Sandblasting passivation can effectively improve the cutting edge quality of cemented carbide inserts; however, the process is difficult to observe directly by experiment, and its underlying mechanism still requires further investigation. In this paper, the discrete element method-computational fluid dynamics (DEM-CFD) coupling method is applied for the first time to the abrasive blasting passivation process of cemented carbide inserts P20. This work aims to reveal the synergistic material removal mechanism and the underlying principle of blasting passivation. Systematic quantitative analysis is carried out to explore the effects of key process parameters, including blasting pressure, abrasive concentration, standoff distance and impingement angle, on liquid-solid two-phase flow characteristics, particle impact velocity, impact force and cutting edge wear behavior. Furthermore, the inherent relationships between these parameters and edge morphological evolution are clarified. The results show that: Significant plastic deformation occurs around the impact center region. The particle motion characteristics are dominated by the flow field, and the two exhibit good consistency. Sandblasting pressure and distance significantly affect the uniformity of particle distribution and, together with abrasive concentration, influence the particle impact velocity at the cutting edge. Blade wear primarily depends on the normal impact force of particles, which increases with higher sandblasting pressure and blasting angle. Surface morphology and cutting edge geometry are affected by the sandblasting process, and the simulation results are in good agreement with the experimental measurements.

Grinding serves as the primary manufacturing process for producing cemented carbide milling tools. However, the ground surfaces of these tools often suffer from defects such as grinding burns, cracks, pitting, and nonuniform roughness, which significantly impair machining efficiency and tool service life. To improve tool performance and gain deeper insight into the grinding mechanisms, this study performed grinding experiments on YG12 cemented carbide end mills by using a resin-bonded diamond grinding wheel. A multi-scale analysis of the surface integrity of the carbide mills under various grinding parameters was conducted by integrating molecular dynamics simulations with electron backscatter diffraction at both meso- and micro-scales. The results reveal that WC grains experience fragmentation and spalling under high stress, with certain grains rotating to accommodate plastic deformation. Moreover, increasing the wheel speed or decreasing the feed rate was shown to enhance the surface morphology and reduce residual stress. The grit size of the grinding wheel also exerts a notable influence on surface integrity; in particular, the D20 wheel produced the highest residual stress of 1557.46 MPa. Combining experimental and simulation methods, this work elucidates the effects of key grinding parameters on surface quality and offers valuable theoretical insights for optimizing industrial grinding processes.

The surface quality of machined gears is closely related to operational energy efficiency and service durability, which affect the achievement of dual carbon goals in sustainable manufacturing. This study proposes a radial pre-stressed grinding method for gear manufacturing. Firstly, an analytical model for the radial pre-stress exerted on the gear inner hole was established by virtue of thick-walled cylinder theory. Secondly, a simulation and experiment were conducted under the same pre-stress conditions to obtain the radial stress. The theoretical, simulated, and experimental results were compared and discussed. Then, gear grinding simulations were performed at different pre-stress levels, grinding depths and grinding speeds. Finally, the grinding parameters were optimized by means of response surface methodology (RSM). This study recommends incorporating gears manufactured with radial pre-stressing into relevant industrial standards for green and low-carbon development. The results indicate that applying radial pre-stress to the gear inner hole significantly influences surface roughness and residual compressive stress after grinding, whereas it exhibits a minimal effect on grinding force. After optimization, compared with the initial simulation results, surface roughness is reduced by 12.5%, the absolute value of residual compressive stress is increased by 52.6%, and grinding force is decreased by 2.1%. The implementation of radial pre-stressed grinding in gear manufacturing requires institutional support, including its integration into green standard institutions, the development of technical specifications, and the establishment of promotion mechanisms. Such integration can be facilitated through national 'Green Factory' initiatives, comprehensive intellectual property protection, and targeted personnel training.

To address the inherently low thermal conductivity of polymer composites in electronic thermal management, this study proposes a strategy for constructing thermal conduction networks through magnetic field-induced alignment of multi-dimensional fillers. During magnetic modification, the pre-modification effects of poly(sodium 4-styrenesulfonate) (PSS) and silane coupling agent KH-560 on the filler surface were first compared. Experimental results indicated that the fillers pre-modified with PSS exhibited a coercivity of 59 Oe and a relative Fe content of 5.59% after magnetic modification, demonstrating superior magnetic responsiveness. After introducing Fe3O4 onto the filler surface, a continuous thermal conduction pathway was constructed by combining external magnetic field alignment with hybrid filling of multidimensional fillers. Herein, twodimensional magnetic boron nitride (mBN) constituted the thermal skeleton, with one-dimensional magnetic carbon nanotubes (mCNTs) bridging the gaps to create a continuous thermal network. When 5 wt% of mCNTs was introduced into the composite containing 10 wt% mBN, the thermal conductivity increased by 134% relative to EP, reaching 0.574 W/(m center dot K). Furthermore, thermogravimetric analysis results demonstrated that the incorporation of mCNTs effectively reduced the maximum mass loss rate of the composites. This work demonstrates the potential of magnetically aligned multi-dimensional fillers to optimize thermal networks, establishing a foundation for low-filler, high-thermal-conductivity composites in thermal management.

