of the L3/L4 lumbar segment was established by reverse engineering, and a Mises stress analysis was conducted on the lumbar fusion cage by importing it into Ansys to understand its structural advantages compared to the traditional lumbar fusion cage. Through static experiments, the influence of the internal nucleus of a symmetrical lumbar fusion cage with different material parameters on its static performance was explored. At the same time, to further explore the superior characteristics of this symmetrical structure in complex human environments, a biomechanical test platform was established to analyze its biomechanical performance under sinusoidal excitation of different amplitudes and frequencies, as well as impact loads of different amplitudes and pulse widths. The results show that under different amplitudes and frequencies, the lumbar fusion cage with a symmetrical structure has a small loss factor, a high impact isolation coefficient, and a maximum energy consumption of 422.8 N·mm, with a maximum kinetic energy attenuation rate of 0.43. Compared to existing traditional lumbar fusion cages in clinical practice, it not only has sufficient stiffness, but also has good vibration damping, support, and impact resistance performance, and has a lower probability of postoperative settlement, which has broad application prospects. [ABSTRACT FROM AUTHOR]

Background: Intranasal agents may be ideal for the treatment of migraine patients. Many new acute intranasal-specific therapies have been developed, but few of them have been directly compared. The aim of this network meta-analysis (NMA) was to compare the efficacy and safety of various intranasal agents for the treatment of acute migraine in adult patients. Methods: The Cochrane Register of Controlled Trials, Embase, and PubMed were searched from inception to 15 August 2023. Randomized controlled trials (RCTs) using intranasal agents (no restrictions on dose, formulation, dosing regimen or timing of the first dose) to treat adult patients with acute migraine were included. The primary efficacy endpoint was pain freedom at 2 h, and the primary safety endpoint was adverse events (AEs). The analysis process followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Results: Nineteen studies (21 RCTs, 9738 participants) were included. Compared to the placebo, 5 mg of zolmitriptan using a conventional liquid nasal spray device was the most effective for pain freedom at 2 h [odds ratio (OR): 4.67, 95% confidence interval (CI): 3.43 to 6.43] and 24 h (OR: 5.49, 95% CI: 3.58 to 8.42) among all the interventions. Butorphanol nasal spray 1 mg was the most effective (OR: 8.62, 95% CI: 1.11 to 66.92) for pain freedom at 1 h, but with low-quality evidence. DFN-02 presented the highest freedom from nausea (OR: 4.95, 95% CI: 1.29 to 19.01) and phonophobia (OR: 5.36, 95% CI: 1.67 to 17.22) at 2 h, albeit with lower odds of achieving complete pain freedom. ROX-828 showed the highest improvement in freedom from photophobia at 2 h (OR: 4.03, 95% CI: 1.66 to 9.81). Dihydroergotamine nasal spray was significantly associated with the highest risk of AEs (OR: 9.65, 95% CI: 4.39 to 21.22) and was not recommended for routine use. Zavegepant nasal spray demonstrated the lowest risk of AEs (OR: 2.04, 95% CI: 1.37 to 3.03). The results of sensitivity analyses for the primary endpoints (pain freedom at 2 h and AEs) were generally consistent with those of the base case model. Conclusions: Compared with other new intranasal-specific therapies in treating migraine attacks, zolmitriptan nasal spray 5 mg was the most effective agent for pain freedom at 2 h. Zavegepant nasal spray 10 mg had the fewest adverse side effects. [ABSTRACT FROM AUTHOR]

We utilized a coherent terahertz time-domain spectroscopy system to measure the dynamic conductivity of an InAs two-dimensional electron gas. Based on the theoretical transmission analysis, the real and imaginary parts of the complex conductivity of the sample were extracted from the transmitted terahertz time-domain waveforms. We also measured the sample at low temperatures and fitted the real and imaginary parts of the conductivity with the Drude model to extract its densities and mobilities. The dominant scattering mechanisms are discussed according to the temperature dependence of the extracted densities and mobilities. [ABSTRACT FROM AUTHOR]

The Jiles-Atherton model was widely used in the description of the system with hysteresis, and the solution for the model was important for real-time and high-precision control. The secant method was used for solving anhysteretic magnetization and its initial values were optimized for faster convergence. Then, the Fourth Order Runge-Kutta method was employed to solve magnetization and the required computation cycles were supplied for stable results. Based on the solving method, the effect of the nonzero initial magnetic field on the magnetization was discussed, including the commonly used linear model of the square of magnetization under the medium initial value. From computations, the proposed secant iteration method, with supplied optimal initial values, greatly reduced the iterative steps compared to the fixed-point iteration. Combined with the Fourth Order Runge-Kutta method under more than three cycles of calculations, stable hysteresis results with controllable precisions were acquired. Adjusting the initial magnetic field changed the result of the magnetization, which was helpless to promote the amplitude or improve the symmetry of magnetization. Furthermore, the linear model of the square of magnetization was unacceptable for huge computational errors. The proposed numerical solving method can supply fast and high-precision solutions for the Jiles-Atherton model and provide a basis for the application scope of typical linear assumption. [ABSTRACT FROM AUTHOR]

