Multi-field Coupling Effect Research Articles

A parametric study on the fatigue life of elevator brake wheels under multi-field coupling effects

A parametric study on the fatigue life of elevator brake wheels under multi-field coupling effects

Influence of temperature and flow rate on alteration layer structure and leaching properties of simulated sulfur-containing borosilicate HLW glass under multi-field coupling effects

During long-term deep geological disposal process, high-level liquid waste (HLW) glass may be exposed to “Thermodynamics-Hydrodynamics-Mechanics-Chemistry” (THMC)multi-field coupling effects. The leaching properties of sulfur-containing borosilicate HLW glass at different temperatures (40–150 °C) and different flow rates (0.01–0.10 mL/min) under THMC coupling effects were studied in this work. The alteration layer structure of waste glass surface was also characterized. The results show that honeycomb-shaped phyllosilicate alteration layer forms after leaching in simulated groundwater and white block-shaped BaSO4 crystals appear on the glass surface at 90 °C after 28 d. The amount of BaSO4 crystals increases obviously at 150 °C. The leaching rates of B, Si, Cs and U elements increase with increasing temperature and flow rate. Particularly, the leaching rates of B, Si, Cs, and U under THMC coupling effects (90 °C, 0.01 mL/min, 10 MPa, pH=8.05) after 28 d in the simulated groundwater are 1.10 × 10–1, 1.73 × 10–1, 2.91 × 10–1, 3.79 × 10–1 g·m-2·d-1, respectively.

The adjustable adhesion strength of multiferroic composite materials via electromagnetic loadings and shape effect of punch

Tunable and reversible dry adhesion possess great potential in a wide range of applications including transfer printing, climbing robots, wearable devices/electronics, and gripping in pick-and-place operations. Multiferroic composite materials offer new routines and approaches to achieve tunable adhesion due to their multi-field coupling effects. In this paper, the classical Johnson-Kendall-Roberts (JKR) adhesion model is extended to investigate the adhesive contact problem of a multiferroic composite half-space indented by an axisymmetric power-law shaped punch, whose shape index is denoted by n. The JKR-n adhesion models under the action of the power-law shaped punches with four different electromagnetic properties are set up by means of the total energy method. The explicit analytical expressions relating the indentation load and indentation depth to the contact radius are obtained, which can include the existing results in open literature as special cases. The generalized Tabor parameter and the interfacial adhesion strength applicable to multiferroic composite materials are defined. The effects of the shape index and the electromagnetic loadings on adhesion behaviors are revealed. It is found that both of them have prominent influences on the relationships among the indentation load, indentation depth and contact radius, the contact radius and indentation depth at self-equilibrium state, and the critical contact radius and indentation depth at pull-off moment. The pull-off force under the action of the conducting spherical punch subjected to non-zero electromagnetic loadings is dependent on material properties, which is different from the classical JKR result. More importantly, our analysis indicates that the pull-off force and the interfacial adhesion strength can be adjusted via altering the electromagnetic loadings and the shape index of the punch, which provides new approaches to achieve tunable adhesion.

Automated Shape Correction for Wood Composites in Continuous Pressing

The effective and comprehensive utilization of forest resources has become the theme of the global “dual-carbon strategy”. Forestry restructured wood is a kind of wood-based panel made of wood-based fiber composite material by high-temperature and high-pressure restructuring–molding, and has become an important material in the field of construction, furniture manufacturing, as well as derivative processing for its excellent physical and mechanical properties, decorative properties, and processing performance. Taking Medium Density Fiberboard (MDF) as the recombinant material as the research object, an event-triggered synergetic control mechanism based on interventional three-way decision making is proposed for the viscoelastic multi-field coupling-distributed agile control of the “fixed thickness section” in the MDF continuous flat-pressing process, where some typical quality control problems of complex plate shape deviations including thickness, slope, depression, and bump tend to occur. Firstly, the idea of constructing the industrial event information of continuous hot pressing based on information granulation is proposed, and the information granulation model of the viscoelastic plate shape process mechanism is established by combining the multi-field coupling effect. Secondly, an FMEA-based cyber granular method for diagnosing and controlling the plate thickness diagnosis and control failure information expression of continuous flat pressing is proposed for the problems of plate thickness control failure and plate thickness deviation defect elimination that are prone to occur in the continuous flat-pressing process. The precise control of the plate thickness in the production process is realized based on event-triggered control to achieve the intelligent identification and processing of the various types of faults. The application test is conducted in the international mainstream production line of a certain type of continuous hot-pressing equipment for the production of 18 mm plate thickness; the synergistic effect is basically synchronized after 3 s, the control accuracy reaches 30%, and the average value of the internal bond strength is 1.40, which ensures the integrity of the slab. Practical tests show that the method in the actual production is feasible and effective, with detection and control accuracy of up to ±0.05 mm, indicating that in the production of E0- and E1-level products, the rate of superior products can reach more than 95%.

