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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and molding speeds on material flow and load demands in the compression molding of rectangular SMC specimens. This method offers advantages over traditional statistical descriptors. Tailored material combinations and component designs are essential for particular applications, prompting the need for unique material models. The study identifies flow stresses and anisotropic parameters that change during compression processing. The research provides a technique to predict SMC characteristics in the main flow direction of anisotropic thermosetting composites. The study successfully maps fiber orientation distribution (FOD) data between simulations, enhancing accuracy in predicting mechanical behavior and failure points. The process chain aids in reducing the reliance on costly CT scans, accelerating product development by considering manufacturing effects early on. Matrix micro-cracking and fiber-matrix debonding cause stiffness anisotropy. Crack initiation in highly loaded areas influenced by unaccounted factors. (Kia, 2008) focused on understanding the coefficient of linear thermal expansion (CLTE) of composites materials, particularly SMC. Results indicated that increasing low profile additive concentration decreased overall CLTE and shifted the maximum position to lower temperatures. Changes in glass content had minimal impact on the maximum position but notably decreased overall CLTE, (see Fig. 16). The biocomposites, including varieties with grass fiber, jute, and industrial hemp, showed good results for panel applications in housing and transportation. By optimizing the process with engineered natural fibers and additives, the goal is to achieve mechanical, thermal, and physical properties comparable to glass-based SMC, aiming to replace glass-polyester composites with natural fiber biocomposites. (Atieh Motaghi, 2017) focused on investigating the microstructure of fiber glass bundles in direct sheet molding compound (D-SMC) through microscopy and micro-computed tomography. Analysis revealed bundle deformation patterns, with bundles at the part edge and corner showing more deformation. Mold filling simulations predicted fiber tow orientation. The research emphasized the impact of flow length on bundle orientation, highlighting the importance of understanding bundle behavior for designing complex parts in the compression molding process. Experimental samples show fiber bundles maintained cohesion through maturation and molding without breaking. Experimental validation of a model predicting compression forces for automotive hoods has been conducted, with ongoing research exploring the impact of filler content, reinforcement type, thickener content, and length on SMC material parameters. (Michael Rabinovich et al., 2008) demonstrate the benefits of using spiral flow testing to assess SMC processability. This method helps in evaluating flow length, glass-carrying capacity, and friction coefficients that impact molding forces and press size selection. The importance of glass content in influencing SMC flow behavior is also highlighted.

Fig. 16. Scheme of the BCSMCP process (Z. Wang, 2010), (Mehta et al., 2005).

3.2. Injection Molding Forming Injection molding forming for composite material refers to the manufacturing process where a composite material is shaped into a desired form using an injection molding machine. The process involves melting the polymer matrix material and injecting it into a mold cavity containing the reinforcing fibers or particles. Once the material cools and solidifies, the mold is opened, and the final composite part is ejected. This method is commonly used to produce high volume, complex-shaped parts with consistent quality and performance characteristics (Elkington et al., 2023; Y. Wang et al., 2010) (Hassan et al., 2003; Santos et al., 2007). Maleated polypropylene (MAPP) is commonly utilized to improve the compatibility between fibers and matrix in injection-molded plant fiber composites, particularly with