PSI - Issue 66

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

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with nearly vertical walls using a multi-stage SPIF approach, where the wall angle is gradually increased in steps. SPIF involves a mode of deformation and failure not seen in conventional SPIF. The new deformation mode combines in-plane stretching and bending, limiting strain path growth and causing failure through meridional fracture without necking. Strain measurements support this by highlighting fracture forming lines (FFLs) as the loci of failure (Silva et al., 2013b). However, the new methodology was used in Ref. (Alkas Yonan et al., 2014).

Fig. 2. The hole-flanging produced by conventional press working (left) and by SPIF (right) (Cristino et al., 2015)

1.4. Workpiece geometry SPIF is utilized for producing common geometries, including simple shapes like cylindrical and conical forms, complex contours such as curved surfaces, and functional parts like ribs and channels used in various industries (Xu et al., 2013). The pyramid frusta, due to their sharp edges and corners, exhibited greater strain concentration and were more susceptible to premature failure compared to cones. The research shown that adjusting the slope angle during the forming process resulted in an overestimation of the sheet's formability. (Hernández-Ávila et al., 2019) used a bilayer sheets made of polypropylene (PP) and Santoprene (ST) in SPIF. It was found that the arrangement of the layers significantly influenced the mechanical and thermal behavior during forming. When PP was placed on the outer wall of the cone-shaped work piece, it provided reinforcement and reduced softening, resulting in higher forming forces. The dual properties of bilayer sheets provide advantages over single-material sheets and blends, enabling the fabrication of complex geometries with enhanced performance. In SPIF, tool rotation and the associated heat generation significantly influence the fracture behavior of ST. The specific heat capacity of the materials plays a key role in determining their heating rate, which in turn affects their fracture response. Under the tested SPIF conditions, PP demonstrates superior formability compared to ST, primarily due to its higher ductility and softening behavior at elevated temperatures (see Fig. 3).

Fig. 3. The different sheets fabricated and shaped by SPIF (Hernández-Ávila et al., 2019)

1.5. Software Programs Several software programs like CAD/CAM, CATIA V5, Master CAM, and SolidWorks are used to simulate and design SPIF processes. ABAQUS, a powerful FEA software suite, is frequently employed to simulate composite forming processes such as SPIF to forecast material behavior and enhance process parameters and tooling design (Centeno et al., 2017; Silva et al., 2013b). The shape memory polymer (SMP) foam in SPIF and a corrected STL (Standard Tessellation Language) file imported into the CAD/CAM have been used (Mohammadi et al., 2015). The material's properties and formability at different temperatures have been investigated. it was found that heating the SMP foam improved its formability by 28%, allowing for the creation of complex shapes. Accuracy was assessed using a laser line scanner, revealing the need for toolpath compensation to achieve higher precision. The two approaches have been developed for predicting forming forces in metal cutting; a semi-analytical model based on forming energy and deformed volume, requiring calibration but offering a simple prediction method, and a numerical