Study on similarity criterion for fluid-thermal coupling responses of metal plate simultaneously exposed to laser irradiation and airflow

Similarity criterion considering the multifield coupling effect is essential for the scaled thermal test under both laser irradiation and airflow. This paper establishes the similarity criterion for the fluid-thermal coupling responses of metal plate simultaneously exposed to the laser irradiation and high-speed airflow by nondimensionalizing the governing equations. The main dimensionless parameters are obtained, and the scaling law when the temperature scaling factor is equal to 1, which means the temperature remains unchanged in the real and scaled model, is firstly established. Moreover, to broaden the applicability, the scaling law when the temperature scaling factor is not equal to 1 is further deduced, and the correction method based on numerical simulation is proposed to eliminate the error caused by the difference of temperature-dependent material properties in the real and scaled model. Numerical cases are conducted and compared to verify the established scaling laws. Results show that errors of the predicted fluid-thermal responses between the real and scaled model are less than 1 %, affirming the reliability of the scaling laws.

Thermal-flow-force-electrical coupling characteristics of microchannel cooling systems in high heat flux chips

To address the challenges faced by designers of multi-field coupled cooling systems for high heat flux chips, this paper proposes a “near-source” microchannel cooling strategy and establishes a thermal–flow-force electrically coupled model for chips. The effects of chip Joule heat and cooling water flow rate on the cooling performance with respect to multi-field coupling effects were studied. The impact of multi-field coupling effects was revealed, and a method for enhancing microchannel cooling performance in light of multi-field coupling effects is proposed. The results indicated that considering multi-field coupling effects in the microchannel cooling process leads to a deterioration in the thermal performance of chips, accompanied by a significant increase in electrical fluctuations and thermal deformation amplitude. Compared to chips upstream of the cooling water, chips downstream subjected to thermal cascade effects were more sensitive to multi-field coupling effects. Moreover, the temperature variance index, output current, and strain energy density of high heat flux chips were positively correlated with Joule heat but inversely proportional to the Reynolds number of the cooling water for cases in respect of multi-field coupling effects. Additionally, serpentine microchannels maximized the operational performance of high heat flux chips by reducing temperature of chip by up to 55.1%, decreasing strain energy density by 96.7%, and increasing input potential by 120%.

Analysis of multilayered two-dimensional decagonal piezoelectric quasicrystal beams with mixed boundary conditions

Piezoelectric quasicrystals have a broad spectrum of promising applications and research value due to their unique atomic arrangement and multi-field coupling effects. This paper presents a mechanical analysis of the static bending and free vibration problems of two-dimensional multilayered decagonal piezoelectric quasicrystal laminated beams. Mechanical models of the beams are established, and the differential quadrature method in conjunction with the state-space method is utilized to obtain the solutions for the beams with mixed boundary conditions. We first investigated the static response and free vibration problem of quasicrystal laminated beams. By degrading them into crystalline materials, we verified the accuracy of the method by comparing the results with the existing ones. Then, the effects of different boundary conditions and slenderness ratios on the stresses, displacements, electric potentials, and electric displacements of quasicrystal laminated beams under normal mechanical loading and free vibration are investigated. Subsequently, the effects of different laying modes on the mechanical properties of the quasicrystal laminated beams when the material principal axis of the beam is changed are also analyzed.