The surface of TC11 titanium alloy was polished and strengthened using ultrasonic rolling process (USRP) technology. The effects of USRP on the surface quality, friction and wear properties, corrosion resistance, and wear mechanisms of TC11 titanium alloy at room temperature, low temperature (−60 °C), high temperature (400 °C), and in corrosive environments were investigated by using optical microscope, microhardness tester, electrochemical workstation, multifunctional friction and wear tester, SEM, EDS, XRD, and XPS. The results indicate that USRP can effectively refine the surface grains of titanium alloy, reducing its surface roughness parameter by 80.4 % and increasing surface hardness and residual compressive stress by 21.7 % and 97.1 %, respectively. USRP is advantageous for producing a layer of TiO 2 on the surface of titanium alloys, effectively enhancing the corrosion resistance of titanium alloy surfaces. USRP technology can improve the stability of surface hardness values of titanium alloys in harsh environments. The results of dry friction and wear tests using GCr15 steel balls as the counter material show that the USRP technology can effectively reduce the friction coefficient and wear loss at room, high and low temperatures. The results of corrosion and wear tests using Si 3 N 4 as the counter material indicate that the USRP technology can effectively reduce the friction coefficient and wear volume in seawater corrosion environments. The USRP technology is most effective in reducing the high-temperature friction coefficient of titanium alloys and improving their wear resistance in low-temperature and corrosive environments. The primary wear form of TC11 titanium alloy after USRP has shifted from adhesive wear to abrasive wear. [Display omitted] • The surface of TC11 was polished and strengthened using USRP technology. • The friction-wear and corrosion-wear behaviors of TC11 under extreme conditions were investigated. • USRP can effectively reduce the friction coefficient and wear under extreme conditions. • The corrosion and wear mechanisms of surface strengthened TC11 were revealed. [ABSTRACT FROM AUTHOR]

• Classic JA model fails to predict the hysteresis accurately, especially the width. • Pinning parameter is better modified as an independent variable on field amplitude. • The improved JA model predicts the hysteresis more accurately than the classic one. Jiles-Atherton (JA) model has been widely used to describe the magnetic hysteresis property of Terfenol-D material. However, the accuracy of the classic JA model is not convincing any more when it is employed to predict the magnetizations under various amplitudes of the applied magnetic fields. This paper measures the magnetic field and magnetization indirectly and approximates the measured results to the best of the classic static JA model. Then it shows that the JA model fails to describe the magnetic hysteresis effectively, especially in computing the hysteresis width. The high computational error is caused from inappropriate value of the pinning parameter to quantify the average energy required to break pinning site. Then the parameter is modified from the constant value to an independent variable on the field amplitude. From the comparisons on the results of the maximum magnetization, maximum magnetization, residual magnetization and coercivity, the performance in describing the hysteresis property of Terfenol-D is obviously promoted by the improved model apparently compared to the classic one. [ABSTRACT FROM AUTHOR]

Composite materials exhibit the impressive high energy consumption and impact resistance, which cannot be attained by employing conventional single materials. Along these lines, a novel entangled metallic wire mesh–silicone rubber composites (EMWM–SRC) was proposed by compressing SR into the pores of EMWM through vacuum infiltration. Quasistatic tests were conducted at various temperatures. Additionally, a comprehensive analysis of the impact velocity, matrix density, wire diameter, and anisotropy of EMWM–SRC under low-velocity impact was performed. The results revealed that the composites maintain high stability up to 300 °C. Compared to traditional EMWM, the proposed composites exhibited higher loss factor, particularly with a significant enhanced in tangent modulus. The low-velocity impact results demonstrated that EMWM–SRC exhibited superior energy absorption capabilities, which was attributed to increased friction between the spiral coils and enhanced interface friction between the EMWM and SR. Notably, EMWM-SRC with different matrix densities exhibited energy absorption efficiencies exceeding 90% at an impact velocity of 3.5 m/s. Furthermore, the effects of impact velocity, wire diameter, and anisotropy on the impact response of composites were discussed in detail. Additionally, a description of the energy consumption properties was explored from the perspective of wire deformation mechanics. Overall, the proposed composites possess significant potential as impact resistant elements with high energy absorption capacity. [Display omitted] • The proposed EMWM-SRC showed excellent performance in low–velocity impact resistance. • The anisotropic characteristics of the EMWM-SRC were investigated. • The composites demonstrated remarkable energy absorption at various impact velocities. • The deformation mechanism of spiral coils was assessed. [ABSTRACT FROM AUTHOR]

