Effect of compaction rate during cyclic compaction on compaction response of vacuum infusion consumables

Compaction response is a critical property of Vacuum Infusion (VI) processes. However, common thickness measurement methods capture combined changes from both fabrics and consumables, complicating the isolation of fabrics’ compaction response. This study establishes a foundational baseline by characterizing the compaction response of consumables alone in Automatically Controlled Pressure Vacuum Infusion (ACPVI). Using a custom-built automated workstation with Linear Variable Differential Transformer (LVDT) thickness measurement (1μm resolution), pressure control (0.1 kPa resolution), and machine vision flow monitoring, dry consumables (vacuum bag, semi-permeable membrane, flow media, and peel ply) were subjected to 15 compaction cycles at either 2 kPa/s or 4 kPa/s. Following cyclic compaction, consumables were degassed for 20 min before silicone oil infusion at 49.5 kPa injection pressure, then underwent pressure equilibration for 20 min. Compaction pressure evolution followed an exponential saturation model with rate constants of 0.0881 ± 0.0018 s⁻¹ (2 kPa/s) and 0.1704 ± 0.0032 s⁻¹ (4 kPa/s). Consumables exhibited viscoelastic–plastic behavior, with compaction response normalizing after 10.0 ± 1.8 cycles, independent of compaction rate. Compaction rate did not significantly affect minimum compaction thickness or maximum relaxation thickness but did influence elastic deformation during compaction: the 4 kPa/s group exhibited 1.32 ± 0.06 times greater deformation than the 2 kPa/s group. Average infusion time was 31.8 ± 5.2 s, and average flow speed was 8.35 ± 1.10 mm/s. Thickness increased by 0.002 ± 0.001 mm at full infusion and by 0.001 ± 0.001 mm during pressure equilibration. This apparatus and methodology enable precise characterization of consumables’ compaction response, essential for decoupling fabric behavior in full layups.