Multi-field coupling in designing embedded microchannels for three-dimensional integrated chip: A topology optimization approach

Topology optimization methods have shown promise in enhancing the heat transfer performance of microchannel structures. However, the thermal-electrical-force multi-field coupling effects in three-dimensional integrated chips present a complex heat generation scenario that necessitates their consideration in the design of embedded microchannel structures. Here, we perform topology optimization of embedded microchannels specifically tailored for three-dimensional integrated chip, with a specific focus on the multi-field coupling effects of through-silicon-via structures within the topology optimization process. A new and improved 2D microchannel structure that exhibits superior heat transfer performance was obtained by analyzing the effects of pressure drop constraints within the channel, as well as fixing the microfin diameter and local heat flux of through-silicon-via. Furthermore, the obtained topology optimization results were validated through rigorous three-dimensional numerical simulations. The findings demonstrate that the new microchannel structure, when compared to the original microfin model, yields a significant improvement in the comprehensive heat transfer performance coefficient, achieving a remarkable enhancement factor of 1.43. Furthermore, under identical flow conditions, the structural stress within the chip experiences a substantial reduction of 43.9%. These outcomes underscore the efficacy of the topology optimization approach in effectively addressing the thermal management challenges associated with three-dimensional integrated chip.

Mechanical Analysis of Functionally Graded Multilayered Two-Dimensional Decagonal Piezoelectric Quasicrystal Laminates with Imperfect Interfaces

Quasicrystals have a wide range of applications due to their unique multi-field coupling effects and distinctive physical and mechanical characteristics. In this paper, the static and dynamic problems of imperfectly bonded, multilayered, functionally graded, two-dimensional decagonal piezoelectric quasicrystal laminates under mixed boundary conditions are investigated. The state equations in a concise and compact matrix form can be expressed by using differential quadrature regional discrete point expansions in any layer of the laminate. This allows for the representation of displacement, stress, electric potential, and electric displacement components. Then, different imperfect interface conditions are introduced to characterize specific structural and electric contact properties at the bounding interfaces, which are further converted to the interface propagator matrix. Numerical examples are carried out to investigate the impact of varying interface compliances, load types, and functional gradient factors on the static bending and vibration phenomena of QC laminates. These results can be used as references to validate existing or future numerical work on QC laminates and could further guide the design of related QC laminate structures.

Numerical investigation of gas and sand production from hydrate-bearing sediments by incorporating sand migration based on IMPES method

Accurately predicting gas and sand production from oceanic gas hydrate reservoirs considering multi-field coupling effects is crucial. To address this, we first systematically summarized the multi-field coupling effect of gas hydrate-bearing sediments (GHBS) during sand production and gas production. After that, we developed a thermo-hydro-mechanical coupled model that incorporates both sand detachment and sand migration (THMS) to describe the complex behaviors of fluid and solid flow. We then solved this model using the implicit pressure-explicit saturation (IMPES) method and incremental scheme for a cylindrical core and presented a detailed algorithm derivation process for reproducibility. The newly developed model was validated through comparison with available experimental data. Subsequently, several parameter effects, including outlet pressure, initial hydrate saturation, load stress, and sand detachable ratio, on the behaviors of fluid and solid flow were studied. The computation results indicate that high sand production can be induced by low outlet pressure, high initial hydrate saturation, high load stress, and high sand detachable ratio. Meanwhile, high cumulative gas production can be caused by low outlet pressure, low initial hydrate saturation, high load stress, and high sand detachable ratio.

Analytical solutions for the plane thermoelastic problem of a nano-open crack in one-dimensional hexagonal quasicrystal non-periodic plane

As a stable material at high temperatures, the presence of cracks and other defects greatly reduces the performance of quasicrystals (QCs). The plane thermoelastic problem of one-dimensional hexagonal quasicrystals (1DHQ) non-periodic plane containing a nano-open crack is analyzed using surface elasticity theory. The closed form solutions are obtained to describe the thermoelastic field corresponding to the nano-crack by the Fourier integral transformation technique. The analytical solutions of the thermal stress intensity factors (TSIFs) and the strain energy density factor (SEDF) at the crack tip are derived explicitly. The influence of the applied loads, the surface effects and the multi-field coupling effects on the TSIFs and SEDF are discussed. The numerical results reveal that the surface effects have an obvious impact on TSIFs with small applied loads, and the surface effects will inhibit the propagation of nano-open cracks. The research results of this study provide some reliable theoretical references for the development of nano-QCs.

