Hydroforming is an effective way for precision manufacturing of complex thin-walled components of aeroengines.According to the micro size characteristics of thin-walled superalloy C-shaped seal ring components of an aero-engine,a two-steps hydroforming process was proposed.The stress-strain analysis of multi-steps hydroforming process was conducted,and the finite element analysis model of multi-step hydroforming process was established.The impact of process variables,such as the height of the blank forming and the hydraulic loading path,on the forming quality of the seal ring was investigated using numerical simulation and process experimentation.Failure modes,such as the loss of section geometric characteristics,inadequate die attaching,and excessive wall thickness thinning,were also investigated.The process parameters were optimized.The results show that the two-step hydroforming process can achieve accurate forming of a thin-walled C-shaped metal seal ring.By using the optimized process parameters:height of blank forming of 1.0mm,first pass cavity pressure of 140 MPa,second pass cavity pressure of 180 MPa,the high-quality C-shaped seal ring with the degree of blank molding of 93.9%,thinning rate of 10.5%and wall thickness uniformity of 85.5%can be made.

A novel optimization design method for loading paths was proposed, which not only converted complex path optimization into the optimization of discrete point coordinates to reduce the difficulty of solving, but also integrated machine learning to enhance efficiency and solution accuracy. For the multi-stage hydroforming of ultrathin M-shaped component, the analytical models for key process parameters were derived based on static mechanical analysis. Through analysis of the process parameter boundary constraints, a process window was constructed, revealing a positive correlation between the maximum fracture pressure and the strain ratio. A loading path with three characteristic points was designed for forming the M-shaped ring. Pre-bulging pressure and deformation distance were found to have significant effects on wall thickness and edge movement, while the design space for pre-bulging pressure, deformation distance and feeding bulging pressure was established. Simulation results from uniform design experiments served as training samples to develop a machine learning model that elucidates the relationship between process parameters and forming quality. Using a genetic algorithm, the optimal loading path was determined and subsequently validated through experiments. The experimental results demonstrated that the formed M-shaped parts using the designed optimal loading path exhibited excellent forming quality. The cross-sectional shape accuracy of the formed component aligned well with the theoretical values. Furthermore, the maximum thickness thinning rate of the part was only 6.66%, further validating the effectiveness of the proposed optimal loading path design method for process parameters design in multi-stage forming processes.

Electropulsing-assisted aging (EAA) has emerged as a promising route for modifying the microstructure and mechanical properties of thin-walled superalloy components. However, the relationships among current parameters, γ″ precipitate evolution, and mechanical response remain insufficiently understood. In this study, EAA and uniaxial tensile tests were performed on GH4169 sheet specimens. An electromigration-informed precipitate evolution model was established based on TEM observations, and a crystal plasticity finite element model (CPFEM) incorporating precipitate shearing and Orowan bypassing resistances was then developed, with a multi-phase representative volume element (RVE) model. The constitutive framework was implemented in Abaqus using VUMAT. Parameters were identified via inverse FE calibration with the particle swarm optimization (PSO) method. The results indicate a temperature-driven enhancement of electromigration during the γ″ coarsening process and a strengthening mechanism based on multi-mode shearing and bypassing. These findings provide a mechanistic basis for describing the EAA-modified tensile response of GH4169 and offer useful insight for future EAA-assisted processing of thin-walled superalloy components.

