Thin-walled arc plate parts are widely used in aerospace critical equipment. However, such parts show inconsistent local stiffness at different locations under clamping, and their stiffness varies during the machining process, which brings difficulties in stable manufacturing. To address the problem, the discrete finite element model of a bilateral clamped thin-walled arc plate was established, and its position-associated stiffness distribution was obtained by Ansys Workbench. Subsequently, a discrete mirror milling simulation was carried out based on the “Element birth and death” method to investigate the its stiffness evolution under material removal. It turns out that under bilateral clamping, the stiffness of thin-walled arc plate exhibits a spatial “saddle-like” distribution with a gradient of change up to 54.38%, and the highest stiffness occurring in the position adjacent to the clamping area, while there is also an stiffness reinforcing zone in the center. During a single machining process, the local stiffness change of the workpiece shows non-monotonous positional correlation characteristics, and the central stiffness reinforcing zone still exists. With the deepening of the machining stage, the difference in stiffness between different positions further increases, with the maximum stiffness decreasing by about 69.97%, and the range of deformation reaches 0.2619 mm, which is a non-negligible influence on the machining accuracy.
In this paper, based on the macroscopic finite element method and the microscopic phase field method, a multi-scale simulation model for laser deposition manufacturing (LDM) of TC4 titanium alloy gradient structure was constructed. The model successfully predicted the microstructure evolution of TC4 gradient structures obtained with different deposition layouts and process parameters. The results show that in the gradient structure of large-spot high-energy density deposition followed by small-spot low-energy density deposition, the grains transit from coarse columnar crystals to fine columnar crystals. The formation mechanism of the gradient structure includes the generation of the coarse columnar crystal interface, the nucleation of the fine columnar crystal and the continuous epitaxial growth and competitive growth of the fine columnar crystal. In the sample deposited along parallel directions, small-size grains grow on the top of largesize grains. In the sample deposited along vertical directions, small-size grains nucleate and grow vertically in a T-shape adjacent to the large-size grains. According to the simulated process, TC4 gradient structures were fabricated by LDM and the experimental observations match the simulation outcomes.
Carbon fiber reinforced polymer (CFRP) bolted joint structures, with their excellent detachability and lightweight properties, have exhibited great application potential in the aerospace field. However, the deformation analysis of such structures under the effect of multi-source assembly variables has been a technical bottleneck restricting its wide application. In view of this, this study proposes an analytical framework named “CFRP–bolted joint–generative adversarial network” (CFRP–BJ–GAN) for the deformation analysis of CFRP bolted structures. The framework first introduces a multi-scale geometric deviation modeling method based on statistical parameters of key features, which enables accurate capture of the structural deformation characteristics at different scales. Subsequently, by introducing an advanced ViT encoder architecture, it realizes the deep integration and efficient processing of multiple types of heterogeneous data, thus enhancing the accuracy and efficiency of deformation prediction. The experimental validation results show that the CFRP–BJ–GAN framework outperforms traditional numerical simulation methods in the calculation of all the proposed evaluation metrics, while a single prediction takes only 8 s, which significantly improves the analysis speed. Therefore, the CFRP–BJ–GAN framework proposed in this study provides an efficient, accurate and practical solution for the deformation analysis of CFRP bolted joint structures.
A study was conducted on the error transmission and accuracy prediction methods during the assembly process of aero-engine rotors, and a digital twin-driven method for dynamic prediction and optimization of rotor assembly accuracy was proposed. This method divides the rotor assembly process into two spaces, physical and virtual, as well as two levels of parts and components. It establishes an assembly deviation characterization model and an assembly accuracy dynamic prediction and optimization model, with the core being the dynamic prediction and optimization technology that integrates virtual and real twin data. It can dynamically monitor any assembly node of the rotor and optimize the process parameters of post-assembly nodes. The experimental results show that this method has a prediction deviation of less than 6% for rotor centroid eccentricity, with an average deviation of 3.61%, and a prediction deviation of less than 5° for eccentricity angle, with an average deviation of 2.94°. The coaxiality of the rotor after optimized assembly using this method is improved by about 16% compared to traditional methods, effectively improving the assembly accuracy of aero-engine rotors and providing theoretical support for the optimization and control of aeroengine rotor assembly processes.
