International Journal of Material Forming最新文献

Warpage deformation and volumetric shrinkage defects in injection molding significantly affect the quality and service life of plastic products. To address this issue, this study proposes a multi-objective process parameter optimization approach. First, MIC screening was applied to 152 central-composite-design/Moldflow samples, and a GAN generated 48 additional samples, producing a 200-sample modeling dataset. Then, a hybrid framework combining the Kepler Optimization Algorithm (KOA) and Ivy Optimization Algorithm (IVYA) was applied for hyperparameter tuning. Furthermore, the interpretability of the Extreme Gradient Boosting (XGBoost) model was enhanced using Shapley Additive Explanations (SHAP), which also provided refined search ranges for process parameters. Finally, multi-objective chaotic game optimization (MOCGO) was used to identify the Pareto front and select a compromise solution. Compared with the initial settings, the selected solution reduced warpage deformation and volumetric shrinkage by 35.7% and 10.1%, respectively.

Owing to the good formability combined with low yield-to-ultimate tensile strength ratio, DP800 steel is widely used in the automotive industry. For process optimization and analysis of the feasibility and resulting part quality, it is essential to use a suitable constitutive model. To assess the predictive capabilities of models for forming applications, very recently a benchmark focusing on simulation of a new laboratory forming test, called material under control (MUC) was launched. In this paper, we show that an elastoplastic model with yielding described by the 3-D orthotropic yield criteria of Hill48 [1] and Cazacu [2], and isotropic hardening accurately predict the observed plastic anisotropy of the DP800 steel. The predictive capabilities of these models are demonstrated through comparisons between simulation results and experimental data in uniaxial tension and MUC-Tests, including punch force-displacement curves and surface strain distributions for all specimen geometries. Furthermore, the effect of specimen orientation on the strain path experienced by the material during a MUC test was investigated using Cazacu [2] criterion. The results presented suggest that the use of 3-D orthotropic yield criteria and isotropic hardening may provide reliable virtual assessments of DP800 steel for forming operations.

Process control and optimization are important aspects of manufacturing processes. Surrogate models, i.e. data driven models obtained from numerical simulations, are often employed to predict the process outcome for given process parameters in real time. In this work, we investigate a Laplace-Beltrami shape-feature approach for constructing a surrogate model for cup drawing process simulations. The resulting surrogate model captures local changes in deformations and field quantities on mesh geometries more accurately than standard methods. However, comparing mesh distortions, especially local mesh qualities, is challenging. To address this, we introduce a measure of improvement of mesh distortion to analyse the obtained error distributions. We demonstrate the benefits of the proposed method in contrast to variance-based methods such as principal component analysis, which do not adequately model local variations.

Magnetorheological elastomers (MREs), due to their excellent controllable mechanical properties, have broad application prospects in assisting forming processes. In this study, several MREs with varying carbonyl iron powder (CIP) contents are prepared and used for the three-dimensional bending-torsion combined forming of hollow rectangular 6005 A aluminum profiles. A numerical-analytical (FE-TA) model is established to analyze the springback of the profile. The FE-TA model and numerical simulations are used to investigate the effects of varying CIP content and magnetic field strength on the profile’s springback. The results indicate that adding MRE increases the springback of the profile, with magnetic field strength having a more significant effect on springback than CIP content. The maximum error between the springback amount calculated by the FE-TA model and the value obtained by numerical simulation is only 6.75%. Finally, experiments verified the influence of magnetic field strength on profile springback and the accuracy of the numerical simulation.

As-cast 7075 aluminum alloy suffers from dendritic segregation, coarse second phases, and shrinkage porosity, which limit its direct structural use. In this work, as-cast 7075 feedstock was processed by additive friction stir deposition (AFSD), and the effects of rotation speed on microstructure and mechanical properties were investigated. AFSD markedly reduced casting defects in the as-cast feedstock, with the pore area fraction decreasing from 2.22% to 0.12–0.22% in the deposits. The coarse dendritic structure was transformed into a 3.24–5.16 μm fine-grained microstructure through dynamic-recrystallization-related grain refinement, while interdendritic segregation regions and coarse second phases were fragmented and redistributed as discrete particles. Increasing rotation speed raised the deposition temperature and promoted slight grain coarsening. The deposits showed simultaneous strength and ductility improvements over the as-cast feedstock. The 500 rpm deposit achieved the highest strength, with a yield strength of 320.6 MPa and an ultimate tensile strength of 434.4 MPa, while the highest elongation of 19.0% was obtained at 600 rpm. The improved strength–ductility balance was attributed to grain refinement, pore defect reduction, second-phase fragmentation and redistribution, and local residual deformation. This study demonstrates AFSD as a promising short-process solid-state strategy for as-cast high-strength aluminum alloy feedstocks.

Pin joining represents a promising approach for the mechanical joining of multi-material structures, as it enables the formation of joints without auxiliary joining elements. To improve process efficiency, a modified pin joining process chain is proposed in which the pin itself acts as the cutting element, eliminating the need for pre-drilled joining partners. However, the interactions between the shear-cutting operation and the subsequent caulking process are not yet fully understood. This work experimentally investigates the influence of sheet thickness, relative pin height and cutting clearance on joint formation and mechanical performance in steel-aluminium joints produced by the pin shear-caulking process. A full-factorial design of experiments is employed. Joint performance is evaluated by tensile-shear and cross-tension testing, while metallographic analyses and microhardness measurements are conducted to characterise cut-edge morphology, undercut geometry and local strain hardening. The results demonstrate the feasibility of the proposed process chain and reveal pronounced interactions between the investigated process parameters. Tensile-shear strength is strongly influenced by the interaction between sheet thickness and cutting clearance. A previously reported non-linear effect of cutting clearance is confirmed for a wide range of process conditions and is linked to differences in burnish-zone formation. In contrast, cross-tension strength increases with increasing cutting clearance and is primarily determined by the geometry of the mechanical interlock formed during caulking. Furthermore, increasing sheet thickness and relative pin height generally enhance joint performance by promoting undercut formation and increasing the available load-transfer area. The findings provide a deeper understanding of the mechanisms governing the pin shear-caulking process and support the identification of suitable parameter combinations for future lightweight multi-material structures.

