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Organic polymer‐based composite materials with favorable mechanical performance and functionalities are keystones to various modern industries; however, the environmental pollution stemming from their processing poses a great challenge. In this study, by finding an autonomous phase separating ability of fungal mycelium, a new material fabrication approach is introduced that leverages such biological metabolism‐driven, mycelial growth‐induced phase separation to bypass high‐energy cost and labor‐intensive synthetic methods. The resulting self‐regenerative composites, featuring an entangled network structure of mycelium and assembled organic polymers, exhibit remarkable self‐healing properties, being capable of reversing complete separation and restoring ≈90% of the original strength. These composites further show exceptional mechanical strength, with a high specific strength of 8.15 MPa g.cm−3, and low water absorption properties (≈33% after 15 days of immersion). This approach spearheads the development of state‐of‐the‐art living composites, which directly utilize bioactive materials to "self‐grow" into materials endowed with exceptional mechanical and functional properties. [ABSTRACT FROM AUTHOR]

Biological strong and tough materials have been providing original structural designs for developing bioinspired high‐performance composites. However, new synergistic strengthening and toughening mechanisms from bioinspired structures remain yet to be explored and employed to upgrade current carbon material reinforced polymer composites, which are keystone to various modern industries. In this work, from bamboo, the featured cell face‐bridging fibers, are abstracted and embedded in a cellular network structure, and develop an epoxy resin/carbon composite featuring biomimetic architecture through a fabrication approach integrating freeze casting, carbonization, and resin infusion with carbon fibers (CFs) and carbon nanotubes (CNTs). Results show that this bamboo‐inspired crack‐face bridging fiber reinforced composite simultaneously possesses a high strength (430.8 MPa) and an impressive toughness (8.3 MPa m1/2), which surpass those of most resin‐based nanocomposites reported in the literature. Experiments and multiscale simulation models reveal novel synergistic strengthening and toughening mechanisms arising from the 2D faces that bridge the CFs: sustaining and transferring loads to enhance the overall load‐bearing ability and furthermore, incorporating CNTs pullout that resembles the intrinsic toughening at the molecular to nanoscale and strain delocalization, crack branching, and crack deflection as the extrinsic toughening at the microscale. These constitute a new effective and efficient strategy to develop simultaneously strong and tough composites through abstracting and implenting novel bioinspired structures, which contributes to addressing the long‐standingly challenging attainment of both high strength and toughness for advanced structural materials. [ABSTRACT FROM AUTHOR]

The main form of roll failure in cold rolling production is fatigue damage. To avoid industrial production accidents, the roll grinding amount after service is usually manually determined in accordance with empirical settings. This leads to excessive grinding. To address this problem, this work takes a 2130-mm UCM cold rolling production line as an example and establishes an elastic deformation model of the mill roll system based on the influence function method. The three-way stress and maximum tangential stress distribution inside the roll are calculated by means of the Hertz formula. Combined with the nonlinear fatigue accumulation model, a roll fatigue prediction model is proposed to quantitatively describe the roll fatigue state. According to the roll fatigue distribution data and actual production situation, the roll fatigue curve is shifted superimposed, and the roll grinding optimization model is established using a genetic particle swarm algorithm. It can meet the requirements of industrial production in terms of convergence speed and optimization. It applies the model to a cold rolling production line in a factory. Field application shows that the model can be used to quantify and detect roll fatigue in real time. The rolls can be dismounted at the right time, and the production accident rate from fatigue can be reduced by 33.3%. The consumption of backup rolls, intermediate rolls and work rolls can be reduced by 23.2, 24.1 and 28.6% each year, respectively. The application of this model can greatly reduce the production cost for a plant, ensure production safety and extend the service life of rolls. [ABSTRACT FROM AUTHOR]

