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Amorphous thermoplastics, as a type of engineering plastic material, are used in various industrial sectors. In order to manufacture high-performance products, it is important to optimize their forming process to mitigate residual stresses. However, stress in a plate is difficult to measure, therefore, modeling provides a powerful way to investigate and understand the evolution of stress. In this study, the forming process of a polyetherimide (PEI) plate was modelled using finite element analysis, and then validated through a comparison with a warpage experiment. This study reveals that the whole forming process can be divided into three stages by the glass transition temperature Tg of the PEI. The second stage, corresponding to the plate cooling from above Tg to below Tg, contributes a large portion of the residual stress in a short time. The final residual stress, the magnitude of which is affected by the cooling rate and plate thickness, shows a parabolic distribution through the thickness of the plate. These important conclusions are beneficial for improving the quality of an amorphous thermoplastic plate, while allowing highly efficient production.

Incremental sheet metal forming can manufacture various sheet metal products without a dedicated punch and die set. In this study, we developed a two-stage incremental forming process to decrease shape errors in the conventional incremental forming process. The forming process was classified into the first single point incremental forming (1st SPIF) process for forming a product and the counter single point incremental forming (counter SPIF) process to decrease shape error. The counter SPIF gives bending deformation in the opposite direction. Furthermore, the counter SPIF compensates for shape errors, such as section deflection, skirt spring-back, final forming height, and round. The tool path of the counter SPIF has been optimized through a relatively simple optimization method by modifying the tool path of the previous step. The tool path of the 1st SPIF depends on the geometry of the product. An experiment was performed to form a circular cup shape to verify the proposed tool path of the 1st and counter SPIF. The result confirmed that the shape error decreased when compared to the conventional SPIF. For the application, the ship-hull geometry was adopted. Experimental results demonstrated the feasibility of the two-stage incremental forming process.

The potential of paper and paperboard as fiber-based materials capable of replacing conventional polymer-based materials has been widely investigated and evaluated. Due to paper’s limited extensibility and inherent heterogeneity, local structural variations lead to unpredictable local mechanical behavior and instability during processing, such as mechanical forming. To gain a deeper understanding of the impact of mechanical behavior and heterogeneity on the paper forming process, the Finite Element Method (FEM) coupled with continuum modeling is being explored as a potential approach to enhance comprehension. To achieve this goal, utilizing experimentally derived material parameters alongside stochastic finite element methods allows for more precise modeling of material behavior, considering the local material properties. This work first introduces the approach of modeling heterogeneity or local material structure within continuum models, such as the Stochastic Finite Element Method (SFEM). A fundamental challenge lies in accurately measuring these local material properties. Experimental investigations are being conducted to numerically simulate mechanical behavior. An overview is provided of experimental methods for material characterization, as found in literature, with a specific focus on measuring local mechanical material structure. By doing so, it enables the characterization of the global material structure and mechanical behavior of paper and paperboard.

In this study, experimental and numerical approaches are used to investigate the effect of pre-punches on the spring-back of U-channels made of St12 with 1-mm thickness. Three-channel section profiles were examined: a simple hole-less channel and two pre-punched channels with holes located in the bending zone and next to the bending zone. The rolls were designed using the constant bending radius method with an increment of 15° at three forming stations. Numerical solutions were obtained using Abaqus finite element software, with both isotropic von Mises and anisotropic conventional Hill’48 yield functions calibrated using R-values (Hill’48-R) and yield stresses (Hill’48-S). The results show that considering the anisotropic properties of the sheet by using the anisotropic Hill’48 yield criteria improves the accuracy of spring-back prediction in the range of 5 to 20%, depending on the calibration method of the yield criteria. The results also indicate that calibration of the Hill’48 criterion using R-values increases the accuracy of spring-back prediction by about 15% compared to stress-based calibration for hole-less and pre-punched channel with holes next to the bending zone, but decreases by about 5% for pre-punched channel with holes located in the bending zone.

Self-lubricating spherical plain bearings are a key component widely used in the aerospace field. The spherical plain bearing made of titanium alloy has a lighter weight and better corrosion resistance. To manufacture the outer ring of a self-lubricating spherical plain bearing with titanium alloy, a two-step extrusion forming process was proposed. Taking a GE15DE1TK spherical plain bearing as an example, the finite element simulation model of the forming process was established, the forming test was carried out, and the outer ring of a self-lubricating spherical plain bearing made by TC4 titanium alloy was successfully prepared. The results show that forming defects such as over extrusion and insufficient extrusion can be improved by optimizing the die structure, the size of the outer ring blank, and the lubrication conditions. The forming parameters for the GE15DE1TK spherical plain bearing are given. The prepared spherical plain bearing can be used directly without other processes to correct no-load rotational breakaway torque.

