Abstract: Bipolar plates are significant components in proton exchange membrane fuel cells (PEMFCs), thus playing a decisive role in the weight, volume, efficiency, durability, and cost of battery stacks. At present, the preparation technologies of metal and graphite plate stacks have become relatively mature, and have been widely used in the fields of commercial and passenger vehicles. However, production of composite material bipolar plates has not been marketed on a large scale in China due to the incomplete localization of raw material formulation, absence of mass production lines and high production cost. Therefore, it is of great significance to find low-cost raw materials, screen raw material compositions and ratios, optimize processing conditions including molding temperature, pressure and time, and shorten the processing cycle for the industrialization of composite bipolar plates. In this review, the characteristics of metal bipolar plates, graphite bipolar plates and composite material bipolar plates were compared. Moreover, the molding process and its advantages in composite bipolar plate production were introduced. Subsequently, recent progress in research of carbon-based composite molded bipolar plates was summarized. This includes resin/graphite composite bipolar plates using thermosetting resins such as phenol formaldehyde resin, epoxy resin and vinyl ester resin as the binder, and carbon black, carbon fiber and carbon nanotube reinforced composite bipolar plates. The effects of the types and ratios of raw materials and molding process conditions on the performance of bipolar plates were emphasized. Finally, the industrialization status of composite bipolar plates was discussed, and the problems faced by major composite bipolar plate manufacturers at home and abroad were pointed out. Prospects in the development of composite bipolar plates were also explored. Additionally, unified performance test standards for composite bipolar plates were recommended to make the performance of products developed by different enterprises comparable.
Abstract: In recent years, efficient electrical equipment for reducing energy consumption has drawn increasing worldwide attention. Although silicon (Si) has been used as a power semiconductor device, its improving effect on the performance of power semiconductor devices is greatly limited by its physical characteristics. Compared with Si, silicon carbide (SiC) as a type of wideband gap semiconductor has more excellent comprehensive physical properties in power device applications, including a triple wideband gap, a triple high thermal conductivity, and a tenfold breakdown electric field. Moreover, SiC can form silicon dioxide (SiO2) on the surface through thermal oxidation, which plays an important role in device manufacturing technology as an insulating layer. Based on these properties, SiC has gradually replaced Si as the preferred material of power devices used in metal oxide field-effect transistors (MOSFETs). The structure of a MOSFET contains a polysilicon-oxide layer (mostly SiO2)-SiC or diamond as the core. This structure is exactly equivalent to that of a capacitor, with SiO2 as the dielectric medium in the middle, and the capacitance value is determined by the thickness and dielectric coefficient of SiO2. However, the anisotropic process during the thermal oxidation from SiC to SiO2 results in a large difference in oxidation rate on different crystal faces, which adversely affects the performance of semiconductor devices. Therefore, studying the growth law of SiO2 on each crystal surface of SiC is of vital importance. Effective and reasonable dynamic models are expected to clarify the behavior. In this paper, the representative modified Deal-Grove model (Song model and Massoud empirical relation) and Si?C emission model were researched and compared systematically in terms of the reaction mechanism and fitting accuracy. On this basis, the advantages and disadvantages of the models were analyzed, and the possibility of the application of the real physical picture model established by our research group was proposed, which can further contribute to optimization and modification for the precise description of the oxidation kinetics of SiC on different crystal faces.
Abstract: Vanadium is an important additive that is used widely in modern industries, as well as an important strategic metal. Vanadium metal elements, compounds, and alloy materials have unique and valuable properties, which have enabled great advances in the world’s industries, particularly in steel, chemical, medical, petroleum, nonferrous metals, energy, construction, environmental protection, and nuclear. China not only has one of the world’s largest vanadium resources but is also the largest producer and consumer of vanadium, occupying an important position in the international market. Vanadium is a rare and precious metal and is prodigiously dispersed in the earth’s crust. There are only a few independent vanadium minerals. China’s vanadium resources are mainly found as vanadium–titanium magnetite and stone coal. In recent years, the extraction of vanadium from stone coal has become an important project in the development of vanadium resources in China. This article introduced the main reserves and distribution channels of global vanadium resources and their market supply, demand, and application status. The focus is on the central structure of organophosphorus extractants, effective groups and steric effects, and the mechanism of synergistic extraction of vanadium via ion exchange, as well as the development and application of new phosphorus extractants for vanadium extraction. Research and development of phosphorus-based extractants, application of new processes, and collaborative extraction are currently the main research directions of phosphorus-based extractants for vanadium extraction. This article analyzed vanadium extraction mechanisms of different extraction systems using acidic phosphorus extractants, neutral phosphorus extractants, and other new phosphorus extractants. The analysis shows that the loss of the organic phase, steps of extraction and stripping of vanadium, extensive extraction and separation times, and occurrence of emulsification are common difficulties currently associated with the extraction of vanadium. Therefore, it is necessary to continuously develop new and efficient extractants, develop clean and green extraction technologies, use synergistic effects based on the original extractants, explore new combinations of extractants, and better promote the development of China’s vanadium industry.