High strength concrete (HSC) with superior strength advantage has been gaining widespread attention and engineering endorsement in recent years. For a better understanding of the mechanical responses and failure mechanisms of HSC, a novel three‐dimensional (3D) mesoscale model considering the meso‐structural features of concrete was proposed in this paper. First, a series of uniaxial compressive tests were conducted to investigate the compressive properties of HSC specimens with a strength of 80–90 MPa. After that, a 3D three‐phase mesoscale model consisting of mortar, coarse aggregate, and the interfacial transitional zone (ITZ) between them, was developed to perform the mesoscopic simulations of HSC. Then, systematic analysis and discussions on the compressive properties of HSC were presented in terms of the stress–strain curves, compressive strengths/toughness, failure patterns, cracking process, etc. Results indicate that HSC exhibited obvious brittle failure characteristics, and its strength was significantly related to the water‐to‐cement ratio and mineral admixture. At meso‐level, the cracking behaviors of mortar and ITZ phases were well modeled using the developed mesoscale model. Additionally, it was found that the cracking behavior of HSC was significantly associated with the ITZ characteristics. The developed mesoscale modeling approach has been proven to simulate and investigate concrete's compressive properties in a reliable manner, and can be applied further to the property analysis of concrete materials and structures. [ABSTRACT FROM AUTHOR]

Split Hopkinson pressure bar (SHPB) with 75-mm diameter is used to conduct dynamic impact compression tests on different strength grades of basic magnesium sulfate cement-coral aggregate concrete (BMSC-CAC). The failure process of BMSC-CAC under dynamic impact compression is simulated using the finite element software LS-DYNA and a three-dimensional random aggregate mesoscopic model. The results show that BMSC-CAC has a significant strain rate effect, and the dynamic impact strength increases as the strain rate increases. Because of the high toughness of BMSC, BMSC-CAC has higher energy absorption than coral aggregate seawater concrete (CASC) and sisal fiber coral aggregate seawater concrete (SFCASC). The LS-DYNA software is used for the numerical simulation of the mesoscale dynamic impact compression. The relative error of the peak stress and strain between the test and simulation results is small. Analysis of the failure process indicates that the damage extent of the aggregate increases, and the failure time decreases with an increase in the strain rate. [ABSTRACT FROM AUTHOR]

The penetration resistance of the new material Basic Magnesium Sulfate Cement (BMSC) is studied through comprehensive application of an experimental and numerical simulation method. This paper consists of three parts. The first part introduces the preparation of Basic Magnesium Sulfate Cement Concrete (BMSCC) and the study of its dynamic mechanical properties. In the second part, on-site testing was carried out on both BMSCC and an ordinary Portland cement concrete (OPCC) target, and the anti-penetration performance of the two materials was analyzed and compared from three aspects: penetration depth, crater diameter and volume, and failure mode. In the last part, the numerical simulation analysis was carried out based on LS-DYNA, and the effects of factors, such as material strength and penetration velocity on the penetration depth, are analyzed. According to the results, the BMSCC targets have better penetration resistance performance than OPCC under the same conditions, mainly manifested in smaller penetration depth, smaller crater diameter and volume, as well as fewer cracks. [ABSTRACT FROM AUTHOR]

Backup rolls of hot rolling mills have long service life, can withstand harsh working conditions during rolling. However, they undergo severe roll wear that affects the contact force between rolls, resulting in roll fatigue and even spalling accidents. In this study, a fatigue-damage prediction model of a backup roll considering roll wear is proposed. The elastic deformation model of a fast roll system is established using influence function method to calculate the contact stress between rolls. Considering the uneven wear of rolls, a dynamic fatigue-damage prediction model of a backup roll based on the fatigue-damage accumulation theory is established. The model can be used to calculate the wear and fatigue damage caused to a roll after rolling a piece of strip steel. The analysis results show that the proposed model optimized the actual grinding quantity of the backup roll. That is, after optimization, the proportion of secondary grinding is reduced by 35.54%, and the backup-roll consumption is reduced by 8.02%. Therefore, the application of the proposed model can effectively reduce roll consumption, improve grinding efficiency, and provide theoretical support and industrial application reference for the prediction and control of fatigue damage to backup rolls in the field of hot rolling. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and numerical study on the dynamic splitting tensile properties of ceramic aggregate concrete (CAC) that is composed of ceramic aggregates and mortar matrix. The maximum ceramic aggregate diameter includes 0.3, 0.6, and 0.9 cm. A series of split‐tension tests of CAC specimens were conducted first. Parametric studies such as the effects of aggregate size and strain rate, on the splitting tensile behaviors of CAC were presented in terms of tensile strength, stress–strain curve, failure patterns, and so on. Subsequently, we developed a three‐dimensional two‐phase mesoscale model for CAC, where the random distribution and size characteristics of ceramic aggregates in concrete were fully considered. Employing the developed mesoscopic model, systematic mesoscopic simulations were performed to investigate the mesoscopic responses of CAC under dynamic split‐tension loadings. Results indicated that the mechanic properties and cracking behaviors of CAC are associated with many factors, such as aggregate diameter, aggregate distribution and strain rate. Besides, there was a good agreement between the tested and numerical results, demonstrating that the developed mesoscale model has a significant reliability and potential in simulating the mechanical properties of CAC. [ABSTRACT FROM AUTHOR]