The precise forming of complex thin-walled metallic components can be achieved through composite manufacturing process, where the macroscopic mechanical response and microstructural evolution exhibit significant coupling effects. A general multiscale sequential simulation framework was developed by coupling crystal plasticity finite element (CPFE) and cellular automaton (CA) models. A bidirectional grid mapping and data transfer method was established to address grid incompatibility and physical quantity mapping between different models. During the transfer from the CPFE model to the CA model, the proposed grid refinement mapping approach achieves lossless data transmission compared with the nearest-neighbor mapping method. In the reverse transfer from CA to CPFE, the average data transmission error is also nearly negligible when the coarsened element size approaches the CA cell size. The proposed multiscale simulation framework is applicable to both 2D and 3D conditions. For simulations of a two-stage uniaxial tension with intermediate annealing, the average prediction error of the 2D and 3D models is about 5%. Although the 3D model exhibits slightly improved prediction accuracy, the computational cost is approximately six times that of the 2D model. It indicates that the 2D model provides a reasonable balance between computational efficiency and predictive accuracy. Furthermore, the multiscale framework was applied to simulate the post-heat treatment process of additively manufactured alloy. The prediction errors for the recrystallized volume fraction and average grain size are both below 10%, and the stress-strain curves during subsequent uniaxial tension is predicted with an accuracy of approximately 95%. The results from the two application cases demonstrate that the proposed coupled model can accurately capture the mechanical response during deformation as well as the static recrystallization behavior during annealing, confirming the generality and reliability of the multiscale simulation framework.

The increasing thrust-to-weight ratio of modern aero-engines has rendered thermal management under high heat-flux conditions a critical bottleneck on the development of next-generation turbofan engines. While the surface air-cooled air-to-air heat exchangers integrated into the bypass duct offer an effective solution for pre-cooling high-temperature bleed air, their application is constrained by strict requirements on pressure loss control, geometric compactness and load-bearing capability. To address these challenges, this study developed a structure-function integrated surface air-cooled air-to-air heat exchanger, featuring a curved base that conforms to the bypass duct casing to simultaneously perform heat transfer and structural support. A numerical framework combining computational fluid dynamics (CFD) and response surface methodology (RSM) was employed to quantify the influence of microchannel geometric parameters on the performance evaluation criterion (PEC), indicating that channel width is the dominant parameter governing comprehensive performance, followed by spacing and depth. With the optimized configuration (spacing = 1.99 mm, width = 1 mm, depth = 3.64 mm), a sequentially coupled thermo-mechanical finite element analysis was conducted for further evaluation of the load-bearing capacity. Experimental validation under representative operating conditions demonstrated good agreement with numerical predictions, with pressure-drop deviations within 15% (hot side) and 35% (cold side), while the temperature-drop deviations below 14%. Weighting only 1.1 kg, the integrated heat exchanger achieved reduced temperature exceeding 110 K, confirming the feasibility and superior performance of the proposed structure-function integrated design for aero-engine bypass duct thermal management.

Refractory high entropy alloys (RHEAs) exhibit significant application potential in the manufacturing of advanced structural components due to the excellent high-temperature properties. In this study, the process combining mechanical alloying (MA) and field-assisted sintering technology (FAST) was adopted to successfully fabricate a high-performance TiCrNbMoTa RHEA and high-precision leading-edge skin samples. The effects of ball milling speed and time on the mechanical alloying behavior of alloy powders were systematically investigated, and the influence of sintering temperature and holding time on the alloy’s microstructure and mechanical properties was analyzed. Additionally, the graphite mold design was optimized via thermo-electric-mechanical coupled finite element simulation to achieve the near-net shaping of skin samples. The results show that the optimal ball milling parameters are a speed of 700 r/min and a time of 8 10 h. While the sintering temperature is controlled at 1400 1450 ℃ with a holding time of 10 15 min, the alloy achieves the best comprehensive performance, with a room-temperature compressive strength of up to 2499 MPa, a Vickers hardness of 1084.4 HV, and a high-temperature compressive strength of 1819 MPa at 800 ℃. And the skin samples prepared by the two-stage heating strategy exhibit a key dimensional accuracy of ± 1 mm and a relative density of 95.4

