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Incremental sheet forming has been largely investigated in the last two decades because of its versatility and cost-effectiveness, which make it viable for manufacturing highly customized parts as well as small- and medium-sized batches. This process allows for reaching greater formability compared to conventional sheet-forming processes. In contrast, it is affected by defects like twisting, which strongly influence the geometric accuracy of the formed parts. These aspects are dramatically accentuated when forming soft materials like thermoplastics. With these premises, the following research aims to investigate the effects of the toolpath strategy on the occurrence of failures and defects in the incremental sheet forming under very severe process conditions. Cone frusta with a fixed wall angle were obtained by thin polycarbonate sheets, imposing four unidirectional helical trajectory-based toolpaths, one traditional, and three stair strategies. The analysis of the forming forces, the evaluation of the worked surfaces, and the monitoring of the defectiveness highlight the advantages of a stair toolpath strategy in terms of reduced twisting and loading and high surface quality, regardless of the lubrication conditions. [ABSTRACT FROM AUTHOR]

In the last decades, metal foams have been bringing increasing attention because they represent a new category of materials with very intriguing physical and mechanical properties like, for example, high stiffness and low density. These materials have not been studied completely, and many research efforts have been carrying out to investigate new foaming techniques. The present work aimed at evaluating the efficiency of electromagnetic induction as a heating technique of foam precursors for the manufacture of closed-cell aluminum foam specimens by the indirect foaming process known as the powder compact melting technique; a conventional and a flexible mold strategy, the latter using a stainless-steel wire mesh, were employed for the manufacture of parallelepiped specimens. The results outlined the interesting perspectives of this manufacturing method. In detail, they highlighted a significant process repeatability and the beneficial effects of the induction heating method, allowing heating the precursor in very little time and in a safe way compared to conventional heating through a muffle furnace; moreover, they showed the influence of the mould choice both on the processing time, with the synergistic interaction between the flexible mold and the induction system in terms of heat generation, and on the surface geometry of the foamed components, which reflected in their different compression behavior. [ABSTRACT FROM AUTHOR]

Recent studies on innovative solutions in structural engineering fields highlight the effectiveness of closed-cell aluminum foams as traditional material/architecture core replacement in sandwich structures. This study aims to investigate the mechanical behavior and the collapse modes of innovative sandwich panels with aluminum foam as the core and stainless steel wire mesh-grid as the skins; the manufacturing process was based on the powder compact melting technique. The results of quasi-static three-point bending tests point out the beneficial effects, in terms of mechanical performance, of the reinforcement skin on the sandwiches, compared to the plain foams; this joins by their effectiveness in withstanding thermal and mechanical loads. Moreover, the investigation of the collapse mechanisms of the sandwiches with different thicknesses allows for testing the goodness-of-fit of the experimentally observed collapses with the ones predicted by the failure map from analytical models available in the literature. [ABSTRACT FROM AUTHOR]

The paper investigates the influence of tool diameter, sheet thickness, and geometry of the workpiece during single-point incremental forming (SPIF) of polycarbonate sheets. An experimental campaign was conducted and involved varying and fixed slope angle tests. The process was performed at room temperature. Cone and pyramid frusta geometries were analyzed. A FE model was developed to determine stress, strain, and thickness distributions during the process. Different defects affected the formability of the polymer, namely thinning, twisting, and wrinkling. Significant differences were found with respect to SPIF of metals due to mechanical behavior of the polycarbonate, in terms of amount of thinning, twisting, and wrinkling. The mechanism of development of the abovementioned defects was identified as well as how they are influenced by the process parameters. The comparison of fixed and varying slope angle tests indicated that these latter were not fully representative of the formability of the sheets. The presence of geometrical singularities in pyramid frusta affected the formability of the materials. This was due to great localization of thinning at the edges and the increase of the forming loads as approaching these regions. [ABSTRACT FROM AUTHOR]