Powder paving is an intermediate process of selective laser sintering (SLS). The dimensional accuracy and mechanical properties of sintered components are directly affected by the quality of the powder paving process, which is closely related to the flow characteristics of the powder and the process parameters of powder paving. This study investigated the simulation and optimization of the nylon powder paving in SLS by combining a discrete-element-method numerical simulation with a process test. A dynamic model was established to describe the flow and paving process of nylon powder at a preheating temperature considering mesoscopic van der Waals and electrostatic forces. The effects of the physical parameters and ambient temperature on the flow characteristics of nylon powder were analyzed, and the intrinsic relationship between the physical parameters of nylon powder, the process parameters of powder paving, and the quality of the powder paving were explored. A multi-objective regression model of the quality of powder paving was established using the response surface methodology, and a genetic algorithm was adopted to optimize the quality of the powder paving. A scientific and intelligent database of the nylon powder paving process in SLS was constructed by matching the process parameters of powder paving and physical parameters of the nylon powder, and the level of the SLS process was improved.

This study investigates the wear failure mechanisms of TiAlN-coated cutting tools through a combination of the discrete element method (DEM) and cutting experiments. The research establishes a mesoscopic-scale correlation between microscopic damage and macroscopic failure to provide scientific insight into wear mechanisms. Three-dimensional discrete element models of the coated tools and workpieces were developed using the bonded particle model (BPM). The micro-parameters in the BPM were calibrated and validated against experimental data from indentation, scratch, compression, tension, and bending tests, ensuring that the relative errors of key parameters was constrained to within 10%. A three-dimensional discrete element cutting model was subsequently established using the calibrated micro-parameters, and cutting simulations were performed at different cutting speeds. Combined with turning experiments, systematic analyses were conducted on stress distribution, parallel bond fracture behaviour, and tool wear failure mechanisms. The results demonstrate that simulation data agree well with experimental measurements in terms of cutting force, parallel bond damage ratio, and flank wear, confirming the reliability of the model. At low cutting speeds, crater wear predominates, with the parallel bond damage ratio remaining below 12%. At a cutting speed of 400 m/min, a high-stress zone near the tool nose initiates crack formation, and the parallel bond damage ratio approaches 30%, while failure modes such as coating spalling, chipping, and cutting-edge breakage are markedly intensified. This study elucidates the relationship between microscopic damage and macroscopic failure of coated tools under varying cutting speeds, offering a scientific basis for optimizing cutting parameters. It also verifies that DEM is an effective approach for analysing the wear failure mechanisms of coated tools.

The intrinsic differences between the γ and α₂ phases in γ/α₂ duplex TiAl alloys complicate surface integrity formation during nanogrinding, while ultrasonic vibration further increases the uncertainty in contact states and phase-region responses. To address this, a molecular dynamics（MD） model for single-abrasive nanogrinding of γ/α₂ duplex TiAl is established, with four trajectories serving as independent physical variables to systematically regulate the abrasive–workpiece contact state. By partitioning the grinding process into an α₂-stable zone, a phase interface zone, and a γ-stable zone, the mechanisms by which trajectory-mediated contact state evolution governs phase-selective deformation and damage are elucidated. The results reveal a pronounced phase-selective effect: tangential vibration disperses shear deformation and reduces subsurface damage in both phases; normal vibration suppresses deep dislocation propagation in the γ phase but aggravates indentation-type damage in the α₂ phase; coupled vibration spatially disperses stress and residual stress, significantly lowering tensile hydrostatic stress, yet the phase interface retains transient high-load peaks. The interface serves as a mechanical transition zone exhibiting a separation between cycle-averaged and local peak responses. The underlying origin is that ultrasonic trajectories, by modifying contact continuity and the force–velocity projection, redistribute the mechanical energy conversion between shear flow in the γ phase and indentation deformation in the α₂ phase. This study provides an atomistic explanation for the phase-selective damage mechanism and offers a transferable analytical framework for machining difficult-to-machine multiphase materials.

