Research on the Technology for Manufacturing Carbon Composite Casings for Small Solid-Propellant Rocket Motors

Abstract

The article is dedicated to the study of the manufacturing technology of carbon fiber-reinforced plastic (CFRP) casings for small-sized solid-propellant rocket motors. The primary focus is on selecting the optimal epoxy binder and technological parameters that ensure high mechanical performance of the composite material. Three epoxy systems were evaluated: "Epikote LR 285 + Epikure LH287", "Kumho KER-828 + ZT 143", and "ED-20 + Etal Inject". Optimal resin/hardener ratios were determined based on mechanical testing of samples in tension and bending. The best strength results ─ both for the pure binder (94 MPa) and the reinforced composite (1230 MPa in tension) ─ were achieved with the ED-20/Etal Inject B system at a 100/20 ratio. A manufacturing process was developed using filament winding of carbon roving impregnated with epoxy resin. The winding was performed with alternating fiber layup angles (0°, 45°, 90°) to ensure isotropic mechanical properties. The influence of winding angle and the mass fraction of carbon fiber in the composite (ranging from 50% to 70%) on strength was studied. The optimal result was obtained at 70% fiber content: 660 MPa in axial tension and 645 MPa in hoop tension. Carbon fiber-reinforced plastic casings with a wall thickness of 3 mm were manufactured and tested. Hydrostatic and hot-fire tests were conducted. At the motor's operating pressure of 33 bar, the casing demonstrated stable performance without failure. The results confirm the high strength and airtightness of the CFRP design, making this technology promising for use in small-scale rocket systems.