Current Applications and Advancements in the Manufacturing of Discontinuous Fiber Composites
摘要
Discontinuous fiber-reinforced composites (DFRCs) are gaining momentum as scalable, cost-effective alternatives to continuous fiber systems with advantages in automated processing, geometric flexibility, and material efficiency. This review critically evaluates four key DFRC manufacturing methods; compression molding, spray-up molding, injection molding, and additive manufacturing, focusing on how each influences fiber orientation, volume fraction, defect formation, and structural performance. Injection molding provides a robust combination of tensile and flexural performance. Compression molding, with its long fibers and dense consolidation, yields the highest absolute strengths, making it suited for critical structural applications. Additive manufacturing offers unmatched geometric flexibility and high throughput options but requires advances in bonding and alignment to close the performance gap. Spray-up molding is a low-cost, scalable route for large non-critical parts, though its mechanical consistency is inherently limited by manual fiber laydown and open-mold curing. Selecting the optimal DFRC process therefore depends on balancing required mechanical properties, part complexity, and production volume. Despite progress, critical limitations remain in the predictability and control of DFRC microstructures. These include the lack of in-situ sensing for fiber alignment, inadequate void prediction models, and the absence of validated simulation tools tailored for discontinuous systems. Addressing these challenges will require integration of robotic fiber placement, hybrid deposition-compression techniques, embedded sensing, and machine learning–based process control. Together, these innovations form the foundation for high-performance, fully automated DFRC manufacturing suitable for structural applications in aerospace, automotive, and consumer sectors.