The effects of deep cryogenic treatment (DCT) soaking time (0, 2, 6, 12, 24 and 48 h) on the microstructural evolution and mechanical properties of an ultrafine WC-Co composite were investigated in detail. The microstructure, phase composition, residual stress, and mechanical properties of cemented tungsten carbide specimens were enhanced after DCT. With the optimal DCT soaking time of 2 h, ultrafine cemented tungsten carbide exhibited the highest hardness and wear resistance. The wear rate of treated specimens was reduced by 24% compared to the untreated specimens. The fracture toughness increased by 17% after 12 h of DCT. A cost-benefit analysis of mechanical enhancements and processing efficiency identified the 2 h as the optimal DCT soaking time. Deep cryogenic treatment caused the refinement of WC grains, precipitation of eta phase, martensitic phase transformation, and an increase in residual compressive stress in cemented tungsten carbide. These factors collectively enhanced the hardness, fracture toughness, and wear resistance of cryogenically treated cemented tungsten carbide.

Aiming to address the requirements for composite phase change material (CPCMs) in various applications, this paper describes the preparation of a kind of CPCMs combining thermal conductivity with flexibility. The CPCMs use paraffin wax (PW) as the phase change component. Olefin block copolymer (OBC) is used for encapsulation. Boron nitride (BN) is incorporated as a thermally conductive filler to enhance heat transfer. The prepared CPCMs exhibit favorable mechanical properties and flexibility. The maximum tensile strength and the maximum yield strength reach 5.05 MPa and 3.53 MPa, respectively. The maximum elongation at break reaches 92.12%. Furthermore, the effects of BN content on thermal conductivity, phase change performance, and overall properties are investigated. CPCMs offer high thermal conductivity while also providing comprehensive performance in terms of flexibility and dimensional stability. The maxima of enthalpy of melting (ΔHm) and the enthalpy of freezing (ΔHf) are 150.37 J/g and 147.92 J/g, respectively. The thermal conductivity reaches 1.02 W m−1 K−1. CPCMs exhibit excellent photothermal performance, capable of maintaining exothermic plateaus at 40 °C for 400s-500s. Because of the flexibility, CPCMs also demonstrate considerable potential in multi-scenario application. In the wearable thermal management experiment, the temperature stabilizes within the range of 36.32 °C to 40.51 °C, which is highly suitable for the human body. In the building experiment, the roof temperature is reduced by 10.86 °C. Moreover, the CPCMs exhibit excellent performance in battery thermal management simulations. Compared with natural cooling, the maximum battery temperature decreases by 9.88 °C. The maximum temperature difference is reduced from 8.92 °C to 2.95 °C, compared to forced air cooling. CPCMs based on PW/OBC/BN offer broad prospects for multi-scenario applications.

This study aims to develop and validate a DEM-CFD coupled simulation model for the wet abrasive jet blunting process of cemented carbide inserts, to better understand the underlying mechanism of this process and to provide a theoretical basis for process parameter optimization. To this end, the DEM contact parameters were calibrated and validated through a combined experimental and simulation approach. The bonded particle model (BPM) parameters for the cemented carbide inserts were calibrated using response surface methodology (RSM), and the CFD model was established with appropriate mesh generation and grid independence verification. The outlet velocities under different blasting pressures were simulated and compared with theoretical calculations, yielding a maximum relative error of 5.32%, which confirms the validity of the model. Based on this model, the motion characteristics of the abrasive flow were further analyzed. The results demonstrate that after being accelerated by the jet, the particle velocity gradually decays and spreads laterally with increasing blasting distance in the main flow region. The blasting pressure and abrasive concentration exhibit opposite effects on the particle velocity.

Ceramic cutting tools suffer from severe accelerated wear during the machining of nickel-based superalloys, which considerably compromises machining efficiency and tool life. Theoretically, pre-stressed cutting technology offers an efficient and convenient method for regulating cutting forces during the machining process. To investigate the mechanism by which pre-stressed cutting suppresses wear in ceramic tools, this study employs a coupled Discrete Element Method-Finite Element Method (DEM-FEM) modeling approach to simulate crack propagation and wear evolution in Sialon ceramic tools under varying cutting parameters and pre-stress conditions. Simulation results are rigorously correlated with experimental measurements to validate predictive accuracy. Finally, a novel pre-stressed loading device for ring parts is developed to perform a pre-stressed cutting experiment. The results demonstrate that applying pre-stress significantly reduces both cutting forces and tool wear: as the pre-stress increased from 0 MPa to 300 MPa, the cutting force decreased from 478.6 N to 381.1 N, accompanied by a notable reduction in both micro-crack propagation and wear rate. In conclusion, pre-stressed cutting effectively mitigates tool wear by improving the mechanical state of the tool, thereby providing both theoretical insights and practical guidance for enhancing the performance of ceramic tools in machining superalloys.

