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

2.3. Hybrid Vacuum-Forming Hybrid vacuum-forming of composite materials combines vacuum-forming processes with other techniques to manufacture composite materials into complex shapes (Elkington et al., 2023; Z. Wang, 2010). (Y. Wang et al., 2010) presents the control system design of a Hybrid Vacuum-Forming Machine System (HAVES). The system combines screw-pin tooling, CNC machine for axis movement, and a PLC controller for regulating heater temperature, vacuum pump, and cylinder control. vacuum forming for efficient product manufacturing. The study concludes that hybrid GFRP with three sets of vacuum infusion layers on two sets of hand lay-up layers exhibit the best mechanical properties with multiple cracks in fractured specimens. The process successfully formed laminates with deep concave features that would be challenging with diaphragm forming alone. Robotic end effectors applied localized pressure to concave areas during diaphragm forming, similar to incremental sheet forming (see Fig. 14). A method is outlined to customize the HyVR process for specific molds, determining the appropriate end effector and its application. A key advancement is the robot's role in securing the laminate to the mold, preventing undesired movement.

Fig. 14. (a–c) The bridging defect during diaphragm forming and two techniques for preventing this defect using; (d) pressure intensifiers and (e) ‘mechanical forming’(Elkington et al., 2023). 3. Compression Molding Forming Compression molding is a manufacturing process in which a heated material, typically in the form of a pre-measured amount, is placed into an open mold cavity. The mold is then closed, and pressure is applied to compress the material within the mold. This pressure helps the material take the shape of the mold cavity and ensures proper distribution within the mold. After the material cools and solidifies, the mold is opened, and the finished product, part, or component is removed. Compression molding is commonly used for producing a wide range of items, including automotive parts, aerospace components, and various industrial products (J. M. Castro & Griffith, 1989). 3.1. Sheet Molding Compound SMC is a type of mixture that is compounded into a sheet form and then compressed under heat and pressure to create final parts with complex shapes and high mechanical properties (Abrams & Castro, 2003; Michael Rabinovich et al., 2008; Shirinbayan et al., 2015). This technique allows for the development of 3D shapes with fiber lengths reaching 40 mm. The research focuses on the interaction between materials, temperature distribution, and forming outcomes (see Fig. 15).

Fig. 15. Process steps, merges sheet forming with GMT (Behrens et al., 2017).

(Kim & Im, 1997) utilized a three-dimensional finite-element program to analyze the compression molding of SMC at room temperature with a rigid-viscoplastic approach. The program was then used to investigate the impact of friction