PSI - Issue 66

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Mohammad Jameel Ziedan et al. / Procedia Structural Integrity 66 (2024) 229–246 Author name / Structural Integrity Procedia 00 (2024) 000–000

physical or chemical properties, which when combined, produce a material with characteristics different from the individual components (AbdulRazaq et al., 2023; Hussein et al., 2020; Talla et al., 2022). Therefore, composite materials aim to create new aspects of mechanical properties such as toughness and stiffness for automobile, biomedical, and aeronautical applications (Al-Mukhtar, 2012, 2019, 2020). However, the formation of defects during the manufacturing process may influence the desired design. Voids and cracks are material discontinuities with distinct characteristics and effects. Voids in composites are empty spaces at the interfaces or within the matrix, which reduce the material's strength and stiffness. Key areas driving extensive research on composites include advancements in manufacturing techniques, testing methods for composite materials, exploration of novel material options, and related research fields. This work aims to highlight recent developments in metal forming, focusing on associated properties and cracking phenomena. A review of various forming methods and their related aspects is provided, with particular emphasis on Single Point Incremental Forming (SPIF), vacuum forming, and compression molding. 1.1. Single Point Incremental Forming (SPIF) Single point incremental forming, also known as mechanical forming, is a thermoforming technique where a single point (usually a plug or mold) is used to apply force to a heated thermoplastic sheet, causing it to conform to the shape of the mold (Bagudanch, Vives-Mestres, et al., 2017; Buffa et al., 2013); see Fig. 1. The composite sheet is heated until it becomes pliable, then placed over the mold. A plug or other mechanical device is then used to apply pressure at a single point, forcing the sheet to stretch and take the shape of the mold (Centeno et al., 2014).

Fig. 1. Single point forming process (Centeno et al., 2014)

1.2. Process Parameters and Optimization Method of SPIF Many studies have been carried out to determine the effective and optimal parameters for the process of SPIF of composite materials (Lozano-Sánchez et al., 2018). Previous studies have explored various optimization methods and process parameters to enhance the formability, mechanical properties, and surface quality of formed parts. Since polymethylmethacrylate (PMMA) is typically brittle, it was modified by adding a plasticizer (triacetin) to relax the polymer chains, along with a nanoclay reinforcement (Cloisite 30B) to maintain mechanical strength suitable for the