Abstract: Zinc is an important raw material and nonferrous metal that has an extremely important role in the development of national economies. For this reason, countries around the world continue to strengthen their research efforts on the development and utilization of zinc resources. Sphalerite is an important source of zinc metal, which often coexists with chalcopyrite, galena, and pyrite in nature. The flotation separation of complex polymetallic sulfide ore is a difficult problem in the field of mineral processing engineering. To achieve the flotation separation of chalcopyrite, galena, and other minerals from sphalerite, depressants are needed. Due to the difficulty of activation after the depression of galena and other sulfide ores, a zinc depression and lead floatation process is usually used. The choice of the sphalerite depressant is critical when separating zinc and other sulfides. The traditional sphalerite depressants are generally inorganic. Although these depressants significantly improve the hydrophilicity of the sphalerite surface and strongly depress the sphalerite, they have a certain inhibitory effect on other sulfide ores while depressing the sphalerite. In addition, these agents are difficult to degrade and have a negative impact on the environment. To achieve high-efficiency flotation separation of sphalerite and sulfide minerals and improve the quality of the concentrate products, the development of new inhibitors is becoming increasingly important. Thence, the effect of the oxidizer potassium permanganate and organic depressant sodium alginate on the flotation of three kinds of sulfide minerals are studied, including chalcopytite, galena, and sphalerite. The investigations involved flotation tests, X-ray photoelectron spectroscopy (XPS) analysis, adsorption behavior analysis, with an additional focus on the mechanism of potassium permanganate strengthening, and sodium alginate depression of sphalerite flotation. The flotation results show that adding either an oxidizer or sodium alginate alone does not enable the selective depression of sphalerite. However, adding a certain amount of oxidizer and sodium alginate together can realize the selective coordinated depression of sphalerite, with little effect on the flotation of chalcopytite and galena. The XPS analysis results show that sodium alginate is chemically adsorbed on the sphalerite surface with oxidation products such as zinc oxide, zinc hydroxide, or zinc sulfate, but is not adsorbed on an unoxidized sphalerite surface. The adsorption test results show that the preoxidation of potassium permanganate on sphalerite significantly increases the adsorption capacity of sodium alginate on the sphalerite surface. Therefore, potassium permanganate can strengthen the sodium alginate depression of sphalerite flotation.
Abstract: With over 100 billion tons of reserves, the ironsands resource is mainly distributed along the “Belt and Road” countries, such as Indonesia. It is the second largest marine resource inferior to petroleum and natural gas. Ironsands mainly comprise vanadium, titanium, and iron. With advantages of easy mining, low cost, and abundance in polymetallic minerals, the ironsands resource has attracted extensive attention for its extremely high comprehensive recycling value. According to previous studies, solid-state reduction is an efficient approach to a number of processes in complex mineral resources such as ironsands, especially in vanadium-bearing titanomagnetite treatments. In this paper, the process mineralogy and direct reduction characteristics of typical ironsands from Indonesia were studied based on the classical mineralogy method combined with various characterization techniques such as chemical phase analysis, MLA, X-ray diffraction, particle size analysis, optical microscopy, and SEM-EDS. Results show that the mineral composition of the ironsands is mainly titanomagnetite, followed by a small amount of pseudo-hematite, hematite, ilmenite, pyroxene, plagioclase, and others. Most titanomagnetites exist as compact monomers or iron-rich aggregates with occasional fine ilmenite flakes formed through solid-melt separation. The iron contained in titanomagnetite phase accounts for 89.79% of the total iron in the ironsands, while titanium and vanadium account for 85.42% of the total titanium and 97.97% of the total vanadium content, respectively. Ironsands can achieve high metallization ratio when they are reduced at 1300 ℃ for 60 min with C/Fe mole ration of 1.2. The reduction course is as follows: Fe2.75Ti0.25O4 → FeTiO3, (Fe, Mg)Ti2O5 → (Fe, Mg)Ti2O5 → Fe. Results reveal that the stable anosovite ((Fe, Mg)Ti2O5) phase is the main factor affecting the final metallization degree of the reduced samples. With solid state reduction treatment, iron is enriched in the metal phase while vanadium and titanium elements are distributed in the titanium-rich phase in the slag. These create favorable conditions for the subsequent separation and extraction process, which consequently lay a firm foundation for the comprehensive utilization of the ironsands.