CO2 corrosion prediction on 20# steel under the influence of corrosion product film

Based on corrosion thermodynamics and kinetics, considering the multi-field coupling effects of fluid flow, electrochemical reaction and mass transfer process, a new corrosion prediction mechanistic model was proposed by introducing the influence factor of corrosion product film on diffusion coefficient of ion mass transfer, which is based on the CO 2 corrosion prediction model proposed by Nesic et al. The influence of temperature, flow rate and pH value on CO 2 corrosion behavior on 20# steel was studied by orthogonal tests. Scanning electron microscopy (SEM) and energy spectrum analysis (EDS) was used to analyze the surface and cross section morphology of the corrosion product film, and the thickness of the corrosion product film was measured. The results show that the introduced influence factor can simplify the ion mass transfer calculation in the presence of corrosion product film, and the relative error between the predicted value of the modified model and the experimental results is satisfactorily controlled less than 10%. Compared with the prediction model without considering the influence of corrosion product film, the influence factor can effectively correct the high prediction value of the mechanistic model under the influence of corrosion product film, improve the accuracy and applicability of corrosion prediction, and provide important theoretical guidance for the design, manufacturing, operation and maintenance of oil and gas production pipelines and related facilities.

Multi-field coupling effect of injection on dynamics and thermodynamics of a linear combustion engine generator with slow compression and fast expansion

An asymmetric reciprocating engine (ARE) with slow compression and fast expansion is designed in this paper, which can improve combustion performance and energy conversion efficiency by optimizing piston motion. However, due to the particularity of piston motion, how to consider the multi-field coupling effect of injection position (IP) on dynamics and thermodynamics becomes a key issue. Therefore, this paper proposes a multi-dimensional coupled model including motion, gas exchange and combustion, and uses an iterative algorithm to solve the model. The results show that ARE has better gas exchange performance and higher acceleration near TDC than conventional engines because of its slow compression and fast expansion processes, which lead to its obvious advantages in gas organization and combustion heat release. Furthermore, increasing IP has a positive excitation effect on the operating frequency and the combustion performance of ARE because the changed motion results in a longer ignition delay and a better fuel atomization environment. However, increasing IP continuously will lead to weak turbulent motion, which will greatly reduce the combustion reaction rate. The results suggest that increasing the IP is beneficial to improve the thermal efficiency of ARE and reduce soot generation, but too large an IP is not supported.

Multi-scale simulation of the fracture behavior of non-stoichiometric gadolinia-doped ceria solid electrolytes under the coupled mechanical and electrochemical field

Solid oxide fuel cell (SOFC) works in a complex working environment, which is affected by many factors such as temperature, load and electrochemical reaction. When there are cracks in the material, the multi-field coupling effect will cause the electrolyte performance degradation, even failure and damage. In this paper, the coupling effects of mechanical and electrochemical field on mechanical behavior of gadolinia-doped ceria (GDC) electrolyte are investigated by using the Atom-to-Continuum (AtC) multi-scale method combining molecular dynamics (MD) and finite element method (FEM). Based on the electrochemomechanical coupling theory, we derive the defect diffusion equation of the finite element form. The non-stoichiometry of the cracked GDC electrolyte is calculated, and it is found that the stress concentration at the crack tip will induce non-stoichiometric effects, causing further concentration of oxygen vacancy defects at the crack tip. Subsequently, the effect of electrochemomechanical coupling effect on the fracture toughness of GDC electrolyte is studied by using the AtC multi-scale method. At 800°C under oxygen partial pressure logPO2=−22, this multi-field coupling effect reduces the fracture toughness of 10GDC and 20GDC by 16.13% and 23.33%, and this effect is more apparent with the increase of oxygen partial pressure gradient and external load.

