Research progress on void formation, evolution, and control in liquid composite molding technology

Liquid composite molding (LCM) is a key technology achieving high-performance, low-cost manufacturing of composite structures for aircraft. Voids are the most significant defect in LCM components, and minimizing void defects and controlling their stability are crucial for the wide application of liquid molding in aircraft structures. This paper reviewed the research progress on void formation and control in LCM over the past decade. It primarily explored the current state of research in four areas: micro- and meso-geometry construction of preforms, multi-scale resin flow analysis, mechanisms of void formation and evolution, and strategies for controlling void defects. The review indicated that the internal geometry variability in dry fabrics and the parameters of the preforming process, as well as their mutual influences, lead to the spatial field distribution of preform permeability, resulting in randomness in resin flow and uncertainty in void defects. Based on this, a robust design process for LCM based on random resin flow analysis was summarized. Finally, to meet the needs of stable control of void defects, the paper anticipated developments in multi-scale stochastic flow modeling, algorithms, and process optimization.