Cu-free resin-based brake material filled with waste foundry resin-bonded sand (waste sand) was prepared using the hot-pressing method. The changes in the physical and chemical properties of Cu and waste sand during braking were investigated, and their role in resin-based composites was discussed. The effects of the content of waste sand on the hardness, impact strength, indentation hardness, elastic modulus, friction coefficient, wear rate, micro-scratch friction coefficient, scratch depth, residual depth, and wear mechanism of resin-based brake material were investigated. Cu-contained composites generate Cu 2 O when braking at high temperatures, which adversely affects the friction and wear properties. Compared to Cu, waste sand was found to be more favorable for the overall friction and wear properties of resin-based composites. This suggests that waste sand can be used as a substitute for Cu in brake material. Waste sand is beneficial for improving the friction coefficient and stability of brake material through the formation of a friction layer. This layer can significantly impact the wear mechanism of brake material, particularly at high temperature (250–350 ℃). The brake material with 10–15% waste sand indicates excellent heat-fade resistance. • Waste foundry sand have been successfully replaced copper in brake material. • The role of waste foundry sand and copper in brake material were comparatively studied. • The effects of waste sand on mechanical and tribological properties of brake material were investigated. • The brake material containing 10–15% waste foundry sand show excellent heat-fade resistance. [ABSTRACT FROM AUTHOR]

Industrial oily wastewater contains both light oil (ρ o i l < ρ w a t e r) and heavy oil (ρ o i l > ρ w a t e r) ; thus, there is a requirement to develop smart surfaces with reversible wettability as they possess the advantages of superhydrophobicity and superhydrophilicity. Herein, using a simple and convenient way of alternate immersion in stearic acid ethanol solution and THF, the wettability of the MR surface could be switched in a short duration to achieve reversible oil-water separation. (a) MR obtained by anodic oxidation was superhydrophilic, after being modified in a stearic acid ethanol solution for 30 min, the wettability was changed to superhydrophobic. At this point, oil could permeate its surface while water could not. (b) After the modified MR was soaked in THF for 30 min, the wettability was restored to superhydrophilic as well as underwater superoleophobic. At this time, water could penetrate its surface but water could not. The sewage treatment technology of oil-water separation based on superwetting materials has been widely employed. However, the stability of substrates was rarely considered in the past few years, which greatly limited the application of superwetting materials in engineering field. As a new robust, three-dimensional porous material, metal rubber (MR) has attracted significant attention for solving this problem. To treat the wastewater containing insoluble heavy/light oil and soluble dyes, herein, MR capable of degrading organic dyes with switchable wettability and high oil-water separation efficiency was prepared. Firstly, the superhydrophilic MR was obtained by anodizing. Then, the wettability of MR surface was reversibly switched between superhydrophilic and superhydrophobic via alternate immersion in stearic acid ethanol solution and tetrahydrofuran (THF) solvent to achieve switchable oil-water separation of MR. The superwetting MR displayed excellent abrasion resistance and retained outstanding oil-water separation performance after 100 times of sandpaper abrasion. Besides, the surface of pure titanium MR was rich in titanium dioxide (TiO 2) after anodic oxidation, which could effectively degrade the organic dyes under ultraviolet light. Therefore, the as-prepared superwetting MR possesses the ability to treat complex wastewater and have applications prospects in controllable oil-water separation and self-cleaning surfaces. [ABSTRACT FROM AUTHOR]

