International Journal of Material Forming最新文献

Magnesium alloys are regarded as the next-generation lightweight structural materials; however, their formability at room temperature remains limited. Hydromechanical deep drawing is an effective technique to enhance the formability of magnesium alloys, with pressure rate (the pressure increment per unit time) being a critical parameter influencing part formability. In this study, a finite element model of an AZ31B magnesium alloy cylindrical component was established to investigate the effect of pressure rate on wall thickness. Under constant process parameters, variations in wall thickness at different pressure rates were simulated, and the impact on minimum wall thickness, thickness distribution, and uniformity was analyzed. Additionally, a predictive equation for wall thickness uniformity of cylindrical parts was developed. Metallographic analysis and hardness testing were conducted to examine the microstructure and hardness distribution in different deformation regions under varying pressure rates, with a focus on explaining the relationship between hardness distribution and microstructure. This study provides insights into the hydromechanical deep drawing mechanism of magnesium alloys from both micro- and macroscopic perspectives, offering a theoretical basis for optimizing the forming process.

Copper terminals with high strength and excellent electrical performance are crucial in power systems of electric vehicles. Radial plastic flow machining (RPFM) is an innovative plastic processing technique that utilizes a specially designed forming channel to fabricate high-performance, gradient-structured (GS) copper terminals in a single step. This study systematically investigated the forming mechanism, mechanical properties, and electrical conductivity of GS copper terminals across varying extrusion thicknesses. The study demonstrated that as extrusion thickness increased, the volume of material flowing into the transverse channel also rose. Consequently, the extent of the low-strain zone across the thickness expanded, whereas the proportion of the high-strain zone remained largely constant. Compared to the original pure copper, the mechanical properties exhibited a combined trend of increased hardness, reduced yield strength, and enhanced ductility. Simultaneously, the electrical conductivity reached up to 99.6% IACS (International Annealed Copper Standard), with virtually no loss in performance. The process established a gradient distribution of grains within the terminals, achieving an optimal balance between high strength, high electrical conductivity, and enhanced ductility, thereby overcoming the traditional trade-off dilemma among these three properties. Therefore, the GS copper terminals fabricated by the RPFM process demonstrated significant performance improvements.

Pressure cure can reduce the cure residual stress (CRS) of solid propellant charges, thereby enhancing the structural integrity and storage life. As the polymerization reaction progresses, it is accompanied by heat release, chemical volume shrinkage, and viscoelastic evolution. In this study, a thermodynamically consistent, fully coupled thermo-chemo-mechanical viscoelastic model is developed. Relaxation tests are carried out on hydroxylated polybutadiene (HTPB) propellant specimens at different cure times revel the viscoelastic evolution mechanism. Consequently, a viscoelastic evolution model is established in relation to the degree of cure (DOC). On the basis, the CRS analysis of the pressure cure HTPB solid propellant charge is performed by means of user material subroutines. The model is validated against literature and experimental results. Furthermore, factors affecting temperature, DOC and CRS are analyzed. Results indicate that the shift factor of HTPB propellant is independent of DOC, while relaxation time first increases and then decreases. Employing the multi-physics coupled viscoelastic model provides a detailed description of the CRS development. An enhanced pressure cure scheme is proposed, which involves releasing partial pressure during cure to future reduce CRS. This model establishes a foundation for designing cure cycles and predicting CRS in solid propellant charges.

Different shot peening sequences can affect the effectiveness of shot peening definitely. To comprehensively investigate the ramifications of different shot peening sequences on the structural integrity of aviation components, this study formulates a shot peening sequence model tailored to the cross-sectional features of H-shaped slide rails commonly found in aircraft, leveraging Abaqus and Python. Combining numerical simulations and experimental data, we utilize the Euclidean distance to assess the similarity of residual stress distribution curves. Effects of six different shot peening surface strengthening sequences on the residual stress distribution and deformation across each surface of the aircraft slide rail’s typical cross-section are analyzed. Results indicate that variability exists in the similarity of maximum residual stress distribution among surfaces subjected to different shot peening sequences. Notably, the fully symmetric strengthening sequence S4 yields the highest similarity in the residual stress distribution curve. Moreover, the maximum deformation of the workpiece groove exhibits a 26.3% disparity under various shot peening strengthening sequences. This indicates that an appropriately selected shot peening sequence can mitigate size errors arising from the strengthening process. This implies that a judiciously chosen shot peening strengthening sequence could enhance the overall shot peening quality of the component.

The increased complexity of geometries and the improved properties of sheet metal components result in narrower process windows, highlighting the need for better process control to minimize deviations and to ensure the production of high-quality parts. In this context, this study focuses on controlling the bending angle of a seat rail component manufactured by a renowned TIER1 company. This angle changes due to material, process fluctuations and post-forming springback. Two types of material, a cold-rolled Dual Phase DP980 steel and a Complex Phase CP980 high-strength steel, are both employed interchangeably when manufacturing this component. Variations in the mechanical properties and thickness of these two materials result in significant differences in post-springback bending angle. To tackle this challenge, various control strategies have been developed including a classical controller and a controller enhanced with a metamodel-based feedforward term. For the latter, two approaches were used: a simulation-based metamodel and an experimental data-based metamodel. Heuristic-based disturbances, reflecting both material variability and process changes (tool mounting variations, tool wear, gap changes and temperature variations), have been considered. To calibrate the new controller parameters and gains, a constrained-based genetic algorithm approach has been utilized together with a numerical virtualization of the process. After this virtual set-up, the new controllers have been tested experimentally in a real environment, using an industrial U-bending tool and a 4000 kN servomechanical press. The new controllers have proven to be an efficient method for enhancing the process robustness. A classical controller, employing a feedback control system, enabled consideration of part-to-part variations. On the other hand, the addition of a metamodel-based feedforward term facilitated anticipation of material properties and sheet thickness changes, thereby preventing scrap production.