Abstract: For the accurate prediction of the migration state of ore-rock dispersions in the ore pass storage section, a prediction model of an ore pass trajectory and velocity was established by taking the orepass structure, which coincided the centerlines of the ore drawing funnel, and the orepass as the research objects. First, during the silo unloading process, the movement law of ore-rock dispersions in the ore-storage section was analyzed according to the similarity of the particles’ movement characteristics and the flow characteristics of an ideal fluid flow unit. Next, the ore-rock migration network was established based from the flow network concept and the Beverloo empirical formula. Analysis was then conducted on the relationship between the section and the velocity of the ore-rock movement in the ore-storage section of ore pass. Finally, under certain assumed conditions, the displacement equation, the migration trajectory, and the velocity of the ore-rock moving in the ore-storage section were established according to the distribution characteristics of streamline and equipotential surface. Results reveal that after entering the ore-storage section of the ore pass, the ore-rock will pass through two speed zones: (1) a uniform speed zone leading to a uniform linear downward motion and (2) a variable speed zone leading to a variable speed curve motion. When the dip angle of the ore draw-hole is small, an “empty ring effect” is achieved, where no displacement of the lower ore-rock is observed. Finally, the quality of the ore-rock drawing-out in a unit time is found to be equal to that of the ore-rock passing through the same equipotential surface. The predicting model reveals the dependency of the ore-rock migration state in the uniform speed zone with a number of parameters such as the diameter of the section of ore-storage and ore-discharge, ore-rock particle size. Conversely, the ore-rock migration state in the variable speed zone is mainly related to the ore-rock’s location and the inclination angle of ore draw-hole.
Abstract: The microcracks in natural rock masses considerably impact the stability of the underground engineering structures. The mechanical properties of the cracked rock masses contribute considerably to the strength of the rock masses and their compression failure mechanism. The instability and failure of the surrounding rocks are often induced by the propagation and penetration of these internal cracks. In practical engineering, rock mass excavation is a process involving dynamic disturbance. The mechanical properties of the rocks under cyclic load are considerably different from those of the rocks under static load. The characteristics and development of microcracks are the main factors influencing rock fatigue failure. From the microscopic viewpoint, the particle-based discrete element method is used to conduct the cyclic loading and unloading tests of the preexisting cracked granite. First, the microcompositions of granite are determined using image processing techniques, and the micromechanical parameters are calibrated based on the indoor uniaxial compression test results. The stage of crack development during rock failure is analyzed by compiling particle flow code to track the type and propagation process of cracks. Results indicate that the orientations of new cracks in fractured rocks with different dip angles are similar to those of the preexisting cracks. Further, the relation between the crack initiation angle and the inclination angle of the preexisting cracks is obtained according to the tendency of new cracks. The crack initiation angle of shear and tension cracks decreases and increases monotonically, respectively, when the inclination angle β ≤ 45° and β ≥ 60°. The cyclic disturbance load increases the axial deformation of the fractured rock mass, and the axial cumulative residual strain curve exhibits an inverse S-shape when entering the acceleration stage faster with the increasing upper stress limit. The peak strength of the model specimen shows a decreasing trend followed by an increasing trend with the increasing fracture inclination. The peak strengths of the laboratory-intact rock are 63% to 89%, indicating an obvious deterioration phenomenon in the rock materials. The growth of shear and tension cracks show different characteristics under cyclic load; the growth rate of tension cracks is considerably higher than that of shear cracks during the unstable crack development stage. The results presented in this study may be used as reference to investigate the deformation and failure mechanisms of rock materials.