With the continuous rise in the power of chips for electric vehicle controllers, traditional air or liquid cooling can no longer meet the current heat dissipation requirements of such controllers. To meet the thermal management requirements of electric vehicle controllers, this study designs and optimizes a novel biomimetic honeycomb microchannel heat exchanger (HMHE) based on the leaf vein fractal network and honeycomb structure. Computational Fluid Dynamics (CFD) was employed to establish the simulation model of HMHE, and the effects of honeycomb grade, channel width ratio (rc), channel width (a1) and channel depth (Hch) on the performance of HMHE were investigated. The comprehensive performance of HMHEs was compared using Figure of Merit (FOM), determining that the three-level Honeycomb Microchannel Heat Exchanger (L3-HMHE) exhibits the optimal performance. Meanwhile, through single-parameter optimization, it was confirmed that the optimal structural parameter range of L3-HMHE is around rc = 0.9, a1 = 8 mm and Hch = 18 mm. Based on the optimization strategy combined with the Response Surface Methodology (RSM), a quantitative correlation model between the structural parameters of L3-HMHE and FOM was established. It was found that the channel width has the most significant impact on the comprehensive performance of the heat exchanger, while the optimal channel structural parameters are rc = 0.8, a1 = 9 mm and Hch = 18 mm, respectively. By comparing the results of numerical simulations and actual experiments, the temperature performance errors and pressure drop errors of the L3-HMHE between numerical simulations and actual experiments are maintained within 6.5% and 11%, respectively, at the load powers of 100 W, 120 W and 140 W, which validates the established numerical simulation model of the L3-HMHE. The FOM of the optimized L3-HMHE reaches 1.283, representing a 77.2% improvement compared with the traditional U-shaped heat exchanger, and it can satisfy the heat transfer requirements under a stable heat generation power of 200 W. The research results provide new insights into the structural design of HMHEs and promote the application of L3-HMHEs in the thermal management of electric vehicle controllers.

Cold-formed steel framed (CSF) structures are widely used owing to their high strength-to-weight ratio and construction efficiency. However, their thin-walled members and open cross-sections increase susceptibility to local failure, rendering them more vulnerable to progressive collapse than conventional hot-rolled steel frames following the loss of a critical member. This study investigates the progressive collapse resistance of a CSF substructure under a middle column removal scenario through quasi-static testing and numerical simulation, with an emphasis on failure mechanisms, internal force redistribution, and resistance evolution. The results demonstrate that the collapse resistance is critically governed by beam–column connection performance, and that conventional connections fail to develop sufficient catenary action. To address this deficiency, an improved connection is proposed, which significantly enhances both the load-carrying and deformation capacities. A simplified design method is subsequently established. The findings provide experimental evidence and theoretical support for the anti-progressive collapse design of CSF connections.

Diamond/copper composites (DCCs) are widely used in heat dissipation of electronic integrated devices on account of their combination of high thermal conductivity (TC) and low coefficient of thermal expansion (CTE). In this study, DCCs were fabricated by spark plasma sintering (SPS) technology. The effects of sintering parameters on the TC of the DCCs were explored. It was found that the TC of the DCCs first increased and then decreased with increasing sintering temperature. As the sintering pressure increased, the TC exhibited a trend of first increasing and then decreasing. With the extension of holding time, the TC exhibited a trend of first increasing and then decreasing. In addition, the effects of the process parameters on the forming process of the DCCs were analyzed from a microscopic perspective, and it was found that the main interface defect of DCCs is the interface gap between copper and diamond. Finally, the main mechanism by which SPS enhances the TC of DCCs was investigated, and it was found that pulsed current can purify and activate diamond and copper particles; in addition, under the action of electric field, copper particles can actively coat the surface of diamond particles. Under the conditions of a sintering temperature of 900 degrees C, a sintering pressure of 50 MPa and a holding time of 10 min, the TC of the composite reached 552 W/(m center dot K), and its CTE was 9.02 & times; 10- 6/degrees C, which meets the usage requirements of highly integrated electronic devices.