In this paper, shape-stable phase change materials (SSPCMs) were prepared from waste jackfruit peel by carbonization-activation and vacuum impregnation, providing a sustainable solution for efficient energy storage and conversion. The specific surface area of activation jackfruit peel (AJP) was significantly increased from the original 0.39 m2/g to 2446.88 m2/g, and the pore volume and pore structure were also significantly optimized. Through vacuum impregnation with n-docosane (ND), the resulting ND/AJP achieved melting and crystallization enthalpies of 107.17 J/g and 107.33 J/g, respectively, marking enhancements of 71.4 % and 73.3 % compared to ND/JP. TGA and leakage experiments showed that the prepared ND/AJP had excellent thermal and shape stability. In addition, the thermal management capability of ND/AJP when applied to an 18650 lithium-ion battery pack was validated through simulations conducted in Fluent. Compared to the air cooling (2 m/s), the highest temperature and maximum temperature difference of the ND/AJP-air cooling (2 m/s) battery pack decreased from 52.64 degrees C and 12.69 degrees C to 45.41 degrees C and 4.76 degrees C, respectively, significantly improving the safety of the battery pack. This work provided a novel approach to biomass waste management, and the resulting SSPCMs exhibited promising applications in thermal management systems.

The rolling bearing is a cyclic symmetry engineering component, whose failure is related to the regular operation of the rotating machine. For the purpose of real-time monitoring of operational status and predicting the occurrence of the failure, a rolling bearing performance degradation assessment method based on the convolutional neural network (CNN) was proposed with the XJTU-SY tested acceleration life data set. Firstly, the fault signal characteristics of the rolling bearing were extracted by using an energy decomposition method with a wavelet package to form some data sets. Secondly, the degradation performance of the data is classified by the Fuzzy C-means Algorithm for fuzzy data, and then the extracted characteristic signals were processed with CNNs. Thirdly, a multi-layer nonlinear mapping of training data was firstly formed with CNN, and then the adaptive batch normalization adaptive network was added during the training process, and then the deep learning model was formed as a result. Finally, the degradation degree of the three typical rolling bearing failures was evaluated and predicted with this method. The t-SNE technology was employed to visualize the output of the data distribution in two-dimensional space. Compared with the experiment results, the accuracy of the outer ring, inner ring and rolling body of the rolling bearing are 90.84%, 83.3%, and 80.95% with the fault assessment method, respectively. Thus, the degradation of the cyclic symmetry rolling bearing can be identified effectively and determined by the proposed method in advance.

To resolve the conflicting requirements between high filler loading and mechanical degradation in highly thermally conductive polymer composites, this study proposes a novel fabrication strategy. Surface magnetization modification of micron-scale (1 mu m, 10 mu m) and nanoscale (100 nm) boron nitride (BN) particles through Fe3O4 nanoparticles was implemented to establish magnetically responsive filler systems, while epoxy resin (EP)based composites were fabricated using external magnetic field orientation technique. Microstructural characterization demonstrated that paramagnetic mBN particles under a 50 mT magnetic field were aligned along the field direction to form three-dimensional interconnected network architectures, effectively forming continuous thermal conduction pathways. Furthermore, significant synergistic effects of multiscale fillers were demonstrated. When micro/nano mBN was blended at a 1:1 mass ratio (total filler loading: 25 wt%), the thermal conductivity of the composite reached 0.806 W/(m & sdot;K), representing a 229 % enhancement compared to EP. The potential of EP/mBN composites for thermal management applications was thereby indicated. Finite element simulations revealed the dynamics of filler alignment: during magnetic field orientation, smaller filler dimensions were found to correspond with reduced displacement, consequently increasing orientation velocity. This study provides a theoretical foundation for gradient structure design, and the development of epoxy resinbased thermal conductive composites suitable for electronics thermal management.