A methodology for rapid manufacturing of complex geometry stretch formed parts from highly aligned discontinuous fiber (ADF) epoxy matrix multiaxial composite blanks is demonstrated in this paper. During typical forming processes, forming and curing occur within the same tool, leading to bottlenecks in processing time. In this new methodology, the epoxy resin is partially cured to increase glass transition temperature above room temperature. Advanced matrix staging allows a blank to be easily removed from a room temperature tool after forming. In a production environment, blanks would be (i) staged in an oven vacuum bag process, (ii) preheated in an IR oven, (iii) rapidly stamp formed into a room temperature tool, (iv) ejected as a near net shape part, and then (v) fully cured/formed in a parallel batch process. To implement this methodology, accurate relationships between viscosity, cure, and glass transition temperature are established and used to manufacture partially cured material for mechanical testing and extensibility characterization. Several key benefits are realized by using partially cured material; namely, the ability to rapidly form and eject a preformed part from tooling and reduced resin bleed during cure and consolidation. The staging process is also shown to retain similar formability and mechanical properties relative to the uncured material form.

Wire rod is a coiled, round-section steel product hot-rolled from a reheated billet, used as feedstock for wire drawing. Introducing a section beyond an installed mill’s range is constrained by its fixed stand configuration and gear ratios, so that a schedule obtained by simple extension can leave a groove under-filled, a problem addressed sparsely in the literature. This study develops and validates, through a plant trial, a roll pass sequence for 18 mm wire rod meeting dimensional and out-of-roundness requirements without altering the mill’s configuration. The finishing geometry, speed and loads were established analytically for an 18.23 mm hot section. An initial sequence modifying only the last two passes of the block under-filled the round; a lead-bar trial traced the deficit to the pre-finishing oval. A spread ratio, the ratio of imposed reduction to resulting lateral spread per groove, was derived from adjacent validated schedules and adopted as the four-pass design target; the initial two-pass attempt left the side dimension deficient by up to 2.7 mm. The developed four-pass schedule, with reductions of 15.6%, 19.6%, 14.3% and 12.1%, raised the spread ratios to 1.41–3.12, and produced rod measuring 17.95 mm (times ) 17.88 mm at mid-coil, within the ±0.5 mm tolerance, at an ovality of 0.07 mm against a 0.75 mm limit, with loads within the installed drive capacity. The section is now rolled commercially. Expressed as a ratio rather than an absolute spread, it supplies a design target for an unscheduled size; validation here is dimensional.

Non-uniform area deformation during hot-press forming can result in local material accumulation and thickness variation in composite hemispherical shells manufactured from planar tow-placed preforms. This study proposes a thickness-compensation-driven preform design method using variable-spacing and variable-angle tow placement. A geometric inverse mapping relationship is first established between the target hemispherical shell and the planar blank. Based on the local area variation ratio and approximate volume conservation assumption, the formed-thickness requirement is projected back to the planar preform as a spatial material-compensation demand. This compensation demand is subsequently converted into constrained path-spacing, path-density, and local tow-angle distributions. Furthermore, coverage-count statistics are employed to transform discrete tow centerlines into an equivalent initial thickness field for finite element forming analysis.The proposed preform design method is evaluated using an Abaqus/Explicit hot-press forming model and compared with a conventional fixed-angle equal-spacing preform under identical tooling, contact, loading, and mesh conditions. The proposed design reduces the thickness-matching error from 0.024 to 0.019 while satisfying the prescribed minimum curvature-radius constraint of 50 mm. After forming, the thickness standard deviation decreases from 0.231 to 0.171 mm, the coefficient of variation decreases from 14.50% to 10.44%, and the root-mean-square thickness deviation decreases from 0.470 to 0.402 mm. The mean and 95th-percentile von Mises equivalent stresses decrease by 10.7% and 21.1%, respectively, while the mean contact pressure remains at a comparable level. The proposed method establishes a quantitative relationship between planar preform material distribution and formed-thickness control. This framework provides a forward design tool for general double-curvature composite components by linking preform architecture with post-forming thickness uniformity.

This work employs the hot oscillatory pressure (HOP) sintering technique for the first time to prepare AlCoCrNiFe high-entropy alloy at varying amplitudes, systematically investigating the influence of amplitude on their microstructure and properties. As the amplitude increased, the grain boundaries of HOP sintered alloy were disappeared, and significant improvements in density and microstructural uniformity were observed. Specifically, when the amplitude increased from ± 1 to ± 10 MPa, the density of the HOP sintered alloy was rose from 93.65% to 99.11%, achieving near-complete densification. The increased amplitude also effectively enhanced their hardness and corrosion resistance. At an amplitude of ± 10 MPa, the Vickers hardness of the HOP sintered AlCoCrNiFe high-entropy alloy was reached a maximum of 481.52 HV₁, which was significantly higher than that of the hot-press sintered samples. Moreover, its corrosion current density was minimized at 9.1 µA/cm², indicating the strongest corrosion resistance. The research results demonstrate that the increasing the HOP amplitude can produce high-entropy alloys with high density, well hardness, and excellent corrosion resistance in lower temperature.