This paper develops a novel three-dimensional (3D) mesoscale modelling approach to study the mechanical responses of coral sands under quasi-static and dynamic compressive loading. A series of algorithms were developed to generate the 3D random particle models with controllable shape and size configurations to simulate the coral sands with random shape characteristics. Subsequently, a new compaction algorithm combining the gravity action and mechanical motion of particle models was proposed to create the 3D sand particulate system with various particle gradations. Using the 3D unstructured meshing algorithm, the finite element model of particulate system was obtained. Finally, the quasi-static and dynamic compressive behaviors of coral sands were numerically investigated in terms of the axial/lateral stress–strain curves, the mesoscopic deformation processes, and the particle breakage patterns. The results indicate that there are obvious differences in the stress–strain curves and deformation modes of coral sands under quasi-static and dynamic compression loads. Through the explicit simulation and quantitative analysis on the deformation process and particle breakage of coral sands, the grain-level responses and failure mechanisms of coral sands under different loading conditions were fully understood. Above all, it was demonstrated that the developed 3D mesoscale model has a significant feasibility in simulating and analyzing the mechanical properties of sand particulate system. [ABSTRACT FROM AUTHOR]

Based on seawater immersion, drying-wetting cycles, carbonation and drying-wetting cycles for coral aggregate sea-water concrete (CASC) with different strength grades, the effect of carbonation and drying-wetting cycles on chloride diffusion behavior of CASC is studied. The results show that the free surface chloride concentration (Cs), free chloride diffusion coefficient (Df) and time-dependent index (m) of CASC in the drying-wetting cycles is obviously higher than that in seawater immersion. The Df and m of CASC of carbonation and drying-wetting cycles is higher than that in the drying-wetting cycles. Carbonation increases the Df and m of CASC, which is against CASC to resist chloride corrosion. The corrosion possibility of CASC structures in different exposed areas is as follows: splash zone (carbonation and drying-wetting cycles)>tidal zone (drying-wetting cycles) >underwater zone (seawater immersion). Besides, the chloride diffusion rate of C65-CASC is 17.8%–63.4% higher than that of C65-ordinary aggregate concrete (OAC) in seawater immersion (underwater zone). Therefore, anti-corrosion measures should be adopted to improve the service life of CASC structure in the oceanic environment. [ABSTRACT FROM AUTHOR]

To study the behavior of coral aggregate concrete (CAC) column under axial and eccentric compression, the compression behavior of CAC column with different types of steel and initial eccentricity (ei) were tested, and the deformation behavior and ultimate bearing capacity (Nu) were studied. The results showed that as the ei increases, the Nu of CAC column decreases nonlinearly. Besides, the steel corrosion in CAC column is severe, which reduces the steel section and steel strength, and decreases the Nu of CAC column. The durability of CAC structures can be improved by using new organic coated steel. Considering the influence of steel corrosion and interfacial bond deterioration, the calculation models of Nu under axial and eccentric compression were presented. [ABSTRACT FROM AUTHOR]