Achieving precise geometric control in the forming of complex ultrathin-walled components remains a persistent challenge due to the intricate coordination of multi-process parameters. Critically, the underlying mapping mechanism between geometric evolution and failure initiation has not been fully elucidated. This study proposed a novel analytical framework that quantitatively reveals the nonlinear coupling effects of process parameters on geometric evolution and defect transitions in ring hydroforming. Combining finite element simulations and experiments, the deformation behavior at each stage of the ring hydroforming process was analyzed. Obvious wall thinning was observed during the pre-bulging and feeding-bulging stages. The pressure and displacement exhibited a coupling effect on the geometric shape, the inappropriate loading paths of them may lead to geometric defects such as insufficient height or material accumulation. Based on the mechanical analysis through static equilibrium relationships, the geometric contour evolution characterization models that mathematically characterize the cross-sectional shape transition from circular to elliptical to U-shaped profiles were established, which were utilized to quantify the interrelations among process parameters and cross-sectional shape changes. Furthermore, by integrating critical constraints including minimum plastic deformation pressure, maximum burst pressure, geometric folding and excessive thinning, a 3D "displacement-bulging height-pressure" parameter-defect mapping space was constructed to visually analyze intrinsic relationship. Displacement and pressure exert a non-linear coupled influence on geometric evolution and defect formation. Specifically, an increase in pre-bulging pressure diminishes the driving efficacy of axial displacement on bulging height, explicitly resulting in a contraction of the parameter-defect mapping space. As the cross-sectional profile evolves, the dominant failure mechanism shifts from excessive thinning to either bursting or geometric folding, with the transition point determined by component geometry and loading history. The M-shaped ring, triple-peak ring and multi-wave corrugated flattened tube were successfully manufactured under loading paths designed within the contracted mapping space. Comparative analysis of experimental, simulation and geometric model results regarding cross-sectional profile evolution and wall thinning distributions further validates the mechanistic insights and demonstrates the framework's potential for guiding high-precision forming of complex ultrathinwalled components.

Electro-assisted forming (EAF) was widely applied for forming thin-walled superalloy components. However, temperature, stress, dislocation, and Taylor factor are affected under different current loading directions and amplitudes, which remains insufficiently explained. This study conducted electrically assisted uniaxial tensile tests of superalloy GH4169 sheets. Based on EBSD observations, the current direction significantly influences the transition of grain boundaries from low angles to high angles, forming a unique deformation polarity. Then, a multi-grain RVE model considering the property difference of grain boundaries and interiors was established. Besides, an anisotropic electrical conductivity tensor and current direction factor were established. Based on this, a CPFEM (crystal plasticity finite element method) model was developed to describe the forming anisotropy. Furthermore, under various current directions and amplitudes, the evolution of temperature and dislocation density, as well as the variation of stress–strain curves and Taylor factor, were analyzed. This study provides a novel perspective for expanding the theoretical framework and an insightful interpretation of EAF applications.

The structural dimensions of thin-walled components with irregular cross-sectional geometries have a significant impact on their service performances. The interaction of deviations across multi-dimensions during manufacturing introduces substantial challenges in achieving precise performance control. To ensure the superiority and stability of the rebound performance of metallic seal rings, this study presented a structural precision control method to harmonize the manufacturability, performances and manufacturing cost for complex components with multiple structures. Using the multi-structured metallic seal rings as application case, the influence of structural variables on rebound performance was analyzed and four factors were identified as significant factors. With the response surface method, a quantitative relationship between significant factors and rebound rate was established. Considering the structural manufacturability, high performance and cost, a structural group was selected for precision control. Introducing deviation variables to the quantitative function of rebound rate, the boundary constraints of the tolerance intervals were solved under performance goal and manufacturability accounting for multi-stage fabrication. With objective functions, the optimal tolerance intervals were iteratively calculated through a genetic algorithm. Experimental results demonstrated that all the rebound rates exceeded 95% with the dimensional precision in the constraint intervals. Furthermore, the developed rebound rate prediction model exhibits high accuracy, with a maximum error below 5%. With the service performance and cost assured, through the application of the strategic dimensional reconciliation of manufacturing tolerance control framework, the complexities in maintaining structural precision across the various stages of fabricating components with intricate geometries have been substantially reduced.