Aiming at the problem that insufficient consideration of resource constraints in aircraft final assembly scheduling algorithms results in unexecutable plans, a resource weighted improvement algorithm is proposed, fully considering the spatial constraints, personnel qualification constraints, and the impact of resources on process fe asibility: Dynamic spatial competition constraints triggered by parallel processes were incorporated into traditional resource constraints to optimize the continuity of operational space; Diversified constraints on personnel qualifications were introduced to minimize labor redundancy and better align with real-world production requirements; And material–process–spatial coupled network (MPSCN) was innovatively constructed, in which the entropy weight method was employed to calculate resource weights in the process network, quantifying the impact of resources on process execution.With the objective of minimizing completion time, space and personnel constraints were embedded into the fitness functions of the genetic algorithm (GA) and particle swarm optimization (PSO). Moreover, process weights were integrated into the initial solution generation stage, leading to the development of the resource-weighted improved genetic algorithm (RW-IGA) and the resource-weighted improved particle swarm optimization (RW-IPSO).The experimental results show that RW-IGA reduces the average makespan by 9.26% compared to standard GA, while RWIPSO achieves a 1.62% reduction compared to standard PSO. As population size increases, the average optimization improvement rates of RW-IGA and RW-IPSO reach 1.32% and 2.03%, respectively. Among the four algorithms, RWIGA demonstrates the best optimization performance, achieving a maximum improvement of 15.42%.
Incremental forming technology, characterized by considerable flexibility, has emerged as a significant development in the domain of sheet metal forming. Nonetheless, single-point incremental forming (SPIF) encounters significant challenges, including limitations in forming precision, quality, and degrees of freedom. The double-sided incremental forming (DSIF) technology, facilitated by the coordinated motion of master and slave toolheads, effectively addresses the shortcomings of SPIF and is particularly well-suited for the manufacturing of curved, thin-walled, and complex-shaped aerospace components. This study systematically reviews the research framework pertaining to this technology, concentrating on three essential directions: equipment development, process parameter optimization, and defect control. The current technological development status is comprehensively analyzed from the perspectives of multiaxis trajectory planning, closed-loop feedback control, forming tool head types, and multi-physics coupling. The results indicate that DSIF significantly improves forming accuracy. Nonetheless, technical bottlenecks still exist in the coupling mechanism of high-degree-of-freedom tool heads, quality consistency of complex curved surface parts, and the loading of auxiliary energy fields such as magnetic, thermal, and ultrasonic fields. Future research should integrate technologies such as digital twin to establish intelligent closed-loop control systems, thereby driving equipment toward higher precision and intelligence. Furthermore, the exploration of integrated automated production lines that combine incremental forming with additive/subtractive manufacturing is expected to provide new paradigms for the fabrication of complex curved components.
A low-density high strength Al–Mg–Zn–Cu alloy was designed and the thermal deformation behavior of spray-cast ingots was investigated. Using the Gleeble–3500 thermal simulation testing machine, the stress–strain curves of the spray-cast ingot under different thermal deformation conditions were measured. A strain-compensated constitutive equation was constructed, and thermal processing maps for the alloy at different strain levels were plotted. An Arrheniusbased constitutive equation expressed in terms of parameter Z showed a linear correlation coefficient of 0.995 between predicted flow stresses and experimental values, indicating an excellent fit. Analysis of thermal processing maps for various strains revealed that both the flow instability zones and regions with low power dissipation coefficients were concentrated in areas of high strain rates and high deformation temperatures. The optimal thermal deformation process parameters were identified as a temperature range of 380 – 420 ℃ and strain rate range of 0.001– 0.1 s–1. Within this optimal parameter range, the extruded strips of the spray-cast ingot exhibited microstructures in which internal porosity was mechanically welded without signs of flow instability. The density of the extruded strip was measured at (2.676 ± 0.006) g/cm3. After aging treatment at 140 ℃ for 40 h, the tensile strength reached (552 ± 8) MPa, yield strength was (423 ± 4) MPa, elongation after fracture was 13.5% ± 0.9%, and section shrinkage rate was 41.0% ± 1.7%. The alloy’s combination of high strength and low density suggests promising applications in lightweight structural components.