To investigate the dynamic responses and comprehending the damage mechanism of coral aggregate concrete (CAC) in compression, both the experimental and numerical investigations were implemented in the present work. Firstly, the dynamic mechanical properties of CAC at different strain rates were tested through the Split-Hopkinson pressure bar (SHPB) tests. Moreover, the effects of concrete strength grade and strain rate on CAC were discussed and analyzed. Subsequently, we developed the three-dimensional (3D) random mesoscale model considering the randomness of aggregate shape, size and distribution at meso-level, which was validated and employed in the numerical simulation of CAC in compression. The results indicate that the splitting failure passing through the coral aggregate is CAC'S primary failure mode. It has been found that the failure pattern, deformation process, and dynamic increasing factor of CAC are associated with both the strain rate and concrete strength grade. Furthermore, by comparing the experimental and mesoscopic results, it has been proven to be reliable to employ the developed 3D mesoscale modelling method to simulate CAC's dynamic performances, which has enormous potential in future research of CAC under intense dynamic loadings. [ABSTRACT FROM AUTHOR]

Based on the drying-wetting cycles experiment and the carbonation-drying-wetting cycles experiment for coral aggregate seawater concrete (CASC) with different strength grades, the effects of carbonation-drying-wetting on the durability of CASC are studied with the surface state, mass loss rate, relative dynamic elastic modulus, ultrasonic wave velocity and cube compressive strength as indices. Results show that the mass loss rate of CASC increases gradually with the increase in cycle times in the drying-wetting and carbonation-drying-wetting cycles. The mass loss rate increases relatively slowly at the initial stage but it increases remarkably after 10 cycles. The relative dynamic elastic modulus and ultrasonic wave velocity decrease gradually with the increase in cycle times. After 6 cycles, the decrease rate of the relative dynamic elastic modulus and ultrasonic wave velocity of CASC tends to be flat and the surface is slightly damaged. Compared with the initial 28 d cube compressive strength, the cube compressive strength of CASC decreases by 8.8% to 11.0%. Drying-wetting cycles and carbonation can accelerate seawater erosion on CASC, and drying-wetting cycles result in salting-out and accelerate the destruction of concrete. Therefore, the carbonation-drying-wetting accelerates the destruction of CASC. [ABSTRACT FROM AUTHOR]

Reinforced coral aggregate concrete beam and reinforced ordinary aggregate concrete beam with different concrete type, concrete strength, and steel type were designed in this study to investigate their shear behavior. The shear behavior of reinforced coral aggregate concrete beam was tested, the failure mode and deflection behavior were studied, and the calculating model for the ultimate shear capacity (V cs) of reinforced coral aggregate concrete beam was proposed. Results showed that the failure mode of reinforced ordinary aggregate concrete beam and reinforced coral aggregate concrete beam were basically the same. As the concrete strength increases, the normal section cracking load (V cr), inclined section V cr, and V cs of reinforced coral aggregate concrete beam increased gradually. Furthermore, V cr and V cs of reinforced coral aggregate concrete beam were as follows: 316 stainless steel > common steel > zinc-chromium coated steel > new organic coated steel. For the coral aggregate concrete structure in ocean engineering, in order to prolong its service life, the use of new organic coated steel was suggested. At the same time, the influence of high-strength coral aggregate concrete and stirrup corrosion was comprehensively considered and the calculation model for the V cs of reinforced coral aggregate concrete beam was presented and was then verified. [ABSTRACT FROM AUTHOR]

An investigation that combines both experimental tests and mesoscopic modelling is conducted to characterize the dynamic splitting-tensile behavior of coral aggregate concrete (CAC). Static and dynamic splitting-tensile strength and failure patterns of CAC with different uniaxial compressive strength (30–70 MPa) are tested by means of MTS machine and Split-Hopkinson pressure bar device, respectively. A three-dimensional (3D) randomly mesoscopic model for the simulation of the splitting-tensile strength and failure of CAC under different strain rates (1–200 s−1) is developed and validated by contrasting tested and numerical results. The experimental and numerical results indicate that the splitting-tensile strength and failure pattern are significantly affected by concrete strength and strain rate. The dynamic splitting failure mechanism that the damage outside the specimen is more serious than the inside, and the fracture in the center of the specimen is more severe than the edge, has been explained from the localized failure patterns of concrete and aggregates. Furthermore, it can be learned from the tensile dynamic increase factor of CAC is sensitive to strain rate significantly, which has a profound significance in the further investigation of reef CAC structures. [ABSTRACT FROM AUTHOR]