Abstract: Concrete structures, such as bridge piers and pile foundations, in tidal/splash zones and soil–air transition zones in saline environments often suffer more severe structural corrosion and reinforcement corrosion than the structures completely in water, soil, or air. The application of plastic-pipe concrete can effectively solve this problem. Plastic-pipe concrete is formed by pouring concrete into a large-diameter plastic pipe with a certain structural size. Plastic pipes can protect the bridge piers and eliminate the water level change area and the soil–air junction area in structural design, to realize the integrated anti-corrosion protection of the bridge piers in the saline environment. The anti-corrosion protection effect of the plastic-pipe–concrete system depends on the impermeability of the plastic pipe–concrete interface. The difference in linear expansion coefficient between the plastic pipe and concrete and the shrinkage of the core concrete will damage the bonding layer between the plastic pipe and concrete, consequently affecting the interface impermeability. To improve the impermeability of the plastic pipe–concrete interface, the effect of a pressure-sensitive adhesive tape (Preprufe double-sided tape) attached to the plastic pipe–concrete interface was studied. Experiments were conducted to determine the interfacial bond strength, interfacial water penetration height, and interfacial air permeability, and the gas pressure–time decay curve was measured, and the interface permeability index was deduced. The experiment results show that the relationship between the interfacial bond strength and the adhesive tape width can be preliminarily considered as a power function distribution. The bond strength formed between the pressure-sensitive adhesive layer and the liquid concrete during the hardening process is much greater than that between the ordinary adhesive tape and the plastic pipe. Pasting the Preprufe tapes can significantly improve the impermeability of the plastic pipe–concrete interface. The interfacial permeability index decreases with the increase in the adhesive tape width, and the interfacial permeability index coefficient of plastic pipe–concrete specimens with 220 mm–wide tape is only 2.86% of that of the specimens without tape. The Preprufe double-sided pressure-sensitive tape has good performance in improving the impermeability of plastic pipe–concrete interfaces. In engineering applications, the adhesive tape width can be selected based on the required effect and cost.
Abstract: Thermal fatigue cracking is the main failure mode of hot work die steel during die casting and hot forging. Thermal fatigue cracking accounts for a large proportion of mold failures and seriously affects the service life of the mold. Because of the high maintenance and replacement costs, thermal fatigue failure will cause substantial financial losses to the enterprise. Therefore, analyzing the fatigue behavior of hot work die steel at high temperatures is of significance in scientific research and engineering applications. H13 hot work die steel is widely used in die casting and hot forging because of its excellent high-temperature performance and toughness. In this study, a 600 ℃ isothermal fatigue test was conducted on H13 hot work die steel samples. The effect of three different strain amplitudes of 0.7%, 0.9%, and 1.1% on the isothermal fatigue behavior was analyzed using a micro Vickers hardness tester, metallographic microscope, microscope with a superwide depth of field, and scanning electron microscope. Results show that the stress–strain hysteresis loop is symmetric. The larger the strain amplitude is, the larger the area of the hysteresis loop. H13 hot work die steel exhibits the cyclic softening behavior during the experiment. The larger the strain amplitude, shorter is the fatigue life. The fatigue life of the sample with the strain amplitude of 1.1% is approximately 61.2% of that of the sample with the strain amplitude of 0.7%. The increase in the strain amplitude promotes the initiation and propagation of cracks, and the propagation of cracks on the sample with the strain amplitude of 1.1% is the most obvious. Under high-temperature and non-vacuum experimental conditions, oxide on the surface of the material promotes crack growth. The microstructure of the sample under isothermal fatigue grows and coarsens. The large strain amplitude not only supports carbide precipitation but also accelerates cyclic softening of the material. The microhardness of samples with strain amplitude is lower than that of samples without strain amplitude.
Abstract: Traction battery is the core component of the electric vehicle. To obtain longer driving ranges, conventional lithium-ion batteries with LiMn2O4, LiCoO2, and LiFePO4 cathodes were gradually replaced by LiNixCoyMn1?x?yO2 batteries. With the increasing energy density and chemical activity of the lithium-ion traction battery, its thermal stability gradually decreases and safety hazards become increasingly serious. In recent years, thermal runaway incidents with traction batteries have occurred frequently at home and abroad, seriously disturbing the development of electric vehicles. Solving the safety problems associated with thermal runaway(TR) and thermal runaway propagation(TRP) of the lithium-ion battery is urgent. In this paper, TR and its propagation behavior, associated with a 42 A·h prismatic lithium-ion battery with a LiNi1/3Co1/3Mn1/3O2 cathode for electric vehicles, were studied under thermal abuse conditions on the cell and module levels. The results indicate that the maximum temperature approaches 920 ℃ inside the cell. The maximum temperature difference is up to 403 ℃ within the cell during TR, and the maximum temperature rise rate inside the cell is 40 ℃·s?1. The TRP time within a lithium-ion battery is 8–12 s under 100% state-of-charge (SOC), and the duration of the vent is 14–18 s. The temperature characteristics of the lithium-ion battery display large differences for the TRP test and adiabaticTR test. In a propagation test, the TR initiates from a forward surface toward the failure point, whereas under the adiabatic test the TR occurs simultaneously in the cell. More than 80% of the particles vented from the cell are LiF and graphite during the adiabatic test. Approximately 90% of the heat released by the TR is used for heating the residual and venting particles of the cell. The study offers a reference guide for the safety design and mitigation strategy of TRP in lithium-ion battery modules, and accident investigations of new energy vehicles.