Grinding results affect the quality of the final product. A single abrasive grain cutting test is an important method to study the complex grinding process. In this study, the discrete element method (DEM) is used to simulate diamond single abrasive grain cutting alumina ceramics to study the damage mechanism of the grinding process, analyze the effects of process parameters and single abrasive grain parameters on the machining damage, cutting force and residual stress, and make a comparative analysis with the single abrasive grain cutting test. Results indicate that the cutting depth and abrasive angle have obvious effects on machining damage, cutting force, and residual stress, while the cutting speed and abrasive grain size have smaller effects. The cutting effect of regular quadrilateral pyramid abrasive grains and regular octahedral abrasive grains is better, the effect on the cutting process is smaller, and the machining damage, cutting force, and residual stress are smaller. The simulation matches the test results, which verifies the reasonableness of the discrete element simulation of single abrasive grain cutting.

To enhance thermal management and optimize coolant efficiency in the peripheral grinding of superalloys, a novel internal-cooling grinding wheel incorporating a directional structural design was developed. The pressurized coolant is delivered to the grinding zone via an integrated system comprising the pipework, tool holder, and symmetrically arranged manifold ports. This symmetrical manifold port configuration enables precise and efficient control of coolant distribution. Through optimization of the symmetrical manifold port positioning using Computational Fluid Dynamics (CFD) simulations, the internal flow field of the grinding wheel was enhanced, resulting in increased outlet flow rates, improved distribution uniformity, and higher effective flow rates. Additionally, cubic boron nitride (CBN) abrasive rings featuring varying groove structures were fabricated via an electroplating process. A vertical peripheral grinding test platform incorporating directional internal cooling was developed to perform grinding experiments on superalloys. The experimental results demonstrated that, compared to conventional flood cooling, directional internal cooling achieved a reduction in grinding temperature by up to 16.9%, a decrease in surface roughness by up to 14.8%, and a reduction in workpiece surface microhardness by up to 6.11%, under equivalent coolant flow rate conditions. Among the tested configurations, the parallel slot design under directional internal cooling yielded the lowest grinding temperature and minimal surface microhardness, exhibiting reductions of 22.7% and 7.12%, respectively, compared to the non-slotted structure. This performance surpassed that of the diagonal slot, V-shape slot, and non-slotted configurations. However, a marginal degradation in surface morphology was observed for the slotted structures relative to the non-slotted design.

Cork powder (CP) is a natural biodegradable biomass material. In this work, a series of shape stable-phase change composites (SSPCCs) based on n-docosane (ND) and CP are fabricated to avoid waste of resources. Four different mesh numbers (80-600) of CP are utilized as supporting skeletons for ND. The honeycomb structure of the CP is gradually destroyed, and the folded construction of the cell wall is straightened with the increase of the CP mesh number. Among them, CP80 and CP160 have a complete honeycomb structure, which can better encapsulate ND inside the cell, and the encapsulation ratio of ND is about twice as high as that of CP400 and CP600. Due to the excellent hermeticity of CP160, the corresponding SSPCC has a maximum melting and freezing latent heat are 122.81 J/g and 121.31 J/g, respectively, and the mass retention after leakage experiments is still as high as 99.43 %. In heat recovery and photothermal experiments, CP-based SSPCCs can be in with good storage performance. Moreover, the melting and crystallization coefficients for ND/CP160 after cycling are only 1.72 % and 2.44 %, respectively, representing excellent thermal reliability and reusability. In summary, cheap and abundant CP can be applied to prepare SSPCC with favorable thermal energy storage and conversion performance.

Lotus shells represent an underutilized renewable resource with desirable porous architecture for producing bio-based phase change composites (PCMs). This research endeavors to fabricate a series of shape-stable phase change composites (SSPCCs) based on n-docosane (ND) and waste lotus shells to enhance heat utilization, solar photothermal energy conversion, and promote environmental protection. Both carbonization and activation processes play a critical role in the formation of desired pore structures. The carbonized lotus shells (CLS) and activated lotus shells (ALS) exhibit superior specific surface areas, reaching 147.70 m2/g for CLS and 1652.35 m2/g for ALS. Notably, the composite of ND integrated with ALS (ND/ALS) exhibits satisfactory latent heat storage of 93.68J/g, excellent leakage prevention, and exceptional thermal cycle stability. Subsequently, the ND/ALS displays a significantly enhanced thermal conductivity of 0.482W/(m·K) with an appreciable increment of 189% compared to ND. Furthermore, the obtained SSPCCs present good chemical compatibility, satisfactory thermochemical stability, and outstanding thermal management capability. In conclusion, the novel waste lotus shell-derived SSPCCs exhibit extensive potential for thermal management, such as heat recovery, solar energy conversion, and temperature regulation. This research not only introduces a promising avenue for enhancing sustainable materials in energy storage and conversion but also pioneers an innovative recycling strategy for waste lotus shells, thereby contributing to both environmental sustainability and efficient resource utilization.