Accurate understanding of coupled deformation and annealing behavior is crucial for design and optimization of multi-pass forming. The two-stage uniaxial tensile tests with intermediate annealing were performed to explore the deformation behavior and microstructure evolution of the GH5188 superalloy. Experimental results reveal that increasing prestrain enhances yield strength but reduces the elongation and hardening exponent due to dislocation accumulation. A significant improvement in ductility and work-hardening is observed only under conditions of large prestrain and high annealing temperature. The enhancement is primarily attributed to the dislocation density reduction and the formation of abundant annealing twins during annealing. Furthermore, a new dislocation density-based constitutive model was developed, in which the parameters are characterized as the function of prestrain and annealing temperature. The model can accurately predict stress-strain relationships under varying prestrain and annealing processes, with an accuracy exceeding 93 %. Finite element simulations of a multi-pass forming process for a thin-walled superalloy part were carried out. Compared with the non-annealed condition, the predicted results based on the developed model align more accurately with the experimental observations, demonstrating the ability to capture the effects of deformation and annealing and its effectiveness in the actual forming application. This work provides a physically grounded modeling approach and theoretical support for optimizing multi-pass forming of alloys.

This study employs a combined multi-layer perceptron-random forest algorithm (MLP-RF) model to predict the densification degree and tensile strength of Inconel 718 processed via spark plasma sintering (SPS). Key parameters (sintering temperature, pressure, heating rate, dwelling time, and electrical modes) were analyzed. A 5-10-10-2 neuron architecture optimized via mean square error (MSE) and average error (AE) evaluations achieved high predictive accuracy, validated by experimental data. Performance metrics, including root mean square error (RMSE) and mean absolute percentage error (MAPE), confirmed model robustness, with a correlation coefficient (R) of 94.557 %. Finally, the sintering experiment was conducted in an environment with a vacuum level of 10-4 Pa. Experimental verification highlighted the influence of electrical parameters on densification and mechanical properties. This machine learning framework enables efficient optimization of SPS process parameters for enhanced material performance.

Electrically assisted (EA) forming can either improve or reduce ductility in different metals. This study aims to resolve the anomalous elongation reduction observed in solution-treated Inconel 718 alloys-a significant ductility loss during 600 degrees C EA tension when compared to its conventional isothermal counterpart-by systematically revealing void healing, growth, and nucleation mechanisms under electric current. Threedimensional void morphology characterization and statistical analysis were integrated with a multi-physics representative volume element model, which accounts for heterogeneous electroplastic effects inducing current detours around defects, to comprehensively analyze void evolution mechanisms. The EA specimen at 400 degrees C exhibited a void morphology strikingly similar to the isothermal600 degrees C specimen, rather than its direct isothermal counterpart at 400 degrees C. However, 600 degrees C EA tension triggered explosive nucleation of small voids, leading to ductility deterioration. RVE simulations further revealed that the localized material softening in highcurrent-density defect regions enhanced void healing efficiency under constrained thermal expansion conditions. However, the current convergence near voids or carbides enhanced void growth and nucleation probabilities. Under 600 degrees C EA tension, current detour effects amplified discontinuous strain concentrations near highresistance grain boundaries (GBs) and likely promoted non-equilibrium GB segregation of detrimental elements, which triggered massive small void nucleation at GBs. This study establishes a theoretical foundation for understanding the ductility degradation mechanisms during EA forming and offers critical insights for optimizing current density control and temperature windows in superalloy EA processing.

During the fabrication of thin-walled superalloy structures, materials often undergo complex loading paths and exhibit different mechanical properties compared to those under simple loading paths. For example, when subjected to cyclic loading, superalloy ultrathin sheet exhibits pronounced Bauschinger effect. Furthermore, the achievement of precise forming in thin-walled superalloy components is hindered by size effect. To enhance the forming accuracy of superalloy components, this study systematically investigated the interplay between pre-strain, size effect, and Bauschinger effect, along with their underlying mechanisms. Cyclic deformation mechanical response of GH4169 ultrathin sheets with different thicknesses and grain sizes were thoroughly examined under diverse pre-strain conditions through cyclic shearing test. The evolution laws of Bauschinger parameters, specifically as they relate to varying pre-strains, thicknesses and grain sizes, were further determined. To rationalize these Bauschinger parameter evolution laws, electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) were used to characterize the microstructure of GH4169 ultrathin sheets. Results indicated that the primary mechanism driving Bauschinger effect in GH4169 ultrathin sheets is the arising of back stress from dislocation slip and accumulation. As the level of pre-strain intensifies, Bauschinger effect becomes more pronounced, which is attributed to the intricate interplay between the evolving densities of moving and forest dislocations. Moreover, as grain size decreases, Bauschinger effect undergoes an enhancement due to changes in moving dislocation density and grain boundary strengthening effect. Conversely, size effect inherent to GH4169 ultrathin sheets exerts a dampening influence on Bauschinger effect. This weakening is intimately tied to surface layer effect, which modulates the dislocation density within GH4169 ultrathin sheets. These intricate interactions underscore the complexity of Bauschinger effect in thin-walled superalloy structures and highlight the need for nuanced approaches in material design and processing.