Abstract: Selective laser fusion (SLM) is an emerging 3D printing technology that can greatly shorten the processing cycle and reduce the production cost of medical implants, thus offering broad prospects for application in the biomedical field. In addition, its excellent corrosion resistance is a crucial characteristic for its application as a biomedical material. However, the corrosion behavior of SLM–TI6AL4V, especially its corrosion resistance, has not been a focus of extensive study to date. In this study, the microstructures and corrosion behavior of SLM–Ti6Al4V, which was produced via selective laser melting with fabrication angles of 30°, 45°, and 60°, in NaF-containing solutions were investigated using metalloscopy, scanning electron microscope, electrochemical measurement, and immersion test. According to microstructural analysis, SLM–Ti6Al4V is characterized by prior β grains with needle α' phases; the prior β grains for the sample with the fabrication angle of 45° are most like equiaxed, and the α' phase are the smallest. In addition, the sample with the fabrication angle of 45° has the smallest lattice distortion compared to the others. The electrochemical measurements reveal that with increasing NaF concentration, the corrosion resistance of all three samples deteriorates, and the critical fluoride concentration of the samples with fabrication angles of 30°, 45°, and 60° are in the range of 0.0005–0.00075 mol·L?1, 0.00075–0.001 mol·L?1, and 0.0005–0.00075 mol·L?1, respectively. From the results of the immersion test, in the solution with NaF concentrations less than the critical value, the surfaces of the three samples remain nearly intact, while in the solutions with more added NaF, active dissolution takes place on the sample surface. Comparing the results of the electrochemical measurements and the immersion test, the sample with the fabrication angle of 45° exhibits superior corrosion resistance.
Abstract: Recently, research on high-entropy alloys has developed rapidly. While studying high-entropy alloys in bulk, scholars have also conducted in-depth research on high-entropy alloy films, especially high-entropy alloy nitride films. Compared with traditional binary and ternary nitride films, high-entropy alloy nitride films have a simpler and denser structure and better performance, and therefore have great prospects for application in many fields. Research on high-entropy alloy nitride films is still relatively scarce, and the influencing factors of phase structure transformation and mechanical properties need to be further explored. Therefore, it will be an important research direction in the future. Based on a single-target Radio Frequency (RF) magnetron sputtering technique, two series of FeCrVTa0.4W0.4 high-entropy alloy nitride films were fabricated on monocrystalline silicon substrates. These are FeCrVTa0.4W0.4 nitride composition gradient multilayer films and (FeCrVTa0.4W0.4)Nx single-layer films, in which multilayer films are used for solar spectral selective absorption films. Through scanning electron microscope (SEM), X-ray diffractometer (XRD), nanomechanical probe, atomic force microscopy, UV–visible spectrophotometry, contact angle measuring instrument, and four-probe tester, the microstructure, and properties of FeCrVTa0.4W0.4 high-entropy alloy nitride films were analyzed. The results show that the film is amorphous when nitrogen is not introduced. When nitrogen content increases, nitride films are face-center-cubic solid solution in structure. When the surface nitrogen flow rate is 15 sccm, the FeCrVTa0.4W0.4 nitride multilayer film and the single-layer film have the best mechanical properties. Among them, the hardness of the multilayer film is 22.05 GPa and the modulus is 287.4 GPa; the hardness of the single-layer film is 22.8 GPa, and the modulus is 280.7 GPa. As the nitrogen content on the surface continues to increase, the mechanical properties decrease. FeCrVTa0.4W0.4 nitride composition gradient multilayer films have solar spectrum selective absorptivity in the wavelength range of 300–800 nm and have better hydrophobicity when the number of nitride films layer is small. With increasing nitrogen content, the block resistance of (FeCrVTa0.4W0.4)Nx single-layer film increases.