A (Bi2O2)2+ layer as a significant carrier generator and transmission channel in CaBi2Nb2O9 platelets for enhanced piezo-photo-catalytic performance

The low photocatalytic conversion efficiency, poor light absorption and high charge recombination rate of traditional semiconductor photocatalysts continues to be a significant research challenge. In this paper, by combining detailed experimental and modeling techniques, we report on the unique potential of CaBi2Nb2O9 (CBN) platelets that can couple both piezo- and photo- multi-field effects to overcome these issues and realize high-efficiency hydrogen production and dye degradation. The surface adsorption of OH− and dye molecules is improved as a result of the built-in electric field, thereby demonstrating an enhanced piezo- and photo-catalytic H2 production activity, with a high rate of 96.83 μmol g−1 h−1. The piezo-photocatalytic decomposition ratio for 100 mL RhB dye of 10 mg/L can reach up to 98.7 % in 32 min using only 0.05 mg of CBN platelets (k = 0.131 min−1). It is shown that the careful introduction of regularly arranged layers of (Bi2O2)2+ into the CBN platelet structure provides a high transport of photoelectrons via a pathway of (Bi2O2)2+ → (CaNb2O7)2− → CBN surface. The electron density distribution of Bi atoms is also found to be enriched on the facets of (020) and (200) crystal planes in the CBN platelets, which is beneficial to the oxidation reduction reaction. Furthermore, the large deformation of CBN platelet during the application of ultrasound leads to an increase of the piezo-induced built-in electric field to improve charge separation and migration. This work therefore provides a new perspective in the design and manufacture of advanced materials with enhanced piezo- and photo-catalytic performance by exploiting multi-field coupling effects.

Numerical and experimental investigations of concrete lined compressed air energy storage system

Compressed air energy storage (CAES) is considered one of the critical technological approaches to bridging the gaps between clean electricity production and electricity demand. An in-situ air storage test in a shallow buried underground cavern was introduced to understand better the connection and mutual influence between aerothermodynamics and cavern safety stability in various aspects of CAES. Moreover, a corresponding finite element model of the multilayer cavity structure considering the multi-field coupling effect and rebar embedding was developed to verify the experimental results. The experimentally measured temperature, air pressure, displacement, and stress are in good agreement with the calculated results, showing the success of the modeling in this paper. The cavern temperature shows large fluctuations for the whole storage phase. The maximum temperature of the air and the cavern walls are 53 °C and 46 °C, respectively. After water circulation heat exchange, the temperature can be regulated within a reasonable range (<40 °C). The cavity walls can reverse the heat output of the air through heat exchange during the discharging phase resulting in a slower temperature drop. The concrete stress is about 1/10 of the reinforcement stress, showing that the deformation between the rebar and concrete is coordinated, and both are in the elastic deformation stage. The sealing layer, reinforced concrete lining, and rock surrounding share the internal air pressure, accounting for 2.07%, 27.55%, and 70.38%, respectively. The surrounding rock is the most important part of bearing the internal pressure, and it is an essential means to improve the safety of the cavity by carrying out anchoring and grouting of the surrounding rock. The thermodynamic processes and stress response are affected by the convection heat transfer coefficient, thermal conductivity, charging time, and leakage rate.

A fractal power-law approach for investigating the interactions between reservoir microstructure and gas migration

As one of the most significant clean energy sources, the migration characteristics and extraction processes of coalbed methane (CBM) have been extensively studied. The structural distribution and evolutionary characteristics of reservoir fractures, as the main conduit for gas migration, significantly affect the permeability and gas production. However, few models have been able to quantitatively and accurately explore reservoir micro–macro interactions under coupled thermal-fluid–solid effects. This work develops a new highly coupled model based on the widely adopted power-law function to quantify reservoir thermal conduction effect, gas pressure evolution, reservoir deformation, in situ stress, the adsorption–desorption effect, and reservoir microstructure evolution. Three parameters are adopted to quantitatively characterize the reservoir structure: (1) fracture power index αf (to characterize the fracture density), (2) fracture length ratio rf (to characterize the fracture size), and (3) the maximum fracture length l. The results demonstrate that the fractal network is a special kind of network in the power-law length distribution. The proposed power-law seepage model is able to accurately characterize the evolution of reservoir microstructure and the impact of microevolution on extraction under multi-field coupling effects, compared to the traditional power-law model. The proposed model can provide a good theoretical and practical support for the study of CBM migration and extraction.