• Based on mechanics and materials science, the damage failure evolution mechanism of thermoplastic resin material PPESK was studied in depth for the first time. • The concept of critical temperature effect is proposed, which effectively reveals the unique temperature-sensitive characteristics of PPESK, which is different from the glass transition temperature. • The full three-dimensional damage evolution constitutive model of PPESK in a wide temperature range was constructed for the first time, effectively restoring the cross-scale mechanical behavior and damage failure characteristics of materials. Poly(phthalazine ether sulfone ketone) (PPESK) is a new type of thermoplastic resin materials with high temperature resistance and corrosion resistance. However, the failure evolution regularities of PPESK at different temperatures still remain poorly understood, which greatly limits the application of this composite. Therefore, quasi-static tensile/bending tests and microscanning microscopic characterization were used to study the multi-scale failure constitutive equation of PPESK. Based on cross-scale experimental observation methods, the spatial damage morphology of materials at different temperatures is explored, and the temperature boundary effect of PPESK is proposed to reveal the failure and failure mechanisms of materials in a wide temperature range. The initiation and evolution of pores at the micro scale of PPESK and the cumulative damage caused by craze propagation and cracking are essential factors of material failure, which also exhibit strong temperature sensitivity. The specific manifestation is the high-temperature viscous flow effect of the resin at the micro scale, as well as the gradual evolution trend of quasi-brittleness and viscoelastic-plasticity between the 295 K–472 K temperature range in the macro performance, which increases its plastic deformation ability by 1–5 times. Specifically, the mechanism of cross-scale micro-pore initiation and crack propagation was introduced, and a cross-scale, fully three-dimensional failure damage evolution constitutive model of PPESK was constructed for the first time in a wide temperature range. The secondary development of the material constitutive model in the finite element software was carried out, and the construction of the constitutive equation of the PPESK cross-scale failure was completed. Finally, the mapping relationship between the material's crack failure form, mechanical behavior, and the constitutive model was further verified by experiments. It is established that the proposed PPESK multi-scale failure constitutive model enables one to effectively describe the complex mechanical response and failure law of thermoplastic resin materials under temperature gradients. Moreover, this theoretical tool is promising for the design of independently controllable high-temperature resistant thermoplastic resin materials, thereby providing important guidance means for engineering applications. [ABSTRACT FROM AUTHOR]

This work addresses the vibration characteristics of imperfect bi-directional functionally graded (BDFG) beams with arbitrary boundary conditions. Two kinds of geometrical imperfections including global and localized types are considered, which are simulated using hyperbolic, exponential and trigonometric functions. Energy equations of beam are formulated on basis of the Timoshenko beam theory, and the domain decomposition method in which the original beam structure is divided to several beam segments. The flexible couplings between beam segments and boundary constraints of beam are modeled employing artificial spring technique. By choosing the Jacobi polynomials as admissible functions, modal characteristics are acquired using the Ritz method. Convergence, stability and reliability of presented method are validated, and penalty technique for artificial springs is examined for the classic and general boundary conditions. Numerical simulations are performed to probe the impact mechanism of geometric and material parameters on vibration performance of BDFG beam. Results show that imperfection may cause appearance of mode veering phenomenon where modal features distort. The types of mode veering are dominated by material distribution pattern, boundary constraints and kinds of geometrical imperfection. [ABSTRACT FROM AUTHOR]

Entangled metallic wire material (EMWM) is a kind of porous damping material. To promote the engineering application of EMWM, it is necessary to establish the constitutive model of EMWM to estimate its mechanical properties. In this paper, a series of quasi-static compression experiments for plate-like EMWM specimens made of austenitic stainless steel wire (06Cr19Ni10) with different densities were carried out in the temperature range of 20–500 °C. It was found that the stiffness of the plate-like EMWM would increase with the increases in the ambient temperature. The non-linear characteristics of the force–displacement curve of the plate-like EMWM would be weakened. Taking the spatial structural characteristics of the plate-like EMWM and the influence of the thermal expansion of the structure into account, a new constitutive model for plate-like EMWM was presented by the combination of the Johnson–Cook model and the Sherwood–Frost constitutive framework model. The accuracy of the model was verified by the experimental data under different temperatures. The results show that the calculated results of the model are consistent with the experimental results. This model can provide an effective theoretical basis for predicting the mechanical properties of plate-like EMWM and guiding its design. [ABSTRACT FROM AUTHOR]

Based on the requirements of underwater acoustic stealth, the classification and research background of acoustic coatings are introduced herein. The research significance of acoustic coatings is expounded from the perspective of both the military and civilian use. A brief overview of the conventional design process of acoustic coatings is presented, which describes the substrates used in different countries. Aimed at the local design of acoustic coatings, research progress on passive and semi-active/active sound absorption structure is summarized. Focused on the passive acoustic coatings; acoustic cavity design and optimization, acoustic performance of acoustic coatings with rigid inclusions or scatterers, and acoustic coatings with a hybrid structure are discussed. Moreover, an overview of the overall design of acoustic coatings based on the sound field characteristics of the submarine is also presented. Finally, the shortcomings of the research are discussed, breakthroughs in acoustic coating design research are forecast, and the key technical issues to be solved are highlighted. [ABSTRACT FROM AUTHOR]