This paper explores the possibilities of the use of computer-aided design models focused on imitating the works of Nature, its form-forming processes and behaviors. Tracking the development of the cybernetic models aimed at architects, the achievements of John H. Frazer and his team of scientists are presented. These are the first working morphogenetic models addressed to architects that use generative and evolutionary tools in search of new architectural forms. Models and design strategies developed between 1968 and 1995, including the Reptile System, the Interactivator and the Janssen Model, are presented. The IT solutions used in them provided the basis for the creation of modern computational tools coupled with digital technology.

Automobile demand is expected to be increasingly diverse in the future. To satisfy this demand, a suitable technology is required to manufacture various car body parts using a single-forming machine. We focus on a technology for the general-purpose production of hat cross-sectional press-formed panels. In general press forming, a single die-set is used for each panel. Manufacturing various panels involves the manufacturing cost of the die-set and the storage space. Herein, we present a new sequential forming process that can form panels with several shapes in the longitudinal direction. This process sequentially performs narrow-width press forming along the longitudinal direction using small dies instead of a die-set. A machine is prototyped to demonstrate this process. Multiple hat cross-sectional panels with different curvatures along the longitudinal direction are formed using this machine. Subsequently, the strengths and shapes of the formed panels are examined. The buckling strength during the bending of the panels is 13% higher than that of panels formed using a general bending machine. However, shape distortion occurred in these panels, which shall be addressed in the future.

Electromagnetic attractive forming (EMAF), as an emerging branch of electromagnetic forming (EMF), has attracted increasing attention due to its unique capacity to shape workpieces toward the coil, offering distinct advantages in forming small-diameter tubes, repairing surface dents, and strengthening hole fasteners. This review systematically classifies and elaborates on the two main approaches for generating electromagnetic attractive force: (1) methods based on dual-frequency discharge and (2) methods based on low-frequency discharge. For each category, the working principles, key technological configurations, experimental verifications, and application scenarios are comprehensively discussed. The dual-frequency discharge approach, implemented through sequential dual-capacitor, dual-coil, and novel single-power circuits, enables controllable attractive forces for sheet/tube forming and hole-fastener strengthening. The low-frequency discharge approach, utilizing ferromagnetic effects, attractive screen, or current-phase-difference mechanisms, extends EMAF to ferromagnetic and non-ferromagnetic materials. Finally, the existing challenges and future research directions are outlined, aiming to provide clear research guidance for the in-depth development and practical engineering application of EMAF technology.

In this paper, Ti-6Al-4 V (TC4 titanium alloy) specimens were prepared by a new process, the variable parameter forming process (VPFP) of selective laser melting (SLM) technology. The surface morphology, tensile properties, and microstructure of the TC4 titanium alloy specimen were investigated. The test results showed that within the 250–300 W of laser power, the tensile strength of VPFP was larger than the quantitative parameter forming process (QPFP). However, the elongation was decreased. By decreasing the index of the hierarchy, the tensile strength increases, reaching 1190.84 MPa. Compared with the specimen without heat treatment, the elongation increases to more than 200%, and the maximum elongation reached 13%. By increasing the heat treatment temperature, the fracture gradually changes from brittle fracture to ductile fracture, and the main metallographic structure of the specimen was gradually transformed from acicular martensite α′ to α phase. This study provides new processes for SLM.

The process of selective laser melting (SLM) is complex and instantaneous, which communicates with a variety of physical phenomena such as solid–liquid phase transition. The microstructure and material properties are favorable evidence to explain the SLM forming mechanism. In this paper, the forming properties of the iron-based alloy, titanium-based alloys, and aluminum-based alloys are discussed, which are relatively mature in research. The influence of processing strategy on the density and quality of metal specimens is briefly introduced. The research progress of microstructure and mechanical properties of metal specimens formed by SLM is mainly introduced. Also, the influence of processing parameters and heat treatment on the microstructure and the effect of microstructure on mechanical properties are summarized. The corrosion behavior of metal specimens formed by SLM is analyzed. Furthermore, the research development of copper-based alloys, shape memory alloys, and high-entropy alloys is presented. Finally, the problems encountered in the alloys forming process are described, and the future development direction has prospected.