The thin-walled eccentric nozzle usually adopts a welded structure for the straight sections at both ends, which seriously affects the assembly accuracy and in-service performance of aircraft. This study proposes a new method of integral hydroforming with a conical tube blank, which significantly reduces the wall thickness reduction compared to the hydroforming process with straight tube blanks. The stress characteristics, feeding behavior, springback characteristics, and wall thickness distribution of the GH3044 eccentric nozzle were studied under different end constraint conditions through numerical simulation and experiments. The results show that the end constraint conditions have a significant impact on the stress state and yield sequence of the conical shell. Compared with the constraint method of both ends fixed, the tube blanks with only the small end fixed can obtain a self-feeding amount of 6 mm under the action of internal pressure, and the average axial wall thickness reduction rate of the nozzle is reduced from 6.2% to 4.2%, and the thickness reduction is more pronounced on the eccentric sidewalls of the tubular components. Furthermore, the overall springback of tubular components with the small end fixed is relatively small, and increasing the calibration pressure can reduce springback. Finally, the GH3044 eccentric nozzles with the inner diameter deviations of the straight sections at both ends meeting the design requirements were successfully formed under two conditions: Small end fixed and both ends fixed. This provides a theoretical basis and technical support for the precision integral net-shape forming of superalloy nozzles at room temperature.
A Ni-based high-entropy filler was developed for the joining of SiCf /SiC ceramic-matrix composites and superalloy hot-end components in aero-engines, and the effect of brazing temperature on the interface microstructure and mechanical properties of SiCf /SiC–GH4950 superalloy joints was studied. The results indicate that the typical interfacial microstructure of the SiCf /SiC – GH4950 joint is SiCf /SiC/(Ni, Co)2 Si + graphite/Cr3C2 + (Ti, W,Cr)C1–x /Co – Cr – Ni – W – Si–Ti + (Ni, Co)3 (Al, Si) + (Ni, Co)3 (Si, Ti)/GH4950. Under the condition of holding at 1220 ℃ for 10 min, the room temperature strength and high-temperature strength at 1000 ℃ of the SiCf /SiC– GH4950 joint were 158 MPa and 66.3 MPa, respectively. The SiCf /SiC– GH4950 joint mainly fractured along the weak zone of (Ni, Co)2 Si+graphite.
Laser self-fusion welding experiments were performed on the novel Ti–3773 alloy. The welding performance, mechanical properties, and corrosion resistance were investigated by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), hardness tester, universal tensile testing machine, and potentiodynamic polarization measurement. The results showed that the optimum welding parameter ranges for the novel Ti–3773 alloy are as follows: Welding powers of 2300 W, 2400 W, and 2500 W with a welding speed of 10 mm/s; welding powers of 2600 W, 2700 W, and 2800 W with a welding speed of 14 mm/s. Under the optimum welding process conditions, the weld center of Ti–3773 alloy consisted of a single phase of coarse β grains, while the heat-affected zone was composed of fine β grains and a small amount of dispersed α phase. The average tensile strength and elongation of the welded joint were 71.38% and 265.67% of those of the base metal, respectively, indicating that the welded joint exhibits superior plastic deformation capacity. The hardness of the heat-affected zone reaches the highest value, which is attributed to finegrain strengthening induced by refined β grains and precipitation strengthening from α phase precipitation. The corrosion resistance of the heat-affected zone is the worst, with a corrosion current density of 3.6191×10–7 A/cm2. After welding, the corrosion resistance of different zones of the Ti–3773 alloy follows the order: Base metal>weld zone >heat-affected zone.
Friction stir welding (FSW), as an advanced solid-state joining technology, has been widely applied in aerospace and other high-end manufacturing fields. However, the joining of high melting point alloys poses new challenges to the development of FSW. The auxiliary heat source-assisted FSW technique, which utilizes external energy fields, can effectively address the issues encountered during the FSW process of high melting point alloys. This method offers several advantages, including expanding the process window, enhancing mechanical properties, reducing the welding upsetting force, and reducing stir tool wear. This paper summarizes the research progress on various auxiliary heat source-assisted FSW techniques for high melting point alloys, including induction-assisted, laser-assisted, current-assisted, arc-assisted, and backside heating-assisted methods. Significant achievements have been made in these studies, such as increasing heat input, reducing the welding upsetting force, optimizing the microstructure, and improving the mechanical properties of the joints. Furthermore, the future research directions of auxiliary heat source-assisted FSW for high melting point alloys are proposed and discussed.