Purpose: Coral aggregate seawater concrete (CASC) is a new type of lightweight aggregate concrete that is becoming widely used in reef engineering. To investigate the corrosion behavior of different kinds of rebar in CASC exposed to simulated seawater for 0-270 d, the electrochemical techniques, including linear polarization resistance (LPR) technique and the electrochemical impedance spectroscopy (EIS), were used in the present work. Design/methodology/approach: The electrochemical techniques, including LPR technique and the EIS, were used in the present work. Findings: Based on the time-varying law of linear polarization curves, self-corrosion potential (Ecorr), polarization resistance (Rp), corrosion current density (Icorr), corrosion rate (i), and the characteristics of EIS diagrams for different types of rebar in CASC, it can be found that the anti-corrosion property of them can be ranked as epoxy resin coated steel > 2205 duplex stainless steel (2205S) > 316 L stainless steel (316 L) > organic coated steel > ordinary steel. Additionally, the linear regression equation between Rp and charge transfer resistance (Rct) was established. Finally, the EIS corrosion standard of rebar was established from the LPR corrosion standard, which provides a direct standard for the EIS technique to determine the condition of rebar in CASC. Originality/value: The linear regression equation between polarization resistance and charge transfer resistance was established. And the EIS corrosion standard of rebar was established from the LPR corrosion standard, which provides a direct standard for the EIS technique to determine the condition of rebar in CASC. [ABSTRACT FROM AUTHOR]

Purpose This paper aims to reduce the cost, limit the time and increase raw material source availability, coral aggregate seawater concrete (CASC) composed of coral, coral sand, seawater and cement can be widely used for the construction of ports, levees, airports and roads to achieve practical engineering values. However, the naturally porous coral structure and abundant Cl− in the seawater and coral lead to extremely severe reinforcement corrosion for CASC. It is well known that Cl− is the main cause of reinforcement corrosion in the marine environment. Therefore, it is necessary to research the reinforcement corrosion of CASC in the marine environment.Design/methodology/approach In this study, linear polarization resistance was adopted to test the linear polarization curves of reinforcement in CASC with different exposure times. Ecorr, Rp, Icorr and Vcorr were calculated according to the weak electrochemical polarization theory and Stern–Geary formula. The effects of concrete cover thickness, exposure time, reinforcement types and inhibitor on reinforcement corrosion in CASC were analysed. The reinforcement corrosion degradation rule was determined, which provided theoretical support for the durability improvement, security assessment, service life prediction and service quality control of CASC structures in marine islands and reef engineering.Findings The corrosion resistance was enhanced with increased concrete cover thickness, and the concrete cover thickness for organic new coated steel should be at least 5.5 cm to reduce the reinforcement corrosion risks in CASC structures. The corrosion resistance of different types of reinforcements followed the rule: 2205 duplex stainless steel > 316 stainless steel > organic new coated steel > zinc-chromium coated steel > common steel. In the early exposure stage, the anti-corrosion effectiveness of the calcium nitrate inhibitor (CN) was superior to that for the amino alcohol inhibitor (AA). With the extension of exposure time, the decreasing rate of anticorrosion effectiveness of CN was higher than that of AA.Originality/value Reinforcement corrosion of CASC in a marine environment was studied. Concrete cover thickness, exposure time, reinforcement type and inhibitor influenced the reinforcement corrosion were investigated. New technique of reinforcement anti-corrosion in marine engineering was proposed. Possible applications of CASC in marine engineering structures were suggested. [ABSTRACT FROM AUTHOR]