Abstract: The state of charge (SOC) estimation is one of the core functions of the battery management system; it can play a significant role in the life cycle of electric vehicles. The SOC estimation method has attracted considerable research attention in recent years, particularly about improving estimation accuracy. However, most studies are limited by only focusing on known or fixed battery model parameters and not considering their temperature dependence. This indicates a need to explore how the lithium-ion battery temperature affects the model parameters, which leads to inaccurate SOC estimation. The principal objective of this study is to investigate the robust H∞ filter-based method for the problem that temperature affects battery model parameters and thus leads to inaccurate SOC estimation. First, the second-order Thevenin equivalent circuit model with two parallel resistor–capacitor pairs is taken as the basic model of the lithium-ion battery. The influence of temperature on battery model parameters is modeled as an additive variable of the nominal resistance value and the total battery capacity, and the temperature change is considered an external disturbance of the system. Afterward, the sliding linear method is used to linearize this battery model; on this basis, a robust H∞ filter for SOC estimation is designed using linear matrix inequality technology. Finally, the effectiveness of the proposed approach is verified using four different types of dynamic current load profiles (the BJDST-Beijing Dynamic Stress Test, FUDS-Federal Urban Driving Schedule, US06-US06 Highway Driving Schedule and BJDST-FUDS-US06 joint dynamic test) compared with the Kalman filter-based SOC estimation method. The simulation analysis results indicate that the proposed SOC estimation approach can realize a higher SOC estimation accuracy even if the model parameters vary with temperature, and it has good robustness to external disturbances.
Abstract: The logic in the traditional space (physics, society, and thinking space) is summarized as the traditional logic (physical logic, social logic, and thinking logic, respectively.) Correspondingly, with the development of cyber (network) space, people began to summarize the basic rules in cyberspace and express them in a logical form. This approach became the concept of cyberlogic, an important research area that differs from traditional logic and paves the way from cyber philosophy to cyber science. In recent years, research in the field of cyberlogic has made progress, and the profound influence of cyberlogic on other spaces has gradually received attention from the academic community. Cyberlogic-related applications have grown rapidly in certain fields, such as computer logic, expert system, public opinion, smart factories, and the cyber economy. In addition, research on the mapping of traditional logic to cyberspace in specific fields has progressed, and the relationship between traditional logic and cyberlogic has been analyzed. However, only a small amount of research has been conducted on the overall cyberlogic system, some of which lacks systematicity. This situation is not conducive to the construction of the cybermatics theory system. This paper systematically studied the logic in cyberspace from a broad perspective and divided cyberlogic into cyberized logic and cyberself logic. First, it reviewed the traditional logic. Then, it introduced the concept of the cyberization of traditional logic, analyzed the similarities and differences between traditional logic and cyberlogic, emphasized the adaptability in the cyberization process, and expounded on the generation of cyberself logic. Finally, this paper analyzed the influence of cyberlogic on traditional logic and summarizes the connotation of cyber-driven logic. This article provided support for systematic research on cyberspace.
Abstract: Wind energy is a new kind of inexhaustible energy. It is gradually replacing the traditional energy as its pollution-free and renewable. China has a long coastline, abundant offshore resources, and vast offshore space. Offshore wind farms have gradually become the focus of wind-power development. Large-diameter single-pile foundations are being widely used in the field of offshore power generation because of advantages including convenient manufacture and installation, clearer stress conditions compared with pile groups, and affordable cost and economy. Therefore, it becomes significantly relevant to study the dynamic response characteristics of large-diameter single-pile foundations under horizontal cyclic loads to eliminate the dangers hidden in engineering and installation and ensure normal usage during service. A numerical calculation model of an offshore, wind-power monopile foundation in heterogeneous soil was established by the finite element analysis software ABAQUS. The wave, ocean current, and wind load on the monopile foundation were equivalent to a bidirectional symmetrical cyclic load. The horizontal displacement, shear force, and bending moment along the pile shaft, and pile-side soil resistance under the horizontal cyclic load were studied. Furthermore, the horizontal displacements along the pile shaft under different cyclic times were compared with one another and analyzed. The results show that the horizontal displacement along the pile shaft accumulates gradually with time, and with increase in the number of cycles, the time lag of the maximum displacement of the pile body at mud surface occurs. The shear force along the pile shaft appears negative. The maximum bending moment of the pile body occurs in shallow soil. The variation in the soil-resistance curve of the pile body vs time occurs at a cut-off point at approximately 2/3 of the buried depth. Additionally, the variation laws of soil resistance within the upper and lower boundaries of the cut-off point are just the opposite of each other. The soil resistance increases significantly at the interface between silt and silty soil. The load along the buried depth of the inner wall of the pile remains unchanged at different time points.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