To effectively predict the deformation behavior of AZ31B magnesium alloy (Mg alloy) in plastic forming assisted by pulse current, the influences of different pulse currents’ frequencies on the flow stress of Mg alloy were studied. The Voce and Hockett-Sherby constitutive models were modified to include the influence of frequencies, and the parameters of the constitutive models were calibrated based on the experimental data. The Cazacu 2004 yield criterion was improved to describe the yield behavior under the action of pulse current, in which the tensile-compressive asymmetry keeps changing with the increase of plastic strain. The three-point bending tests of AZ31B Mg alloy assisted by different frequency pulse currents were carried out. The improved constitutive model and yield criterion were embedded in ABAQUS using user material subroutine VUMAT for the corresponding three-point bending simulation. It is found that the improved constitutive model and yield criterion considering the current frequencies and tensile-compressive asymmetry can obviously improve the simulation accuracy.

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This critical review examines advances in preprocessing and remelting processes for aluminium alloy chip recycling, emphasizing pre-treatment and remelting techniques that improve both resource recovery and material quality. Pre-treatment strategies, particularly cleaning methods and compaction are critically evaluated. Various cleaning methods, including centrifugation, ultrasonic solvent washing, extraction, and distillation are compared based on their ability to remove residual cutting fluids. Cold compaction, which augments chip density to approximately 2.5 g/cm³, significantly curtails oxidation losses and enhances metal recovery. During remelting, NaCl-KCl-based fluxes with limited fluoride additions (e.g., 3–7 wt% Na₃AlF₆) disrupt oxide networks but require careful dosage control to minimize furnace corrosion and environmental hazards. Moreover, mechanical stirring combined with suitable melting temperatures reduces porosity while enhancing melt purity. Future research should prioritize the development of low-energy cleaning methods, flux composition optimization, and scalable production techniques to further advance sustainable aluminium recycling.

The single-stage light gas gun has been employed to drive the T2 copper welding on Q235 carbon steel. The effect of the Zn interlayer on the microstructure at the interface of impact welded the T2 copper/Q235 carbon steel composite has been studied by both experiment and numerical simulation. The simulation results are mainly consistent with the results of the experiment. The 100 µm Zn interlayer can broaden the lower limit of the T2/Q235 weld window, resulting in a 3.11% reduction in energy dissipation during the impact welding. While the 25 µm Zn interlayer achieves a reduction of up to 11.6%. As the thickness of the Zn interlayer diminishes, the plastic strain, pressure, and temperature of the flyer plate gradually increase, allowing for the modulation of welding parameters through varying Zn interlayer thicknesses.

The coarse columnar crystals and inter-dendritic Laves phases of laser deposition manufactured (LDM) GH4169 are the two the primary reasons for the undesirable strength and plasticity compatibility and anisotropy of the alloy. In this study, we used friction stir processing (FSP) on LDMed GH4169 samples, the microstructure difference between the FSP zone and the LDM zone were compared, the microstructure refinement process in the FSP zone were analyzed, and the mechanism of microstructure refinement and its influence on the properties of the room-temperature tensile properties were proposed. The results show that fine equiaxed grains with an average grain size of ~ 3.13 μm were obtained in the stir zone (SZ) due to intense plastic deformation and recrystallization processes.The size and shape of the Laves phase changed significantly after FSP, the Laves phase fragmented in the thermo-mechanically affected zone (TMAZ), distributed in long strips along the rotational direction of the tool, and distributed as small particles in the SZ; while the MC-type carbides precipitation exhibited no significant change.The strength and plasticity of the FSP samples were significantly improved relative to the LDM samples, the yield strength and tensile strength reached 546 MPa and 1063 MPa, respectively, and the elongation reached 43%. Numerous strengthening mechanisms to increase the yield strength of the materials are analyzed and calculated in detail.

Developing and optimizing manufacturing processes for composite components is commonly supported by finite element (FE) simulations. Initial concepts are modeled and parametric studies are conducted to determine optimum process parameters. Built-in application programming interfaces (APIs) typically allow for a script-based automation of systematic model modifications for many FE solvers. However, the evaluation of simulation results typically depends on a manual inspection by experts, despite its repetitive nature. This study aims to use APIs to develop a fully-automated method for identifying and evaluating critical features and thus, the quality of draping simulations. The focus thereby lies on providing a validated framework for the automated evaluation of draping simulation results, rather than claiming perfect virtual representation of experimental draping. Three different metrics (deviations of fiber angles, the boundary contour and topological defects) are used to determine the overall draping quality of simulation results. With the developed routine, all quality metrics can be estimated quite well for simulation results. The routine is designed to be extended for the use with experimental data for a reliable real-life quality assessment.