To investigate the densification and strengthening mechanisms of MWCNT/Inconel 718 composites, samples with different MWCNTs content are fabricated by spark plasma sintering (SPS) at varying sintering temperatures. The densification process, the room-temperature flexural and compression properties, the mechanical properties at high temperatures, and microstructure evolution are discussed. Increasing the sintering temperature improves material densification by reducing the number of indented pores and gully defects in the heating and holding stage. The incorporation of MWCNTs, though impeding material density by affecting the bonding of powder particles, can enhance the mechanical properties of the composites through load transfer and Orowan strengthening mechanisms. The composites prepared at 1050 °C with 0.5% MWCNTs content show a high relative density of 97%, a flexural strength of 1090 MPa, a compressive strength of 1523 MPa, and a high-temperature (1200 K) compression strength of 138.5 MPa, which are all much higher than that of Inconel 718 alloy. Finally, turbine blades with complex curved areas are prepared at a temperature of 1050 °C and an MWCNTs content of 0.5%, providing a new idea for forming high-strength superalloy matrix composites that can withstand ultra-high temperatures.

Ultrathin-walled superalloy capillaries, with an outer diameter of 0.9 mm and a wall thickness of 50 to 60 μm, are indispensable components of the heat exchange system in hypersonic precooled aeroengines. To meet rigorous standards for dimensional accuracy and mechanical properties under extreme conditions, this study proposes a process solution design methodology for a novel and green electrically assisted (EA) capillary microforming technology. The methodology systematically addresses three key aspects: critical components, process route, and process parameters. Innovative designs for critical components, including the charging method, charging device, and drawing die, ensured stable excitation of capillaries by pulsed current during the EA drawing process. Given the variations in superalloy elongation under room temperature and EA tension, the EA capillary microforming process route was derived from the conventional capillary microforming process route, which was designed through theoretical calculations and validated by finite element simulation. The temperature and stress field distributions within capillaries during the EA drawing process were analyzed to calculate the drawing safety factor for various passes and temperatures, determining the optimal temperature in the drawn region that maximizes the electroplastic effect while ensuring safety. Additionally, optimal temperature and duration ranges for intermediate EA capillary annealing treatments were established based on the mechanical properties of pre-strained superalloy plates after EA annealing. The effectiveness of the designed process solution was preliminarily validated through process experiments.

The Inconel 718 superalloy was fabricated using spark plasma sintering (SPS) technology with varying sintering temperatures and heating rates. The densification and mechanical property of the sintered superalloys were characterized through tensile and compression tests at room temperature, as well as microscopic analyses. The evidence suggests that the plasma generated between the particles results in evaporative melting on the particle surface and plastic deformation of the particle boundaries, accelerating the densification process is by 3 similar to 4 times. Besides, the grain size refinement coefficient affected by pulse current in the holding stage is 0.7-0.8, leading to a significant grain boundary strengthening during SPS process. The dislocation dominated by ball milling and SPS parameters also helps improve the strength and plasticity of the sintered superalloy. The superalloy sintered at 1050 degrees C with a heating rate of 100 degrees C/min demonstrated the highest tensile and compressive fracture strengths, measuring 1410 MPa and 1983 MPa, respectively, with the tensile and compressive yield strength of 712 MPa and 1557 MPa, respectively. Lower sintering temperatures or higher heating rates results in lower levels of densification and decreased strength. In addition, plasticity is reduced at higher sintering temperatures or lower heating rates due to excessive precipitation of brittle phases.