Laser Induced Graphene/Silicon Carbide: Core–Shell Structure, Multifield Coupling Effects, and Pressure Sensor Applications

AbstractLatest advances have witnessed the laser scribing of various active materials from synthetic polymers to natural sources without masks, post‐treatment, or toxic substances. However, laser induced graphene (LIG) on renewable precursors usually requires flame‐retardant pretreatment and multistep pulsed or defocused irradiation. Laser scribing of silicon carbide (SiC) from polydimethylsiloxane (PDMS) is limited by its high transparency over a broad wavelength range. Here, a structural design strategy is adopted to solve these two dilemmas at the same time, that is, laser scribing of carbonized cloth/PDMS to prepare LIG/SiC composites. Natural cotton cloth is precarbonized and inserted in PDMS substrate to facilitate heat absorption for the in situ formation of SiC, while the soft PDMS attached to the carbonized cloth absorbs heat and isolates oxygen, enabling the conversion of amorphous carbon to LIG. Under these multifield coupling effects, a core–shell LIG/SiC electrode is formed on the carbonized cloth with tunable mass ratio, morphology, and graphene defects. Experimentally, the LIG/SiC pressure sensor exhibits a good sensitivity of 1.91 kPa−1 in the super‐wide sensing range of 0–226.7 kPa. By demonstrating different scenarios such as real‐time monitoring of large body movements, tiny pulses and heartbeats, the flexible pressure sensors hold great promise in wearable electronics.

Bending and Wave Propagation Analysis of Magneto-Electro-Elastic Functionally Graded Porous Microbeams

In this paper, a microstructure-dependent magneto-electro-elastic functionally graded porous (MEEFGP) beam model is proposed using a variational approach. To account for the microstructure effect, the extended modified couple stress theory is incorporated in the new model. In addition, the porosity variation of the two-phase beam model through the thickness direction is also considered. The new developed model is verified in terms of its correctness with a FEM model. Based on the equations of motion and boundary conditions derived by Hamilton’s principle, the static bending and wave propagation behaviors of the new model are analytically determined. The results prove the existence of the microstructure effect and the magneto-electro-elastic multi-field coupling effect. There are significant differences between the new model and the classical model at the microscale. Moreover, the porosity also has an important influence on the mechanical properties of the new model. The results predicted by the new model can provide the theoretical basis for the design of microscale acoustic wave devices and micro-electro-mechanical systems.

Continuous Flat Pressing of MDF Quality Control Model Framework and Collaborative Programming Approach Based on Wood Fiber Hot Pressing Mechanism.

The increasing demand for forestry resources is driving the need for smarter systems capable of saving and protecting forests that can optimize agile forestry production. This study uses the continuous hot-pressing process of wooden medium-density fiberboard (MDF) to investigate the possibility of automatic quality control of the continuous flat pressing process. For this purpose, conceptual digital twin modeling for mechanism and sequence parameter control was conducted based on the cellular automata (CA) theory. A distributed coordination mode framework was constructed, and a craft control programming method was proposed for the quality control of MDF continuous flat pressing. Based on the MDF continuous flat press craft mechanism and control standards, a framework of five distributed flat press cooperative control mode elements for the cylinder array of the continuous panel system (CPS) was defined. To satisfy the distributed distance servo and pressure servo demands of the multi-stage hot pressing craft design, five kinds of synergy collaborative control modes of multiple rack groups were constructed using mode elements: For the four types of typical deviations in slab production, i.e., thickness, slope, depression, and bulge, a multi-zone mutual cooperative mode craft control sequence was programmed. According to the type and intensity of real-time deviation, the corresponding regulation sequence was applied. This effectively counteracts the deviation caused by the uncertainty interference due to the multi-field coupling effect in actual production. The application tests demonstrate that the adjustment and response time of the continuous flat press were greatly improved, and the quality superiority rate is controlled above 95%, thereby confirming the effectiveness of the control strategy.